Britbike forum

Classic British Spares Klempf British PartsBaxter Cycle BritBike Sponsor SteadfastCyclesSRM Engineering Lucas Classic Motorcycle Industrial tec supply Hepolite Pistons The Bonneville ShopLowbrow Customs

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Ron T. in KY
Ron T. in KY
Northern KY
Posts: 414
Joined: August 2001
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
quinten 94
Rohan 64
Top Likes Received (30 Days)
quinten 14
Newest Members
Gearhard, yornocT120R, robert wilby, Jonah A, paulski
11,838 Registered Users
Who's Online Now
1 members (Jon W. Whitley), 32 guests, and 73 robots.
Key: Admin, Global Mod, Mod
Thread Like Summary
gavin eisler, kevin, NickL, Noe, splash
Total Likes: 18
Original Post (Thread Starter)
#824118 09/18/2020 2:49 AM
by splash
So a few months ago I posted this problem. It's doing it again after I thought I had it under my thumb. I was running good until yesterday. I almost didn't make it home because it was barely grabbing at low RPMs.

After rereading old thread to refresh my memory I pulled the primary cover and 3 springs. The clutch plates were still fairly dry from the last time I had it apart. I used just enough oil to keep the chain wet when I was in here last time. I tried to pull out the clutch rod and it will not release. I recall it coming out the primary side with no difficulty if I remember correctly, no? I also found metal flakes at the bottom of the primary cover held together by greasy material. I'm at a stand still scratching my head about how these parts interact with each other still. I wish I could see it all in action moving with the clutch disengaged or engaged to fully understand.
Liked Replies
#824556 Sep 23rd a 02:24 PM
by DMadigan
To assemble the damper you need to put the mainshaft in a soft jaw vice, put the hub on the mainshaft, put the damper housing and spider on the hub, put in the large dampers, use a clutch holding tool to turn the damper housing to compress the dampers, put in the small dampers.
You need an impact driver to set the screws.
The A65 changed from the six countersunk screws to three through bolts to fix the screws backing out problem.
2 members like this
#824175 Sep 18th a 08:17 PM
by koan58
Splash is correct in that 99% of the function of oil in the chaincase is to lube the chain. The only other parts requiring any lube are the rollers and the end of the pushrod.

These only require the tiniest lubing, as they are only occasionally in use, whereas the chain is constantly spinning.

If your slipping clutch is not due to too much oil (most common) it is likely due to over-tight pushrod adjustment. Or possibly if the clutch centre nut is coming loose (the nut at the other end of the mainshaft can also produce these symptoms).
1 member likes this
#824214 Sep 19th a 02:20 PM
by reverb
...hello Splash; even my original 1948 clutch works good; imagine how many kilometers it have so I think that you have a combination of couple of worn out parts, something assembled not the right way and glazed plates.
For example; you can have all the parts worn out BUT if you have the basket and the center rotating isolated no matter the wobbling; the pushrod with a clearance of 2-3mm (be careful because in units that nut tends to tight but you would notice when pulling the handle bar lever) and not so many indentations on the basket slots (even do not matter if the plates tabs are worn) the thrust washers not worn out then the springs are tight; the clutch SHOULD work; not excellent but should work.
The slip is only due to the springs; glazed or oily plates or that the basket and center are not isolated doing their work.
1 member likes this
#824205 Sep 19th a 08:19 AM
by TR7RVMan
Hi Splash, Can you post photos here? I'd like to see your basket slots & hub slots.

Remove rod, I'd like to see both ends. If rod doesn't pull out the end is mushroomed. Rod should never mushroom. Generally mushroomed rod is from improper rod adjustment.

Do you have Verner calipers? Take all 12 plates & stack them together. Squeeze them & measure thickness of entire stack. What is that thickness.
Take photos of the friction plates & steel plates.

Measure the overall length of springs. Measure how thick with wire is of springs. Reach in with verner & measure thickness of wire.

The friction plate is first plate installed & sets in back of basket. Make sure the plate sets perfectly flat to back of basket & the edges of plate are not binding at inside corner of basket. Repro baskets are chamfered here not sharp square so plates may not set flat.

If a steel plate falls comes off the hub & falls off the back, getting stuck behind hub, that is very rare. Something is out of spec or assembled wrong. Or the thrust washer has gotten so thin the basket has moved to the right. On very rare occasion you can add "stuffer" plate in the basket behind the first plate. That is not normal procedure though.

I expect you tightened nuts. If you have incorrect washer under clutch nut it may not/will not hold inner drum in position. If you try with finger in trans filler hole you can feel loose clutch nut. Flash light & like a dentist mirror you can see it through hole. Loose right nut will not make plate fall off hub, but will effect clutch adjustment.

Primary oil on 1970 is self leveling. It will set it's level to about 1/2" deep. That will be very close to 150cc oil. You can't trick the primary. It will find it's level.
No matter oil level is not causing your problems.

Lucas motorcycle oil 20-50 should not make clutch slip, no matter regular or synthetic oil.
You have a lot going on here. There is no room for error. Everything must be near perfect or it won't work properly.

Start with the above stuff. If you can't post photos here I think you have my email.

If you do not have at least a verner caliper you can't measure anything. That will be a problem
1 member likes this
#824343 Sep 21st a 12:11 PM
by Tigernuts
Originally Posted by splash

This photo shows a real mess. You've found the cause of the slip, but what was the cause of the clutch centre coming apart? If the spider happened to be extremely badly worn, this could happen, but the wear really would be extreme to allow movement on this scale. Otherwise, the screws that fasten the outer plate on the centre to the rear plate must have come undone - completely undone by the look of it. Can you put a screwdriver in the heads and turn them easily? It looks as if the hub nut isn't a locknut too. It mat not have come undone yet bit if it isn't a locknut, it's another problem waiting to happen.

The pushrod must be mushroomed at the right hand end, as I suggested some posts back. I suggest you need a number of items: (a) a new complete clutch centre (b) a new clutch pushrod and possibly mainshaft bushes (c) a proper workshop manual which covers your actual model and year (I say this because I thought - apparently wrongly - that your bike was an oil-in-frame model, but the photo is of a pre-OIF frame (off the top of my head I can;t recall why I thought your was an OIF bike, I may have imagined this).

I'd also advise checking everything else in the primary case very carefully for wear and / or damage due to having been assembled incorrectly.
1 member likes this
#824251 Sep 19th a 11:45 PM
by TR7RVMan
Hi Splash, I see a huge problem that is causing back plate to fall behind hub. As did LAB.

I will say without question this is bad. Back side screws coming loose is probably the cause. Those screws generally need blue loctie & I always stake the screw head at slot as well. But... excess wear of spider back side will cause similar condition.

Your next step is to remove the cush hub & inspect back side.

Might find other things wrong behind also. I'd expect the screws to be damaged & very likely the screw threads in spider to be wallowed out as well. But tear down & inspection will show what's needed. Should you need spider, I'd get a new LF Harris hub. Not cheap. Get the later design with hex bolts instead of flat head screws. Much stronger in my mind. They are interchangeable. I believe mid production or so the '70 650 got the later hub with hex bolts from new at factory.

If we were together with all the parts this would make sense. Looking at exploded view it's hard to tell what holds what if you aren't familiar with what's going on.

The small hub with taper goes onto main shaft with key. This hub has external spline. The spider has internal spline to match. So the spider slides over the hub. The fat washer under main shaft nut is just right size to press against spline of spider. Close exam when you take nut & washer off will show this. The end of the tapered hub is slightly shorter. So the spider is pinched tight against shoulder on tapered hub. At the same time the nut pushes taper of hub tight to main shaft.

So, the spider is fixed tightly to main shaft via the splines & tapered hub.

What about the drum where clutch plates ride? The spider has 3 legs or arms if you will. The rubbers go against them. The drum has 3 large protrusions where the clutch springs will be. So the rubbers press on them. So clutch plates rotate drum, pushing rubbers, which push spider arms, turning spider & main shaft.

So the side plates of cush hub secured by the 3 screws ride on shoulder on each end of spider. You can see in photo outer plate has moved to left of machine & not longer is riding on shoulder of spider.

The end plates each side screwed to spider is what holds the drum centered over spider. So it looks like the back side screws may have come out.

I can't explain why, but when the drum has too much play on sides of spiders the force on clutch tends to cant the drum, wanting to separate clutch plates & slip. Normal bad wear on spider & back plate will allow similar to happen.

From what you say about ongoing problem with steel plate falling off back & getting stuck I wonder If the back plate may not have been perfectly seated for some reason. I've had a fair amount of these apart. Expanded cush rubbers can simulate a tight feeling plate when it's actually not seated yet. Accidently using T150 small rubbers will cause this. They look similar.

None the less next step is remove cush hub. If not too tight on spline you can work it out, leaving tapered hub, basket in place with chain in place as well.

On the other had I'd pull basket so you can inspect thrust washer & back side of basket. It could have taken damage as it's position relies on a stable back plate. Cush hub back plate is the outer thrust surface for the basket.

Please photo what you find. The photo you just posted solved the mystery. Now we need to see why it went wrong & what is best plan for repairs.
1 member likes this
#824522 Sep 23rd a 01:09 AM
by koan58
Perhaps its because I’m a long term owner of pre-unit (ie much older) parts that I’m less concerned about the signs of wear in your pics.
Admittedly my thoughts are only based on the pics, and measurements and first hand examination would be more convincing, as Don says.

Of course, a new clutch shock absorber hub would be best as advised. However, you may wish to try the following, if you’re as tight as me!

The rubbers look to be ok, so see how the 3 screws fit into the threads. If they wind in straight, without much slack, they may just do further service.

They, and the holes they go into, will require thorough solvent de-greasing, then thorough drying, before application of loctite, and serious tightening. See my earlier advice on this, using a vice and screwdriver bit (it works!).

Then dot punch next to the slot as Don mentioned posts ago.

That should sort out the shock hub.

The thrust washer shows unusual wear patterns, but that may be due to the unusual movements of the parts. Install a new washer, bronze/copper side to the basket, steel side to the hub flange.

I don’t know what is the best centre nut for your model, mine uses a nut with tab washer, but yours may take a locknut.
Either should work fine, when torqued properly. That is a crucial thing, to torque that nut properly. Don’t rely on shocking it tight with an air gun, it needs torquing.
1 member likes this
#824473 Sep 22nd a 04:53 PM
by Dibnah
Probably not glazed plates then!
1 member likes this
#824633 Sep 24th a 07:04 AM
by TR7RVMan
Hi splash, My apologies, yes I did miss the pictures. Very sorry.

The thrust washer is discolored, but not chewed up. If it's still flat and... the center bore still fits good on small hub, and if it's got grooved & not worn thin, it could be reused. Again I find the solid bronze washer works better with chamfer facing basket. I think I see a small "shoulder" worn in the chamfer?? I find I've seen that when chamfer is facing the small hub.

Actually the back plate doesn't look that worn. If I get time tomorrow,

Looking a photo of spider & rubbers. Those are correct rubbers, installed correctly. However in the photo it looks like spider has a "step" worn in the arms. Looking at arm at 1 o'clock position. You see the machined area where the spider rides in bore of rear cover. Then you can see shoulder at base of arm. The shoulder steps down to the arm. As I recall & from photos of my lightly worn spider, years/miles ago the step is actually worn into the spider arm & base circle. Here's a link to CBS & ebay new spider to compare:

You can see where they machine the OD of the spline, then pull tool bit outwards & face the spider or something like that.

If I get a chance I'll measure the end play of my old worn spider. The cush rubbers must be removed though.

If you have a proper holder in your vise made from a piece of flat steel & old clutch steel plate with long handle bolted to it, installing rubbers is safe & easy job, with no damage to you or hubs. I've installed lots of rubbers, if at all possible you'll need to make the tools. If you keep bike, you'll use them again. Rubbers don't last long these days.

The brown rusty looking deposits on spider arms are somewhat normal. These arms take a beating on the back plate.

I wonder if the loose screws allowed things to wobble & accelerate wear?

In the end of the day you'd be best off with new later version with hex bolt cush hub assembly.

I don't know what your end play is, but if you reused it, it would still work, just not as good as it should. The clutch should not slip. It will release, but probably not perfectly. Your budget. Our time is free so if you choose to take a chance on the old one, you don't have a lot to loose financially.

I see L.A.B. posted link to the 3 screws Classic British Spares. Good price. They say thread is 28tpi. I'd verify the thread before ordering.

At this point in my mind, you need rod, thrust washer, main shaft lock nut, primary gasket. New cush hub assembly, or... 3 screws.

Sleeping on it, thinking about the 3 screws I'd use red loctite 271, easy to buy. It holds very strong. Will release with heat gun. Heat until spit boils freely, they'll come out. Clean all threads & head areas bone dry. Freely apply 271 to threads & head. Tighten screws tight as you dare. Don't break head off, but really tight. Not a rattle gun. You need to feel the tightness.

Main shaft thread is 9/16-18. You can use clevelock type lock nut which looks like most of the Triumph lock nuts. Or the conical all steel lock nut. They are domed shaped with the top of dome pinched in to lock. Avoid nylock. they don't hold tight enough. I always use loctite 242 or 243 as well. Torque to 50#. Do not guess!! The same holder tool for installing clutch rubbers is used to hold cush hub during torqueing

Notice on new version cush hub the hex bolts are swaged over on their ends. Swaging looks rather like a screwdriver slot. If not swaged they can/will back out! Just like your screws. Triumph got smart with the long hex bolts. It is impractical to drill your hub & install hex bolts. You need to machine relief in drum for head clearance. As well as drill all the way through drum. Drilling hardened back plate not easy either.

Any thoughts?

1 member likes this
#824646 Sep 24th a 11:10 AM
by Tigernuts
Originally Posted by splash
Originally Posted by TR7RVMan
We'll see the condition of parts after splash posts them.

I posted 6 new pics above. Did you miss them?

Koan, or someone, what is a way to hold the clutch basket when torquing down the main shaft nut?

To tighten the clutch / mainshaft nut, put the gearbox in top gear and lock the rear wheel. The brake will very likely not be powerful enough - you need to torque that nut to 75 ft/lb. You can jam the chain against the rear sprocket using something like a plastic wedge (tree felling wedges are excellent for this).
1 member likes this
#824695 Sep 24th a 08:23 PM
by koan58
The use of the rear brake in top gear to hold the mainshaft while tightening the nut is what I’ve used most times over the years on my bitsa.
I’ve never checked it with a torque wrench (my sin) but just done it up as tight as I could until the brake started slipping, then just shocked the spanner with a hammer a few times for good measure. Then bent over the lock washer tabs.
In 40 years, I’ve not had the nut loosen, and it is a standard nut as fitted since time immemorial.
I’m not suggesting that this is the way you should do it, it is just my single experience.
I certainly knew I was getting it about as tight as an average human could with an ordinary socket bar.

Why would that nut come loose, assuming it was well tightened in the first place?
The nut (and possibly a lockwasher) merely bear on a very stiff, thick washer that in turn bears on the ends of the internal splines of the spider, thus clamping the spider firmly against the step of the centre hub (splines connect both of these items).
If you find any noticeable slack in that spline connection, it will allow fore/aft relative movement that could loosen the nut.
But it maybe just that the nut wasn’t quite tight enough in the first place.

I don’t see any obvious connection between the loose main nut (from what I understand it wasn’t obviously loose anyway, just easily released) and the 3 screws coming undone at the back of the shock hub.
I think that is most likely simply due to not getting the 3 screws tight and secured at the last assembly (possibly related to the difficulty of getting the rubbers fully in).
Is it possible that the rubbers were still slightly protruding from the hub when the backplate was screwed on? This may deceive into thinking the resistance of the screws meant that the plate was fully home? Just a thought.

The way to install the rubbers fully and easily has been described by DMadigan (and myself some posts ago, though mine doesn’t assume you’ve got a gearbox mainshaft kicking about to stick in the vice. Though the method can be used on the bike, using the rear brake as the vice.

The really useful tool is the one Don described, which is effectively
with a handle attached. This can deal with all your engine/gearbox nut tightening situations, (other than the main gearbox sprocket nut) as well as making installation of clutch rubbers easy.
They are usually made from a couple of old plates, a couple of tube spacers and a bit of bar, oh and 2 nuts and bolts.
The handle makes a big difference to usefulness, without it the locking disc merely allows the use of the disc with the rear brake to tighten nuts.
With it, all nuts can be tightened independently of the rest of the bike (say an engine on the bench).

I’m not keen on the idea of wedges between chains and sprockets or between cam gear wheels (to lock them), the enormous axial forces exerted on the shafts makes me uncomfortable. Maybe I’m just too sensitive to my old metal?!
1 member likes this
#825527 Oct 3rd a 12:46 PM
by desco
Google P 80 rubber lubricant.
Tried to send a link but it did not work
P 80 is far superior to grease.

found this;
1 member likes this
#825831 Oct 6th a 09:26 PM
by desco
Pressure plate nuts are WAY to far in. Nut should about flush with the top of thread of the bolt.
Chain adjuster may be too tight. All your questions would be answered if you had a genuine Triumph Shop Manual.
1 member likes this
#826143 Oct 10th a 06:30 PM
by Dave Lid
Dave Lid
Hi Splash take these guys advice wink having followed this thread i am in the process of a clutch refurb and picked up on loads of advice that's been given albeit my clutch wasn't slipping it just would not free mad Not knowing what the PO had done with the clutch all sorts of little hitches have appeared 7 plate clutch having plain at both ends fitted confused so using a vernier and mic gone through all advice given making sure all within tolerance,be sure to order the correct part just found that you can get rollers 1/4" x 1/4" and 1/4" x 6mm so lengths and widths diameters etc all add to the woe's of a Triumph clutch
1 member likes this
#826168 Oct 10th a 11:36 PM
by gavin eisler
gavin eisler
Thanks Desco.
Hi Splash I am talking from bitter experience. 40 + years with a three spring clutch.
I know it all "looks " OK. But its not, your cush drive is fecked , new rubbers dont replace lost steel.

If the drum isnt too notched you might get away with new plates, complete new centre hub and thrust washer. Forget the bearings they have zero effect on slip, even new they are dissapointingly sloppy.
If the drum is notched then its hot plastic time.
New front sprocket, chain and clutch, ouch. But hey, youve fixed the top end, now you have to get that stuff to the back . hing in there.
And dont thing about going belt , that opens a whole can of worms with engine breathing.

If you do refresh the primary completly a whole lot of noise goes away. For a short while. And you will be able to find neutral from rest, woooh.

On a more open note, its amazing how often this crops up, folk spend money on the motor new this and that , crispy valves and such , and completely neglect the poor old trans which has had years of maladjustment , skipped oil changes and general abuse. The clutch is the most wearing part of it all. new plates and springs dont cut it when the hub chain and sprockets are all past their best..

I know i was yer dads bike, hopefully he rode it like it was meant, if he did , you need a new clutch
1 member likes this
#849365 May 19th a 06:39 PM
by splash
For the record...New inner hub with spider and rubbers shifts much smoother and hope this was the answer to the problem.
1 member likes this
#849926 May 25th a 04:02 AM
by TR7RVMan
Hi Tigernuts, The brass bushing is on the right end of main shaft. The main shaft is mostly hollow & the bush fills the hollow on the right end.

The left end at clutch has no bush & the size hole you see only goes for about 4-1/4" then widens to OD of the bushing.

A worn bushing can allow wobble of rod at right end. Mostly causes some unwanted wear on the pad of the lifting piece in center of cam. It does cause some lost motion, but I don't know if you'd know it.

Regarding the knife blade, I've read that for years. I've tried it many times. I've found there is actually no room to reach by nut & depress end of spring. Apparently the Triumph factory had some sort of super skinny knife?? I tried grinding a pocket screw driver. Gave up & just forced the spring nut off.

I now grind a chamfer on at least the top end of spring with cutoff wheel in Dremel. Put a piece of metal in spring coil such if I slip it can't notch the next coil down. I use the smooth side of hack saw blade for the metal "safety piece". This makes life so easy next time to remove or adjust plate wobble. It will not make nut unscrew as the pip is (or should be) large enough to hold the chamfered end perfectly. Been doing this for about 7 years on several clutches now. No problems yet.
1 member likes this
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor

© 1996-2021
Powered by UBB.threads™ PHP Forum Software 7.7.5