Low RPM Vibration

[Richard Cadena]

I have a 2009 ZO6 with 8,500 miles. When I put the car in reverse or go forward in first gear the car sometimes exhibits a low sounding vibration.

I know it is not an average car. I mean after 8,000 miles it basically got more powerful. It is quicker to spin the rear tires big time.

Provided I keep the rpm a little higher when starting out than I did when it was brand new there is no vibration at all.

Is this just what happens with a civillian race car? Is this a function of "break in"?

90 percent of my miles are on the Dallas North Tollway and it runs like no tomorrow as usual. When I am in third gear and entering the tollway the noise from the motor scares motorcycles away.

The vibration happens only happens once in a while in first and reverse when I am just getting going.

Thank you for the help.

I wish everybody on the forum a Merry Christmas and a Happy New Year!

Richard D. Cadena

[NORTY]

The low pitched "rumble" you hear is from the clutch/transmission. The TR 6060 trans is known for making this sound. It is nothing to worry about but it is disconcerting. The best way to make the car do it is to let the clutch out super slowly with the engine iding. A friend of mine has an '08, I'll see what he did for his car. (My car has a T56 so it doesn't apply.)

[Richard Cadena]

Originally Posted by NORTY

The low pitched "rumble" you hear is from the clutch/transmission. The TR 6060 trans is known for making this sound. It is nothing to worry about but it is disconcerting. The best way to make the car do it is to let the clutch out super slowly with the engine iding. A friend of mine has an '08, I'll see what he did for his car. (My car has a T56 so it doesn't apply.)

Thank you for the information.

General comment about my ZO6

For the last couple of days I had to opportunity to put some good tollway miles on the car. The speed limit is 70mph so I do 80mph. Very little traffic. The ZO6 is a great highway car. I love the feeling of that power, traction and balance.

Richard D. Cadena

[c4c5specialist]

HI there,

LETS BE VERY VERY CLEAR!

There is no noise from the transmission that is like that, at all, EVER!!!!

If there was, I would be extremely concerned.

Now, its obvious that your low RPM condition is what your talking about.

This is due to interaction from the clutch plate, to the torque tube drive shaft to the input shaft of the transmission.

Add all those clearances to the formula, plus the power pulses of the engine being low and not damped, create the condition.

If these noises are coming from the transmission, YOU HAVE A PROBLEM.

Allthebest, c4c5

[NORTY]

Originally Posted by NORTY

The low pitched "rumble" you hear is from the clutch/transmission. The TR 6060 trans is known for making this sound. It is nothing to worry about but it is disconcerting. The best way to make the car do it is to let the clutch out super slowly with the engine iding. A friend of mine has an '08, I'll see what he did for his car. (My car has a T56 so it doesn't apply.)

OK, I spoke to my friend with the '08. He told me it's a very common problem for which there is no cure. What he told me is that the torque tube mounting system has a "harmonic" action in conjunction with the clutch and engine harmonics. Kind of a "perfect storm" of conditions cause the "low frequency rumble." The good news is that it'll never get any worse. I wonder if the 2 different drive axle OD's have any effect on it? Haven't heard of any 2011's having the prob with the ZR-1 axles.

Paul~ Do you suppose that replacing the transmission mounts with Pfadt solid monts would cause more or less sound being transmitted? (I'm thinking "more.")

thanks

[Richard Cadena]

I am learning to avoid the rpm range that causes this. I basically can't idle my car in reverse backing out of a parking space and then shift into first at idle rpm and proceed forward.

Yesterday I drove it for eighty miles (tollway 80mph, freeway 50mph stop and go, city street 35mph) and no harmonic anything.

If this is not the problem I still have two years left on the bumper to bumper warrantee. I will keep the forum upto date on the situation.


Thank you again,

Richard D. Cadena

[LLC5]

Originally Posted by Richard Cadena

I am learning to avoid the rpm range that causes this. I basically can't idle my car in reverse backing out of a parking space and then shift into first at idle rpm and proceed forward.

Yesterday I drove it for eighty miles (tollway 80mph, freeway 50mph stop and go, city street 35mph) and no harmonic anything.

If this is not the problem I still have two years left on the bumper to bumper warrantee. I will keep the forum upto date on the situation.


Thank you again,

Richard D. Cadena

What RPM are you engaging reverse and first at?

[Richard Cadena]

Whatever the idle rpm is. I believe six or seven hundred rpm. This morning when I left for work the car was cold so the RPM is a little higher then idle RPM. No vibration. If the car is warmed up I have to watch it.

Richard Cadena