I test drove my car with newly swaped t56. things went ok. i have a vibration though. most noticable under heavy acceleration, especially in second gear. i am thinking pinion angle. it was late and i didnt crawl back under it yet.

i would say there is a slight vibration when free reving the engine that wasnt there with the 700 r4 though. i did use search and saw some talk about the index marks on the FW/PP. i thought it was only a stock PP thing since my spec clutch said nothing in the directions about it. But now i am wondering... does the spec cluth have an index mark?

LT1 flywheel
Spec stage 3 pres. plate & disc
custom fab X-member w/ torque arm relocated to it
E.S. trans bushing
stock torque arm & rubber bushing

 

The pressure plate should have a mark on it. The question is though does your flywheel have one. My replacement flywheel did not have one so through trial and error I mounted the pressure plate each way without the clutch to find where it didn't vibrate. The last position I tried was the perfect with zero vibration.

 

I talked to spec tech department, they said it doesnt have a mark. but the guy did'nt seem all that sure of himself. Did you do that trial and error while leaving the bell housing trans off, free reving test? or did you put it together ever time and test drive?
Thanks

 

I ran it with no trans, throwout, or clutch disc. Just the flywheel and pressure plate. I free revved it at various RPMs. Just make sure you don't hit the clutch pedal while getting in and out of the car to test it.

 

The clutch for LT1 is neutral balanced.

If you had a clutch balance problem, it would be the same whether in or out of gear, light or heavy or no load at all, etc. Sounds like whatever your issue is, it isn't the clutch.

Could possibly be pinion angle but it's just a guessing game. It's dark out so I can't see up under your car too well right now.

With all that "custom fab" business, it's impossible to guess what's wrong; but I'd suspect it's somehow related to all that.

 

I've read numerous times people say it is neutral balanced but the instructions that came with my clutch clearly point out the balance mark and the white X on the factory flywheel. And I've read a few times people complain about vibrations and they took it apart to find the mark didn't line up. Once lined up the vibration was gone.

 

And that would explain the reference to "heavy acceleration, especially in 2nd gear" .... how?

See my signature for helpful troubleshooting mental discipline. Evaluate it one word at a time; in this case, concentrate on the part about "fits all the facts". Zero in on "all".

 

Yeah I missed that part. I jumped right to the vibration while free revving that wasn't there with the 700r4. I sometimes have a selective reading problem

 

I am going to start with the pinion angle, seems easyest and most likley. in referance to the custom fabed crossmember i was very care full to get the center of the out put shaft within a couple of mm of where it was on the 700R4. the torque arm mount has adjustment built in, so i have some wigle room there.

Is it possible if it is not the pinion angle, that it is just amplifying the problem when the car is under load/acceleration? essentialy turning the whole car into a tunning fork.

On the balance of an lt1 flywheel, if they where balanced nuetral, wouldnt that mean all lt1 rotating assemblys would have had to be balanced from the factory? the indext wieghted flywheel/flexplate for the one piece rear main engines was to ofset a known imbalance in the engine was it not? so why would the Lt1 retain the indexpin and bolt pattern? Is my logic haywire?

 

some pictures of the X-member, its not a hack job or anything. unless the torque arm mount is not rigid enough, i don't think it would be related to the crossmember itself.

 

I went under the car, not in the dark, to measure pinion angle. I think my transmission yoke may be shot. there is more play in the spines than I would expect. I was originally thinking great, the tailshaft bushing is shot. but I took the drive shaft off and I cant budge the output shaft a micron. I can wiggle the yoke pretty good on the splines,( side to side, not rotationaly) if I bury the yoke all the way into the trans it lessons quite a bit, but doesnt go away.

can anyone tell me what the normal amout of yoke shaft should be out of the trans. i have about 1 1/2". The seal is riding right where it was on the 700r4, but it seems excesive. I figure I have 2 5/8"on the splines.
I Am 99% sure the 700r4 was not the cars original, or meant for an f body, and now I am wondering if the drive shaft is right. I can make out what I think is an older wear mark a 1/2" farther up the yoke shaft. (there are some dents in the tunnel that look like a drive shaft may have broken at one point.)

I still have to measure pinion angle...

 

i measured pinion angle, it was at 5 degrees down. i changed that to 1.5 down. all road speed related vibration is gone. there is still an ugly vibration under load as engine rpm increases. it is there free reving as well, just not nearly as obvious.

so... on to the clutch.