RAM clutch slip

[moscowphil]

Anyone else out there had this problem? - My Scura has a genuine RAM single plater, which I put in to replace the original "grenading flywheel" scura clutch, just for peace of mind. The RAM only has about 8,000 miles on it, but recently started to slip when cold, but was fine once the bike was warmed up.   A quick visual check showed no sign of any oil near the clutch, and virtually no wear of the clutch plate . So I checked the slave cylinder, and what was apparent was that the piston was backed up as far as it would go in the cylinder, and so was putting pressure on the push rod and so stopping the clutch from fully engaging. I guess the reason the clutch slip went away when the engine was hot was simply due to the expansion of the castings  relieving some of this pressure.

As a temporary fix I put washers between the slave cylinder and the back of the gearbox, to create a bit of extra "headroom" for the piston. (Sounds easy but was a pig of a job). This has cured the problem, and I now have a fully functioning clutch again - for now. However it's only a matter of time before the problem will re-occur, as the washers are only about 1mm thick, and from the design of the clutch, I reckon it will only need the plate to wear another 0.2mm or so to take up all the extra 1mm.  

I suspect the problem stems from the fact that the RAM clutch was actually originally designed as a replacement for the 2 plater cable operated clutches, and so the necessary clearance between push rod and diaphragm could always be found just by adjusting the cable or the screw on the actuating arm.  But with the hydraulic mechanism there is no adjuster, so no way of adjusting it that I can see, other than my bodge with washers. 

Unless there's something strange about my set-up, I assume others must have suffered a similar problem. If so, how did you get round it? I don't fancy having to replace the clutch every 8.000 miles, when it's hardly worn at all, so are there any other fixes other than periodically sticking more washers in to take up the wear? Shorten the push-rod? fit a different slave cylinder? Any ideas gratefully accepted!

[footgoose]

I recall something was talked about a spacer or actuating rod or ?? being different when going to a single plater from dual. There's a thread with that I'm sure tho I can't say where. Now... where in H*** did you get a Ram clutch?? And.... what was the condition of the Alum stock flywheel? Mileage?

[czakky]

I remember something to that effect also Footgoose. I think it was pretty recent.... Wait til Docc the super searcher is on the scene, he's gotta knack for finding old threads.

[Lucky Phil]

How did you measure the thickness of the friction plate. The difference in thickness between a new plate and a worn out plate is quite small, maybe less than 1mm.

These clutches are known for their high wear rate on the earlier friction plate versions.

Ciao

[docc]

I remember something to that effect also Footgoose. I think it was pretty recent.... Wait til Docc the super searcher is on the scene, he's gotta knack for finding old threads.

I do *remember* that thread . . .

[czakky]

I gave it a shot couldn't find anything... Sorry

[Scud]

There a few good threads here about changing from the stock single-plate to the dual plate. Given that the RAM kit was meant to replace the dual plate, you might look carefully at the parts list in one of these threads.  I think this might be one of the most complete:

 

http://www.v11lemans.com/forums/index.php?showtopic=18068

[moscowphil]

I recall something was talked about a spacer or actuating rod or ?? being different when going to a single plater from dual. There's a thread with that I'm sure tho I can't say where. Now... where in H*** did you get a Ram clutch?? And.... what was the condition of the Alum stock flywheel? Mileage?

 

I recall something was talked about a spacer or actuating rod or ?? being different when going to a single plater from dual. There's a thread with that I'm sure tho I can't say where. Now... where in H*** did you get a Ram clutch?? And.... what was the condition of the Alum stock flywheel? Mileage?

Got the RAM clutch ages ago from Agostinis in Mandello. I've no idea whether they are still available. The stock flywheel had only done a few thousand miles when I replaced it, and it looked fine - though I didn't have it crack tested. You might well be right about the actuating rod being a different length. I assumed that as I was going from a single plater to an almost identical single plater there would be no problem, but on reflection the RAM is not identical to the original, and it would make sense that RAM designed their clutch so that the original actuating rod (as used on twin-platers) could still be used. I'll see if I can track down the thread you mentioned. Thanks.  

[moscowphil]

How did you measure the thickness of the friction plate. The difference in thickness between a new plate and a worn out plate is quite small, maybe less than 1mm.

These clutches are known for their high wear rate on the earlier friction plate versions.

Ciao

Well you are right in thinking that I can't have measured the thickness of the plate very accurately - short of removing the clutch the only way to do it was using a caliper through the inspection hole. It looked pretty much un-worn but I wouldn't like to put a figure on it. However, I'm unconvinced that a friction plate can be worn out after less than 1mm wear. In theory the thickness of the friction material should be of no consequence providing there is some friction material left. The friction material does not provide structural strength to the plate, this is the job of the inner steel core, so loss of friction material as the plate wears should not cause any problems apart from the lack of adjustment one I've experienced. After all, a similar single plate diaphragm design is used in virtually all car clutches, which regularly last 100,000 miles, despite being given a much harder time than my clutch ever gets.  I wonder whether the reports of clutch plates being "worn out" at low mileages are actually other people suffering the same lack of adjustment problem as me?

[moscowphil]

There a few good threads here about changing from the stock single-plate to the dual plate. Given that the RAM kit was meant to replace the dual plate, you might look carefully at the parts list in one of these threads.  I think this might be one of the most complete:

 

http://www.v11lemans.com/forums/index.php?showtopic=18068

Thanks Scud. The finger of suspicion is definitely pointing at the push-rod ....

[Lucky Phil]

 

How did you measure the thickness of the friction plate. The difference in thickness between a new plate and a worn out plate is quite small, maybe less than 1mm.

These clutches are known for their high wear rate on the earlier friction plate versions.

Ciao

Well you are right in thinking that I can't have measured the thickness of the plate very accurately - short of removing the clutch the only way to do it was using a caliper through the inspection hole. It looked pretty much un-worn but I wouldn't like to put a figure on it. However, I'm unconvinced that a friction plate can be worn out after less than 1mm wear. In theory the thickness of the friction material should be of no consequence providing there is some friction material left. The friction material does not provide structural strength to the plate, this is the job of the inner steel core, so loss of friction material as the plate wears should not cause any problems apart from the lack of adjustment one I've experienced. After all, a similar single plate diaphragm design is used in virtually all car clutches, which regularly last 100,000 miles, despite being given a much harder time than my clutch ever gets.  I wonder whether the reports of clutch plates being "worn out" at low mileages are actually other people suffering the same lack of adjustment problem as me?

 

What you fail to understand is that clutch slippage from a worn friction plate is due to the fact that the pressure plate travel reaches its limit at the engaged end of the travel and therefore cant apply the same degree of spring pressure.This is usually signified by slipping and running out of actuating free play which is what you have.

Clutch fiction plate thickness reduction of 1mm would be a worn out clutch.

Ciao

[docc]

 

 

How did you measure the thickness of the friction plate. The difference in thickness between a new plate and a worn out plate is quite small, maybe less than 1mm.

These clutches are known for their high wear rate on the earlier friction plate versions.

Ciao

Well you are right in thinking that I can't have measured the thickness of the plate very accurately - short of removing the clutch the only way to do it was using a caliper through the inspection hole. It looked pretty much un-worn but I wouldn't like to put a figure on it. However, I'm unconvinced that a friction plate can be worn out after less than 1mm wear. In theory the thickness of the friction material should be of no consequence providing there is some friction material left. The friction material does not provide structural strength to the plate, this is the job of the inner steel core, so loss of friction material as the plate wears should not cause any problems apart from the lack of adjustment one I've experienced. After all, a similar single plate diaphragm design is used in virtually all car clutches, which regularly last 100,000 miles, despite being given a much harder time than my clutch ever gets.  I wonder whether the reports of clutch plates being "worn out" at low mileages are actually other people suffering the same lack of adjustment problem as me?

 

What you fail to understand is that clutch slippage from a worn friction plate is due to the fact that the pressure plate travel reaches its limit at the engaged end of the travel and therefore cant apply the same degree of spring pressure.This is usually signified by slipping and running out of actuating free play which is what you have.

Clutch fiction plate thickness reduction of 1mm would be a worn out clutch.

Ciao

 

Why would shimming the slave make any difference then?

[Lucky Phil]

 

 

 

How did you measure the thickness of the friction plate. The difference in thickness between a new plate and a worn out plate is quite small, maybe less than 1mm.

These clutches are known for their high wear rate on the earlier friction plate versions.

Ciao

Well you are right in thinking that I can't have measured the thickness of the plate very accurately - short of removing the clutch the only way to do it was using a caliper through the inspection hole. It looked pretty much un-worn but I wouldn't like to put a figure on it. However, I'm unconvinced that a friction plate can be worn out after less than 1mm wear. In theory the thickness of the friction material should be of no consequence providing there is some friction material left. The friction material does not provide structural strength to the plate, this is the job of the inner steel core, so loss of friction material as the plate wears should not cause any problems apart from the lack of adjustment one I've experienced. After all, a similar single plate diaphragm design is used in virtually all car clutches, which regularly last 100,000 miles, despite being given a much harder time than my clutch ever gets.  I wonder whether the reports of clutch plates being "worn out" at low mileages are actually other people suffering the same lack of adjustment problem as me?

 

What you fail to understand is that clutch slippage from a worn friction plate is due to the fact that the pressure plate travel reaches its limit at the engaged end of the travel and therefore cant apply the same degree of spring pressure.This is usually signified by slipping and running out of actuating free play which is what you have.

Clutch fiction plate thickness reduction of 1mm would be a worn out clutch.

Ciao

 

Why would shimming the slave make any difference then?

 

Well if it is indeed a worn out friction plate and it may not be, I just think its a likely possibility having high wear rate for these units mentioned by a well known and respected Guzzi mechanic/dealer in Australia.

I also am aware that there are later Ram specific friction plates available that are advertised as being of greater durability ( see MG cycles, version 4 I think and they are up to and it is 6.68mm thickness as opposed to 5.5 for the old version). The later plate also requires a shorter actuating rod.

So put it all together and you have a possibility.

The question here is when the Ram plate is worn out is it the pressure plate/diaphram that reaches its limit of effectivity or is it the actuating system, ie the piston travel on the slave? That I don't know.

If the limiting factor is the slave travel then either shimming it out or at some point in the life of the clutch you go to a shorter rod and get extra wear out of the friction plate. Maybe the Ram unit doesn't have a high rate of wear its just a case of the actuating system isn't well matched to the diaphram design, don't know.  As is often the case though in these forum posts its impossible to tell what parts were used in the clutch conversion so that also a factor.

I have a new single plate Ram unit in the workshop to go into the V11 when I fit the Daytona engine and was debating with the previously mentioned knowledge on the wear rates of the earlier versions which mine is whether or not to even use the original new plate or just buy the latest version with the greater durability.

Upon reflection I wouldn't be surprised if the original 5.5mm plate though is too thin for the operating system and that is the limiting factor. I was surprised when I saw the new version 4 plate was over 1mm thicker than the original, i was expecting just a material change. Also 1mm of wear or there abouts will be a worn out clutch in most cases. The friction material on all single plate clutches I have ever see car or bike is generally only around .5mm above the securing rivets so that amount of wear on both sides and the clutch is gone. 

Ciao   

[moscowphil]

Thanks to everyone for all the replies. Having read them all and done a bit more digging on tinternet, I've come to the following conclusions (until I change my mind!)

(1) My problem is definitely caused by lack of piston travel in the slave cylinder. Possibly this is because the push-rod is too long, but probably not. What seems much more likely is that (to quote lucky Phil) "its just a case of the actuating system isn't well matched to the diaphram design". When you think about it this makes perfect sense. The actuating mechanism was designed for the 2 plater, and with this clutch each 1mm of wear on the plates simply requires the pushrod and piston to back-up 1mm to compensate. Whereas in a diaphragm clutch this amount is magnified substantially -the piston probably needs to back-up  4 or 5mm to compensate for 1mm of plate wear. So the bottom line is that the slave cylinder used on V11s probably simply doesn't have enough piston travel for the RAM clutch. (And of course the RAM clutch was originally  designed for cable actuation, where this wasn't an issue, as the free play could be manually adjusted).  

(2) So the ideal solution would be to find a slave cylinder with a longer total piston travel which could be fitted in place of the original. Theoretically possible I'm sure, but next to impossible in practice I suspect.

(3) Which leaves me with the options of either replacing the clutch plate at ridiculously short intervals (and even using a thicker plate is not going to improve matters if the problem lies with the slave cylinder), or converting to a 2 plater (expensive, and seems like a backward step)

or:

(4) Carry on bodging it with shims until such a time as the plate is actually worn out, and bodging it no longer works, at which point I'll either stick another single plate in or convert to a 2 plater.

 

So carry on bodging it is then. Seems like the proper Guzzi way of doing things. 

 

[Scud]

I talked to the guys at MG Cycle, who said that the current RAM clutches are very durable. The only problem is making one appear in your shop - I've had one on backorder for close to a year now. You might call those guys and explain your issue, they may be able to advise you and supply a part if needed. I think there is a difference in rod length between single and dual plate clutches. If you have a too-short rod, it may be that the clutch slave has to use up most of its range of motion just to engage initially.

 

I don't think that a twin-plate is a big step backwards. I have one of each. If I ride the LeMans (twin plate) for a while, the first time I get on the Scura (single plate) I find the clutch engages very quickly. While I like the idea of keeping a single plate clutch in my Scura, I'm probably going to end up putting a used twin-plate in there. I prefer the twin-plate, but no so much that I'd be willing to do a lot more maintenance on it - worse yet, letting it sit for a year waiting for a part.

 

FWIW - I have a complete, used twin-plate clutch on the shelf awaiting installation (assuming the new RAM doesn't show up before I'm ready). I can take a measurement or photo of any part for you. Also - I'm pretty sure there are some detailed threads on here with photos of all twin and single-plate parts laid out side-by-side.