digmyvette

I purchased a 2000 C5 coupe about a year ago. It had 69,000 miles and two owners. The first owner serviced it at the selling deal for twelve years and ended up trading it in for a new C7. The second owner had it for a couple of years until I purchased it from the same dealer. It looked all original from the plug wires to the tail pipe. The car ran/runs good, no real problems except there is a harmonic vibration between 1600-2400 RPM, rolling or not, clutch in or not. I have changed the clutch (new weights in correct place on flywheel), new torque couplers, new harmonic balancer, spark plugs and wires and a/c compressor. Water pump not noisy or leaking, but have not been able to isolate the source of the vibration. I have heard some say "they all do it", but my 01 vert didn't. You can feel the vibration thru the steering wheel which is making me think engine mounts. Has anyone else had this problem and if so, were you able to correct it?

Bill Curlee

MAN,,,, The engine mounts would be a VERY GOOD place to start!! Ive seen them outright FAIL. That would be a very logical and not all that expensive place to start as they do age and separate!

Unless you have a high HP engine, the replacement OEM mounts are good. I would also look at the trans mount for damage also.


BC

digmyvette

Thanks for the confirmation. I checked the rear mound when we did the clutch since it was all out. Its good with no signs of wear but will change soon anyway when I fix the ripped axle boot that tore while the rear was out. Engine is stock now but would like to do a cam/head/intake/throttle body/MAF/header/tune package next year at tax return time. Lingenfelter had a camshaft, I think it was GT2-III by CompCams (XR275HR) I had in my 2001 Vert which dyno'ed at 386 RWH (with AR long tube 1 3/4 headers, crossover pipe, Veraram and a tune). Car ran strong. Specs are 112 lope separation-110 centerliner 275/277 duration with 0.566/0.0568 lift. Checked the web site now and it's not offered, but CompCams still has it. I would like to be close to 500 RWH so if we get 425 on the dyno, we'll be close!

Bill Curlee

Well,,,,,,, If you have the HP to stress OEM mounts, I really don't think your going to worry about the little bit of extra Vibration and Harshness that a good set of POLY MOUNTS will introduce.

Polyurethane Mounts. I think Hinson has a good set but they are EXPENSIVE!

http://www.hinsonsupercars.com/p-860...-corvette.aspx


Bill

vettenuts

How long after the clutch swap did the vibration start?

digmyvette

The vibration was there since I bought it. Thought it might has been the torque tube couplers but no change after replacement. Replaced the clutch assy. due to time/miles; it looked original so I don't think any of the weights came off the flywheel. Changed the balancer for same reason, PM. Nothing abnormal in the torque tube, bearings were solid so didn't change them. Will change the motor mounts with Hinson's in a couple of weeks and post the findings.

73Corvette

Paul 75 L82

I'm going with out of balance clutch or flywheel.

digmyvette

Okay, except we had the issue with the original clutch. Doesn't seam likely the new replacement would have the same out of balance condition. I hpoe the mounts resolve the issue. If not, i'm going to pull the torque tube and check the input shaft as well as the complete rotating assembly. I will have the clutch checked then just to rule it out.

thbwlZ

Do you actually know the history of the clutch in the car??
Your post says there were 2 owners before you, and you said the clutch "looked original". That could mean a previous owner replaced the original with a stock replacement. It could mean a number of things. Just transferring the FW weights is not the best way to match the original FW/PP combo. It ignores the PP and their own balance tolerances.

Having said that, vibrations from engine/clutch imbalance would be felt through the shifter. You are feeling it in the steering wheel only?

Hopefully replacing your mounts solve the problem.

But keep in mind, as Bill said, if you replace with the stiffer Hinson poly mounts, you may feel new vibrations anyway. Why would you go away from the stock design mounts? Aren't you at stock power levels?

If you are concerned about vibrations, switching to stiffer mounts might leave you...... a little shaky

digmyvette

Thanks for the input. The first owner had all services/repairs done at the selling dealership. There was everything from oil changes to fluid exchanges, trim items ect., three pages worth so doesn't look like anyone else services the car. No clutch. The owner had it only 19 months. Again, oil change service records at the dealer showed up on the VIS, so I don't thing anyone else serviced the car. The clutch looked like it had 71,000 miles on it. No signs of abuse or chatter. Still had some life on it, could have put it back if I was going to resell the car but I want to keep it. My plan is to breath some life into the LS1, 450hp at flywheel or so. Therefore the Hinson mounts with heat shields for the header protection. Stock for now, but the day is coming soon. I like what I read about their mounts: "The Hinson Motorsports Urethane Engine Mounts features an interlocking stainless steel design similar to our popular transmission mounts. With this internal stainless steel structure, it allows the engine to "float" in the urethane for a giving but secure ride without the high NVH levels of other designs. You can expect to see drastic improvements in throttle response and reduced drive-line movement. These features result in faster and smoother shifts plus more deliverable power through the drive-line." Now I don't always believe everything I read, but this sounds good enough to try. I'm from the old school where "tight is right".

And remember, the vibration I'm getting is harmonic induced, at a specific RMP range. If i'm hard on it, you pass thru the band so quick it's never felt; it's at cruise that it's a problem. The inside rear view mirror vibrates so bad you would thing it's going to fall off! I was hoping someone else might have experienced this same problem and was able to correct it. If the mounts don't do the trick, (we know if there collapsed when we get them off) I'm going to try to connect the pico-scope(vibration analyzer) sensor while the laptop and DTP connections are connected to a C7. (pico-scope software does not support C5 application).

thbwlZ

very good to have that kind of detailed maintenance history. Hopefully the mounts will solve it.

v98roadie

"Its good with no signs of wear but will change soon anyway when I fix the ripped axle boot that tore while the rear was out."

I had the same type vibration and eventually found the rear end housing was damaged. It was one I bought off Craig's list to install 3.73 gears in. Couldn't tell it by looking. Can't imagine that being your issue given the age and care, just throwing out some information. Best of luck figuring it out.

digmyvette

I found this today. I do have the miss-aligned pipe. Will adjust and post findings....

Subject: Exhaust Boom at 1500 RPM (Install Spacers to Exhaust Hanger)

Models: 2000 Chevrolet Corvette
Built from S.O.P. through December, 1999
Condition
Some customers may comment on an exhaust boom heard inside the vehicle at 1500 RPM. Customers may also indicate an exhaust pipe outlet to fascia misalignment.

Correction
Install one 2 mm (.079 in) thick washer on each stud (2 per side), P/N 11505463, between the bumper bar and the muffler hanger, using the following procedure:

Raise the vehicle.
Remove the two nuts securing the left rear muffler hanger to the bumper reinforcement bar, then lower the exhaust.
Object ID: 665034Click here for detailed picture of the image.
Insert a washer on each muffler hanger mounting stud, as shown in the figure, then raise the exhaust.
Install the muffler hanger mounting nuts.
Tighten
Tighten the nuts to 16 Y (12 lb ft).
Repeat steps 2 — 4 for the right rear muffler hanger.
Check alignment of the exhaust outlets, relative to the fascia.
If required, align the outlets by loosening the intermediate exhaust flange. Some adjustment is possible by applying upward or downward force on the exhaust pipe while the bolts are loose.
While holding the pipe, tighten the flange bolts.
Tighten
Tighten the bolts to 50 Y (37 lb ft).
Notice: Very little adjustment of the exhaust outlets to fascia exists by this method. If the exhaust outlets are misaligned due to improper contouring or bending of the exhaust pipes, replacement of the muffler is required. Refer to the Engine Exhaust sub-section of the 2000 Service Manual for replacement procedures.

96TTdodge

Digmyvette, did you figure out what this was?

73Corvette

You said you balanced the "new" clutch the same as the original... so IF the old one was causing the vibration WHY wouldn't the NEW one do the SAME thing?

digmyvette

I found the source of the vibration......engine mounts were collapsed! I tried to post pictures but was unable at this time.

Bill Curlee

EXCELLENT! Glad it was that easy!

Bill