Tremec Question

[GMJim]

I'm with Jody. Take it apart and put it together by the numbers.
Jim

[Jeremy]

The vibration is present when tested while the car is not moving. When the car is moving, the vibration is present at all times, just worse the more load that the car is under. If I am cruising in the range where the vibration is present, it is hardly noticeable. If I am getting on it, it is worse.

As for replacing the other parts, I am not too upset with that. I had an even worse vibration that the driveshaft fixed. The factory axles kept eating bearings as they were slightl scored. The rear end had seen 200 K miles.

The flywheel was factory and the clutch cheap, so I didn't mind replacing those. I did not have the money when I built the car the first time. Overall I don't feel that I spent money on things that did not need to be replaced.

I will pull the tranny this winter and check the bellhousing alignment. Is there a way to check the input shaft bearing without disassembling the tranny? If it needs to be replaced, is this something that I can do or have a shop do? I have talked with the tranny shops in the area and they either won't or don't know if they can work on Tremecs.

Thanks to everyone that has chimed in to this point.

[GMJim]

Jeremy
Best way to check the input shaft bearing would be to check end play. It should be .000" to .004". End play is the movement directly in and out or forward and backward in line with the output shaft. If you can wiggle the input shaft and you get excessive side to side movement then end play should be checked. If not then don't worry about end play. Just a note about vibration under load and no vibration under light load at the same rpm. If a weld yolk on the driveshaft isn't welded on straight or if you have a U joint worn or offset (as in a dropped needle bearing lying in the cup). This will cause a vibration. One other thing to check would be the rear end. How much does the driveshaft angle change under load? Is the rear suspension up to snuff? Bushings, springs shocks etc?

[Jeremy]

The rearend was rebuilt by a pro with new gears and everything. The bushings and shocks are all new. The pinion angle has been checked and re checked and everything is as recommended.

Everything and I mean everything but the tranny has been gone through. That's why I am leaning to an out of alignment bellhousing or a worn bearing on the tranny. I wish it wasn't so.

[GMJim]

Jeremy

I know your frustration! It's difficult to believe that the vibration is actually inside the transmission. I think you are on the right track with the bell housing alignment. When you pull it apart examine each component closely before you take the next thing apart. Get back to us when you do the job.
Jim

[Jeremy]

Well, the vibration may be engine related.

About a month ago I changed from a 180 t stat to a 195 t stat. The car ran better but I started getting some run on.

Today I backed the timing from 18 initial to 12 initial and switched to ported vaccuum for the vaccuum advance and drove the car. The vibration has shifted higher in the rpm range by a good margin. The vibration is not noticeable until after 3-3500 rpms.

The motor revs freely and I get a hint of vibration at redline.

Part throttle response takes more throttle input now but the car is still pretty responsive. The car does not feel as strong up top (according to the butt dyno) but seems to rev quicker.

The idle is smoother and lower as well with less drop off when I turn on the AC.

As for the idle, I can increase it with the idle screw as I only changed timing. I may try manifold for the vaccuum advance and see if that makes any difference.

Any thoughts as to why the timing change made a difference on the vibration?

[GMJim]

Check the advance curve mechanism in the distributor. Make sure it's working and set up to max out at whatever your motor likes without pinging (detonation). You may be experiencing an ignition problem.
Jim