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#838503 01/30/21 8:27 am
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I've been experiencing some difficulty lately with finding a shop that I trust to line ream the timing side bush on a "70 Lightning. This has got me to considering possible alternatives, to wit: adjustable reamers with pilots.

It appears that a suitably sized reamer is available to cover the necessary dimensions, this journal is on the 2nd regrind. Since I don't have any experience with these type reamers I'm hesitant to jump right in without first seeking some advise/insight from someone who may have already been there.

Questions arise such as:
1) if set up with a mic, will they (adj. reamers) hold true when used for fairly precision jobs like the timing side bush?

2) If a suitable "donut" is machined to fill the roller bearing outer race on the drive side (or perhaps use the roller bearing inner race
itself) to act as an end point for a pilot, can the bush then be hand reamed to the appropriate dimension with any expectation of
required accuracy?

Seems feasible but then again theory and reality often clash.

This bike had oil pressure problems ( unheard of regarding A65"s grin ) and after exhaustive efforts with OPRV's (both types), various oil weights, gauge readout locations, etc. a final teardown revealed uneven wear in the bush (approximately 80 mi on the engine). Bad job on the original line bore...?
Crankshaft possibly tweaked and wobbling....? Questions, Questions.
Any thoughts or information regarding the above are highly appreciated.

Thanks,
Phil

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If it’s worn out after 80 miles I’d be wondering if there was enough flow from the pump? Is there any discolouration to the crank? Blueing?


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Quote
1) if set up with a mic, will they (adj. reamers) hold true when used for fairly precision jobs like the timing side bush?

No, adjustable reamers tend to cut tapered holes and with what in the UK is called threepenny holes, ie like a hexagon.

Send your cases to someone who knows what they are doing.

Such as Site Sponsor EdV

https://www.shopevengineering.com/

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Have a look at this YouTube video - Here which shows one way to line bore the timing side bush.

Note that careful measurements are made with the cases assembled to check the drive side housing is Concentric, then the drive side is removed and the timing side is also checked for concentricity.

By using a mill with the cases bolted down the result should be that the timing side bush is perfectly Concentric with the drive side once bored.

There are other ways to do this but using a solid mill seems best.


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With care, the bushing can be sized with a sharp reamer and a proper alignment bushing


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I think that CBS were selling piloted reamers for Triumph cam bushes, Maybe they have the same for a Lightning.
If you are in So Cal, I think they are in San Diego.

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Originally Posted by S-NJ-W
I think that CBS were selling piloted reamers for Triumph cam bushes, Maybe they have the same for a Lightning.
If you are in So Cal, I think they are in San Diego.

I think the Ts bush is a little more tricky than a cam bush. Reaming the A65 cam bushes aren’t too tricky.


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Sorry, misread the original post. Gunner has it right.

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It seems the timing side bush will always be the Achilles Heel of of the A65.
When done right, with precision (& a certain amount of plain luck) they can, and often do, hold up very well.
However, when things aren't "just right".....well...hello low oil pressure.

For the amount of miles I tend to put on my rider every year, I always considered the bush to be more than adequate. The needle/roller conversion is certainly
a good way to go, I just never considered it totally necessary. BUT that was before finding experienced machining services for things such as "line bores"
started to become a problem. Right now I believe Ed V is the only shop ( in the U.S.) that's doing the bearing conversion. I spoke with Ed a couple months ago and he indicated he had roughly a one year back log of engines waiting for that treatment. So it would be a case of getting in line....of course Ed may be able to do a line bore considerably quicker.

The '70 engine I've referenced is not from my rider. The bush in my rider was done back in the Nineties by a very experienced automotive machinist who has long since retired....never had a lick of trouble with it. I will add this caveat however: my rider has a "66 engine, so no oil gauge port. To paraphrase something I read early on in my A65 education: "Want to make yourself crazy? Start monitoring your A65 oil pressure." This '70 engine has so far proven the validity of that statement!

Thanks for the replies and input gents, very much appreciated.
Thanks also for that video Gunner....good stuff.

Phil

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Best done on a mill, not that difficult but you should clock up from the parting face
and the drive side bearing..

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If your journal was worn out after only 80 miles I would check the oil pump especially as its a 66 engine.

The A65 oil pumps evolved over the years becoming better each time, see THis link for a history of the pump.

Hopefully you have one of the DD or iron pumps fitted, if not I would buy the SRM or new Hepolite pump.

Also worth reading the installation tips on the E&V engineering site Here. Ed suggests fitting the pump and spinning it over with a cordless drill attached to the tacho drive with a rubber pipe. With oil feed connected and pump spinning it should be possible to hear pressure build up and the OPRV blow off, there may be some leaks visible around the pump.


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Originally Posted by gunner
Have a look at this YouTube video - Here which shows one way to line bore the timing side bush.

Note that careful measurements are made with the cases assembled to check the drive side housing is Concentric, then the drive side is removed and the timing side is also checked for concentricity.

By using a mill with the cases bolted down the result should be that the timing side bush is perfectly Concentric with the drive side once bored.

There are other ways to do this but using a solid mill seems best.

Yes that is the right way as long as you are completely confident that the split face and the outer face are dead parallel ....by the look of the gear the guy in the vid has i would say he didnt miss that point.

However the question i ask is "is it necessary and why is it necessary? "

back in the day all you did was get an undersize bush and grind the crank to specified sizes and shove the new bush in and guess what it worked.

The internet has turned this whole thing into some kind of back art!

People go on incessantly about "line boring or align reaming" which by the way are totally different operations, and few seem to be able to explain what they involve, For those who think u can support a reamer from the ball/roller bearing and it will magically make the reamer line up the bush , you cant! ...if you don't believe me just put the crank into the bearing and see how much lateral movement there is over that distance, A reamer will follow the hole , the only way to make a hole "shift over a bit" is with a single point cutter ..

it is only necessary to do the milling thing as per vid if the bush hole has become oval or hammered out of round or if the cases have slightly warped by 50 years of hot cold cycles , but generally they haven't perceivably "shifted" ....other that that , well ya know.... racing guys shouldnt bother cause they are going to blow the things up any how ,

Example:

I dropped a rod on my A10 on the timing side it blew that side of the case to bits, i didnt lose my case numbers a VERY GOOD THING!

MAN did the experts in the club have a fielded telling me what i had to do if (as i did) i got a half case ( obviously from another motor) and fitted that . you MUST GET IT LINE BORED ETC .........i told them i would if it was necessary . IT wasnt! ....i made a new bushing to match the crank (which unbelievably was still ok) and with a bit of careful hand fitting reassembled it ........the bottom end is perfect. 5k miles and counting

I did not spend thousands and wait 6 month for some prema donna to do it.

man that ecercise shut a few mouths, fact is BSA did a very good job on making therir cases uniform and doweling insures alignment




but having said all that i would advise someone who isnt an engineer to just go with the latest trend and get it done , finding someone will be the hard part as will paying for it , doing that sort of work takes skill and a lot of gear and i dont grudge what they charge for a second ...its the lengly wait i object to.and if you get a comedian they will stuff it up big time

Just saying ....but ive only been a fitter turner for 40 years so what would i know?

now i will sit back and wait to be howled down hahhaha ive got sore figures after that lengthily post with probably no one will read anyhow ROFLMFAO


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You got lucky and I didn't, so the engine bottom is back with machinist for line boring this time.

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Originally Posted by Ignoramus
For those who think u can support a reamer from the ball/roller bearing and it will magically make the reamer line up the bush , you cant! ...if you don't believe me just put the crank into the bearing and see how much lateral movement there is over that distance, A reamer will follow the hole

you don't use the bearing on the drive side to guide the reamer, you use the bearing race, which is held tight in the case and cannot move. Turn a bush to fit tight in that race with a Concentric bore to fit the reamer pilot and how can it be out of alignment?


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Whilst i agree to a point my main objection to 'just fitting another t/s bearing' is that
yo only get two undersizes and very often the crank only needs a couple of thou to
bring it back to round. Re-lining the steel backed bush is the best way but takes a while.
I tend to agree about the line boring with the proviso that the bush housing has not
been flogged as they very often are after running with a knackered bush for a long
while.
As the 2 case halves have only a single dowel it's normally possible to move them
around anyway so the bearing alignment is never that brilliant. Plus, as you bolt
the barrel down, unless the faces are spot on (which they seldom are) that will move
things as well. This is the case on lots of makes not just beezer. As an example i've just
put a replacement cam in an a65, you couldn't turn it without the cases being bolted
together all round and the barrel nipped down. Once done, it turns beautifully. The
crank has a needle race main so that ran nicely anyway.
Don't rely on the timing side area being flat or true, the parting faces are the ones to work from.
The cases move around all over the show as they heat up and cool down anyway.

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Originally Posted by Adam M.
You got lucky and I didn't, so the engine bottom is back with machinist for line boring this time.

It had nothing to do with "luck" what it had to do with is that I worked in the engineering trade for 40 years and was able to access if doing what i did was the right way to go.

Originally Posted by Thunderlizard
Originally Posted by Ignoramus
For those who think u can support a reamer from the ball/roller bearing and it will magically make the reamer line up the bush , you cant! ...if you don't believe me just put the crank into the bearing and see how much lateral movement there is over that distance, A reamer will follow the hole

you don't use the bearing on the drive side to guide the reamer, you use the bearing race, which is held tight in the case and cannot move. Turn a bush to fit tight in that race with a concentric bore to fit the reamer pilot and how can it be out of alignment?


pretty simple , a reamer taking out only a few thou will follow the hole that is there , a reamer wont just take a whisker off one side of a hole , thats how it works in practice anyway., that is why i said that if it needs more removing from one side of the bush than the other you have to use a single point cutter as the guy in the video did

Originally Posted by NickL
Whilst i agree to a point my main objection to 'just fitting another t/s bearing' is that
yo only get two undersizes and very often the crank only needs a couple of thou to
bring it back to round. Re-lining the steel backed bush is the best way but takes a while.
I tend to agree about the line boring with the proviso that the bush housing has not
been flogged as they very often are after running with a knackered bush for a long
while.
y.


Yes i should have said thats what i did ....relined a steel housing ...making sure obviously that it was a good one and only gave the new bush sufficient interference to not "grow the od " there fore make it too tight in the case . I left a few tenths on the id to give a bit to hand finish to give the desired clearance ........ from faltering memory i think i gave it 8 or 9 tenths clearance maybe a whisker more all i know is that there were no sparklies in the oil after a 100 miles or so , but remember we are talking A10 with a smaller diameter bush ID than the A65

Material choice is also pretty important to make a new lining

and yeah always take as little off the crank as you can to just clean up and make new bush to suit .......i know its not like back in the day where you could just go get an undersize bush off the shelf THEN try to find a machinist to grind the crank to the factory specified sizes specified sizes

But honestly there is so much rubbish talked on the internet about the necessary engineering required , most of it from those who have zero understanding of the trade

and yeah making sure barrels sit flat is pretty much a given ...

many so called tradesman engineers theses days cant even read a mic (unless its digital) even then they think its a precision G clamp no feel at all just from what ive seen let alone hit a size within only a few tenths on a grinder


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Many different ways to skin a cat

On my 350 motors, I made a custom pilot that takes place of the ball bearing and used a shell reamer to ream the crank bush

I also mounted my TS crankcase on my milling table and bored the crank bush inline with the opposite side

Keep your options open


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Originally Posted by C.B.S
Many different ways to skin a cat

On my 350 motors, I made a custom pilot that takes place of the ball bearing and used a shell reamer to ream the crank bush

I also mounted my TS crankcase on my milling table and bored the crank bush inline with the opposite side

Keep your options open


I must admit that with a properly supported SHELL reamer you would be in with a chance on a soft material like bronze . I maintain however that with one of those adjustable ones with the long blades or a standard length machine reamer no way .

here's the thing , you have to have some clearance between the pilot end and the bush , Even at at absolute minimum sliding fit clearance on something only maybe 3/4 long you will still get lateral movement over the length of the crank . Unless you make your custom support collar dam near as long as the crank in which case it will likley tip in the bearing housing when it is force to cut unevenly

Buy the time you have done all that it would have been quicker to do it on a mill , i maintain that the only way to cut off center on an existing hole is with a single point cutter

IF you are doing many cases probably making some custom fixture is an ok compromise using a shell reamer OR an adapted "David Brown" style adjustable reamer (not the floating blade type those will DEFINITATLEY just follow the hole no question at all ) the ones where you adjust them with a grub screw in the point with split blades that can move a few thou ,,, i used those extensively and man you sure can get accuracy with them and they repeat! but how many machine shops will have or make the required special support fixture without charging 1000s ? Most machine shops dont even know what a "David Brown" reamer is !

Just out of interest , shell reamers arnt adjustable ( unless its a terminology thing and what you mean by shell reamer isnt what i understand them to be ) so how do you use them for more that one size ? unless you have like 400 of them all made to specific sizes?


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I think rigidity is everything

The pilot I am using covers a good part of the shank

Honed to approx .0005" working clearance

The shell reamer arbor has a tapered end and key, with only removing approx .002-.003" off the ID I don't see any reason of how my set-up would follow an existing hole

If you look at the original Triumph 350 / 500 arbor, you will see they locate off the ball bearing from the opposite side of the case (timing side through the drive side)

Now talk about lateral movement...

My cutting reamer is a specific size, then I have the crank from standard ground down -.001" from the I.D. of the bushing once done

Talking about 350 / 500 motors BTW

Last edited by C.B.S; 02/01/21 6:08 pm.

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Originally Posted by C.B.S
I think rigidity is everything

The pilot I am using covers a good part of the shank

Honed to approx .0005" working clearance

The shell reamer arbor has a tapered end and key, with only removing approx .002-.003" off the ID I don't see any reason of how my set-up would follow an existing hole

If you look at the original Triumph 350 / 500 arbor, you will see they locate off the ball bearing from the opposite side of the case (timing side through the drive side)

Now talk about lateral movement...

My cutting reamer is a specific size, then I have the crank from standard ground down -.001" from the I.D. of the bushing once done

Talking about 350 / 500 motors BTW


my x used to say that about rigidity being important, perhaps thats why she is my x

Yep as per my previous post "damm near as long as the crank " for the pilot .........obviously u are set up to do many of them ....i was more talking about the engine rebuilder down the road who wont have specialized gear as u do so will just feed the unfortunate customer a whole load of BS about how they will do it


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Just curious, have you tried using an expandable reamer on a BSA timing side bush? have you watched someone else try it? or are you speculating that it won't work?


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There are many A50 / A65's on the road today, and many built as we type / read this

Surely, there are more than 1 way to do the job, or at least how I look at it

I saw the comment about an expanding reamer

With a 6 flute adjustable reamer, I do not see any issue, just making sure its rigid and inline

Reamers can be tricky, take small cuts and measure as you go


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I have tried the reamer solution. I bought a piloted adjustable reamer (size K IIRC), made a target piece to accept the pilot, and then tried it. It was very hard to start reaming and impossible to do it without chatter & grooves. So I decided that I'd bought a crappy reamer & bought a better one. The results were still very poor.

After months of wasting time (& ruining bushings) I decided to learn to do it on my buddy's mill. Once I figured out the setup & oversized a few bushings, I find that it's a 1 hour job to size the bush just like Ade in the youtube video. Doing it without a DRO would not be much fun.

I'm just too impatient and am done with trying to ream a timing side bush. Milling is easier and you'll learn if you timing side is Concentric to the drive side.


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Originally Posted by Thunderlizard
Just curious, have you tried using an expandable reamer on a BSA timing side bush? have you watched someone else try it? or are you speculating that it won't work?

nah im just speculating based on 40 years as a fitter and turner .........but way back in the dim distant past i did take one to an engine rebuilder ...he totally stuffed it up using an adjustable reamer ...exactly as Ray Elliott ha described above

he then proceeded to go round the open end of the bush and bash in some center punch marks to make it seem like an ok fit ......then when i inquired regarding the appropriateness of this "remedy " he said "oh well its only a motorbike" ....the id was chattered and oversize . What an expert , then he wondered why i wasnt so keen on paying him.......gee i dont know perhaps i was just being churlish

funny thing is this guy had a good reputation so he must (or his 1st year apprentice must have) been having a bad day


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Interesting examples but neither one sounds like the reamer was the problem


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