Clutch slipping low RPM's?

[DevilDRake]

Hi All,

Just a question as I've never had clutch issues in any car and I'm not sure what it feels like.

The previous owner fitted a very expensive button clutch (about 10,000kms ago) and I think it may be already slipping.

In low rev ranges (2000-4000rpm), it seems to jump up in revs a bit but it doesn't free-rev, the car vibrates as if the clutch would be engaging/disengaging very quickly.
This only happens when the car is cold, when it's completely warm it no longer does this. It only ever happens at lower RPM's also which I thought was strange.

Any idea behind this? I've tried explaining the best I can, but i've noticed it's been getting worse too within the past couple of weeks.
I try not give it over half throttle when cold otherwise it'll do the vibration and seem to skip a few 100 RPM before the power kicks in properly.

If you do believe the clutch needs replacing - have any recommendations? I believe i'll go HD next time, not a button as it's a daily driver.

Cheers

[Russ59]

I would consider checking the Slave cylinder when it's cold to see if it is operating smoothly (ie - the push rod is moving freely) chances are that the piston could be sticking slightly when cold but once you have used it a bit it could be freeing up ??

[DevilDRake]

I guess that could be true, but I tested the car this morning and now it's doing it when the car is warm too.

If I plant it in second, it'll vibrate a fair bit between 2000-3500 rpm then again slightly higher rpm. But after 4500+ it'll pull with no issues all the way to redline.

I'm stumped.

[DevilDRake]

To be honest I've thought it could be unrelated - maybe a drive shaft but I would have thought that it would vibrate on load all the time, not just certain RPM.

[Russ59]

Maybe it's not related to the clutch at all, possibly a fuel issue ?? Maybe try having it checked to see if it's throwing up any error codes ? I agree I doubt it will be a drive shaft I would expect you would feel that all the time !

[DevilDRake]

I don't believe it is a fuel issue, it has been tuned and not only that it doesn't feel like it's not getting enough. Besides it would do that at a higher RPM i would think.

Question - Would a clutch slippage make the car shudder at all or just free-rev? Because i feel it shudders more than freerevs.

[Russ59]

Clutch slipping would normally just be free revving and shouldn't cause shuddering unless the flywheel or pressure plate have issues How many k's are on the current clutch setup ?

[DevilDRake]

I believe it's only about 10000ks so it shouldn't be shuddering. It's only happened in the last two week and its getting worse. Is there any tailshaft rubbers or anything on liberty's?

Edit: I'm starting to think its more drive train related as I have no issues stopping or taking off, just low rpm under load, starting to do it high rpm aswell.

I wish I knew more about these AWD cars, I'd like to be able to guess what would be the cause of this.

[Russ59]

I don't know what to suggest mate other than to try and see if there are any codes throwing up, without actually hearing it or driving it to feel what's going on it's difficult to say. I'm beginning to wonder if you have a crook coil pack or some electrical gremlin going on but it only causes issues when the engine is under load ??

[DevilDRake]

No worries, I did think about it being coils too but then I figured it doesn't always do it under load, only low RPM (so it would be firing less).

I had one more further inspection this morning, Full throttle in 2nd gear it'll go from 2000-4000RPM shuddering but still putting the power to the ground (well mostly), then it'll drop down about 400rpm to 3600 and stop shuddering and keep climbing the rev range as per normal. This is why I'm thinking it's the clutch or pressure plate. This all happens within the one second gap though obviously as it doesn't take long to climb in 2nd gear.

But it does drop down a few 100 RPM when it finally stop shuddering so it's either slipping and then gripping back on, or something cuts it for a split second but I can't figure out what.
It doesn't seem to free-rev, but i would say as it gets worse, it seems like it free rev's more.

I'm going to put it on stands this weekend and have a good look underneath at drive shafts/oil leaks etc, and see if i can find anything.

If not, I may try make a video of the cluster when I do it and you will see the needle fly up, drop down slightly (you may hear the shuddering) then climb as per normal. I wonder if I'll be able to feel shudder under the clutch pedal if i left my foot on it to see?

If anyone has more input of options just to check out let me know, I'll have a look when it's in the air on the weekend.

Cheers

[Russ59]

I guess a couple of other things to check would also be spark plugs ?? And what about your battery, how old is that, maybe it has a cell dying ?? You would be amazed what things can happen to the computerised technology on modern cars when the battery is on it's way out and they are especially prone to dying when cold weather strikes. Just trying to think of all the cheapest options first before going down the clutch path especially as it has only done 10000 k's !! I suppose it could always be a faulty clutch, it does happen

Best of luck with it be interested to hear how you get on

[GONEWALKABOUT]

if your having driveline concerns, get underneath and see if anything is loose, worth a shot. hopefully it could be something obvious

[DevilDRake]

Well a few more days have gone and I'm sure it's the clutch now.

at 100kph in 6th gear, if i flat foot the rev freerev now.. Looks like I'm clutch shopping!

[Russ59]

Sounds like it may have been a faulty clutch installed ?? 10,000 k's is an awfully short life span no matter how much of a beating it was dished up Be sure and post up the findings when you replace it, I'm sure a lot of others would be interested to hear what went wrong, and what brand of clutch it is / was ??

[DevilDRake]

It was a stage 3 exedy hyper single clutch kit. I believe that every- day driving killed it. The previous owner used it on weekends which made it fine but in the three months I've used it for daily driving, must have killed it.

Car is booked in Thursday, fitting an exedy HD in and machining the chromoly flywheel that's already in there form the hyper kit.