Colin

Hey guys,
Non-GTO question. I have an LT1/T56 in my Vega. Yesterday I rewelded the clutch hydraulic bracket on the firewall to make the geometry correct. When I first tried the BMR Fabrication firewall bracket for my clutch the geometry was so bad that I bent my pushrod.

Yesterday, I cut and rewelded the bracket so I get a straight stroke. I did have to bend the pushrod a smidge to get it perfectly straight into the clutch master.

I have a few drops of clutch fluid that are leaking from the dust boot on the inside of the car. I am also not getting any disengagement of the clutch (verified with my wife trying to turn the rear axle with the clutch pedal pushed in).

There was a fair amount of air in the lines. She said that there are only tiny bubbles every once in awhile that are bleeding when I pump the pedal. The LT1 clutch hydraulics are bled by pumping the pedal.

Did I blow out my clutch hydraulics? Inititally, I thought that I didn't have enough stroke but I have over 1.5" and no clutch engagement. These are brand new hydraulics.

Thanks,
Colin

Colin

Alright, so I took the hydraulics off. Ten minute job. Should I be able to push the clutch fork in at all (toward the engine). I'm wondering if I'm not having a problem with my throwout bearing. All parts were new at the time of installation.

Colin

Update: I took off the spacer and bolted up the slave cylinder. It's bolted at the same installed depth as it would be with the spacer on (2"). Without further bleeding I wanted to benchmark if the clutch fork would disengage. The video tells the story.

The clutch fork is obviously moving. Thing is, I'm not sure it's moving enough. I filmed the video myself and couldn't get a measurement of the travel. I was told 15/16" is the travel but I'm not sure if that's at the master cylinder stroke or the stroke at the throwout bearing. No one has really defined that measurement. It's getting almost 1.5" at the master cylinder.

Look at that slave cylinder flex, though.

Now, about the setup. I have cut the master cylinder pushrod. It's been threaded with a rod end on it (3/8x24). I had a lot of air in the lines but I bled the system. I'm assuming there's little air now as the clutch picks up pressure as soon as I push the pedal. I'm wondering if it's a travel issue? i.e. not enough pedal pushing in the master? Anyone have an idea how much that clutch fork should move from rest to disengagement of the clutch disk?

I can feel it now, I'm close. :th:

10 pounds per horsepower should be fun.

Here's a link to the video: http://www.opseth.name/colinsfiles/T56Clutch.wmv

Colin

Another update: I bled my hydraulics today. There was a fair amount of air in the line. The pedal is now much more stiff. When I push on the clutch pedal it will bottom out the clutch master. I can feel the clutch master bottom out but I don't push any further.

No clutch disengagement whatsoever. Clutch fork is moving.

C'mon guys. This is the largest LT1 site on the Internet. No one here has any idea what my issue could be?

Colin

Alright,
So I found a spec for the LT1 T56 clutch fork travel. It should be about 17mm or 0.669291339 inches. That translates to roughly 5/8" of an inch plus a smidge. I measured my travel and am getting closer to 7/8" or plenty more than needed. I'm thinking it's a mechanical issue now, not a hydraulic one. What should I be looking for when I pull this sucker apart? I'll take pictures, obviously.

Colin

Here are pictures of the pressure plate with the transmission out of the car. Anyone see anything out of spec?

Colin

OK... Got it all apart. The very light surface rust is the remnants of when he cut my flywheel. He said that it would clear up during clutch break-in. The clutch pilot bushing is new. You can see a bit of grease in there remaining from when I installed and greased it. On the pressure plate you can see that the throwout bearing has been making contact. When I looked at the clutch disk and pressure plate, the clutch disk was firmly pressed against the flywheel. It did not stick in any way when I removed the pressure plate. In fact, they both slid off as a pair but weren't stuck to each other in any way. There is no appearance of any sticking or impressions of the clutch disk on either the flywheel or pressure plate, something I'd expect to see transferred if the clutch disk was sticking. The clutch disk is also clean on both sides with no grease or grime anywhere on it.

I did take a picture of the clutch disk from the side. It is a Valero unit (as is the pressure plate). You can clearly make out the "engine side" stamp in the metal. Is that the correct side facing the engine? All bolts were tight and about the same tightness, as I'd torqued them when I bolted the unit in. Hi-res images are available on request. These are about 1/2 the size of the originals.

rclearyiii

Everything looks good from what I can see in the pics. Maybe the flywheel was shaved too much? They do make shims to compensate for if so.

Colin

THANK YOU for a reply. I was starting to go crazy here, lol.

On my website I was chided for having so much surface rust where the throwout bearing rides. I can tell that the throwout bearing was pushing on the pressure plate but I suppose it's possible it was binding up even though it was moving. I was getting plenty of travel, verified by measuring the clutch fork travel at the slave cylinder hole (about 7/8"). Something doesn't make sense.

Did I have the clutch disk installed correctly, with the extended spring side toward the engine?

Another person suggested checking the clutch installed height. Where is that spec and how do I measure it?