Drivetrain Vibrations

[Greatwhitet/a]

Hey guys,
I am chasing a vibration. From what I understand this is a common problem. Here is the dirty: I have a LT1 M6. The vibration starts around 70 and increases from there. It only occurs at those speeds accelleration or deceleration. It is especially noticeable with clutch in. The vibe disappears with decreased speed. I have just had my pinion bearing replaced, and the mechanic who has years experience with rearends said things looked good. Vibe still there. When I put the car on jackstands the vibration is still there. Hence, no tire issues causing it. What am I looking at here fellas?

[zooguy]

Stock tues cars have poorly balanced steal drive shafts. Get one out of a LS1 they are balanced better and aluminium.

[Greatwhitet/a]

Good suggestion. My fault for not listing that the drive shaft is aluminum. Do these go out of balance often. I have had this looked at, and the fella said the shaft looks good. (over 30yrs experience and all his business does is driveshafts). Also I am thinking it maybe either trans related or axle related. Could the bushings on the trans and torque arm be bad and cause this? Also could a bent axle cause this? If so can you swap axles from a v6 rearend into an V8 one?

[95ImpySS]

A bent axle will cause vibration. You cannot just look at a drive shaft and tell if its balanced. You should pull it out and have a shop put it on a balance machine to double check it. If the bushings on the tranny are shot there will also be a viberation. A buddy of mine had a viberation only in 5th and 6th gears. Turned out the bushings for 5th and 6th were gone. The rest were about to fail. Have you changed your pinion angle? If you have any adjustable suspension parts that are not adjusted properly your pinion angle could be off and causing vibration.

I'm pretty sure you cannot swap axles between v6 and v8 cars.

[Greatwhitet/a]

I hate to say it, but I think the 5th and 6th gear idea is a good possibility on this car. I have heard it is a rather expensive situation. Any advice on how to deal with a t56 rebuild in an economical manner would be greatly appreciated. As far as the axles(not driveshafts to clarify) are concerned, I was under the impression that the both the V6 and V8 models came with 10 bolt rears with 28spline axles. The differences were the gearing and posi option. (maybe TCS and ABS too; hear about odd combo's from the factory here and there)

Also how did the trans act with the bushing issues?

No pinion angle changes by the way.

[Greatwhitet/a]

For anyone that comes by this thread and is looking at the same problem. I am going to list the parts replaced and what they did in my search for the solution here...

1. Initially my vibration was ridiculous...I took 95impyss advice and visited the local driveshaft guru... lifted the rear of the car and spun here in 6th to highway speeds and a little beyone. Me oh my!!!! Shit was bad. Clink, Clank, Clunk, Ratty, Tatty, Tat, with a few whirls and whines too. First discovery, the pinion bearing was shot and the pinion could be moved easily up and down by hand. So took her to a mechanic that is good with rear ends. Gave him 300$ and he said he would fix it. Week later its fixed.

2. Two weeks later she is whining like a mofo and leaking rear fluid etc... she is not fixed. Take it back to the guy, and he is like "my daughter's car whines like that all the time she is fine" Valuable lesson here - in the 3 years since I have handed the car over once to allow someone else to wrench on it. All other work has been done by me. And this was a "perfomance specialty shop" Needless to say my blood still boils.

3. I purchased new 46k 3.23 rear out of a 35th anniv camaro, new fluids.... installed it in the apartment parking lot at 3am... spent less than the money I lost.

4. Clunking and Clanking Fixed... still had vibes... ends up the driveshaft is a aftermarket aluminum shaft never had the balance checked to this day (and was and is fine), but the u joints looked suspect. New hi perf U joints bought. yep tried to melt the old ones out-didnt have flame hot enough. Trusted shop installed. small improvement

5. Wheels were balanced at the start of all this, but decided to recheck them. This time looking for any bends, flats... wheels balanced with weights on inner and outer lip too.
Wheels did have ever so slight wobble on right, and being 17x11 didn't help. Unfixable for several years still vibing the passenger seat at high speeds and noticeable in pants and stick.

6. New poly motor mounts and rubber trans mount. My headers were banging the k member in the turns, so.... wow. BIG diff. I love my prothane motor mounts!!! Not suggesting the trans mount. But the combo of motor prothanes and rubber trans mount=just the right amount of firm and vibe absorption. (I do drive this car everyday)

7. New clutch...old dual compound clutch was fried I think composite and kevlar? anyway since day one I had chatter but with a clink.. well I always though it was inclusive in the chatter. Nope all the clutch springs were toast as in snapped into several pieces. Not sure how much this helped the vibes, but I know the new clutch didn't hurt.

8. New wheels- Finally 90% smooth...This made a huge difference in the high speed category. 70+ is buttery now. My tires in the back are still wide @ 10", and I am running 19" tires with around 1" less sidewall. Yes, larger overall diameter than stock. No, I have no ABS issues.

9. Biggest helpers obviously rearend and wheels. Last mod needs are new bilsteins... next few months.

[nateleduc]

For anyone that comes by this thread and is looking at the same problem. I am going to list the parts replaced and what they did in my search for the solution here...

1. Initially my vibration was ridiculous...I took 95impyss advice and visited the local driveshaft guru... lifted the rear of the car and spun here in 6th to highway speeds and a little beyone. Me oh my!!!! Shit was bad. Clink, Clank, Clunk, Ratty, Tatty, Tat, with a few whirls and whines too. First discovery, the pinion bearing was shot and the pinion could be moved easily up and down by hand. So took her to a mechanic that is good with rear ends. Gave him 300$ and he said he would fix it. Week later its fixed.

2. Two weeks later she is whining like a mofo and leaking rear fluid etc... she is not fixed. Take it back to the guy, and he is like "my daughter's car whines like that all the time she is fine" Valuable lesson here - in the 3 years since I have handed the car over once to allow someone else to wrench on it. All other work has been done by me. And this was a "perfomance specialty shop" Needless to say my blood still boils.

3. I purchased new 46k 3.23 rear out of a 35th anniv camaro, new fluids.... installed it in the apartment parking lot at 3am... spent less than the money I lost.

4. Clunking and Clanking Fixed... still had vibes... ends up the driveshaft is a aftermarket aluminum shaft never had the balance checked to this day (and was and is fine), but the u joints looked suspect. New hi perf U joints bought. yep tried to melt the old ones out-didnt have flame hot enough. Trusted shop installed. small improvement

5. Wheels were balanced at the start of all this, but decided to recheck them. This time looking for any bends, flats... wheels balanced with weights on inner and outer lip too.
Wheels did have ever so slight wobble on right, and being 17x11 didn't help. Unfixable for several years still vibing the passenger seat at high speeds and noticeable in pants and stick.

6. New poly motor mounts and rubber trans mount. My headers were banging the k member in the turns, so.... wow. BIG diff. I love my prothane motor mounts!!! Not suggesting the trans mount. But the combo of motor prothanes and rubber trans mount=just the right amount of firm and vibe absorption. (I do drive this car everyday)

7. New clutch...old dual compound clutch was fried I think composite and kevlar? anyway since day one I had chatter but with a clink.. well I always though it was inclusive in the chatter. Nope all the clutch springs were toast as in snapped into several pieces. Not sure how much this helped the vibes, but I know the new clutch didn't hurt.

8. New wheels- Finally 90% smooth...This made a huge difference in the high speed category. 70+ is buttery now. My tires in the back are still wide @ 10", and I am running 19" tires with around 1" less sidewall. Yes, larger overall diameter than stock. No, I have no ABS issues.

9. Biggest helpers obviously rearend and wheels. Last mod needs are new bilsteins... next few months.

Just something to add for others to view. I've been chasing down a vibration for awhile now. At first I thought it was my Transmission causing the problem. I had it rebuilt by Texas Drivetrain Performance. But still the vibration occured. Next I had the U joints replaced and balanced (ls1 DS). Still, vibration occured. I replaced my engine mounts and trans mount with poly mounts. Still a vibration.

Finally I swapped my rear axle for a buddies who didn't have the issue. No more vibration.

Moral of the story, research fully. What I've found is that I have a vibration regardless of what gear. If you still have the vibration in 4th, as well as 5/6th. Chances are its not the transmission, but something else.

[93camarolt1m6]

i have a vibration when cruising light throttle replaced all bearings in rear, swapped tires and rims for 2000 model camaro stockers, the only thing i havent done yet is swap drive shaft out for an aluminum ls one but jk yards here seem to never have any so i may have to invest in a new one. but when i first bought my car the vibration was so horrible it felt like you was really riding on rail road ties and after all i have done i got it 80% improved so like i am thinking new ls drive shaft and maybe new torque arm bushings. anyone else with any suggestions?

[Greatwhitet/a]

Seems like driveshaft would be right on track if you haven't gone aluminum yet. Try and find someone parting out a Ls car here, lstech, craigslist, Fbody Facebook....

Sent from my XT907 using Tapatalk

[bigtoyz]

I might still have my stock one laying around here that was good. I replaced it with a spohn chrome moly one when I did my engine build. If anyone would need it let me know and I'll try and find it. Just pay for the shipping and you can have it.