Clutch Issues
 

Hi All,

Last week I was reversing onto my drive when I suddenly started to loose drive (unfortunately my music was quite loud at the time so I can't say if it made a noise or not!); so I put the car into neutral and since then it will not go into any gear.

Below is some more information:

2004 6 Speed MT (42,000 miles)
Exedy Stage 1 Clutch (2000 miles)
ACT Lightweight Flywheel (2000 miles)

The releasing bearing, pilot bearing, pilot bearing seal and clutch hose (now stainless steel) were all replace at the same time during an engine swap.

The clutch pedal is intact (Oddly we don't seem to have the issue at all in the UK compared to the US)

There is no fluid visibly leaking from the master/slave cylinder or hose.

There is no air in the system as this has been bled today.

I can see that the push rod is moving sufficiently when the clutch is depressed.

The engine noise does change when the clutch is fully depressed but still not enough to select a gear.

It will not go into any gear while the engine is running but will when engine is not running (presuming fork is ok)

I have absolutely no issues with the clutch in the 2000 miles since it was installed.


Any ideas?

Thanks all :)

Going to drop the box off and grab a look; from local specialists they say it is either the pilot bearing or the friction plate.

My guess is that it will be neither.

Hi Charles,

I appreciate you haven't seen the car but what would be your educated guess?

Thanks.

I'm not Charles, but I would say that the master or slave clutch cylinder is bad.

That was my first thought too however there is absolutely no visible fluid loss around the firewall from the master, the slave is fluid free around the rubber boot and the push rod is still moving.

Are there any scenarios in which the master can fail without visible fluid loss?

Didnt you say you can see the push rod moving , Im assuming you mean the push rod in the slave cylinder.

The internal seals can fail and fluid can bypass. So when you push the clutch pedal in fluid bypasses the seals and does not create hydraulic pressure. Thus not engaging the clutch forks. That can happen to either the slave or the master cylinders.

Explain "the rod moves". Which rod? Master or slave?

Which makes me wonder what was happening when you bled the system.

Easy, I agree about the seals failing and by-passing, on the Brake Master, but wouldn't fluid be visible leaking if it were the clutch cylinder , as it only has the 1 seal in it .

Thanks for the responses guys.

CRO8TIA: Yep.
Easy: Both.

There is good pressure.

Rat, the only thing I can think of ,apart from an internal issue, is the clutch fork is flexing or is fractured, can you drop the starter, use a mirror and flash light to look inside the bell housing while some one operates the clutch . Sorry I cant be more help.

And yes, if the pilot bearing is flogged out, it will cause your symptom's, I have seen worn pilot bearings that cause your issue, and some that dont.

Well, we have seen some pretty weird stuff with the clutch system in the RX-8, but assuming your visual inspection of the pedal assembly is valid...... my guess would be a failed release bearing (as opposed to pilot bearing) or a failed hydraulic system (as alluded to by my associate, Easy, and my friend, AlNielsen).

Pilot bearings rarely fail unless it was not greased after a swap. In the event the pilot bearing DID fail, it causes incomplete clutch disengagement (which will lead to hard-shifting and destruction of the synchros) by inducing clutch disc oscillation. This is the clutch disc and input shaft wobbling and causing incomplete disc disengagement.

On the other hand, when the release bearing collapses, it causes incomplete pressure plate action which also causes incomplete disc disengagement.

I would think so, too.

The fork is pretty robust and not likely the problem unless the fork fell off the pivot point, as there is a spring-clip that holds it on the pivot ball. This might be visibly observed with erratic fork motion outside the bellhousing as it travels through it's motion when the clutch pedal is pressed. When the starter is removed, not much is visible other than a pressure plate bolt or two.

I'll trow this one in, maybe the fingers on the pressure plate have failed.

Thanks for all of the thoughts everyone!

Fingers crossed it is the pilot or release bearing. Slightly frustrating since they were both replaced 2k ago.

The engine was replaced at the same time (by a reputable UK based rotary specialist) so it has barely finished the run in period which should at least testify to the clutch not being abused.

I'll hopefully give you all an update after the weekend once I've had time to drop the box.

Cheers :)

It was the pilot bearing; I'll get some pictures up tomorrow.

The place that installed the last pilot bearing are a UK renowned rotary specialist and the guys who do the work there race RX7s (and an RX8 with a 20B mmm) so I would be surprised if they made any mistakes.

Besides not being greased; what could cause a pilot bearing failure in such a short period of time?

Shallow installation, cockeyed installation, too much force used during installation, wrong size/application, no pilot bearing seal used.

Pilot bearings rarely fail absent these issues so this one is curious to me.......... :dunno:

the most common is actually lack of lubrication and heat fatigue related failures.

mazda either does not lube them or they use too little to even notice that they are lubed at all, i always pack about a tablespoon of grease into the bearing bore and haven't seen any recurring failures yet.

pilot bearing failures are actually fairly common in the 8 for that reason.