Weirdest clutch problem, Video inside.

**ajansen** · 26-04-2013, 11:40 PM

Figured i'd post this up to try and find out opinions.
Basically ive had problems of late at high rpm/boost where my clutch pedal will lower almost all the way to the floor, then as soon as i get off the accelerator it brings itself back up. Note the clutch will not slip, this is at 22psi 450+rwhp in 3rd-4th gears. not game enough to try 5th. normal driving is no problem shifts perfectly.

This video is in neutral and im not touching the clutch at all. The movement is purely the force of the clutch assembly. Was pointed out to my by HKSTRD that this is an odd occurance and only seen in Pull type clutches.

OPINIONS WELCOME.

**Rens** · 27-04-2013, 06:20 PM

Does the engine and gearbox move excessively during hard acceleration, putting pressure on the clutch line?

Where's that bracket meant to be fitted?

**ajansen** · 27-04-2013, 06:28 PM

no movement at all. poly mounts.

clutch line isnt being stressed. im planning to remove the slave all together then do the same test to rule it out being a hydraulic problem.

**dnegative** · 27-04-2013, 06:52 PM

Seen this before where if you rev the car pretty hard in 1st it will creep forward.

Why it does it, I have no idea

**ajansen** · 27-04-2013, 06:53 PM

this happens in all gears. but no slippage

**dnegative** · 27-04-2013, 08:10 PM

New clutch? The bearing looks like its pulling back on the diaphragm springs so if it was worn or you were making more power it would probably slip.
Can you get a video with you depressing the clutch pedal?

I've got a ACT 1JZ pressure plate here and to pull the springs back is fucking hard work so idk
Its got to be something simple

**ajansen** · 29-04-2013, 05:58 PM

pressure plate had done 5000km when I bought it. its done another 15000km on top. brand new everything else. so far im at 450+rwhp which I would have thought to be on the limit of a single plate with such light clutch pedal.

ill get a video of clutch operation tonight hopefully.

**4th surf** · 29-04-2013, 09:34 PM

I've seen this on a low mileage 120 series Prado. Problem noticed at higher revs in low range 4X4.

While not a turbo Supra the 120 Prado runs the V160 box with a pull type clutch. The vehicle in question is a Miner (mine site supervisors drive) and often in the pit or other such nasty places. Now these things rarely get cleaned due to the fact that if you have not done an induction to be able to use the washdown area you aint allowed to use it. The complaint? basically the same as you're having in that the clutch pedal would go down by itself but no slipping noticed. Hydraulics looked at and checked (suspecting leaking clutch master), no problem found, checked pedal adjustment, within specs. Couldn't reproduce the fault so returned it to service (remember everyone has a different driving style and when you aren't "passed out" to drive in certain areas on the site reproducing a fault is sometimes next to impossible), returned the thing to service and a few days later... "My clutch feels like trying to compress a brick and the pedal still keeps sinking". So asking myself why I hadn't done that before I removed the inspection covers on the bellhousing and found the problem.. Full of red dirt! So to the washdown area it goes, stick the HP hose in the hole with the engine running and work the clutch a bit. Problem solved. I ended up fixing both complaints.

So what I suspect your problem is is that you are using a used pressure plate, it may be slightly out of balance due to wear or previous "enjoyment". This may not be noticed as a vibration or shudder as such until higher revs where some fingers may lift thus pulling the slave out a bit and with the fluid displacement as a result of that the clutch pedal will sink.

**stealth** · 30-04-2013, 12:14 PM

So what I suspect your problem is is that you are using a used pressure plate, it may be slightly out of balance due to wear or previous "enjoyment". This may not be noticed as a vibration or shudder as such until higher revs where some fingers may lift thus pulling the slave out a bit and with the fluid displacement as a result of that the clutch pedal will sink.

Yeah this is what I was thinking, the cover being out of balance is causing an harmonic, but only at high rpm.
Clutch problems are such a prick, especially with a 154 I can imagine lol