Since there are so many cases of the AMV8 clutches wearing out or slipping , I thought it might be good to start a new discussion thread here. (or continue the discussions from other threads)


It seems that our AMV8s have a weak pressure plate, but soft disc material, or visa versa. basically, the two extremes can result in a clutch pack being very sensitive to clutch release operation techniques. It seems a common failure mode is slipping of the clutch under full throttle . (it wont matter what gear you are in, though in the taller gears, it usually means you can spend more time at the max torque area of the engine RPM/torque curve which is the most likely place the clutch will show slipping).


The traditional small engine'd car, higher rpm clutch release can prove to be deadly to the AMV8 clutch, because the friction generated is much higher and therefore, the wear is accelerated on the discs. A lower rpm, faster release style, (1500rpm to 1000rpm) should all but eliminate wear on 1st and reverse gear starts, and allow the clutch to last as long as the car. surely over 100,000miles. jackrabbit starts should be no issue as well, due to the fact that once the clutch has been released fully, the discs are at synchronous speed with the driveline and there is no wear. a full clutch dump, will result in the rear tires breaking free from their slip % and will spin, or at least give a chirp. tires are cheaper than clutch jobs.

There was also a misconception that there is somehow wear to the clutch when driving hard. as long as the clutch is quickly released and the RPM is near matched to the driveline speed, there will be no wear. a dyno run or full throttle run doesn't effect a properly working clutch. its pressed against the flywheel and there is no movement, so no wear or heat.


Break in for a clutch. (most clutches), is just a few cycles of shifts. mostly, very nice and smooth 1st gear releases. Depending on the flatness of the disc friction surface, it wears slightly to make total contact. (slight wear, mates the surface best) . however, there is more than enough disc contact and pressure to do dyno runs or wide open throttle runs, with smooth shifting. (best effort gear vs rpm matching)
drag racing starts, which just HIGH rpm clutch dumps and throttle modulaton should be avoided until the clutch has been "broken in". all other performance activities should be no problem for most all decently designed clutch kits.

Speed shifting, common for old American V8 drag racers, should be avoided. (flooring the car and just before redline, while keeping the throttle floored, push the clutch in, redline the engine, and dump the clutch in the next gear, using the increased kinetic energy of the engine at the higher rpm to be dumped into the driveline, at the cost of the clutch discs which transfer the energy disparity through the discs. Often time, they (pressure plate force and friction coefficient of the discs) can't even complete the task, which never allows the pressure of the pressure plate to accelerate the vehicle, which progressively increases heat due to sustained friction, lowering the friction and potentially completely burning/glazing the clutch and over heating the pressure plate, which can reduce spring pressure due to heat caused fatigue and destroy the entire unit.


The Valero clutch disc which has been said to be used by AM, is used on many ford mustangs, has been shown to have some defects, where the rivets have been found to pop out. its quality and wear qualities have come into question here. It would be interesting if the rivet problem is isolated to a manufacturer lot, or if they are the result of damage caused by misuse or over heat of the clutch on our cars.


The discussion is open. Post your thoughts, questions, observations, knowledge, on the topic here.

 

I mentioned this in another thread recently, but I think its worth repeating, especially for owners who are not experts with manual transmissions, or not familiar with the V8V clutch (kind of where I was 8 months ago).

You can really minimize your clutch usage by getting accustomed to the release point and then only depressing the clutch to that point. For the first few months I drove my V8V I depressed the clutch to the floor, shifted, and then released the clutch. Now I probably only depress the clutch 1/3 to 1/2 that far; the entire clutch cycle probably takes half as much time. This has really been a revelation to me, and also an embarrassment (that it took me so long to figure this out). If you don't currently shift this way you should at least give it a try...

 

If you must start up on a hill, or live in the hills as I do, learn to use your Emergency Brake to help you get started (Manual Transmission). This may take a little practice but really saves the clutch. When you come to a stop, pull up the handle on the emergency brake. Remove your foot from the brake and place it over the throttle pedal. When you get ready to move forward, release the clutch until you just start to feel the friction zone. Then do these three things all at the same time--but do it smoothly. Slowly release the emergency brake, press on the throttle and release the clutch.

 

be careful though, because if you don't push all the way, you could use the synchros to make the shift work. however, if you get good at matching the RPM drops. (e.g. wait a little longer before you shift from 1st to 2nd, but shift quickly from 2-3rd, etc. This is because of gear ratio spacing which is wider from 1-2nd than the other gears), you can make a smooth shift with the pedal not full depressed. also coasting up to a stop, you can pop it out of gear with your same method. don't keep the pedal depressed for more than a second or two ... better to exercise it, than to hold it.


with the stock clutch, don't do high RPM releases. all you will end up doing is wearing and possibly glazing the clutch disc friction surface. it only takes a hp or two to get the AMv8 rolling. better to release the clutch and apply throttle , where the high engine torque, AND very high gear ratio for 1st gear, can accelerate the car nicely without wearing the clutch much.

 

How does this apply to SS cars? I'm confused how to drive mine while protecting the clutch.

I usually keep the handbrake on while starting on a slope, until I feel some resistance. Just cause I hate rolling back.

I also am very delicate with the throttle when engaging 1st, and feather it for every shift, but specially careful from 1st to 2nd.

 

I thought sportshift had hill assist available? My fiat abarth has, takes a bit of getting used to but basically it holds the car in place while you clutch and put in gear.

Nope just looked in the manual and it's apparently on AMs.

 

I was thinking about this today while driving. I'm not exactly sure what it means to use the synchros to shift, but i don't think its happening because the process of shifting when I only depress the clutch half-way feels no different than when I depress the clutch all the way -- the only difference is that the clutch it depressed for less total time.

 

Hill assist only in ASM2, if you have an 09 like me you don't get it, you just get the substandard creep mode, which will only hold the car in the lowest of inclines.

 

you don't need any clutch, if you match the gears perfectly. less clutch if your close and you better have it all the way in if you are not. its a good thing if you don't feel any difference with the clutch half way in, however the synchros are good, and are taking some of the wear to force the two spinning masses to synch up. (rather than using the clutch if the speeds are even a little different) . so, don't worry about pushing the pedal all the way in for up shifts, and especially down shifts, but putting it in neutral is certainly a case for having the clutch only half in. (as you approach a stop)

 

maybe it's just me, but always pushed the clutch nearly all the way to the floor on all my cars. Mucho cars and decades later no failed clutches so far.

 

I also push my clutch all the way in, and I leave it that way when at a signal light, I don't bother to put the car in Neutral. This procedure disengages the clutch plate completely--so no wear. What's the issue?

 

I googled this. Apparently there has been an ongoing debate on various internet sites for years: do you push clutch all the way down, or just until it engages? It seems to me some engineers or mechanics should be able to answer this question definitively, but apparently not from what I found.

 

This will be my only comment here as the clutch issue is so contentious, particularly on this forum. First and foremost every car, even cars that are identical, built back to back by the same people are different to some degree, so the same driver driving two cars the same way will observe differing wear over time. The TOB (throw out bearing) will spin when the clutch is disengaged from the flywheel,(pushed to the floor) and working against the pressure plate, e.g. it is under load and wearing. The TOB has no way to be lubricated once installed. When clutch is engaged (not pushed to the floor) the TOB may spin. Some TOB rest on output shaft and spin continually. Irish07 could perhaps inform on AM cars. Regardless, torque tube bearings are under a continual load in varying degrees and are not lubricated after installed, so the spinning issue of the TOB is a moot point. Any wearing part used less will last longer, save rubber seals.

 

The issue is major leverage based wear on the release bearing > (TOB), and keeping the pressure plate flexed is more damaging than cycling it (it will lose clamping ability sooner by stopping with your foot pushing in the clutch.

 

The reality is this. if you are not all the way in, and you are not perfect on the shift as far as matching RPM, the difference in the speed of the drivetrain vs engine = wear. its that simple. if you are really good at shifs, you can afford to do a half in shift, but just because its a successful shift, doesn't mean there is not excessive wear on the synchros. the synchos wear based on how good you shift! .