Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65 bearings yet again...

A65 bearing and rod issues have been discussed over and over on here, and other forums, on club nights, garages and sheds, rallies, and so on.
Blood has been drawn! This is clearly no trivial matter!

From what we've seen on a few high mileage engines with dropping oil pressures, one bearing shell on the drive side has started deteriorating.
A friend is working on one such engine just now.
Just as per Tridentman's recent post actually.
As discussions do, the thread wandered off a bit, but to re-cap:

Are the drilled rods really prone to breaking from the oil hole? These are the steel cap type.
Will a plugged oil hole lead to untold damage to the cylinder and/or main bearing? Many seem to have done this with no issues.
Does the very minimal pressure drop from when the bearing passes over the oilway affect lubrication very much at all?
Are new bearing shells from say SRM better wearing than the white metal originals?

The engine in question has an SRM oil pump and OPRV, and is sound in every way except for that single bearing shell and a very lightly scored journal, which may be ground.
It's a road bike, sensibly used and in good shape over all.
I'm thinking that I'd use the engine with no further mods than uprated bearings, except maybe for peening the oil hole in the rod shut.

What do you, the A65 experts say?

SR

on alloy you will do damage to the grain structure of the material by peening the hole closed bad bad idea imo

the bsa engineers seemed to think the hole was a good idea....so do i

ive seen a few broken rods but dont believe they had anything to do with the hole

if you are a mathematical fellow do a calculation of the cross sectional area of the rod at the hole part them calculate the area of the hole and figure out what % of the area has been removed by the hole its minuscule

"Will a plugged oil hole lead to untold damage to the cylinder and/or main bearing?"
no. Not at all.
my bike ran for years with the drive side rod oil hole plugged, it didnt break, and it still has the same mains. Bore wear did happen, but not because of this, no air filters was the reason. This on an end fed crank 750.
The std set up with the Timing side bush is a different matter, as the bush wears the drive side big end is the first to suffer.

Thanks for the input!

Ignoramus, IMHO peening might even be a good thing, rolling over the edge of the hole and inducing compression in that area.
But your concern is a viable one and will be taken into the discussion. The tiny reduction in cross section is of no consequence, I agree.
There are other ways to plug the hole too of course.

Gavin, you, along with Mark Parker and others have had the same experience, and the mileage to back it up too.
If it was my engine I don't think I'd bother though, in a sound but standard engine, that is.
I can't imagine the minuscule squirt lasting a tiny fraction of a second 2 times per revolution would have any impact on the hydrodynamic wedge in the bearing.
I don't have numbers but the oil inside the crank cavity creates a lot more pressure from centrifugal forces than you see on the oil pressure gauge.
That is unless the cavity is less than full, which would happen with a poor pump, leaking OPRV, and worst of all a sloppy main bearing. Different scenario.
Kommando says the original bearings were white metal and not what he'd have specified for a relatively high powered engine.
I'm thinking modern bearings may make a big difference.

My friend the engine builder has done most of the A65 plain mains around here. He's adamant that with a decent oil pump and OPRV (he favors SRM) a standard engine will run forever.
He makes and line-reams the bearings himself, as well as grinding the journals.
"Forever" in this context would mean well over 100.000 km I guess.

like all good analogies/metaphors it was simply to illustrate a point Allan ......not to be dissected , i am well aware of why the hole is there but maintain that the BSA engineers who knew more about the matter than you or I put it there for a reason........what i fail to see is why anyone would blank it off ...and yes i am aware that the early ones didnt have it.

You may have noticed that I actually removed the post before you had placed yours. My point however wasn’t to nit pick what you wrote, it wasn’t a good metaphor at all and read the wrong way would give someone the wrong idea, but I don’t think you got my point. Most importantly the oil hole is only there to help spray oil up the cylinder, it has little bearing on the oil flow across the journal.

Allan : "t I don’t think you got my point. Most importantly the oil hole is only there to help spray oil up the cylinder"

i know that is why it is there .......and no i didnt see you remove your post

But in the interests of clarity i have also amended my comment

one poster has a tag line "there are no bosses in technical discussions" ...........i do like that one

What year engine? Before I make any more comment, that would be good to know

This whole thing has come up before. Popular theory , which is what I believe, you can take with a tiny pinch of salt if you want , is that early motors suffered due to random sparks from the 4 CA breaker systems, , in an attempt to solve the overheat and sometimes terminal engine failure caused by the random sparks, BSA increased the oil flow through the crank with the hole to help with cooling, it wasnt till the 6CA plate came in that the problem was cured directly. The hole was maybe a solution to a problem that was really a bad spark thing.

Gavin : "BSA increased the oil flow through the crank with the hole to help with cooling, "

exactly the point i was trying to make earlier regarding oil FLOW, however since my comment wasn't widely appreciated i removed it in the interest of harmony

The main bearing does not need much oil as its rolling element, the cylinder probably does not need the oil but you can give it extra oil without the hole'





The oil film thickness is the critical factor inside a plain bearing, the pressure inside this oil film is many times greater than the oil pressure shown on a gauge but not easily measured. The oil pressure gauge is just confirming your clearances are correct to give the right amount of oil for the oil film in the plain bearing to stay in place and not fail resulting in metal to metal contact and rapid wearing of the plain bearing. So its a proxy reading not a direct reading of what you need to know. What is more worrying about the hole in the drive side top shell is its location at the exact point the pressure from combustion is highest and the oil film needs to stay in place, it reduces the area of the oil film at exactly the wrong point and just this alone says it needs eliminating.



Yes they are, never fit Whitemetal, but for a road bike the SRM are overkill and the overlay layer wears out quicker than the Al/Sn alternatives, but if you use the Al/Sn then you also need to fit an oil filter in the return oil line.

The steel capped rods i've seen had no oil holes.
My own original '72 a65 has no oil holes in the ds rod. (from the factory)

The normal reason for the drive side big end bearing giving up is lack of
oil due to worn ts bush, this is normally due to no oil filter being fitted or
infrequent changes.
I've built a few over the years with various configs, the oil holes didn't seem
to give problems, if you don't want the oil hole , fit a blind shell that side.

From about 1992-2014 there were only aluminium tin shells available new.
All the tri-metal types were old stock and hard to find. Al-tin are fine.

Thanks to all!

It's a late engine, I believe the engine # started with GD, which would make it a 70 I think? I haven't seen the bike and I can't say if has a proper filter fitted.
The rods are steel capped but with holes. I talked to my friend on the phone yesterday (it's a senior thing, actually talking on the phone) and he had peened the holes shut.
I'm used to Triumphs who never bothered with oil spray holes that I know of, and cylinder lubrication has never been a problem. The A65 system appears largely identical.
The shells will be supplied by Classic Motorcycles, the best parts source in Scandinavia. What brand they are, and whether oil holes or blind remains to be seen.
Fot it's sins, I haven't seen a tendency on a Triumph crank to wear one set of shells faster than the other, or much at all, even if people sneer at its archaic oil pump.
A65 bearings seems to wear faster on the DS, and they do so for a reason. Not knowing these engines that well, I still have opinions though and I believe A65s were let down by poor oil pumps, leaky OPRVs, and white metal shells.
The shells on this engine bore evidence of plastic deformation. Why this happens sooner on the DS is the question. Could it be due to the spray hole, or is it an oil distribution thing in the crank? This particular engine has SRM pumps and OPRV but wasn't born with them, so the damage to the shells may have started earlier.

My opinions and thoughts are based on my association with people suffering A65s for decades, and on what I've found in magazines and on forums.
I do therefore realize my opinions to be of little value in this context, but if I was to embark on a project, these things are what I'd concentrate on.
I believe the A65 to be a sound design, let down by a few sub-standard components.
A friend (yes I have more than one!) has got a genuine Lightning Clubman buried deep in his garage, I may want to help him with that...

PS. Clarification; the TS rod has no holes, while the DS one has two.
Inspected the bearings today, and the shells are of the VP variety. The TS pair looks good for more miles while the DS big end journal is worn 2 thou.
Both shells looked much like the one in Tridentman's post.
The main bushing is a little sloppy as well, though the journal appears to have stood up well. It will ground for roundness and a bushing made to suit.

SR

These engines were all designed before the computer software for modelling oil film thickness was written. Once it was written and all the crank/bearing parameters entered then you could see where the issues were going to be and change the parameters to get equal flows and pressure at both big end journals. Even without this software the evidence on all the twin engines (BSA.Norton and Triumph) show the driveside to have greater wear issues than the timing side. The solution is to first either move the hole in the shell to the lower shell or eliminate it completely plus changing the relative sizes of the hole in the big end crank journals so the flow of oil into both big ends was equal. That would then leave you with the initial start whereby the oil will always get to the timing side first, so the driveside is always going to suffer from this issue, maybe a 10/50 instead of a 20/50 would work here. I certainly use a 10/60 fully synthetic in my Commando engine, the magnetic drain plug on all the previous 20/50 dino oils furred up every oil change but since going to the 10/60 there is no fur at all, is that due to the synthetic oil or the quicker flow on cold starts or both ? .

Perhaps one of the other factors causing plastic deformation is the temperature of the bearings.
As well as lubrication the oil serves the function of cooling the bearing.
I have never measured temperatures in the two (timing side and drive side) big end bearings but because the oil travels first to the timing side first then the drive side I would have thought that the drive side bearing sees higher temperatures and that this could cause more plastic deformation/deterioration of the bearing material?
Would very much welcome Kommandos comments on this--he is a bearing expert---I am just a simple thick heat transfer guy.

For Whitemetal at least, being a soft and also low melting point material, then a lower oil flow will cause it to deform from higher heat, but that could be due to the oil film collapsing and heat being generated from metal to metal contact. The whitemetal is so soft and compliant the steel crank journal will be untouched so no clues such as a blued crank to show which one is the cause.

Thanks for the info John!

I occasionally copy and paste technical info from this and other forums for my own "Book of Knowledge" I keep. Just random tech information about mainly bikes that I have accumulated for years. Recently, I have only been infrequently saving anything.


But, with all of the bearing info that has been shared, it was time to expand the book.

Thanks again!

It would seem that many little design and manufacturing errors sometimes stacked up against the poor A65.
To recapitulate a few counter measures:
Journals ground to spec.
Correct bearings used, no white metal. Correct shimming and line reaming is a given,
Steel cap rods, or custom ones, sans the oil hole.
Enlarge the journal oil ways on the DS a safe amount.
A decent, and tested, oil pump, and OPRV.
Use a good 10/60 synthetic oil for safer cold starts.
Add a good return filter.

How does that sound kommando?

Let me add one thing maybe not discussed often enough; don't lug these engines. It's a killer.

SR

Most definitely don't lug an A65! it kills them. They like to rev.

If that is a true 70 engine, it "should" have the revised drilling for the drain oil at the OPRV. Early engines used an angle drilling into the sump, late engine were a straight shot to the suction line from the sump to the return side of the pump. The casting was revised on the late cases to make it possible.

The angle drilling cases were all over the place on separation between OPRV drain and the pressure side from the pump. I have seen cases that have had 2 or less threads to make a seal. That is a pretty critical area to have minimal seal.

Late cases are better. But, what are they using for a seal between the OPRV and the cases? it should e a very thin washer (1/32", 0.8mm) if I remember right. Some gasket sets & replacement seals for the OPRV are 1/8" (3mm) or so. Not good, as it raises the OPRV too high and the pressure side can bleed into the drain side.

I actually prefer to lightly chamfer the mouth of the OPRV cavity and run a thin O-ring as the seal. Just make sure it doesn't bottom out in the cavity

Good info and something I didn’t know. Does this thickness washer apply to all engines?

The best fix for an A65 is an end fed crank, ball located , no thrust issues , more oil to big ends. Les Mason knew a thing or two Wonderful . and before you say plain bushes are OK look at the size of a BMW plain bush R series and compare to BSA. The thread that precedes just adds fuel to the fire.
buying a Devimead in 1981 has convinced me, apart from the end feed mods its BSA crank, rods , cams, pistons and ile pimp, YMMV. theres a good bike in there just waiting to get out.

The fuel fitting for a Holley carb uses a thin metal washer, and fits the OPRV.

Lets look at how the stock shystem might work , oil at pressure enters the timing side bearing, BSA provided a shelf on the crank side to prevent oil from this bearing spraying up the t/s of the the bore wall, no need for oil cooling to the bore here it would seem .

The crank is spinning at start up in a sump full of oil , throwing oil everywhere, .the cam bushes rely on this , and they dont wear out , significantly so that works OK.

oil in the crank centre passage that has made it past the timing side bush leak , goes to the timing side big end, some squirts out, whats left goes to the drive side, if theres a hole in the shell that lines up with the rod the oil pressure wedge has gone ,

at operational speeds there will be a general thick emulsion or miasma of combustion gases and oil concentrated on the timing side which gets 2/3 of the oil pumps output, 1/3 from the bush, 1/3 from the timing side big end , possibly why the drive side inlet cam is the first wear.

While all this sturm and drang is goin on the oil pump is doing its best to empty the sump, once it does , less oil is thrown around , the lack of oil scraper on the whipping flywheel encourages spray to the cams,
cool oil to the TS bush gets sliced by the crank spinning round then fed and warmed again before meeting the drive side big end.
Its only a wee oil pump. Look at any other oil pump from a bike bigger than a 500.
The moral of the story is , if you dont have a 4ca breaker plate fit your drive side big end shells so the hole is covered and live on, if you do have a 4ca plate it wont matter , your engine is going to fail soon , one way or another ( and, get an end fed crank , if you want to live happily ever after).

Edit, this is probably the third or forth i I have typed this sort of pro end feed prose, I cant stop myself, all the other end feed guys will be reading this and thinking smugly ,
yeah,
then all the timing side bush guys are goin
naw,
thats not strictly adequate, well neither is the stock bush set up, its pish. Yeah fit a filter , its still pish, try finding an original steel backed bush, maybe fit some " bronze". euch find a 10 dan machinist to hit that 0.0015 sweet spot. Sure every back yard cheap do it upper can do that.
re edit, this not aimed at you Stein, Im sure your guy goes up to eleven. just ranting.

Can't agree with a lot of your thoughts Gavin, the pump is not much smaller than a norton's.
There are hundreds of a65' +a50's out there that have standard bushes fitted.
Where the failing was mainly was no oil filter plus the majority of the bikes were sold in the 'states
where they were a cheap toy so little maintenance was done. Ball and roller races are ok with that
bush arrangements are not.
Whilst the end feed setup is a better idea many people don't like the use of a needle roller instead of
a proper roller bearing. I am not a fan of the use of the combination type bearing used by the main
converter of these motors. The actual load capability of the steel housed bush is greater than the needle race.
A lot of people don't like the idea of running a thin walled needle race in aluminium and say a steel sleeve should
be used. I'm not knocking it but the *** conversion is not the be all and end all of engineering in many people's
opinion. No circlip on the feed seal for instance. It was designed by Mr Mason as a compromise, BSA would
not change the casting to accommodate a ball or roller race.
The end feed setup is often used as compensation for people's inability to do the original job correctly.
I've done several over the years, indeed i have one on my bench at the moment with an end-fed A10 crank fitted
the main reasons i end fed/needle converted this one is that the customer was convinced it was better and the crank
main journal was stuffed anyway. I still don't use the combination needle race though.
The pump on a 650 triumph for instance is the same as it's 500 brother and the 750. Over the years they expanded
and if they were in production now they would probably have a deeper timing cover to accommodate the
2 inch bore piston pump further upgrades would require......
Dave Madigan came up with the best a65 oil pump solution i've ever seen but no-one was interested.
Much better than a reproduced identical aluminium gear pump.

I still say, put together properly with a good oil filter and standard bush these motors are good for over 50k miles.
That's all you could expect from any of it's cousins without a fairly major overhaul.

Good to hear ya Nick,
"The end feed setup is often used as compensation for people's inability to do the original job correctly."

Thats exactly where I fit in, some guy in a shed trying to keep his bike running. . Hard works no easy, and easy works hard to find.

I looked an an XR750 stlylee HD oil pimp the other day for a Buelll , it was like comparing a Hare to a Rabbits heart HD to BSA
the hD was twice as wide , twice as high. it cost two arms and a leg. add a zero to SRMS pump.

It's little more than a hobby for me Gavin, but i've got a couple of guys who can machine stuff well
and i have some experience with the a65's so as a combination it works. As long as blokes don't
want the engine in 20 minutes and can stand dealing with this obnoxious old ghit, i'll do 'em.

David's oil pump used the inner of a suzuki pump and was costed out at less than the *** one.
The relief side on the bike would have needed beefing up to cope as the pump was miles more efficient.
A bleed to the rockers etc. A proper job, not just a copy of the original.
I'm saying this in the hope that he will resurrect the project and start making 'em.

As for the HD pump, of course it's bigger, its American. Is it better though?????

A bigger pump would be the ticket, but ,its a tight space.
For me its been a lifetime, crashed my Tbolt in 79, had the devi ever since 81 , served me well, the t bolt had a fucked TS bush, still ran fine till the end. nobody cared about oil pressure back then, it either ran or it didnt.
I think what kills A65s is not running, cold starts, bad timing and museuming if thats a word, they need ridden to keep working.
And
Happy New Year,

Roughly what does it cost to have an end feed conversion done?
Not that I'm considering it on the current bike. I'd spend on a Newby belt drive first.

A better design may be the answer rather than a bigger pump.
David's device was driven at 50% engine speed rather than 33%. i think.
The rotors were of the Gerotor type rather than gears etc.
The pump doesn't have to be bigger to be far better. (don't just think American!)

Talk to EV Engineering if you're in the 'states.

About a grand for the end feed last time I looked UK, more like two once other stuff gets added.

, trying not to think Murkin, agreed something neater than a Buell pimp would be do able.

Blimey,,,,,,,,,,,,,,,,,,,,, i will have to revise my prices.
I'm still charging 500 Guineas. (mind you, i insist on the gold coins.)

I have never owned an A65, my list is based on general Brit Twins plus a few pointers from the A65 ie BSA/Vandervell's odd decision to use whitemetal.

The end feed option is attractive, it eliminates all the oil loss from the timing bush and redirects it to the big ends without needing an up-rated pump, but like the bush it replaces its at the margins of the design parameters unlike the full ball/roller bearings used on the Norton and Triumphs. Norton never used a timing bush, Triumphs did initially on the Unit 350/500 and took the derision to change it to a ball bearing 68/69, BSA did the same change on the Unit singles in 66 but never on the A65.

Rich B, thanks for the info on OPRV and oil-ways. This is a genuine 70 with the raised engine no pad with BSA embossed on it. I'll have a look when I pop in maybe later today.

I too think end feed and a rolling element bearing is better. Triumph and Norton rarely have these particular issues, except on the C-series Triumphs. They displayed some of the same problems with wear as the A65, but kept their ball bearing DS, so never had the axial play problems. As we know, Triumph still felt forced to to something about it.
However, the cost of such conversions is an obstacle for most owners, most of whom rides their P&J infrequently.
And yes I agree, that's a big factor too. "Museuming", I like it :-)
As a side comment; triples displays much of the same as the A65, though to a lesser degree. As we know, the crank is fed in the exact same way as the A65, only through two plain bearings. These are in my experience prone to premature wear too, but can be changed with the engine still in the frame. I did mine when I overhauled the top end. The bearing material was worn away completely.
Some say nitriding the journals will add life to both journal and bearing. I don't know. That's one for kommando I think.

Pump size... engineers knows the requirements and will size the pumps accordingly, with a reserve. The A65 wasn't the first plain bearing motor ever built and the knowledge were there, tables available and expertise to draw on. It's when the quality of the pumps, alignment of oil ways, well the precision of everything, deteriorates, the biggest oil pumps won't save an engine.
The central flywheel cranks will whip a bit, and worse with increasing speed. I think my friend (Chief Engineer by profession) may have a point when he says an A65 should run low compression pistons, be kept over 3000 rpm for proper oil flow, and under 5000 for longevity. But where's the fun in that?

Oils and filters are important. Most old bikes I know of seems to run on 20-50, as I indeed use to recommend.
Like kommando, I did run my Trident on 10-60 synth until it burned it off so quick I couldn't afford it.
I will revert to this know that I have normal oil consumption, in the light of kommando's experience. If I ran an A65 I'd seriously consider the same.
"Museuming" will eventually let the oil film dry up and oxidize, which is a bad thing. Except for the fact that an A65, or most Brit bikes in fact, will fill their cases with oil, which is good for the crank, less so for the cylinders and top end. Wear will happen, and steel fragments will contaminate the oil, so a proper oil filtering system is vital. Many hold the opinion that frequent oil changes will suffice. On a frequently used bike, maybe, but why not use a proper filtration system anyway.

I've learnt a lot from you guys. Thanks to each and everyone of you!

SR

PS. kommando replied as I was writing that. Thanks! Which 10-60 oil is it you use?

This is the one, not checked the zinc content for camshaft/follower protection but you can get that separately to add if required.

http://www.millersoils.co.uk/products/0/142

CFS 10W60



As long as the shell bearings last or you catch their failure early then the crank journal life will typically be doubled.

Thanks again kommando.

I'm not worried over ZDDP content. Only low friction, fuel saving, catalytic converter friendly types of 0-30 or less do have a lower content, around 800 ppm I believe.
Thicker oils, like 15-40 and up still contain anywhere from 1000 to 1200 ppm. Over 1200 isn't advisable, and I would never add ZDDP to any oil unless I knew the exact specs of both oil and additive.
I know it has been discussed at length on AccessNorton, along with scar tests and such, you may have followed this closer than I did. I don't regard scar tests on motor oils as relevant though, it's like testing a mouse trap with an elephant.

I'm sure the CFS 10W60 vastly exceeds any requirements a sound old Brit Bike would have. I don't know of any stockists around here, but I'll have a look.

SR

The triple does not have the oil feed problem of the A65 because it has a four bearing crank. An A65 crank whips from the offset weight in the middle with bearings spaced far apart on either side. The whipping tilts the crank in the bearing which makes supporting the oil film across the bearing near impossible.
Alternatives are moving the counterbalance to the outer webs where the bearings are or support the crank in the middle. End feeding the crank and using a needle bearing is a half way measure. NTN gives an inclination tolerance of 1/2000 for a radial needle bearing (pg A39 http://www.ntnamericas.com/en/websi...edle_roller_bearings_2300-vii_lowres.pdf). That is 0.0005" for a 1" bearing.
The stock setup would last longer with more oil to compensate for the loss.
According to a GM study on main bearing caps, the main cap shells should not be grooved. There is an increase in the load per area across the two shell lands compared to a ungrooved shell. No [***] Ollie. There is less surface area with a groove on same width bearings. But oil has to be fed into the crank and having half the feed time closed off disrupts the flow to the rods. Maybe GM did not take that aspect into account.

Seem to remember seeing some main bearings with grooves on the back, this allowed the oil to still flow to big ends but stay full width bearing material.

So all the best advice for running an a65 comes from people who've never owned or run one eh?
You lot should go into politics.

Sorry chaps but that's how it's looking.

.
what every a65 really needs is
oil dippers on the rod caps .
.

Another highly experienced A65 owner i suppose????
We've heard 'em all me old cock. Like the ones from the blokes that finished behind me on the the track, and there were plenty of them.
Besides that the lower end modifications required to fit scoops and babbitts on these is harder than an end feed.

There’s a lot of mention about poor oil flow to the drive side journal because of oil holes etc but no one has yet mentioned the sludge trap that gets plugged restricting oil flow to the drive side journal.

NickL, I don't run the washing machine, tumble dryer or the dishwasher in the house, do you think I can get out of repairing them using that excuse

Fresh perspective and all that...?

David Madigan's info on grooved bearings is interesting, and we triple owners have looked at the main shells many a time wishing we could dispense with the groove.
But we can't..
On an A65 however, converting to end feed would let you run without the groove, and is something we have discussed.

SR

There's a groove on the A65 con rod bearing? Where?

No there is no groove, the groove was referred to in context of the Triumph/BSA triple engine has main bearings and they have grooves.





The grooves are to allow the oil to move from the oilways in the crankcase into the crank and then into the big ends through oil galleys drilled into the crank.

Stein Roger, as you probably know there are some that has converted a65 to end feed plain bearing using a needle bearing innerring. This way you will get rid of the groove in the shaft and possibly get approx 1/5 more bearing areal. The Guzzi 850 motor has almost identical dimensions (only a few mm longer) as the a65 on the main bearing where the oil is entering and the same groove in the shaft. Never heard of problems with the Guzzis with its short and sturdy crank, so the flexing and oil supply in the a65 is surely to blame.
In my end feed conversioned cranks I use needle bearing NKS 40 (40x55x22 which sits in a thin wall steel sleeve machined into the c.case) with innerring 32x40 which works excellent being the biggest bearing that can be put in there without breaking into the oil channels. A bearing outside the alternator is of course needed for locating the crank axially.

Sorry Nick, I was comparing the triple mains and the A65 TS main, but kommando covered that.

David Madigan's comment is valid, the triple crank doesn't whip, but the triples still run their plain mains faster than you'd expect. Something is borderline here, whether it's the bearing line, assembly technique, lubrication, or what have you. It's not uncommon to see worn mains while the big end journals measure up fine. Hence the comparison with the A65 TS main.

I'll be fitting a gauge to my Trident to monitor wear, and maybe change to Millers oil. I've had a look at the type kommando use, it'a a blend of 3 esters and PAO.
This makes it a "true" synthetic, unlike Castrol. Nothing against Castrol, they have served me well, but perhaps the extra protection possibly offered by a true synthetic is just what it takes.
ZDDP is in the 1000-1200 ppm range, which is nice for cams and followers.

I've made contact with a local supplier of Millers, and he seems to know his stuff. Replying to queries on the weekend suggests he's a gearhead too...

But I've side railed myself. Fixing the underlying causes of premature wear and failures is most important, and I thank you all for your input!
I concede that those of you that have actually made these things last, and have proved it too, are the ones I listen the most to.
Like you NickL, you puffed a little back there, but I do take your comments to heart, also in the recent axial play thread!

SR

Arnstein, no I didn't know how you did the end feed conversion, but it makes perfect sense. I had forgotten that on an A65 the groove is in the journal, on a C series 500 Triumph the journal is plain and the bearing is grooved. Same results though.
I did know about the outrigger bearing you use on the DS, but it takes it all to a level I'm not even close to, I'm not a toolmaker... My friend the Chief could do it, but I don't think he's interested.
On a standard engine, would you consider a ball bearing to be strong enough on the DS?

SR

I think maybe the simplest / cheapest way to make the A65 more dependable regarding crank bearings would be ,as said, to use an innerring (with lubrication holes) meant for needlebearing on the t s together with the original type of steel capped bush and then end feed the crank the easiest way https://1drv.ms/u/s!AsKcYdC1qRK7jQjhEcOLyG9e3Q4n?e=seGmG1
Or, for to avoid bearing outside alternator, do as SRM does and machine in the combination bearing NKIB 5907. I never used the C3 type only the ordinary one but with a retaining ring and the usual interference fit.

Thanks for the pic, neat installation which avoids all the welding and drilling other people seem to do.

SR

Not to diverge from the A65 issue but the high wear rate of triple mains is likely from assembly. Assuming the crank mains have been measured and in line, the centre mains are aligned with the end roller and ball bearings with two dowels on each side. If these dowels were a precision fit it would be difficult to mount the cases together since they would have to be dead square to go together. The mains clearance is 0.0005" - 0.002" which is probably the clearance of the dowels in the case. The only way to get close to alignment is to mount a flat plate across the cylinder joint and tighten it along with the case bolts. That only aligns the vertical misalignment. There is nothing to correct the horizontal except the crank.

Yes I think you're right. It's definitely not the best design possible, and easy to screw up. It requires fitting skills rather than assembly skills, which is doomed to fail on an assembly line.
I have my thoughts on thermal expansion as well, the center section may possibly grow faster as it heats up, pushing the mains up and out of center. But that's purely speculation.
I always take care to warm the engine up good before gunning it. As I do with any engine, but some engines are more sensitive, like the A65 for example.

SR

DS ball bearing was used with success by one of Marcs on this forum, now is used by Allan Gill ( if my memory serves me right ) and I'm building another one. My former A65 was used with stock arrangement of bearing for 10 years and perhaps 25000 km with not a hiccup and is used by the new owner in Calgary, who called me last summer to tell me how happy he is with the bike working still like it should.
So even with stock configuration, but regularly maintained these bikes are reliable as regular street bikes.
Only improvements made to this engine were iron oil pump, charging system with solid state reg/rec, oil filter in return line and Boyer ignition. Timing side bush was solid bronze and I believe installed without line boring, but giving good pressure ( no flickering light on idle on hot engine ).
And because of changing its cylinder head to small port version I was able to take it above 7k revs on lower gears more than couple times, closing a tacho ones on third for a second. So yes this bike was ridden quite hard and survived it.
I write all this to say - don't overthink it, I found a Trident much more difficult and fragile bike comparing to old trusty A65.

I'm only having a laugh, same with Stein Roger.

It's just that over the years i've heard so much stuff about how crap the A65 bottom end is and how they all fail.
I raced a standard 650 and 750 converted bog standard bottom end sidecar for 2 years without touching the bottom end
on an A65. In fact i sold the engine to another bloke who raced it too. That was in a sidecar outfit and was used to 8000rpm
regularly. (I won't mention the transmission and other problems though) Incidentally, we used standard gtx 20/50 oil in that motor.
Yes, when i went to a big motor i end fed it etc but the standard setup on a road bike is adequate. (I feel i've proved that!)
It's interesting also that in the 2 years i raced the bike as a morgo triumph, i broke 3 cranks. It made me feel the A65 was
a far stronger motor overall. (and leaked a lot less oil.)
What sort of mileage do you blokes expect from an engine used normally on the road as a classic? I don't expect more than
30k before a rebuild is required. If you cannot put an A65 bottom end together in standard form that will last 30k, i suggest you
either take it to someone who can or buy a triumph. My road A65T is certainly ridden as hard as my T120 is.
Arnstein's hot-rod is a different case, more engineering effort needs to be put into motors like that, and he certainly has done that.

NickL OK, an A65 put together right will stand up to racing use and abuse. At least yours did, but it does come down to skilled assembly doesn't it.
The crank held together better than on a Triumph, well with the bigger big ends and shorter stroke, perhaps it should.

Conclusion after this discussion, other forums and articles, talking to people, is that if I were to build an A65 for myself, I'd let the Chief do the bushing, and consider a ball bearing on the DS.
I'd use a tested and certified oil pump and OPRV and perhaps have the crank dynamically balanced. I'd keep the engine otherwise standard.
An OIF A65 won the Classic Cup in Scandinavia years ago, not by being the fastest, but fast enough and always finish.
When I him asked about "the secret" the guy grinned: "it's completely standard, I'm just in it to have a bit of fun".

I have no desire to super tune or big bore an A65, I'll leave that to others. The likes of Mark Parker and Arnstein have proved what's possible, kudos to them.

Thanks again to all.

SR

NickL, you missed the wink on the end of my comment, I was adding on a twist.

i was serious about the oil dippers .
the a65 was so close to being a viable engine .
being only sixteen when BSA went out of business
they no doubt had there own reasons
for not answering my emails

Question: Why did BSA change the d s ballbearing to a much more expensive set up with a roller bearing? Because of the roller bearings better load capacity or did they want to spend more money on the A65 without reason?

The roller is better but only you and a handful of others need the extra load capacity. The rest are taken to a rally or two in mid summer by riders who never see the north side of 4000 rpm...

SR

I'm doing mine with a roller for both of those reasons. But seriously, I needed a new bearing and the roller just looked so much better.

I recall reading John Healy say something about the switch being due to factory reorganizing and roller bearings being available on the shelf. Something like that.
In other words, I think he implied that it was a practical or economic reason rather than a quality one.
If that is so, they sure went to a lot of trouble remachining the case and changing the crankshaft size to accomodate it.
I'l search for it if John doesn't happen to post on it again.

Hardly, Ive had RHP rollers that are loose on the drive shaft after 3000 miles, the RHP ball bearing I have fitted currently is so far is outlasting that. Not saying that the ball is better than the roller but more likely the bearing not made to suitable specification.

I strongly agree that they didn't change to a roller for no reason, however this came at a point where they were also drilling holes in conrods to fix a different problem. As the A10 had roller bearings fitted albeit of a different size (the ID of the A10 roller is much larger than the A65) Im not sure of the OD of that bearing compared though. They knew the A10's didn't have these problems so likely switched back to what they knew worked.


....Just as assumption, I've known several people who use a ball bearing drive side on a 650 without problems. It probably wouldn't hold up to 750cc+ and probably wouldn't last for those people lugging their motor in a high gear.

The bearing for ball and roller has the same ID/OD and width of the inner and outer race's as each other, changing bearing type isn't a problem in this instance.

True but at the time of the bearing change a thrust washer was added, and changes to the crankcase, timing bush, crankshaft counterweight, to account for the roller end float. There is that problem.

It depends on the full question or the follow up question. If your using a late set of cases then either bearing will fit with no modification.

If your using it on a early set of cases then your story is different. I haven’t dealt with an early set of cases so I’m not qualified to give opinion, but from what I have seen of the TS Bush, the “thrust face” is steel? You would probably have to make an all bronze Bush thus having a bronze thrust face.... Maybe....

But as I say the bearing size wise isn’t a problem.

It is not a good idea to control end float with a roller bearing, the ends of the rollers will be trying to drill themselves into the lip

Information given by INA says that their roller bearings series SL and SL01 are made for to take axial loadings as well as radial.

Ahhh,, you got me there.....................................

(Quote) "Hardly, Ive had RHP rollers that are loose on the drive shaft after 3000 miles, the RHP ball bearing I have fitted currently is so far is outlasting that. Not saying that the ball is better than the roller but more likely the bearing not made to suitable specification."[/quote]



Mr. Gill, are you saying that the rollerbearing came loose on the shaft because it is a roller...and that a ballbearing will not?! To be sure any bearing, roller or ball, not getting loose on a shaft an interference fit is needed, and sometimes a torqued nut, as on A65,

And, as fa as I know the early ballbearing motors did no have any thrust washer. because of the ballbearing it is of course not needed.

A good point is also that they were using the same roller bearing in large numbers in the triumph factory as well.
The simple way would have been to have just converted to a double lipped roller that size, if they thought just the
higher load capacity was needed, they changed several things at that time including the crank dimensions and
case castings. It's likely there were other factors behind it as well.

Hey Stein, as for the skilled assembly of an a65 being so critical, i have no mechanical engineering qualifications at all,
the a65 motor we built in 1991 for the outfit was the first a65 engine i had ever seen inside. I bought a set of brand new
unstamped cases complete with main bush and started there. It just went downhill ever since.....................

That’s not what I said, I didn’t say the bearing id became slack because it’s a roller. What I said was it is probably the quality of the inner cage. What I was pointing out is that the ball bearing is perfectly fine, it probably wouldn’t last in your 800/850 motor and I wouldn’t use a ball bearing on my 823 either. There is also no chance the nut came loose on the end of my crank, but thank you for your suggestion.

I had seen a wrongly pictured item for the TS bush, it was probably off an A10 maybe? It appears to have the same cutaways as the later bushes do, looking at the parts books. Still a ball bearing can walk if there is too much end float. You set the end float of the crank against that Bush face and the ball bearing won’t walk. The oil film is probably just enough in this case, unlike the roller where it will constantly kiss the thrust washer or the lip of the outer cage.

Maybe one of the reasons for going away from the ball race and including a ts thrust was that
when the engine is hot, the tendency for the thrust from the oil pump was pulling the drive side
bearing from it's housing.and allowing the crank to move over to the timing side. The natural
thrust of these engines is definitely toward the worm driven oil pump.

"The natural thrust of these engines is definitely toward the worm driven oil pump" - maybe a case for a spur gear drive oil pump?
Metric roller bearings are available with a separate thrust collar which serves as a second lip on the inner race. Since the single lip on the inner race already provides for the thrust in the drive direction I do not see why the inner race cannot be reversed (lip toward crank) and a thrust collar used on the sprocket side to have the roller bearing take both thrust loads. Solve the whole problem of shimming the crank just as the ball bearing did.
I do not know of any manufacturer that makes them for imperial bearings but it would not be difficult.
One advantage of the Triumph wheeze pump on the camshaft is that it removes any loads on the crank or flex effects on the pump.

My drive side crank shaft wore where the bearing seats, SRM sleeved it back to size. it had a roller, still does.
my crank had run with a slack rotor nut, maybe that did it.

Doesn't the A65 have a similar breather set up on the end of the cam?