Pulled trans again for chatter - here are results

[bondtimbond]

As I indicated in an earlier thread about my having to bite the bullet and pull my trans again to see why I have a chatter problem, I did so today and found some interesting things. I would like some advice from those with experience.

My car is a 67 small block, and I installed a new LUK rep set clutch assy last November. Flywheel was resurfaced. From the start I had a light chatter on low speed engagement that wouldn't go away. Advice from this forum and from LUK was to pull trans and check runout of flywheel.

Upon removal of clutch pressure plate, I observed that the pilot bearing was loose in the crank - came out by hand and spins freely in the crank!! It didn't go in that way for sure, in fact I had trouble driving it in. This bearing came with the LUK kit, and was not magnetic (I checked it). The original pilot bearing that I removed prior to installing the Luk kit in November had to be pulled out with a puller as is normal, and wasn't excessively worn either. I went ahead and installed the new one that came with the Luk kit since I had it.

Flywheel and pressure plate both look pretty good (however they were only installed a couple of months and maybe a hundred miles or so). I can tell however that there is some minor spotting on the flywheel, probably indicating some uneven engagement. I checked runout and it is about .003" best I can tell using a dial guage. How much runout in a flywheel is too much?

By the way, I did NOT get the flywheel and/or clutch assy balanced last November thinking that it wasn't necessary, but now maybe I should...

Advice?

 

[cfalson]

Is it a pilot bearing or bushing, if it's a bearing change to a bushing, millions in the field and never a problem?
Is it the bushing correct one for your engine, early 327's have a sightly smaller diameter?
Check the throw out bearing sits correctly on the fork with the clips on?
Is the input shaft in good shape no ridges, is the bearing in good shape?
I would think from your description the input shaft is the problem either a worn shaft or front bearing.
Charlief
66 Coupe

 

[bondtimbond]

Yes, it was a bushing that came with the Luk kit, and I checked to make sure it was bronze with a magnet. Kit was for a 327 so I assume it was the correct bushing for my car. Throwout bearing is in good shape and was installed on fork correctly (many threads on that). Input shaft appears in good shape, and I did replace the input bearing on the trans along with the clutch work last November.

 

[cfalson]

Before the clutch was replaced, did you have the chatter problem?
Who cut the flywheel and is it cut correctly?
Those are the last things I can think of, before pointing to the LUK clutch/pressure plate, if this is a new problem.
Charlie

 

[henny496]

Hello
What type of clutch did you install?? Did you change to a scattershield???
Tom

 

[bondtimbond]

I installed a LUK rep set standard clutch kit. Don't know what a scattershield is.....

 

[henny496]

tranny

Hello
I guess you have a stock clutch with the regular GM bell housing then
What is the first gear in your tranny? How tall a rear end gear do you have?
They used to call Muncies clutch eaters since first gear was around a 2.20: 1
I am not sure if this matters, but did you notice if your input shaft on your tranny was sloppy when you pulled it out??? Again I am not sure if that would do it
If you have a tall 1st gear and a tall rear end gear, that may only add to the problem on a new clutch
T-10's have a first gear in the 2.60 range
I am only guessing after this?
Some aftermarket clutches that are not primarily for highway use will chatter and if you put on a scattershield the tranny may not be aligned and needed offset dowels in the block
You don't have either, so that was my only guess. Perhaps some one else may be able to offer more help
take care
Tom

 

[bondtimbond]

Does anyone know how close to perfect alignment the trans input shaft must be to centerline with the crank? What is the spec allowable? I will be attempting to check this next. I had the flywheel re-resurfaced and there was some excessive runout, actually a dip in the surface. That may have been contributing to or causing my problem, but I am not going to put things back together till I think I have checked everything. The flywheel and pressure plate is out now at the balancing shop.

 

[JohnZ]

The hole in the bellhousing for the trans bearing retainer should be concentric with the crank centerline within .005" total indicated runout; I've never found a stock bellhousing out of spec, but every Lakewood or McLeod I've installed has required offset dowels in the block to bring them into spec. :eyerole