The Stovebolt Site Forums The Shop Area Driveline SM318 Rear Bearing Retainer

I disassembled my ‘52 SM318 and found that the rear bearing retainer was worn substantially. The universal joint yoke has some score marks on it and measures 1.435”. The bushing measures 1.452”. I know that’s too much clearance but would like to know what they should be. I didn’t see that clearance listed in the shop manual.

I posted a want ad in the Truck Parts Wanted forum, but was also wondering if anybody knows another place where I might get replacements.

Any help will be appreciated.

Does any of my fellow “Bolters” have a measurement on the end of pilot shaft (clutch shaft) where it enters the pilot bearing and what would be an acceptable clearance?

On the output flange, why not just repair what you've got? A replacement bushing should be available, or if not, any machinist with half a brain can make one from a piece of bronze. If the flange hub is worn, a thin sleeve can be machined and pressed onto it to re-establish the proper clearance. On the pilot bushing, I've usually tried for a clearance of about .005". I'll measure an input shaft when I get out into the shop later today and update this post. The pilot bushing is usually made of sintered bronze powder combined with a lubricant, something that's called "oilite". It's supposed to be self-lubricating. The pilot bushing can be a pretty sloppy fit and still work, since the only time there's any relative motion between the tip of the input shaft and the bushing is while the clutch pedal is depressed. A few therapy sessions with a good psychiatrist can usually help a chronically depressed clutch pedal develop a better self-image!
Jerry

I was going to re-bush the rear bearing (output flange) if I couldn’t find either a new bearing sleeve or a good replacement rear bearing retainer. The original bushing is dimpled and has oil grooves, I assume to feed and retain the 90 weight oil.

Seeing this, I decided to it would be best to try and obtain one. The best I could do could do would be to put a groove on the bottom of the bushing to feed oil to the bearing. If that is my only option, that is what I will do.

I have found pilot bushings are available from several vendors. My crank, along with the block is out to a machine shop, so I can’t measure the pilot bushing. I would have thought that the dimensions and clearances for all of these parts would be listed someplace, so I would know if the parts are useable or not.

Thank goodness Stovebolt exists and there are many knowledgable people that are so willing to help me get these answers! All I can say is thanks!

If you run out of other options, I can make that output yoke and the support bushing play nicely together. It's not that difficult to machine those grooves into a new bushing, and a ball-end carbide burr in a Foredom rotary tool makes dimples anywhere they need to be. I use a felt tip marker to make a series of dots, and put a dimple at each dot. The shaft doesn't care if a lube dimple is a few thousandths out of perfect position.
Jerry

Maybe this will fit

Opps that’s a tailhousing bushing disregard

That one should work- - - -it says it fits a SM-318, and that's the output flange- - - - -the slip yoke is just in the rear section of the U-joint on the transmission in question.
Jerry

Although I can’t use a mic to get an accurate reading, the OD measures 1-9/16” with a ruler.

It’s funny because this past Saturday I texted that same company for a rebuild kit. I just texted them and asked if they had a bushing. Keeping my fingers crossed!

If that bushing fits all the transmissions listed in the ad, any good transmission shop should have several on the shelf. Your local NAPA jobber would also be another possibility. Nothing beats having a local supplier to use for comparison purposes.
Jerry

I just located an new sleeve bearing for the rear bearing retainer from the Filling Station. It’s measurements are 1.565" OD X 1.445" ID X .083" THICK X .885" wide. In the description It stated “ If the clearance exceeds .010", the bushing should be replaced.” My yoke which rides on this bearing measures 1.435” which puts me at the maximum clearance. I suspect after its pressed in, the ID will close up a bit tightening the clearance.

My yoke does show a bit of wear, so now I wondering if the yoke is worn more than I think.

Does anyone know what this clearance should be, or have a known good yoke readily available to measure, so I at least have a measurement to compare mine too?

Rear Bearing Retainer Sleeve

From what I see of that yoke, I wouldn't re-use it. Perhaps there is a speedy sleeve that would fit it or get another one. You only want to do this once.
Fred

It would be simple to set the yoke up in a lathe and machine the OD down about 1/8", then fabricate a sleeve to press over it. I'd suggest using a piece of stainless steel tubing for the sleeve and machine and finish-grind it to the proper OD after it's pressed on. That repair should outlast the rest of the truck with no wear concerns. Drop me a PM and I'll be glad to do that for you if you like.
Jerry

I have that support with bushing in it NOS GM part number 591633. Still in the GM box. If interested email me bwbugay@aol.com

The part number listed on my Rear Bearing Retainer is 591634. I don’t know the difference between the two. Maybe a fellow “Bolter” could tell us.

[Edit] I looked up the parts in the Master Parts Catalog and the casting is listed as 591634 and the part number is listed as 591633, one and the same!

Problem Solved! I just receive from a fellow “Bolter” an GM NOS Rear Bearing Retainer and a used yoke in good condition to match.

For the benefit of fellow “Stovebolters” looking for the same info, the OD of the yoke measures 1.435” and the ID of the new Rear Bearing Retainer measures 1.4405” giving a final clearance of .0055”.

Thanks to all that gave me some advice!