so did they replace the pilot bearing?

assuming your FW & PP are now properly balanced for external rear motor and you still have a vibration and the pilot bearing WAS replaced....you may have issues with the tranny.

was there any side to side movement of the trans input shaft?

or are you not doing this work yourself?

 

The pilot bushing was replaced with an ac delco one. It had been installed backwards. The vibration is gone now from 2k-4k rpm. 4500k it still shakes the center console trim. He said the input shaft had no play in it when it was out of the car.

 

Well after about 30 miles, it is back in full force.

 

I'm thinking there may be something going on with your crank centerline. Dunno. Unfortunately this may be one of those things where you have to tear it apart to see what's going on.

 

Yeah we are going to dig into it more later. Runs smooth as silk with flywheel attached but with the clutch and pressure plate off.

 

I've never seen a valeo PP balanced with weight added. It's always been balanced by removing weight from the plate in the edge locations shown in the pic in post #6.....those locations are 120* apart if I remember right.

I had a similar issue with a Autozone PP above 4000. Bought a valeo PP to solve it after rotating the PP into 3 different positions to try and see if it would get better.. I'm 99% sure the PP balance is your problem.

I called Valeo tech support years ago and they had this to say about the PP balance....

"Valeo checks the spin balance of their plates and the spec is 20 gcm max."

I'm assuming that they dynamically spin balance the plate.

Have a read through this...
https://www.camaroz28.com/forums/dri...-plate-663827/

 

Ace,

Thanks and I’ll pass it along. I agree that the PP is my issue. To be clear though mine is a McCleod clutch not Valeo. I am half tempted to stick a Valeo in though. I’m gonna tear it back apart in Sept when its not so dang hot.

 

I just checked RockAuto and they have Valeo kits in stock. I just ordered myself one as a spare, I'll check for the balance holes when it comes in....as I think one report I read of said that one Valeo kit didn't have them....which is a little concerning.

Edit:LoL, well looks like that report was my own....I guess I'll have a backup to my backup seeing as how I completely forgot about the one I have sitting in my garage.
https://ls1tech.com/forums/lt1-lt4-m...l#post19730784

 

McLeod, and every clutch company selling a LT1 clutch these days uses the same offshore PP.....which from what I have seen has no balance holes drilled in any of the 3 tabs on the PP.

Every one I have had balanced, neutral in my application, the machine shop drilled out material on the 3 "ears" of the clutch disc mating plate that are 120 degrees apart....not add weight by welding on something

The FW is what is balanced in terms of having the external weight cast in it. I believe the PP should be neutral on a stock, external balanced, motor

 

Thanks for all the help. I’ll update when we tackle it again.

 

Do you know if they statically or dynamically balanced it? If static was good enough, then I'll go that route in checking these others I've got.

 

The Valeo kit I ordered a couple of days ago arrived this morning. I have not fully inspected it, but did see 3 holes drilled in one tang on the PP. So, it looks like Valeo balanced it.

 

I use a machine shop called, ironically, The Balance Shop. They spin the PP on FW after they first balance FW

The 3 holes in one ear would indicate the PP was balanced. If there is a paint dab (typically yellow) on the PP that lines up as close to the crank dowel pin as possible

 

Maybe your input shaft on your trans is bent? :shrug:

 

Maybe. In about a month we are pulling it out again. My mechanic does all of the work in his driveway with me helping when I can.

 

I put a Spec stage 3+ in my car back in '07, never a vibration all the way through 6800. Previously it had a Ram clutch and PP in it that also did not vibrate at all. It was a Powergrip iirc. I replaced it because it was getting worn when I had the engine out and the pp had a few hot spots on it. I've been incredibly pleased with the Spec and I'll be putting one in my Cobra when I have the tranny rebuilt in that car.

 

Also, I kept that clutch setup for an ole crap moment. If I think of it, I'm trying to dig it out and knock tht Cobb webs off and take a look.

 

Well I dropped the whole shebang two days ago. Engine, k member and all. Got the trans off tonight and the throwout bearing is bent again. When you spin it, its wobbly like an egg. The input shaft looks straight when I spin it and when I wiggle it, there is only the smallest amount of side to side and up and down motion to it.

 

Sigh, I hate to say it, but you may have to tear the rotating assy apart and have the balanced checked to see exactly how, or if it was balanced correctly. Something just ain't jiving. I am not 100% positive, but I also think the trans input shaft should have absolutely no play in it whatsoever.

 

Agreed something isn’t jiving. I am going to have the trans looked at first. It seems more likely to me that with just the flywheel on, the engine runs smooth. Then the first day the PP is balanced it runs fine for 20 miles and then bam, the input shaft messes it all up and it goes wonky again. Either way, the whole thing has become and in the garage winter project. Be done sooner if I had $5k just lying around 😏