Atlas Clutch Plates to Thick??

Hi All.

I recently put some new friction plates in my Atlas (63 model so 5 double sided fiction plates and 1 single sided plate, friction plates with "tangs"on the outside). The old ones were slipping and had tried cleaning them etc etc to no avail.

Obviously I would expect the newer friction plates to be thicker, but they were to thick to get all plates to fit within the clutch cage.

I ended up only using 4 (and doubling up on 1 set of steel plates as a shim) and its working fine, but was wondering if anyone else has had this issue before?

I recently installed a new set of Barnett friction and plain plates in my Atlas. No problem with fit.

Is your clutch basket original 1963 vintage? I think earlier Dommie clutches used only 4 friction plates and we're not as deep as the 5 plate versions. Maybe someone can tell you depth of 5 plate clutch.

Slick

Assuming you actually had genuine std thickness clutch plates fitted inthe first place there can be no problem.
What is the rthickness of your old and new friction plates?
By removing one friction plate / 2 friction interfaces you have successfully reduced the torque your clutch will transmit, when fully engaged, before slip occurs by 1/6th........thus making the clutch even more prone to slip problems ......IF you use the throttle that is.

Can anyone tell me the proper total height for the disc stack for the Atlas clutch? I can't find it anywhere online, just many admonishments to ensure it's correct! Clutch is stiff as all get-out so I'm trying to ensure the basics are correct (cable routing, stack height, lever type) prior to moving on to anything more drastic.

AgentX said:

Can anyone tell me the proper total height for the disc stack for the Atlas clutch? I can't find it anywhere online, just many admonishments to ensure it's correct! Clutch is stiff as all get-out so I'm trying to ensure the basics are correct (cable routing, stack height, lever type) prior to moving on to anything more drastic.

Click to expand...

The Atlas clutch pull is stiff to put it mildly. The best thing you can do for yourself is get a Venhill Featherlight clutch cable. These are said to reduce lever pull by about 25%. I can attest to that. Venhill will custom make if necessary.

The design of the AMC clutch as used in the Atlas, Dommies, and hybrids, is not critical of stack height as is the Clutch used on the Commandos. If the plates go in and the pressure plate goes on, you are good to go.

While you are in the primary case, do the following:

Check the rubber shock absorber cushions .... they can get "gummy" from prolonged exposure to oil.
Check the shock absorber center body (also called a spyder) .... they tend to fracture from hard shifts, wheel stands, etc.
Install one of DynoDaves actuator shaft seals ... about $30 and worth it.

Use Ford type F ATF in the primary rather than oil. It provides a bit more friction and does not deteriorate the shock absorber rubbers. Only fill until the chain just picks up oil as you turn the engine over on the center stand.

PM if you need links to Venhill, DynoDave, etc.

Slick

Once again, many thanks... I was in the process of getting a Venhill cable when I saw your message, because there's definitely a kink or something that's causing a bit of notchiness in the cable pull when it's detached from the gearbox.

And I adjusted the pushrod adjuster screw. When I was tightening the locknut back down, this happened...threads in the outer pressure plate began to strip as I tightened the locknut. (Should this not be tightened so much? I didn't feel like I torqued it down hard at all and am working in a driveway without access to my torque wrenches or anything more than a few spanners and screwdrivers...)







(Edit: Are the spring adjusters tightened too far down on the studs here? The domed tops of the studs were projecting a bit past the top edge of the adjusters...)

So I need a new outer pressure plate at the very least. Since that was shot, I went ahead and checked the rest of the clutch. Center looks more than a bit chewed up, yeah? Can I dress this with a file? Does it need to be replaced?




Plates and friction material were stuck together hard, but looked pretty good once apart. Probably could benefit from a good cleanup with an appropriate substance. (Gasoline? Brake cleaner?) They were stacked just shy of the outer edge of the basket.


Thanks again for any input.

AgentX said:

Once again, many thanks... I was in the process of getting a Venhill cable when I saw your message, because there's definitely a kink or something that's causing a bit of notchiness in the cable pull when it's detached from the gearbox.

And I adjusted the pushrod adjuster screw. When I was tightening the locknut back down, this happened...threads in the outer pressure plate began to strip as I tightened the locknut. (Should this not be tightened so much? I didn't feel like I torqued it down hard at all and am working in a driveway without access to my torque wrenches or anything more than a few spanners and screwdrivers...)

(Edit: Are the spring adjusters tightened too far down on the studs here? The domed tops of the studs were projecting a bit past the top edge of the adjusters...)

So I need a new outer pressure plate at the very least. Since that was shot, I went ahead and checked the rest of the clutch. Center looks more than a bit chewed up, yeah? Can I dress this with a file? Does it need to be replaced?

Plates and friction material were stuck together hard, but looked pretty good once apart. Probably could benefit from a good cleanup with an appropriate substance. (Gasoline? Brake cleaner?) They were stacked just shy of the outer edge of the basket.


Thanks again for any input.

Click to expand...

It appears that the clutch pushrod adjusting screw was not engaged in enough threads of the outer pressure plate and simply could not
withstand the torque of the locknut. The problem lies with WHY the adjusting screw was not further engaged in the pressure plate.
My guess is that the handlebar adjuster was not fully loosened and/or the inner cable was not the right length and/or the cable was not
correctly engaged in the actuator inside the gearbox.

The spring screws seem to be tightened about right. You could loosen them up a bit, but at risk of having a slipping clutch and the
pull will not really get a whole lot better. The Venhill cable and most efficient routing are the only things that can help out with
the stiff draconian clutch pull.

Your clutch hub looks like mine did when I got my bike. Notched, yes. But still usable. I dressed mine with a file and don't experience
any dragging or difficulty shifting.

I have new Barnett clutch plates. They were sticking together badly soon after I installed them clean and dry. I disassembled the clutch,
wiped some ATF on the friction surfaces, and clutch worked fine again. However, the damned primary cover leaked ATF this time, even after carefully anointing the appropriate surfaces with sealant, so I opened it up again and found some of the plates stuck together again.
Yes, I know someone near and dear will now write a tome all about wet clutches vs dry clutches and how we are all damned if we do and
damned if we don't.

@AgentX

Spring tension nuts should be tightened exactly as in your photo. If, and only if, you are getting slip, tighten 1/2 to one turn more.

Best source for AMC clutch parts I have found is AMC Classic Spares in the UK. http://www.amcclassicspares.com
Price more than makes up for post if you are in the US. You will want to get an exploded view of the clutch to get part numbers. I can provide a link for this tomorrow, or you can try Google, or use the search function above.

Remove the three screws in the center plate to get at the shock absorber center .... might as well get new rubbers if you will be sending off for parts.

You can try dressing up the center body with a file, but if finances allow, it would be best to replace with new. The notches and roughness will contribute to drag and heavy pull.

You mentioned plates stuck together. I have had new Barnett plates stick when assembled dry (no oil or ATF). There was a thread recently on this issue. Try a search. All the pundits say the plates should be cleaned with gasoline, kerosene, or mineral spirits, then assembled dry. I found that I had to assemble with a smear of ATF to prevent plates sticking if the bike is not used for weeks at a time.

Slick

Hm, possible the wrong actuating rod is in there? Too long? Not seated properly or something? Something wrong in the operating lever assembly? Seems like that'd be impossible, though.

Doubt anyone has the proper spec on the rod length on-hand, either. But if so, it'd be great to know...

Slick, I am getting a new center because I just don't want to take this damned thing apart again and I'm already ordering stuff from Norvil. (Edit: Now checking AMC spares too) Unless anyone knows a good US source for these parts?

Have an inquiry in with Venhill to get a longer clutch cable than the 53" stock length, since the GS has higher bars and the housing is more like 55".

Appreciate the help from both of you guys!

@AgentX

Here is a link for clutch exploded view

https://andover-norton.co.uk/en/shop-drawing/302/clutch

Note: the race plate is shown backwards ... the rollers are supposed to run in the groove of the race plate.

Slick

@LazyEye6

Sealing Atlas primary case:

posting.php?mode=quote&f=16&p=308451

Slick

lazyeye6 said:

It appears that the clutch pushrod adjusting screw was not engaged in enough threads of the outer pressure plate and simply could not
withstand the torque of the locknut. The problem lies with WHY the adjusting screw was not further engaged in the pressure plate.
My guess is that the handlebar adjuster was not fully loosened and/or the inner cable was not the right length and/or the cable was not
correctly engaged in the actuator inside the gearbox.

Click to expand...

So this is the big mystery for me today. As you can see from the photos, the clutch pushrod sits very close to the outer pressure plate threads and the adjuster can only grip a few [now ex-]threads on the outer pressure plate before it bottoms out. I checked the position and operation of the system without the cable attached, and when it's fully seated, it throws the rod out just fine to operate the clutch. Yet, it still won't allow the adjuster to screw in any further than it had been. Can't see any way to change how it sits, and the manual shows this adjuster screw flush with the lock nut. Thus I'm concluding it's the wrong pushrod...guess I'll order one with the new pressure plate and compare when it arrives. (anyone know if, say, a Commmando clutch pushrod is longer than the Atlas?)

EDIT: I think I have a hypothesis! The G-15 and the Norton Atlas have separate pushrod parts numbers. Guessing I have the wrong one in there...the AMC chaincase on the G-15 is narrower...so...seems a likely reason to be a centimeter or so off on the measurement. /EDIT

Only other potential problem could be if there's another section of rod or a few ball bearings or whatnot in the tunnel taking up space. I'll tip it over and see if anything slides out before I complete my parts order, I suppose.

@AgentX

If there are different part nos for the clutch pushrod between Atlas and G15, then it is reasonable to assume the length is different. I am reasonably certain Cdo pushrods are longer .... possibly PO put a Cdo rod in there.

Best to order new rod according to proper part no. I would have guessed all hybrids and Atlas/Dommie pushrods would be the same .... the gearbox mainshaft length being the determining factor, but as I said, that would be a guess.

You should check actuator in gearbox .... no telling what was done in there. DynoDaves website gives profiles for Atlas actuator and Cdo.

Slick

Cool. Thanks. At first glance the gearbox side looks like what's in the manual, but I'll give the site a check and look it over.

Weird. Part 040084 is listed for the G15.


Per this conversation, 040084 is longer than older clutch rods and the same length as the Commando. I wonder what gives here.

AgentX said:

Weird. Part 040084 is listed for the G15.

Per this conversation, 040084 is longer than older clutch rods and the same length as the Commando. I wonder what gives here.

Click to expand...

Afraid that I cannot add anymore than what I have previously said. I see no reason why the G15 should take a longer pushrod than an Atlas. Maybe someone else can shed more light on this.

I have a Cdo pushrod at my shop, I can make a measurement tomorrow, and you can compare to what you have.

Slick

Much appreciated.

The difference in length between the various parts numbers seems to be within 3mm or so at most, so I think there's something else causing my issue here.

AgentX said:

lazyeye6 said:

It appears that the clutch pushrod adjusting screw was not engaged in enough threads of the outer pressure plate and simply could not
withstand the torque of the locknut. The problem lies with WHY the adjusting screw was not further engaged in the pressure plate.
My guess is that the handlebar adjuster was not fully loosened and/or the inner cable was not the right length and/or the cable was not
correctly engaged in the actuator inside the gearbox.

Click to expand...

So this is the big mystery for me today. As you can see from the photos, the clutch pushrod sits very close to the outer pressure plate threads and the adjuster can only grip a few [now ex-]threads on the outer pressure plate before it bottoms out. I checked the position and operation of the system without the cable attached, and when it's fully seated, it throws the rod out just fine to operate the clutch. Yet, it still won't allow the adjuster to screw in any further than it had been. Can't see any way to change how it sits, and the manual shows this adjuster screw flush with the lock nut. Thus I'm concluding it's the wrong pushrod...guess I'll order one with the new pressure plate and compare when it arrives.
Only other potential problem could be if there's another section of rod or a few ball bearings or whatnot in the tunnel taking up space. I'll tip it over and see if anything slides out before I complete my parts order, I suppose.

Click to expand...

Something tells me you have the wrong push rod –one that is too long-don’t forget there should also be one ball bearing in there :!:

@AgentX

Commando clutch pushrod measures 249 mm long x 6 mm dia. If memory serves me correctly, it is about 2.5 -3 mm longer than an Atlas.

Do your clutch plates fill the basket? The last plate should be flush or just under flush from basket top. Obviously, if your stack is too deep, the pushrod is relatively longer.

Slick

texasSlick said:

@AgentX

Commando clutch pushrod measures 249 mm long x 6 mm dia. If memory serves me correctly, it is about 2.5 -3 mm longer than an Atlas.

Do your clutch plates fill the basket? The last plate should be flush or just under flush from basket top. Obviously, if your stack is too deep, the pushrod is relatively longer.

Slick

Click to expand...

Thanks once again for the continuing assistance. I just got back from investigating further...my rod is the same length as yours and matches the (non-authoritative) information in the link I provided for part 040084. Shorter rod is supposed to be about 3mm shorter as you stated.

Had the same thoughts regarding stack height and re-installed the pressure plate to re-check how it looks altogether. It's a stack using five metal plates and reaches 2mm or so shy of the outer edge of the basket. Guessing with brand-new friction material that'd be a hair closer. No room for more plates, in any case.

I tipped the bike way over and also checked with a flashlight; there's nothing else hiding in the pushrod tunnel.

So, I think the time has come to stop seeking causes and implement the simple solution of the shorter Atlas rod, since I'm ordering parts anyhow. The extra 3mm should put it about right. Also had the thought the pressure plate could be out of spec, but there's a new one of those in my order, so...we'll see!