nikon

iTrader: (2)

Doubtful its randomly picked up a miss when he changed motor mounts...At this point it could be your flywheel, but I think you would have felt it with the old mounts too. Possible that one of the weights is sticking on the flywheel.

raven154

iTrader: (14)

Dose it vibrate when the clutch is drepressed and you rev the engine while not moving? Or, does it only do it driving?

PSIEDV6

OK, so far I have changed the balancer, plugs and wires. I am still having a pretty good vibration at 1900 - 2700. The vibration is still there when clutch is in not moving or moving. It is not the drive line, this is a motor issue.

So can someone tell me how the flywheel gets out of balance?

Also is a LS7 flywheel and clutch a good upgrade or is there a better way to go?

TexVette

iTrader: (2)

I don't know much about the dual mass flywheels other than they suck. LS7 clutch/flywheel is one of the consensus upgrades if staying under ~ 450 wheel and you don't drag race a lot. At least you're narrowing down the problem. Very interested to see it fixed.

Is there good clearance between the bellhousing and body of vehicle? Also, around the back of the heads?

Can you get a video of the motor bay when this happens (maybe have someone rev it)?

qwank

iTrader: (3)

Is there a flywheel you can use to replace the dual mass style that will work with the stock clutch and throw out bearing for people that are planning on staying mostly stock?

nikon

iTrader: (2)

The flywheel can get out of balance of one of the springs fail..weights move outward as the rpm rises (dual mass) . It could very well be your problem...or the truck motor is just trying to jump out of your car and into a pickup :-)

TexVette

iTrader: (2)

I have not heard of anyone doing "just" a flywheel. They usually get the ls7 package that has a new clutch and flywheel together.

If you go to single mass flywheel, you get the katech spacer to use your stock throw out bearing.

The LS7 throwout will work and you will not need to get the spacer with this one.

serik21

Did you check your motor mounts?

BudRacing

iTrader: (3)

Completely sounds like the DM flywheel to me. I changed mine out and a lot of the vibrations went away along with the huge shutter at shut down... and this is with stock motor mounts on a 100k car. There are still some slight vibes at idle, but I'll attribute those to the motor mounts and nature of the engine.

jmargo

iTrader: (10)

As in installing the new UMI mounts correctly ?

qwank

iTrader: (3)

I installed my UMI mounts a few days ago, and I also get an engine vibration. I can feel it at all rpms, but mostly 2500+. I'm thinking its the flywheel also. and I also get the vibration at 800-900 rpms that feels like the car is going to shake apart (feels more like a typical engine grounding out), but I'm guessing that's a result of the almost solid design of the mounts.

Fuzzy_Wuzzy

iTrader: (8)

I think a lot of this is the nature of the mounts, i just put them on my car too (w/32000 miles, vibes are noticeable at idle, if bogging the engine a little, and in that 1900-2500 rpm range. although on the highway i can't tell the difference.

I have not had a chance to dig around on the car any, the balance does appear to have a slight wobble to it when running, but i don't know what new looked like either.

DMM

This is why I asked UMI if they could make the mounts with softer rubber bushing vice the solid poly bushings in their introduction thread...and I was labeled an ******* for doing so. Shocking that everyone finds them too rigid for installation in a Cadillac.

qwank

iTrader: (3)

I agree, I think regular rubber bushings would be perfect. I'm pretty sure mine came with the part numbers of the Prothane bushings they used. I'll see if I can cross reference them to see what application they are used for and if softer rubber ones are available.

Scott96LT1

iTrader: (2)

Oh no. GM decided not to correct this. But that vibration complaint makes me wonder. I have a weird noise on take off from a stop that occurs at no other time. I'm going to do UMI motor mounts and CS trans and diff bushing along with the LS7 clutch within the next year. I hope that dumbass noise goes away. I ran my Camaro today while revving with the throttle cable and watched the whole body torque to the driver's side (its got prothane motor and trans mounts). I need my V to be like that.