[gtobird]

I've run both pilot bearings and pilot bushings in my cars without a problem on my manual trans cars. I'm about to assemble my tranny to my engine and thought I would run something by one and all.

When you use a pilot BUSHING, the crankshaft and bushing will rotate around the tranny input shaft when the clutch is pushed in. Okay, so the oil impregnated bushing allows this to work without problem.

So, how does this work with a pilot BEARING? I understand that the bearing is supposed to allow the same thing to occur by having the inner race track the tranny input shaft while the outer race rotates with the crankshaft.

What I don't understand is that I don't see an interference fit between the tranny input shaft and the inner bearing race. So, wouldn't the tranny input shaft also possibly rotate inside the inner race of the bearing, causing damage to the tranny input shaft? Or is the fit just tight enough that it's greater than the force required to spin the inner race at a different speed from the outer bearing shell?

New Years resolution is to understand how this works.

OJ

[marxjunk]

yes it rotates in the inner bearing race..its not friction fit..the bearing is supposed to work better on side load forces..like 5000 rpm clutch dumps...

Oldsmobile uses a bearing...and ive pulled 3 or 4 out of cars that where failing...the liners where dry rotted and getting ready to come apart..because they where dry...they are supposed to lifetime lubricated..but i have one out of my 70 F85 with 88.xxx orig miles and its failed..or is ready to fail...

pontiac a bushing...ive never had to change a bushing in a pontiac unless it was installed wrong and beat up......its oil impregnated bronze type alloy..when it gets a load or hot...it lubricates its self

unless theres an alignment problem...its kind of passive..it just sits there..because centrifugal force keeps the clutch plate and input shaft in line..

ive seen pontiac motors with no bushings in them at all and they went 40 or 50 thousand miles with no issues...but they wherent raced, just driver type street cars that people converted to sticks and had no idea there should be a bearing/bushing in there...as recent as last year...

all was fine til he rickey racered it and dumped the clutch and the clutch plate came apart...in less than a week..it killed the input shaft bearing..still ran and drove, just got hard to shift

[propuckstopper]

Here is an excerpt from a previous thread I posted. I hope this provides some sort of help as it relates to my experience directly:

As I mentioned in a previous post in this thread, I did go through some work and effort to have a custom Oilite bushing made up. The main reason I did this is because I thought that these cars originally came from the factory with a bushing. Why? Well, the vendor I bought the steel (magnetic) bushing from only offered a bushing (but not a bearing) in their catalogue. Being a true newbie to four-speed stuff, I didn't know that bearings were even available for this application. After installing and hearing the squealing produced by this steel bushing, I immediately Googled the issue and came upon piles of information on these undesirable steel bushings. So my next move was to track down a proper Oilite bushing, and I finally got one in my hands. But I still did not yet know that these cars actually left the factory with a bearing!

It was not until I consulted both my 1965 and 1968 shop manuals that I realized these cars came from the factory with a bearing. Which leads me to wonder now:

The research I did uncovered many people that don't like the bearings because of possible bell housing misalignment. They say if you are ever to use a bearing, you must make sure that your bell housing alignment is spot on. And this makes nothing but sense to me.

BUT...How many of these cars over the years were driven into Joe's Transmission for a clutch replacement, which likely would have included replacement of the pilot bearing? My bet is that Joe's Transmission not once checked bell housing alignment. Ever. They would have removed the old pilot bearing, installed a new one, replaced the clutch, and told the customer to have a nice day. Yet somehow, these bearings survived. My guess is that GM must have had pretty darn good alignment from the factory, seeing that these cars left the factory with a bearing.

Anyway, here I now sit with a brand new Oilite pilot bushing in my car. I can't yet give a report on its performance, as we have sixteen-thousand feet of snow here and the car is resting in the garage until at least May. (EDIT AS OF DECEMBER 31, 2015: I have about 1500 miles on the Oilite bushing now, and not a hint of a squeal).

But I do know three things, and I hope it saves someone some hassle or helps them with their choice down the road.

1. There exists steel (magnetic) pilot bushings out there in the marketplace. If you choose to go this route, be sure to lube the bushing to avoid metal-to-metal contact. These magnetic bushings sell for about $5.00 or so.

2. You can buy an Oilite pilot bushing from places like Autogear or McLeod Clutches. No lube is necessary, and the bushing is softer than the input shaft of the transmission. These Oilite bushings cost about $40.00 or so.

3. You can do what the factory did, and use a roller bearing. You can install it as-is and take your chances, or check and correct any bell housing misalignment issues.

In hindsight, I think any of the above solutions will work.

Jeez. For the amount of time and research I have done on this topic, I could have done a frame-off!

[gtobird]

Originally Posted by propuckstopper

Here is an excerpt from a previous thread I posted. I hope this provides some sort of help as it relates to my experience directly:

As I mentioned in a previous post in this thread, I did go through some work and effort to have a custom Oilite bushing made up. The main reason I did this is because I thought that these cars originally came from the factory with a bushing. Why? Well, the vendor I bought the steel (magnetic) bushing from only offered a bushing (but not a bearing) in their catalogue. Being a true newbie to four-speed stuff, I didn't know that bearings were even available for this application. After installing and hearing the squealing produced by this steel bushing, I immediately Googled the issue and came upon piles of information on these undesirable steel bushings. So my next move was to track down a proper Oilite bushing, and I finally got one in my hands. But I still did not yet know that these cars actually left the factory with a bearing!

It was not until I consulted both my 1965 and 1968 shop manuals that I realized these cars came from the factory with a bearing. Which leads me to wonder now:

The research I did uncovered many people that don't like the bearings because of possible bell housing misalignment. They say if you are ever to use a bearing, you must make sure that your bell housing alignment is spot on. And this makes nothing but sense to me.

BUT...How many of these cars over the years were driven into Joe's Transmission for a clutch replacement, which likely would have included replacement of the pilot bearing? My bet is that Joe's Transmission not once checked bell housing alignment. Ever. They would have removed the old pilot bearing, installed a new one, replaced the clutch, and told the customer to have a nice day. Yet somehow, these bearings survived. My guess is that GM must have had pretty darn good alignment from the factory, seeing that these cars left the factory with a bearing.

Anyway, here I now sit with a brand new Oilite pilot bushing in my car. I can't yet give a report on its performance, as we have sixteen-thousand feet of snow here and the car is resting in the garage until at least May. (EDIT AS OF DECEMBER 31, 2015: I have about 1500 miles on the Oilite bushing now, and not a hint of a squeal).

But I do know three things, and I hope it saves someone some hassle or helps them with their choice down the road.

1. There exists steel (magnetic) pilot bushings out there in the marketplace. If you choose to go this route, be sure to lube the bushing to avoid metal-to-metal contact. These magnetic bushings sell for about $5.00 or so.

2. You can buy an Oilite pilot bushing from places like Autogear or McLeod Clutches. No lube is necessary, and the bushing is softer than the input shaft of the transmission. These Oilite bushings cost about $40.00 or so.

3. You can do what the factory did, and use a roller bearing. You can install it as-is and take your chances, or check and correct any bell housing misalignment issues.

In hindsight, I think any of the above solutions will work.

Jeez. For the amount of time and research I have done on this topic, I could have done a frame-off!

I bought one of the Oil impregnated bushings a while back for about $12.

[gtobird]

Originally Posted by marxjunk

yes it rotates in the inner bearing race..its not friction fit..the bearing is supposed to work better on side load forces..like 5000 rpm clutch dumps...

Oldsmobile uses a bearing...and ive pulled 3 or 4 out of cars that where failing...the liners where dry rotted and getting ready to come apart..because they where dry...they are supposed to lifetime lubricated..but i have one out of my 70 F85 with 88.xxx orig miles and its failed..or is ready to fail...

pontiac a bushing...ive never had to change a bushing in a pontiac unless it was installed wrong and beat up......its oil impregnated bronze type alloy..when it gets a load or hot...it lubricates its self

unless theres an alignment problem...its kind of passive..it just sits there..because centrifugal force keeps the clutch plate and input shaft in line..

ive seen pontiac motors with no bushings in them at all and they went 40 or 50 thousand miles with no issues...but they wherent raced, just driver type street cars that people converted to sticks and had no idea there should be a bearing/bushing in there...as recent as last year...

all was fine til he rickey racered it and dumped the clutch and the clutch plate came apart...in less than a week..it killed the input shaft bearing..still ran and drove, just got hard to shift

Okay, I'll bite.... How does centrifugal force keep the clutch plate and input shaft inline? The clutch disc slides onto the input shaft splines. The input shaft (front) then goes through the center hole in either the bushing or bearing, which sits in the crank. That's what keeps the disc aligned. The pressure plate is bolted to the flywheel, keeping it aligned. I don't see how centrifugal force has anything to do with alignment. What am I missing?

[marxjunk]

inertia...youre missing inertia..anything in motion stays in motion..

if one can be ran for 40,000 miles (saw it with my own eyes) with out a bushing or bearing...how or what forces would a person deduct from this? Ive seen it at least 4 times in my life..first handed...i'm not a scientist or a physicist...but heres how i see it..

everything on the flywheel is balanced...the bearing retainer and the actual bearings in the input have pressure when loaded..the input take the easiest route..so in a spinning motion unless theres a side force..it will spin true...some slop or a strange side force and the spin takes and elipse....and **** flies apart...inputs actually have 2 set of bearing..one in the retainer and one inside the gear on the inside..and they are rollers..not balls..so they self align and spin in a circle when at speed...not an elipse..unless theres a side force...hence the pilot nearing helps keep the input aligned and spinning true..and not in an elipse.... some outer bearings on the input (under the retaine) are ball..but i think those are pre muscle car..

if you pull a bushing out of the crank..most show little to no wear at all..most input shafts show a light polish from contacting the bushing..i have some 90xxx mile transmissions that the input shaft looks brand new...i understand they are case hardened...but if it needed that bearing to operate...wouldnt they both wear out? i think so...so some force is keeping that shaft in line and since it spins...it must be centrifigul and inertia...

the time the pilot comes into play is a side force pushing the input around...so worn out bearing...dumped clutch...broken bellhousing..etc..

its a pilot..not a guide..maybe i am not using the right terms, but thats how i see it...i dont have a PhD, but i have experience...

[gtobird]

Originally Posted by marxjunk

inertia...youre missing inertia..anything in motion stays in motion..

if one can be ran for 40,000 miles (saw it with my own eyes) with out a bushing or bearing...how or what forces would a person deduct from this? Ive seen it at least 4 times in my life..first handed...i'm not a scientist or a physicist...but heres how i see it..

everything on the flywheel is balanced...the bearing retainer and the actual bearings in the input have pressure when loaded..the input take the easiest route..so in a spinning motion unless theres a side force..it will spin true...some slop or a strange side force and the spin takes and elipse....and **** flies apart...inputs actually have 2 set of bearing..one in the retainer and one inside the gear on the inside..and they are rollers..not balls..so they self align and spin in a circle when at speed...not an elipse..unless theres a side force...hence the pilot nearing helps keep the input aligned and spinning true..and not in an elipse.... some outer bearings on the input (under the retaine) are ball..but i think those are pre muscle car..

if you pull a bushing out of the crank..most show little to no wear at all..most input shafts show a light polish from contacting the bushing..i have some 90xxx mile transmissions that the input shaft looks brand new...i understand they are case hardened...but if it needed that bearing to operate...wouldnt they both wear out? i think so...so some force is keeping that shaft in line and since it spins...it must be centrifigul and inertia...

the time the pilot comes into play is a side force pushing the input around...so worn out bearing...dumped clutch...broken bellhousing..etc..

its a pilot..not a guide..maybe i am not using the right terms, but thats how i see it...i dont have a PhD, but i have experience...

I too have seen engines put together and run without the pilot bushing / bearing for substantial miles, so I'm not doubting it can be done. Your explanation misses the fact that the disc would still slide on the shaft splines keeping the disc centered. However, you would think it would kill the tranny input shaft bearings without a pilot bushing / bearing, so I have to agree that kinetic forces (rotational motion) is keeping everything from destruction for a good while. On a properly assembled engine with a pilot bearing / bushing it would have much less effect from what I can see.

I have experience and an engineering degree (don't hold the engineering degree against me as it usually screws up reality of building cars).

OJ

[tom s]

This another one of those deals I must be a lucky pontiac owner.I have driven and built pontiac engines since 1962.Virtually all have been stick shift cars.I have used both bushings and bearings with no failures.I have NEVER checked alignment on one of them.What I do when installing a clutch assm is use a old input shaft from a trans.I never use the plastic ones that come with clutch kits.I have used factory bells,Mcleod and most other EXCEPT a Lakewood.Trans from T-10s,ST-10s,muncies,saginaws and Tremics and even rope shaft 62-63 tempests.Carry on.Tom

[propuckstopper]

Originally Posted by tom s

This another one of those deals I must be a lucky pontiac owner.I have driven and built pontiac engines since 1962.Virtually all have been stick shift cars.I have used both bushings and bearings with no failures.I have NEVER checked alignment on one of them.What I do when installing a clutch assm is use a old input shaft from a trans.I never use the plastic ones that come with clutch kits.I have used factory bells,Mcleod and most other EXCEPT a Lakewood.Trans from T-10s,ST-10s,muncies,saginaws and Tremics and even rope shaft 62-63 tempests.Carry on.Tom

Hey Tom. I was very fortunate when I went to install my new clutch. An old transmission guy that I know told me he had a few old Muncie parts lying around. He found an old input shaft and we machined it slightly to create the perfect alignment tool.

He asked me to first try the supplied plastic alignment tool, then the actual Muncie input shaft. I could not believe the difference in accuracy from the steel to the plastic. The plastic unit seemed "floppy", while the steel was very positive. Really, I shouldn't have been so surprised.

I have that Muncie input shaft in my toolbox now, and won't be getting rid of it anytime soon. The supplied plastic alignment tool has since celebrated a couple of birthdays in the landfill.

[gtobird]

Last assembly I did had the tranny and engine out of the car. Because I moved, I lost my alignment tool so I just put the pressure plate and disc in place loosely on the flywheel. Then without the bellhousing, I just inserted the tranny and aligned it all and tightened up the pressure plate.

Then I removed the tranny, installed the bellhousing and re-attached the tranny. Zero issues with the installation. All went well. Of course it's a pain in the azz lifting the tranny just to align the clutch disc, but when you want to get it done and don't have an alignment tool, you do what you have to.

By the way, my original 76K mile engine still has the factory pilot bearing in it and looks good. Still looks unblemished in the crank.

[marxjunk]

kenetic....and rotational forces..those are the words i was trying to use..i was so tired i was wandering.....

i dont hold the engineering degree against ya..lol..and im just talking...i dont have thin skin..so no harm no fowl



going on a bunch of work hrs and little sleep...and i see i'm talking in circles.. and heres what i was trying to say..


theres no benifit of a bearing over a bushing..real world experience....the bushing is dead simple and they dont fail....

i dont understand everything i know about this stuff..but id buy a bushing any time over a bearing..

i gotta get some sleep..because i wrote this and i dont even understand what i was trying to say...

[rexs73gto]

I'm just the opposite, I wouldn't put the bushing back in any thing over the bearing. I have in the past worn out 2 bushings & have never had any problems with the bearing. I always put a little extra grease in the pilot hole to have some extra in there to keep everything greased & ready. Because it's a sealed bearing it won't get grease on anything except the bearing ever.

[cuz68]

GM used the bushing, I have never saw one fail.

[propuckstopper]

Originally Posted by cuz68

GM used the bushing, I have never saw one fail.

I am not sure you are correct on this. According to my old GM Master Parts Catalogues, it looks like they used a bearing.

Although, as mentioned previously in this thread, I used a bushing because I did not have the MPC knowledge before I ordered my custom Oilite bushing.

[rexs73gto]

I didn't want to spend a bunch of money for the bearing at the typical parts store so I started looking around , & found some on ebay but they were most all china junk . I went to my local Farm & fleet store & found the bearing for $ 5.00 that was made in America & had the bearing inclosed on both sides of the bearing, unlike the others I had in the past. Being closed off on both sides keeps the dirt & other junk out of the bearing itself which will cause it to fail,,, maybe. I have put bearings in every one of my builds since 1974 & have never had one fail. But as mentioned in my earlier post I have had 2 of the bushings go bad on me. Both in Firebirds, but also both with 3 speed trans. I don't know if that was the cause or not but since I've used the bearings I have had no bearing concerns .

[TedRamAirII]

Originally Posted by rexs73gto

I didn't want to spend a bunch of money for the bearing at the typical parts store so I started looking around , & found some on ebay but they were most all china junk . I went to my local Farm & fleet store & found the bearing for $ 5.00 that was made in America & had the bearing inclosed on both sides of the bearing, unlike the others I had in the past. Being closed off on both sides keeps the dirt & other junk out of the bearing itself which will cause it to fail,,, maybe. I have put bearings in every one of my builds since 1974 & have never had one fail. But as mentioned in my earlier post I have had 2 of the bushings go bad on me. Both in Firebirds, but also both with 3 speed trans. I don't know if that was the cause or not but since I've used the bearings I have had no bearing concerns .

Spill the beans! Brand and part # ?

[GOAT WHORE]

Originally Posted by cuz68

GM used the bushing, I have never saw one fail.

Wrong

[rexs73gto]

I'll get the part number for it in the AM when I'm out & about, but it's a much better bearing then the cheap ones that are being sold on ebay. I don't think I would use the bearings on ebay from,,, whoever with the price of 8 of them for $ 12.00. That just seems way to cheap & that cheap I would think means built cheap to. Plus looking at the name & address for them at that price scares me. I don't like to give my CC number to someone out of the country. Not in this day.

[GTO JOHN]

Good tech info posted here Thanks to all.

I thought the factory used the bronze bushings and when I needed the last one nobody had them available anywhere. Years ago I had bought one for about $2.00 now they were out of stock everywhere or discontinued.

NAPA was selling a new bearing for $27.00 but there was no way I was going to use that!

Finally found someone who could order the Dorman bushing 690-023 for under $4.00 so I bought all they had.

[rexs73gto]

I was out in the garage the other day & remembered that there was some one wanting the part number for the cheap pilot bearing that came from Tractor supply. It was back in the bearing section & I found the bearing that looked the same & came back later to make sure it was the same size. The only difference is that this one has a seal on both sides instead of just one side as the correct number from any parts store would have. It's an SKF Br7109, I paid just under $ 6.00 including tax for this one & have put these now in about 5 different engines in the last few years with no problems & a lot less cost. At just under $ 6.00 you can buy 4 for the price of one from your local Autozone or Advance parts store. Plus there made in the USA.