This is getting no response in the tranny forum, so I'll try it here:

After I finished my T5 swap, I've had some vibration. It's RPM dependant, so it's gotta be from the trans forward. I thought it might have been because of my Energy urethane trans mount, so I pulled it out last night and put the stock rubber one back in. It's less noticable, but still there. So that tells me it's just as bad, I just don't feel as much of it because of the rubber mount.

While I did the t5 swap, I pulled the motor to replace the rear main seal, oil pan gasket & timing chain cover gasket. The motor seems to run fine and doesn't throw any codes.

The car has crisp throttle response and doesn't seem to exhibit any substantial vibration when I rev it in the garage, or at least none that I can recognize. It may have somewhat more vibration than before, but now that I'm looking for it, I may just be noticing things that were always there.

When I take it out, the vibration seems to come on at around 3,000 rpm, all the way to whatever RPM I choose to take it to. It doesn't seem to get significantly worse as the rpms increase though. Cruising along at 60mph in 5th gear I don't feel it.

I've checked that the plug wires were firmly connected at both ends, I checked my IAC and TPS, and I changed that trans mount. I had the flywheel resurfaced before installing the t5, and I've got a brand new Centerforce Dual Friction clutch, pressure plate, and self-adjusting throwout bearing. I checked for vacuum line leaks and couldn't find anything. After the car was off for 5 minutes I unplugged the vacuum canister and it still had plenty of vacuum.

The only "modification" is that one of the dog ears on the trans broke off and I had it welded back on, but I checked the deck with a straight-edge before I installed the tranny and it was as flat as can be. If it is high or low, it's only by a couple thousandths. There's no way something that minor could bind the input shaft could it?

Anybody have any ideas here? I'm afraid do drive the damned thing because I don't want to cause any damage.

 

don't take my word on this and check it out before you take any thing on. but i have a faint recolection of gm going to an external ballenced flywheel/flexplate with the later engines. that would explain why you have vibration problems after the trans install. a flywheel installed in the wrong orientation can throw the harmonics out of ballance. if i am wrong and the engine is internally ballenced, then check the flywheel to make sure the balence on it is true or that you installed the pressure plate correct (there are little painted dots that are supposed to match up). whatever the case, going back to the rubber trans bushing is just hiding some of the problem. remember to verify this because it may be s**t.

 

I've got an old 2-piece rear main seal block and I've never heard of a 2-piece block using a balanced flywheel except for the 400s. Of course, I've never heard of a 1 piece block with a balanced flywheel either.
What's this about installing the pressure plate correctly tho? If that thing is spinning around on a neutral flywheel, that sonofabitch better be neutal too!

 

>>What's this about installing the pressure plate correctly tho? If that thing is spinning around on a neutral flywheel, that sonofabitch better be neutal too!

what i mean is that the pressure plate and flywheel are weighted to be nuetral if oriented correctly. all i can say is that in all the clutches i've replaced, there has always been painted marks to line up. and as for my external incling, i think it only applies to the new ls1 and the older 400 as you stated.

 

Hey, I didn't read anything about installing a (new) pilot bushing/bearing. I have no experience with the T5's or even pulling automatics (and don't want it either). When I got my 81Z I had a vibration problem. I lived with it till I pulled the muncie out for a rebuild and clutch/pressure plate replacement. The pilot bushing was so worn out I could put my thumb in it! That caused two problems, 1st the clutch wasn't seating flat and would slip when starting up (hard) from a dead stop, 2nd since the input shaft wasn't properly holding the clutch assembly in alignment I had a vibration problem. The rebuild and new pilot bushing fixed the vibration problem. Automatics don't use pilot bushings, I don't know if T5's do either.

 

There is a certain amount of tolerance in how the clutch bolts up to the flywheel. That is, even though real clutch bolts (you did use real clutch bolts, didn't you?) have only a few threads and a larger shank between the threads and the head that sort of "dowel pins" the pressure plate to the flywheel, it's still possible to get the PP on the FW slightly off center.

Usually when I am installing the clutch I run the bolts in by hand, all 6 of them, while I hold the PP up and jiggle it all around, to make sure it's as centered as possible. I've also got into the habit of starting motors up with the PP bolted to the flywheel before I put the BH back on, to check for this.

Clutches as they come out of the box are supposed to be neutral balanced. I usually send the flywheel to the balance shop after turning, to make sure it's balanced too.

 

I had no idea there were special pressure plate bolts. I just used a pile of bolts that I had hanging around.

Are these bolts a dealer item or will an autoparts store have them?

EDIT: Looks like it's a dealer only item. I guess the car sits until next week. Anyway, thanks for the information. This just may be my problem. I'll swap bolts next weekend and see if it helps.

 

Speed shops have them in Mr. G and other brands.

 

We don't have speed shops. We have parts houses and a Chevy dealer.

 

EDIT: Looks like it's a dealer only item. I guess the car sits until next week. Anyway, thanks for the information. This just may be my problem. I'll swap bolts next weekend and see if it helps. [/B][/QUOTE]

Jim I am to have swap out an auto for the t5 I am having the same problem with the vibration. I have tried a new harmonic balancer but thta did not work. Please keep us informed as to the results of what you do and find. My car is in storeage and I can not do anything

 

I have the same problem. I need help to