I have a vibration at 3000-3200 RPM. I have been thinking it was from the new clutch flywheel installation, but now I think maybe the AC, b/c when I turn it off it smooths out. What could be the possible culprit? This is on the 96.

 

I would bet it's the new clutch/flywheel. How were they balanced? I have the same problem with mine, btw, although it has quieted down a little with the new ATI balancer.

Mike

 

Give details on the new clutch/FW. Single mass, dual mass? Was it match balanced to the old? This is the typical vibration range for the flywheel balance problem. Also, do you feel it at any higher rpm's (4200, 4500)?

 

Guys, Read his OTHER post before you respond.

http://forums.corvetteforum.com/show....php?t=1099098

Did you check the flywheel? Did you take it back to the dealer???

In your first post you said the vibration started AFTER the dealer install a new flywheel and clutch...

 

USAF.. do you have the old flywheel?

 

He does.. Read first thread...

 

Yeha that whole discussionb originated from my earlier post...I am still trying to get a handle on it, and I think it may be in the accessory drive, because it goes away when I shut off the AC. There still may be a clutch/flywheel issue at the higher RPM though.

 

Did a shop do some work on your engine and leave off the braces that go from the bottom of the A/C to the exhaust bolts? It happened to me. I finally tracked it down and bought the parts from Chris at Superior and plan to put them on next week.

There are two sets of braces. There is the bracket that goes from the alternator back to the intake manifold, and an accompanying brace that goes from the alternator to an exhaust manifold bolt. Then there is the pair of braces that go from the underside of the A/C mounting casting to the exhaust manifold, secured on a different bolt.

They don't all show up in the same parts drawing, so don't trust what dealer parts guys say. I've been to the parts counter and been told the wrong story. There should be a total of 3 that go down to the exhaust manifod, secured in two places.

Now, I have a 94 and the 96 COULD be different. These braces missing will cause a rev dependent vibration with the A/C on. On mine it is now about 3200. When I was missing the brace from the alternator the vibration showed up at about 2200. It also shows up when just the heater is running, and goes away entirely when I switch the heat-A/C to off.

 

Look at Figure 38 on page 1B-39 of the Helms. It shows one brace there. I have looked at two other bone stock 94s and they have two braces there. I was able to buy two and will begin the teardown and install next week.

This brace (or 2 braces) do not show on the drawing for the alternator support, and that's where the parts guys go wrong.

What I bought are numbers 10105400 and 10128423 for braces and 9440071 for the bolt shown.

 

I dont have helms, I have chiltons. I'll take a look in there but can you send me a pic of your own?

 

I can't get my camera down in there to take a useful picture. While tearing things down to add the braces I'll get some pictures.

I'll experiment with using my camera to post the page of the helms.

 

There should be 3 braces / brackets that attached to the AC and alt. Check the bolts. Dealer forgot to tighten down my alt and ac bolts and belt almost feel off... lots of vibrations.

you really should take the inspection cover off the bellhousing and check and see if the dealer added weight to the new flywheel. Make sure they put the weight in the correct holes.

robert

 

I can't get my camera down in there to take a useful picture, it would have to go where the ASR module sits. While tearing things down to add the braces I'll get some pictures.

I'll experiment with using my camera to post the page of the helms.

 

OK, Here's a picture of the back of my AC compressor. The Braces are missing right now. You can see the braces for the alt at the top right.




Here's the page from the Helms, Vin P at the bottom.



Hope this helps. These braces will cure the vibration you have with the AC running.

If you are missing the balance slugs from the flywheel you will have a vibration, probably worse than I have from these missing braces.

 

USAFPILOT,

Here's the after photo from installing the two AC compressor braces I bought from Chris at Superior. It did cure my vibration with the AC on.



If those guys at the dealer left out the weight slugs on your flywheel, they probably don't even have the service manual. Those morons may have left off this brace, although I don't know why they would have to be in here for a clutch repair? Maybe a brace was left out previously? I believe the late 94 to 96 cars would have nly the brace nearest the engine and not the outer brace that is held by the AC compressor bolt.