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Discussion Starter · #1 · (Edited)
I found a badly worn pilot bearing in my crankshaft when doing some checking on my clutch.

The previous owner had installed a stepped pilot bearing, I assume to make for the 1/4" set back from the block plate.

Lakewood instructions make no mention of this special pilot bearing in there instructions for this bellhousing.

Also, should one run a long throw-out bearing because of the extra distance from the diaphragm fingers? That is probably why all my linkage adjustment is all taken up. Linkage is all nearly new, btw.
Thanks for any comments on this.
Below is a picture of the type of pilot bearing that I took out.
 

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Discussion Starter · #3 ·
You have the classic signs on bellhousing mis-alignment with your worn pilot bushing.
Yes, I agree and will be addressing that when I go back together with it.

Can you comment on the use of the extended pilot bushing?
 

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Discussion Starter · #5 ·
You never mentioned what transmission you have? Some manufactures have extended pilot tips and the extended bushing is not required.
The trans is a Muncie M21.

I measured the thinkness of the block plate, .145". A bit more than 1/8".

I not sure that's enough to worry about adequate pilot shaft penetration.

But I'd defer to someone that does it for a living, like you.

Thanks for your time.
 

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Stock original Muncie needs the extended bushing with the deeper depth Lakewood setup.

Plus you need a longer TOB to take care of your clutch fork angle to utilize the stock mechanical clutch linkage. We use the McLeod 16505 adjustable TOB for 95% of all installs.
 

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Discussion Starter · #7 ·
Thank you sir. I'll get one of those TO bearings.
 

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Good thread and thanks JODY for your input re: the stepped pilot bearing with a Muncie and Lakewood
 

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Stock original Muncie needs the extended bushing with the deeper depth Lakewood setup.
Interesting... so if I have a #15000 Lakewood housing/block plate and M20 with a flush mounted pilot bushing, that may explain the sloppy shifting and 4th gear disengagement ??..or from misalignment...or both ?? I replaced the bushing earlier and it was elongated. I plan to put an original 621 housing back on next time I drop the trans...
 

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Basic mechanical guidelines and practices; the diameter of any given shaft must be support by the length of the diameter for longevity.

Simplified, most GM input shaft pilot tips measure around .590". Bare minimal, the input shaft pilot tip must be supported by the pilot bushing the same .590" length. It is a quick measurement from the bellhousing transmission register hole to the pilot bushing outer edge vs the input shaft pilot tip and overall length to determine what bushing is needed.
 

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(thanks for the advice)... So is it good practice to just install an extended bushing... or, is too much input shaft engagement just as detrimental is too little ?? (binding, excessive heat, etc)
 

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Discussion Starter · #12 ·
Jody, I downloaded the file on your web site that explains how to check the bell-housing for concentricity and parallel.

I put my mag base on the flange of the driveshaft, is that ok. I did not have my flywheel mounted.

I came up with +.054" at 1 oclock, parallel

+.048 at 11 oclock for concentricity.

So I would need .027" shims under the bottom bell-housing bolts or should I shim both lower bolts on both sides?

Then do the concentric check again, correct?
 

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Jody, I downloaded the file on your web site that explains how to check the bell-housing for concentricity and parallel.

I put my mag base on the flange of the driveshaft, is that ok. I did not have my flywheel mounted.

I came up with +.054" at 1 oclock, parallel

+.048 at 11 oclock for concentricity.

So I would need .027" shims under the bottom bell-housing bolts or should I shim both lower bolts on both sides?

Then do the concentric check again, correct?
Your alignment numbers are terrible and quite typical with a Lakewood safety bellhousing. Do you have another bellhousing to recheck and compare the dial indicator reading?
 

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Discussion Starter · #14 ·
Your alignment numbers are terrible and quite typical with a Lakewood safety bellhousing. Do you have another bellhousing to recheck and compare the dial indicator reading?
Unfortunately no.

But in further checking, I have found a high bolt hole on the block surface and I don't think the bell housing was registering on the dowels much if at all.

So I got some longer dowels coming and will check numbers again to see if they change
 
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