Pilot bearing? - ClassicOldsmobile.com

Pilot bearing?

Old August 5th, 2018, 09:24 AM
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Pilot bearing?

I've heard some rumors that some 455 BB don't have a pilot bearing spot machined in the crank so a manual swap gets difficult. Can someone shed any truth to this and is there a way to tell before I order a ton of parts are rip it apart?
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Old August 5th, 2018, 09:59 AM
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that is correct. Unless it was a manual car that it came in most if not all Olds small and big block were this way. You can get the crank drilled and install a bushing if your re-building the engine. I had one done 30 plus years ago and the engine had about 30K on it and recently pulled it and everything looks perfect, trans and crank
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Old August 5th, 2018, 10:00 AM
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I believe only manual transmission cars were drilled for pilot bushings.. There's some adapter ones available from different vendors.
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Old August 5th, 2018, 10:05 AM
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I don't suppose there is any way to know if the engine was out of a manual car without looking at the back of the crank?
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Old August 5th, 2018, 11:28 AM
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Read some of the posts on converting to manual. Looks like best option is to have crank machined for bearing.
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Old August 5th, 2018, 11:44 AM
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Originally Posted by Delasangre4231 View Post
I've heard some rumors that some 455 BB don't have a pilot bearing spot machined in the crank
Actually, MOST 455s (and all other Olds motors) do not have the crank machined for a pilot bearing. Only those motors that came from the factory with a manual trans have the crank machined, typically. No, there is no easy way to tell without pulling the trans.
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Old August 5th, 2018, 03:56 PM
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Like DG65 mentioned. I did several years ago buy one of the adapter pilot bushings. Cannot remember where I bought it but there out there. Check with BTR and other Old's engine builders in this Club or ROP. It's thinner and does fit in the back of the crank. If I remember correctly when I installed the M-21, I made sure there was an air gap between the input shaft on the transmission and the back of the crank. I put a little model clay in the back of the crank for test fit. Yes it was a pain in butt taking the trans in and out a few times, because it is a hit or miss on this, may not work. I may have gotten lucky but there was enough space where the input shaft did not touch the back of the crank. But it worked for years with no issues on a well built 455. It maybe worth investigating further. My 2cents
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Old August 5th, 2018, 04:43 PM
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Old August 5th, 2018, 05:29 PM
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Read the installation instructions. The "drilling the crank" included drilling a clearance hole for the transmission input shaft. Some have reported that they cut 1/2" or so off the end of the input shaft.
Joe P knows more about this.
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Old August 5th, 2018, 05:34 PM
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Either of those mods I can do, taking the crank out to have it machined would be a problem.
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Old August 5th, 2018, 05:55 PM
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I would not cut the "snout" off the main input shaft. If you go this route imo measure the snout and drill the crank at least one step larger. Don't forget the modeling clay.
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Old August 5th, 2018, 05:57 PM
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Any particular reasoning for that?
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Old August 5th, 2018, 06:15 PM
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I wouldn't want to cutoff the input shaft, myself. Someone claimed to have done it and it worked fine. Using the clay is a good idea Here is a print that may help. Its kinda hard to read, but the best I have.

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Old August 5th, 2018, 06:20 PM
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I would not cut a piece off the input shaft-nope. Its hit or miss but you may be fortunate like me.
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Old August 5th, 2018, 06:32 PM
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I think I could pull the input shaft and have a machine shop cut it so its true and even and stuff, then since its all apart do new bearings to the trans and it should work nicely.
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Old August 5th, 2018, 06:39 PM
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I wouldn't cut off the input shaft. I like the idea of using clay to check. Also find out the diameter of that bearing from Supercarsunlimited.
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Old August 5th, 2018, 06:45 PM
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You guys keep saying that but I am not hearing why. I have an email out to them.
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Old August 5th, 2018, 09:11 PM
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The clutch disc has a splined hole and slips on the input shaft. The pressure plate pushes the clutch disc against the flywheel to transmit power from the engine. The bearing supports the input shaft/clutch disc and keeps it centered when the pressure plate is pulled back. There is a reason the input shaft was made that way was for a reason, and I don't know what it is. I hope I explained this clear enough. I wouldn't cut off the input shaft.......check with clay and see what you have.

I am not sure if the bearing you are getting will be 1.707" or 1.377". The 1.377" diameter would appear to me to be a bearing bore because of the +.0005" tolerance. The item you provided a link to could possibly a bearing in an adapter to fit the 1.707" diameter.
I believe I read somewhere that someone sold a drill bushing to drill the "dead hole".
.......Just my two cents worth
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Old August 6th, 2018, 07:32 AM
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Originally Posted by OLDSter Ralph View Post
I gave this exact diagram to the machinist and he was able to use it for drilling the crank if you go that route
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Old August 6th, 2018, 09:43 AM
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I just don't want to pull the crank. Honestly this truck is starting to turn into a money pit and I'm thinking of selling it now.
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Old August 6th, 2018, 09:55 AM
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When you start changing things, it does cost money.
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Old August 6th, 2018, 09:59 AM
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My reasoning (jmo) is that I believe I've seen a couple of types of differently machined areas but still all automatic or non-pilot bearing drilled crankshafts. My worry would be "if" this "sneaker" roller bearing insert was not true center then one would not only have to machine the crank for the correct factory type oilite pilot bearing and also install a new main input shaft in the 4-speed. I've thought about trying a "sneaker" bearing myself. I would drill the crankshaft if I did try it. Jmo. Please keep us informed and I hope you have success which ever way you go.
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Old August 6th, 2018, 09:59 AM
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Well I was told the transmission in it was solid and it blew up in 30 miles. So I'm a bit pissed at the seller.i called the trans shop and they said if it's not the right year of 700r4 they would need to replace the whole body and they don't exist anymore, and if it is right it'd be $1500-2000. For the manual swap I can get an Oldsmobile to SM465 4-speed bellhousing for $80 and a rebuilt SM465/NP205 combo for about $1000 but then the bottom end has to come out and I'm really not setup for this in the parking lot across the street. Brake jobs I can do, not full motor teardowns and swaps. So I'm out, I'm going to wait for the title and sell it.
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Old August 6th, 2018, 10:25 AM
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Originally Posted by Delasangre4231 View Post
Well I was told the transmission in it was solid and it blew up in 30 miles. So I'm a bit pissed at the seller.i called the trans shop and they said if it's not the right year of 700r4 they would need to replace the whole body and they don't exist anymore, and if it is right it'd be $1500-2000. For the manual swap I can get an Oldsmobile to SM465 4-speed bellhousing for $80 and a rebuilt SM465/NP205 combo for about $1000 but then the bottom end has to come out and I'm really not setup for this in the parking lot across the street. Brake jobs I can do, not full motor teardowns and swaps. So I'm out, I'm going to wait for the title and sell it.
You might want to educate yourself before spending money next time. The 700R4 isn't strong enough to live behind a BBO in stock form, especially in a heavy vehicle. I don't care how "solid" it is. As for the bellhousing, the only Oldsmobile bellhousing that will accept the large pilot on the truck transmission is the rare one used behind the Olds 350 diesel in manual trans trucks. I've only ever seen one of these for sale. If you really can find one for $80, I'll pay you twice that for it. The passenger car bellhousings won't fit the SM465.
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Old August 6th, 2018, 10:33 AM
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I am not sure what year and make vehicle you have and what engine you have. I have to assume you also don't have the pedals and linkage for a manual transmission as well as a shifter for the transmission ?
I am wondering why you don't consider installing a good automatic transmission (such as TH350 or TH400) in the vehicle. What was your intended use ?
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Old August 6th, 2018, 10:35 AM
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It's a 74 GMC Suburban 3/4 ton, 455 BB. I wanted a beater for the winter so I didn't screw up my nice car. It was sold as a just fix the brakes. Which I did and it ran and drove all of 30 miles when the trans blew.
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Old August 7th, 2018, 07:57 AM
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Speedway auto parts has an adapter for BOP to Chevrolet bolt pattern automatic transmission.
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Old August 7th, 2018, 08:42 AM
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Exclamation

I used the conversion bearing in my 70 442. Here is what I learned:

1. Drilling the crank for clearance is really difficult. The crank material is diamond hard!
2. The recess in the automatic crank may not be concentric with the crank center line.
3. The conversion bearing is a cheap chineseum manufactured part.

I did the conversion, and discovered that I could not shift into reverse without grinding gears.
The reason is that the non concentricity of the bearing prevented the total release of the input shaft when the clutch pedal is depressed.

I still drove the car for about 500 miles, and the conversion bearing started to squeal, and was failing.

I pulled the engine and had the crank drilled per the Mondello Tech Manula, and used a BCA7109 bearing.

Flawless over the past years.

"Do it once and do it right"
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Old August 7th, 2018, 11:59 AM
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Thank you, I have decided to sell it and do something else. I don't have the time or space to do something like this. I am just working out of the parking lot across the street. No garage.
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