The Stovebolt Site Forums The Shop Area Driveline Pilot bearing

Hey all,

Looking for a pilot bearing for my 41 with 54 235. From my search, it appears as though GM has used the same pilot bearing since the beginning of time. I have found several variants and still have not found a winner. The original was a oilite bronze bushing.

Some on the market a sintered iron and bronze but without specific verbiage indicating if they are oiled.

I have found a National PB-656-HD bushing that seems correct non-ferrous but the physical part is not wrapped in wax or plastic wrap leading me to think it is not an oilite. The current GM part is Delco CT1088 and it is oil impregnated, but it has "relief" cuts in the ID which Novak states increased wear.

Any intel on this is appreciated.

Paul

Call Brake & Clutch Supply in Waco, TX.
Talk to Richie. He will know what you are looking for and might have it. 254-752-4307

I did a little more researching and came upon a company called Auto Gear.

http://www.autogear.net/

They cater to the more high performance muscle car crowd but the pilot bearing is the same part number. They make a true oilite bronze bushing from raw stock, produced in NY and sold for ~$8 plus very modest postage. Sounds real good, I will let you know how it turns out.

From searching, I could never determine if the other national/BCA/Napa bushings were oil impregnated or not.

Paul

Any of those would be powder metallurgy (oilite, or super
oilite). If they were just simply made from a solid bronze
bushing where would they get any lubrication from???

Oilite can be bronze or iron based, either way they are vacuum
impregnated with enough lubricant for the life of the bearing.

I think the "relief" cuts that Novak is talking about just
means that there isn't as much bearing surface in those,
therefore that would wear out sooner than one with 100%
bearing surface.

There is no magic to making a pilot bearing. You could get a
chunk of solid material from McMaster Carr:
http://www.mcmaster.com/#sae-841-bronze-rods/=z5b23g
and with a bench lathe and good sharp carbide bits turn out
your own bearing. But why bother when you can buy them
already made for about $3 from Classic parts.
http://www.classicparts.com/Trk1Flip/index.html#95/z

dg

Just trying to pass along information that may be useful to others, not showing off my knowledge.

Some of us don't have machine shops.

I bet that $3 pilot bearing is one of those Chinese semi-ferrous junkers floating around.

Yeah, probably like the one I've had in my 216 for the last 10,000 miles.
http://www.pbase.com/dennygraham/image/136174138/large
Ain't showin' of Paul, many of the guys that are doing serious
restroation or engine work have small bench lathes or know
someone who has one. Should have just keep my mouth shut
and let you figure it out for your self.


dg

Nah- no need to keep quiet, Denny. I learned some from both of your posts, and what Paul is posting. It is helpful to somebody like me to see both ends of the "part needed" spectrum. (Make one- vs.-buy one for $3) And I like to read & brush up on the part's function/design/composition, et cetera. I'm currently making some small 316 Stainless wiring & fuel clips for my truck. Just because. I think I could get plastic ones for $9 per 100. I'll have 20 hours involved in making maybe a dozen of mine after plasma-n' them, de-burring, drilling, bending & polishing them. (keep in mind these 'holding' parts, though important, carry very little stress in the truck's life )

Paul's "Chinese semi-ferrous" comment is true to some extent; as well as the fact that your 216's (potentially) Chinese semi-ferrous bearing has lasted 10K miles.

Here's my question (and forget you can buy them for $3): In this bearing's location, and working under the assumption the clutch & all other parts in the equation/vicinity are being replaced with new parts, how much stress is this particular bearing under? (Which would warrant me wanting to assure I knew its exact composition)

Brad

I don,t recall where I bought my clutch plate etc but it csme with roller bearings instead of a bushing.

I see GM Chevrolet part number 14061685 (AC Delco CT1078)
listed for the 1997-2004 V8 and V6 but no mention of it
fitting the stovebolts. It's a needle bearing pilot.

And although the sintered metallic "bushings" are listed as a
"bearing" in a lot of the catalogs, they are, none the less,
a "bushing". They are shown in the parts books as 3752562 and
are the same from 1939-1969, which is the latest parts book
that I have available to me.

The dimensions of the bushing and the bearing are different
enough that I would not think them interchangeable. Somewhere
in that time gap there appears to be a change in the dimensions.

The 14061685 needle bearing ID is .006" larger than the
bushing ID and if that is accurate it would be a sloppy fit
for the clutch shaft pilot. The OD of the bearing is also
larger by .002" which is a lot for a press fit bearing cage
which is normally a couple of tenths. Driving that in would
not do well for the needle clearance and would probably
overheat the bearing and destroy it in short order.

It's difficult to find accurate dimensions for the needle
bearing, other than what is listed in vendors catalogs, which
I wouldn't trust. I don't have a needle bearing to measure
nor do I have access to plug gauges to accurately check the
ID even if I had one to measure.
In addition, the bushing dimensions in the parts books from 50
years ago are given in fractions and may have been nominal
dimensions as interpreted by the technical writers.

Confusing isn't it!
DG

Since little useful contributory information was added, that would probably have been the best decision.

I suppose you can add your wisdom to the "serious restorers".

Denny,
the guy at the transmission shop told me to force oil through the new bushing using my thumb. So I placed the bushing on my palm, filled it with oil and then applied pressure with my thumb. It kind of sweat oil droplets on the outside and then became quite wet.

Fred

Pilot bearings were used in GMC stovebolt-era sixes, and pilot bushings were used in stovebolt sixes (216/235/260). Can anyone find a GM document listing a roller-bearing pilot bearing/bushing (for a 216/235/261)? Bushings have worked satisfactorily for many years (in these low revving engines).

Does anyone know anyone who used a failed bushing from a modern/chinese clutch assembly set (or, from any country)?

I believe my '37 Chevy originally came with a bearing. See Old Chevy manual 1929-41, group 0.649, illustrations pg. 7 and 9. To my relief someone replaced it with a standard bushing in years past with no apparent problems.
At the risk of passing on undocumented advice I will share what I have been told by my mechanic friends. They say to take a magnet with you to the auto parts counter and accept only a non-ferrous part. They say the newer bushings that contain iron particles were done to save money in manufacturing and tend to fail early. I am not where I can share the part number but the one I placed in my other project that did not attract a magnet had a suffix to the part number "-HD" which I assume means heavy duty. Note that Paul has referenced a part number ending in "HD" so I am guessing that is the optimal one. In my limited experience, these bushings are not dripping with lubricant and seem dry so don't let that scare you away.
Kent

The maintenance manual for the military Chevy trucks reference a roller bearing.

http://chevy.oldcarmanualproject.com/military/1945_46/4x4cmt0203.htm

None of the babbit engines I have come across had the roller bearing. I presume they received bushings after getting new clutches.

Since the pilot bushing is used in a very large number of GM applications over many decades, there are a large amount published and anecdotal references. In general, it appears as though rollers are not recommended for restoration work as they are not as tolerant to lateral misalignment. Old engines that have non-factory/original installed crankshafts, bell housings, clutches, transmissions...have an increased potential for misalignment. The bushing is more tolerant to having a transmission input shaft that is not exactly parallel with the crankshaft more so than the roller bearing.

The National number PB-656-HD is made of bronze and is non-magnetic. National PB-656 (the cheaper $3) version is magnetic. I could not ascertain if either are impregnated with oil but none are packaged in wax paper or plastic wrap and the boxes don't have oil stains so I would conclude that they are not the preferred "oilite" type. This I do not know for fact, but the evidence is pretty strong. Both old style and modern GM (Delco CT1088) pilot bushings are oilite and bronze. Oil is impregnated into the oilite bushings under high vacuum so soaking a dry version in oil may not have the same results.

Metallic bushings are not recommended as they have to potential to fuse to the transmission input shaft and could cause damage. Bronze being a softer metal than the input shaft should not cause harm to the input shaft in the event of a failure.

Non-oilite bushings SHOULD be lubricated with grease upon assembly.

Oilite bushings SHOULD NOT be lubricated with grease as the carrier in the grease can plug the pores in the bushing causing oil starvation. The oil in the pores of the bushing continue to seep out as the bushing warms from friction and should lubricate for the life of the clutch.

For the effort it takes to access this bushing, the choice in materials seems rather evident.

Paul

Thanks for the link/information, Paul

The domestic 1942 truck manual and 1942-47 truck manual show the roller bearing: "cage roller type Hyatt bearing".

The 1947 and later manuals (at least through 1960) show show an oil-impregnated bushing/bearing ("sintered powered bronze bushing, oil impregnated").

Paul, Respectfully, when we get to posting here on Stovebolt we tend to start speaking to the issue. We start discussing alternatives, suggestions, where to purchase or how to make. We fade away from talking at, or to, the original poster. We talk to the post. No one was challenging you. You, in fact, did abuse a list of suggestions and experienced info in a sarcastic way. I would have reacted to that the same way DG did. We all know that not everyone has a lathe. The info from anyone should always be welcomed. Each reader can decide if it's useful or not. From the length of your posts here, you seem like a "serious restorer". When DG says "you could get" or "why bother when you can buy" he is not talking at you.
It means "a person could get"...it's info passed along to the thread. If you are a real sensitive person, you will miss that nuance in forums. We are truck guys speaking our piece in a Post, not Emily Post. https://en.wikipedia.org/wiki/Emily_Post

Yikes, too much drama for me. I am not into theater, at least not on a truck website.

OK, you have unleashed the hounds.

"Any intel on this is appreciated."

Sounds like a threat to me. You have no horse in this race mind your own business.

All I was trying to do is find a decent source for a part and to let others know what I found. Not all issues are black and white and evidently new information was revealed.

This has gone too far...I am done with this. Lighten up.

Ha, Tim...yeah you got me there...perhaps I should have qualified my request with any "pertinent" help is appreciated.

Here is an issue that I have been working through on my 52 with 235.

The motor was originally a powerglide motor, and evidently when they made the motors for the power glides, they did not do the machine work for the pilot bearings in the crank.

That means that the pilot bearing for my crank is 30 thousands smaller outside diameter than the normal pilot bearing.

I did eventually find one and my whole build is waiting on it so I can continue. This only happened with PG motors from 50 - 55 or something like that.

Jim

Where did you find the correct pilot bearing? I looked and looked when I had your problem on my '53 Powerglide engine. I ended up spending a lot of money having a stock one turned down to fit.
Hind sight 20-20, I would have had the crank pilot hole drilled to the correct diameter.

Carl,

I found it through an internet search.

An outfit called "PARTSGEEK" I think they are a jobber or distributor for numerous manufacturers. It is a Dorman pilot bearing made for this specific situation.

http://www.partsgeek.com/catalog/1956/chevrolet/bel_air/clutch/pilot_bearing.html

Jim

Thanks Jim! I paid $40 for machine work alone.
Carl

I am needing one as well, for a 1962 261 using an S10 T-5 tranny. What would fit this combo? Buy Where?

I sourced a real oilite bronze bushing from:

http://www.autogear.net/

Part number 0-127-006

The machining was perfect and it fit well. I would not trust the local chain auto parts stores (napa included) or reproduction companies products as none of them can verify that the bushing is oil impregnated. Also make sure it is non-magnetic.