drivetrain/clutch shutter! tranny mounts?

[Casey]

Hello,

I have bought a CAV GT secondhand and it has the Audi 016 transaxle with what I believe is the 5 puck single disc clutch. As the clutch engages, it can set up an degrading driveline shutter that is problematic if you need to slip the clutch when parking or the like.

I noticed that the sheet metal mounting points on the cars rear frame section are somewhat flimsy and the rubber tranny mounts are bouncy.

Has anyone had trouble with this too?

Anyone change the mounts or reinforce the sheetmetal area on the frame where the tranny mounts to help this probllem?

I know that this clutch is prone to this. However, if the natural frequency of the drivetrain mounting points could be changed, then the shutter might be elliminated.

[chuck smith]

My ZF mounts very solid to the frame by two ears on top of the tranny and I have no stutter. Maybe if you change to poly mounts it will firm up. My motor is solid mounted also.

[Casey]

I noticed that about the ZF. Lucky dog. If things go well, I will likely convert the tranny to a ZF.

In the mean time, I think more solid mounts will help. I wonder if anyone has delt with this too.

[Cliff Beer]

Hi Casey, I have the exact same problem with my CAV (early monocoque). I thought that perhaps I smoked the clutch by starting the car in 3rd a few times when I first bought it as it was difficult to find 1st gear because the linkage was very, very sloppy/loose - and maybe in so doing I destroyed any smooth take up. However, having driven the car in this condition for a few thousand miles I'm starting to wonder if it's instead a matter of very soft engine mounts creating too much movement and a pendulum effect. My first impulse was to order some poly mounts and try that (planning to do in the next few weeks). So, I'll let you know if I figure this one out!

[Cliff Beer]

ps. I believe it is the early mustang mounts which are appropriate.

[Russ Noble]

Casey,

I have never so much as laid eyes on a CAV but my experience tells me that I would pull the trans and check the clutch itself and the flywheel. That is, once I had quickly checked that there were no torn mounts and that the release mechanism operated smoothly and there was no problem with the driveshafts.

By all means fit beefier mounts if that's what you want anyway, and maybe it's an easy option, but I think you will have to delve deeper to completely solve the problem. Cliff Beer could throw some egg on my face in a couple of weeks though.....

BTW good luck with your venture into Europe and also with the McKee.

Cheers

[Brian]

The GTD guys have commented on this in the past. If you have the sintered metal clutch plate,(AP Racing) it's difficult to completely remove the shudder. I've put poly mounts all around (Prothane and Energy Suspension I think) in my GTD to reduce the engine movement, but can't comment as I have not driven the car yet.

Brian

[Dave Peterman]

Hi
Shudder in sintered racing clutches is very common. AP, Tilton and Quarter master,Coleman use basically the type of sintering. If you have a solid mount hub on the drive disc there are no springs to help dampen the shock of engagement. Racing clutches are not designed to be slipped. Over the years I have seen many customers tear up brand new units trying to load their cars on the trailer slipping the clutch. Another source of problems mainly in multidisc applications is not indicating in the bellhousing.

[Casey]

I noticed that the mild steel sheetmetal frame platform that the tranny mounts to is very flimsy. In fact, the stitch welds ont he right side of mine have broken and both mounting platforms are deformed. I can't believe they use such thin metal for this. I am going to redesign this mount.

If I put poly bushings on it now, the mount platform is still not strong enough.

I am considering reconfiguring the tranny mounts and mounting it solid.

Yes these multi puck clutches do chatter more. I am not a clutch slipper, but this is the real world and I park the car occasionaly. I think if I get rid of most of the flex and the driveline shutter, the car will be much nicer to drive.

[Casey]

Early mustang tranny mounts?????

Can you be more specific. It would be nice to replace it directly with a poly mount.

[Casey]

I don't think any Mustang mounts are the same from what I have seen. The closest poly mount I have found is for a BMW 330. Cylindrical poly puck with a threaded rod on either side.

[Casey]

ZF trannys mount metal-to-metal via their two hanging spots above the diff case, right?

Any reason why I shouldn't just redesign it to mount my tranny solid and quit screwing around?

I mean the car is loud anyway. It is not a Mercedes.

[Julian West]

Originally Posted by RacerDave

Hi
Shudder in sintered racing clutches is very common. AP, Tilton and Quarter master,Coleman use basically the type of sintering. If you have a solid mount hub on the drive disc there are no springs to help dampen the shock of engagement. Racing clutches are not designed to be slipped. Over the years I have seen many customers tear up brand new units trying to load their cars on the trailer slipping the clutch. Another source of problems mainly in multidisc applications is not indicating in the bellhousing.

IMHO this is very true, changing the engine/trans mounts won't stop the shudder... the cause is the solid centred clutch. I run an AP sintered clutch & found the easiest way to reduce or stop the shudder is to try a different technique on the clutch pedal.

Full throttle starts are no problem, for road use, parking etc, try less revs as the clutch 'takes up'......it might be different in your application but it works for me.

Dave, when you say 'indicating the bellhousing', do you mean *indexing*??? do you know how to do this?

Regds,

[Casey]

Yes, tecnique helps slightly. However, it is impossible to just take off when you are backing in confined are as, etc. I don't mind the clutch shutter so much. My brother had a dune buggy that had a similar clutch and it was the same characteristics.

However! The clutch is NOT the big issue. The clutch shutter hits the resonance frequency of the drivetrain unit. Therefor you get a degrading oscillation and the whole damn engine and transaxle rocks back and forth in a stupid manner.

I am talking about changing the frequency of the drivetrain, by changing the modulous of the mounts. If you change the frequency, the clutch may not hit that frequency as to put the drivetrain into resonant shutter.

As I am "blessed" with the weaker Audi box. I am under the understanding that I must run this type of clutch to hold my 480 hp. If I were to run a more typical clutch it may not be able to hold that kind of power as its diameter was intended for an Audi not a tough V8.

I see no sense in replacing the clutch with the same thing. If there was another clutch that would hold the power that wouldn't shutter I'd be game.

No, I do not have the "means" to change gearboxes at the moment to solve my clutch issue either.

Does anyone see a reason why I souldn't solidly mount my transaxle?

[chuck smith]

no good reason not to in my mind. Another thing I get in my Daytona with a 427R Roush motor is poor vacuum signal at low rpm and this causes trailer hitching, combine that with a sintered clutch and you have some very noisy takeoffs

[Bob Childress]

Hi Casey,

A couple of thoughts come to mind about your trans shudder problem before you go all the way to solid mounts.

Depending on how your trans is now supported, it would be an easy test to order polyurethane blocks from McMaster Carr and just replace the rubber mounts you presumably have now. Like you said, it may be just enough to damp out the frequencies that cause the entire drive train to shudder.

Also if the way the car is shifted can "dodge" the symptom then you should look over the comments by Ian in:

slave cylinder

Changing the leverage of the clutch pedal (increasing the size of the engage/disengage sweet spot) made it much easier for almost anyone in my ZF car to always catch a smooth shift.

The CAV is a good car and it is easy to upgrade. Good luck with your project.

[Dave Peterman]

Julian:
You are correct that is another term for what I meant.

[Casey]

Hey guys,

Two things;

1
The sheet metal mounting platforms on the CAV are total crap. I agree and would love to just put in polyurethane pucks, but the mount platform is just crap and would need to be strengthened(mine is currently failing). I may strengthen it, but it would be better engineering to just get rid of that and build solid mount points.

2
In regard to driving. I am actually a race driver and am currently dealing with lawyers in a 7 figure sponsor deal to send me to Europe to race F3 and train for F1. Driving technique is not a problem here.

I cannot start off from a stop at lower RPMs, I do not slip the clutch on shifts and yes, I can toe-heel double-clutch downshifts perfectly. If it was a dog-box, I would only need the clutch for stopping and starting anyway.

Trouble IS, this is my fun car. I drive it on the street and SOMETIMES you MUST slip the darn clutch in tight quarters.

[Casey]

Does anyone else with a CAV think the mounting platform on the black painted steel rear subframe is flimsy crap?

My car is the 17th chassis built, so perhaps it is an early production weakness.

[Cliff Beer]

Casey, do you have a monocoq