1 2 3
Gearheadotaku
Gearheadotaku UltraDork
5/25/13 2:12 p.m.

Uh-oh.

Test drive didn't even get out of the garage.

Push in the clutch and you cannot select a gear, it's like you're not pushing in the clutch. Shut off car, select a gear and restart. Release clutch, car won't move.

Berkley.

Took everything back apart, (berkley), and cannot find anything wrong. Disc is facing correct way and you can see on the flywheel where it is touching. There are no marks on the pressure plate though. Hmmmmm

Disc fits the input shaft fine. With the trans out, I tried each gear and everything seems to rotate as it should.

1991 Firebird 305, T5 new LUK clutch

akamcfly
akamcfly HalfDork
5/25/13 2:19 p.m.

Bleed the master/slave?

If cable, check for kinks. Did you hook it back up?

Gearheadotaku
Gearheadotaku UltraDork
5/25/13 2:27 p.m.

If it were a hydraulic issue, the clutch would be stuck engaged allowing the car to move when in gear. I think....

Jaxmadine
Jaxmadine Reader
5/25/13 2:31 p.m.

Pivot arm bolt?

fasted58
fasted58 PowerDork
5/25/13 2:41 p.m.

not familiar w/ those but

wrong pressure plate or throwout brg.

.02

HappyAndy
HappyAndy SuperDork
5/25/13 2:53 p.m.

Hydraulic, cable or mechanical release mechanism? If its hydraulic is it an external or internal slave cylinder? I know from experience that the internal type can be a real PITA to bleed.

Gearheadotaku
Gearheadotaku UltraDork
5/25/13 3:30 p.m.

new hyd system. External. Pre-bled kit from factory.

anyone know where to get thickness specs for the flywheel?

iceracer
iceracer UberDork
5/25/13 6:29 p.m.

did you have the flywheel machined ?

When you bolt on the pressure plate, watch to see if the fingers move.

HappyAndy
HappyAndy SuperDork
5/25/13 6:58 p.m.

Since its external I assume it (the slave cyl) has a simple push rod that moves a clutch fork. Can you actually see the end of the push rod or the end of the clutch fork move? How far out of the slave cyl housing is the push rod, and did you compare the new and old slave cylinders and push rods? with everything new and un good shape the slave cyl push rod should be close to fully retracted before you push on the pedal.

Lastly, before you take it all apart again, try reverse blleding the clutch hydraulic system. Force fluid up through the slave cylinder to the M/C and resevior.

noddaz
noddaz HalfDork
5/25/13 7:01 p.m.

Interesting... Is the throw out bearing on the right place on the fork? It almost sounds like something is depressing the pressure plate. New hydraulic system? How does the slave cylinder look compared to the original?

Gearheadotaku
Gearheadotaku UltraDork
5/25/13 7:19 p.m.
iceracer wrote: did you have the flywheel machined ? When you bolt on the pressure plate, watch to see if the fingers move.

The flywheel was machined, but by the previous owner. How much finger movement should I see and at what time?

Trans_Maro
Trans_Maro SuperDork
5/25/13 8:27 p.m.

Busticated input shaft?

Gearheadotaku
Gearheadotaku UltraDork
5/25/13 10:50 p.m.

the use of a flywheel shim was suggested by the guys over at 3rd Gen. ATP sells them but I never used on before. Thoughts?

Trans_Maro
Trans_Maro SuperDork
5/25/13 11:03 p.m.

Hmm..

Did this pressure plate have a diaphragm spring or was it the old truck style with coil springs and three levers?

I'm asking because a couple years ago we put a pressure plate (three lever style) in my buddys ramp truck and had intermittant clutch issues.

It turned out that the clutch company included a throwout bearing that was a bit too small in diameter.

It would slop around a bit when it engaged and would only push two fingers ot it would catch and drag on disengagement.

We finally found a correct T/O beaing for the truck-syle pressure plate and the problems away.

This was in a Chevy 350 powered truck with a 4-speed.

iceracer
iceracer UberDork
5/26/13 11:06 a.m.
Gearheadotaku wrote:
iceracer wrote: did you have the flywheel machined ? When you bolt on the pressure plate, watch to see if the fingers move.
The flywheel was machined, but by the previous owner. How much finger movement should I see and at what time?

As you press the clutch pedal, the release mechanism pushes the fingers toward the flywheel which moves the pressure plate away from the clutch disc.

From the position of the fingers before, you should see them move out as you bolt down the pressure plate, not a lot, but will indicate that the problem may or not be the clutch. In the hundreds of clutches I have replaced, I never saw a need to machine the flywheel. If it is that bad, replace it.

Gearheadotaku
Gearheadotaku UltraDork
5/26/13 4:08 p.m.

update.

diaphragm type plate (lots of small fingers) yes they move when tightening down the plate

Put the clutch and cylinder back together and used an old input shaft as a trans stand-in.

Pedal out: Disc seems locked in place, can't turn the shaft (without turning motor) Can wiggle the T/o bearing a bit.

Pedal in: Shaft can be turned.

That all seems normal to me.

Clutch fork is only moving about an inch at the cylinder push rod, not enough to break the plastic retainer packing strap.

Checked the master rod movement at the pedal, seem to be getting full travel. Disconnected at pedal, it did not pull out of cylinder further.

Why did I check that? When installing the operating cylinder, you have to push the rod in a fair amount to get everything to line up. Was wondering if the master was holding operating cylinder out a bit. Doesn't appear to be.

The more I think about the cars behavior, its like the clutch is stuck 1/2 way down. The cylinder should move more and not be such a fight to install.

Junkyard_Dog
Junkyard_Dog Dork
5/26/13 4:31 p.m.
Gearheadotaku wrote: Clutch fork is only moving about an inch at the cylinder push rod, not enough to break the plastic retainer packing strap

Um, are we sure this isn't supposed to be removed on assembly?

Gearheadotaku
Gearheadotaku UltraDork
5/26/13 4:39 p.m.

They're suppose to snap the first time you hit the pedal.

GVX19
GVX19 Reader
5/26/13 6:07 p.m.

After you check every thing is correctly installed. And the clutch is working correctly. Push the car out to the road. Push start it. Press the clutch in while driving and hit the throttle if the clutch slips. Keep doing it until you burn off the excess material.

mad_machine
mad_machine MegaDork
5/26/13 6:59 p.m.

silly question. If you replaced the slave and master Cylinders, did you bleed them?

HappyAndy
HappyAndy SuperDork
5/26/13 6:59 p.m.

In reply to Gearheadotaku: this all sounds as clear as mud. Is the clutch slipping / dragging, or not releasing at all? I thought it was not releasing, but the comment about the pedal being stuck half way has me confused.

I still think that you need to reverse bleed it. I'll explain why, clutch hydraulics are a bit different than brake hydraulics. Brake MCs (with some exceptions) have a spring to fully return the push rod and open the ports for fluid to flow into or out of the resevior. Many clutch MCs are different, they don't fully return to open on their own, but relie on an external spring in the oedal linkage and the the pressure of the fluid pushing the MC piston back out (this pressure comes from the spring in the pressure plate pushing back on the the clutch fork or hydraulic throw out bearing when the pedal is released). By reverse bleed bleeding you will be pushing fluid up through the system which will push the clutch MC piston all the way out to the end of it's travel, forcing any air trapped in that MC to go back out through the resevior. When thats completed the clutch MC should be able to move the slave cylinder through its full range of travel, ehich it sounds like it can't do now.

.

Gearheadotaku
Gearheadotaku UltraDork
5/26/13 7:10 p.m.

In reply to HappyAndy:

The "pedal half way" is the best description I could find for the behavior of the system. Not engaged enough to move the car, not released enough to allow shifting with the engine running. the pedal moves it's full travel and has normal resistance the whole way.

My experience with failed hydraulics leaves the clutch engaged allowing the car to drive, but not shift.

There aren't any bleed valves in the system, it's supposedly pre-bled and ready for install. There is fluid in the reservoir. New defective hydraulics?

This is a retro-fit job so I don't have any old parts to compare to.

egnorant
egnorant Dork
5/26/13 10:04 p.m.

Have you ever driven this car? Has the transmission been verified? With the checks as reported, I would begin to suspect the transmission has problems.

When running and you try to place it in gear is it grinding or just won't slip into gear?

Bruce

Gearheadotaku
Gearheadotaku UltraDork
6/1/13 6:28 p.m.

Update:

Put everything back together, Can engage gears without grinding now, car still won't move. Can turn driveshaft with car in gear, (engine off) can hear the disc slipping against the flywheel or plate. Removed slave cylinder, same results.

Loosen trans to bell housing bolts allowing trans to move back about 1/4 inch. Clutch feels now feels engaged, cannot turn driveshaft.

There are 2 different flywheels for 5.0 cars with 1 peice rear main (found this out after I put this together) TBI shows a different wheel than a TPI.

Why?

The TPI looks like a lighter unit and is what I have in the car. In pictures it looks like it may be taller, and would cause my problem. But they use the same clutch.....

So, do these cars have different crankshafts?

Is there more than 1 V8 Bellhousing? Shorter bell would cause this too.

Lastly, I have a Non-WC going into a 1991 car. The bell and trans came together so I know they match. Came from an '86 T/A.

Cross posted over to 3rd Gen as well.

fasted58
fasted58 PowerDork
6/1/13 6:37 p.m.
Gearheadotaku wrote: Update: Loosen trans to bell housing bolts allowing trans to move back about 1/4 inch. Clutch feels now feels engaged, cannot turn driveshaft.

Throw out bearing too long?

1 2 3
Our Preferred Partners
eG4XD8St7ka2qBURFzQAyb5PUmEsLWBTo99Y8Zgt4vhJHU1s6d6rsyHbv9nv0V56