Pilot Bushing Help
Thread Starter
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Pilot Bushing Help
My uncle brought this to my attention the other night. The crank that is in my engine right now was out of the LS4 that I brought back from Michigan. That engine came with an automatic transmission....I will be running a standard transmisison. I checked rear of the crank for splines and sure enough it doesn't have any on the inside. My input shaft is a 26 spline, does anyone know where I can get a pilot bushing for my application? Thanks.
Team Owner
Joined: Jun 2001
Posts: 23,363
Likes: 1,059
From: Virginia USA
Re: Pilot Bushing Help (bence13_33)
Pilot shaft bushings go into the back of the crank where the flywheel bolts onto. The splines on you tranny input shaft are coupled to the drivetrain by the clutch disk. All the pilot shaft bushing does is support the very front end of the input shaft. The input shaft of your manual tranny will have a smooth end that inserts into the pilot shaft bushing. There are also needle-bearing styles that can be purchased. So to sum up it doesn’t matter how many splines your input shaft has because the splines do not insert into the pilot shaft bushing.
Hope this helps.
John
Hope this helps.
John
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Re: Pilot Bushing Help (bence13_33)
Bence - don't make the mistake I did. I picked up a pilot bushing from Napa & installed it in the rear of the crank without checking it on the end of the pilot shaft of the trans.
To make a long story short, the i.d. of the bushing was too small to allow the shaft to rotate, but big enough for me to draw in the trans with the bolts.
Go to Chevy & get their bushing (which is now the roller style they sell)
And make sure it slips freely on the shaft just to be sure.
Good luck with your project :cheers:
To make a long story short, the i.d. of the bushing was too small to allow the shaft to rotate, but big enough for me to draw in the trans with the bolts.
Go to Chevy & get their bushing (which is now the roller style they sell)
And make sure it slips freely on the shaft just to be sure.
Good luck with your project :cheers:
Race Director
Joined: Jun 2000
Posts: 10,037
Likes: 668
From: FL
Re: Pilot Bushing Help (71coupe)
Bence,
I'll give you the possible bad news now. The back end of the crank must be machined for the pilot bushing. About 1" diameter and about 1" deep. Sometimes to save money, GM did not machine those cranks destined for automatic applications. If your crank is not machined, you will have to pull it and take it to the machine shop. :cry
I'll give you the possible bad news now. The back end of the crank must be machined for the pilot bushing. About 1" diameter and about 1" deep. Sometimes to save money, GM did not machine those cranks destined for automatic applications. If your crank is not machined, you will have to pull it and take it to the machine shop. :cry
Race Director
Joined: Apr 1999
Posts: 10,861
Likes: 713
From: Beverly Hills/Pine Ridge Florida
Re: Pilot Bushing Help (SteveG75)
I can attest to the incorrect ID bushing from personal experience. Was helping a friend put the trans on his motor, luckily sitting in a cradle. This was prior to installing the entire unit in his 64 coupe. We fought the trans for an hour. Finally took the bellhousing off, etc. and measured the OD of the output shaft compared to the ID of the NEW bushing from the machine shop that built the motor. Wouldn't fit. Ground it out with a Dremel, bought the correct one, checked the fit, installed it....the trans slid right in. Double check the bushing you buy. Chuck
Burning Brakes
Joined: Dec 1999
Posts: 1,188
Likes: 1
From: Saskatoon Saskatchewan Canada
Re: Pilot Bushing Help (bence13_33)
I hate to mention this but...From lots of engine swaps in my past that is one of two critical checks going from auto to standard. The other is GM didn't tap out the whole that the clutch cross bar ball socket screws into. Check that out before you drop the motor in. It's easier to tap it Now:) 
[Modified by paso, 12:10 PM 4/6/2002]
[Modified by paso, 12:10 PM 4/6/2002]
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Thread Starter
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: Pilot Bushing Help (paso)
Paso:
Thanks for pointing that out, I will be sure to tap that hole before I drop the engine in. You are correct, it will be much easier now than with the engine in the car.
I really hope I don't have to pull the crank back out to have it machined for the pilot bushing....can someone confirm whether this is true or not?
Thanks for pointing that out, I will be sure to tap that hole before I drop the engine in. You are correct, it will be much easier now than with the engine in the car.
I really hope I don't have to pull the crank back out to have it machined for the pilot bushing....can someone confirm whether this is true or not?
Pro
Joined: Jun 2001
Posts: 683
Likes: 0
From: Calgary
Re: Pilot Bushing Help (paso)
Paso, my clutch cross shaft ball screws into a threaded hole just below my dip stick. I thought all Vettes were this way. I know Camaros used the hole by the oil filter.
I had to drill and tap this hole in my 400 block.
[Modified by 74vetteman, 12:32 PM 4/6/2002]
I had to drill and tap this hole in my 400 block.
[Modified by 74vetteman, 12:32 PM 4/6/2002]
Burning Brakes
Joined: Dec 1999
Posts: 1,188
Likes: 1
From: Saskatoon Saskatchewan Canada
Re: Pilot Bushing Help (74vetteman)
I am not sure when GM started not taping the hole when they knew the car was not going to be a standard shift but I have noticed it not tapped.
Bence as mentioned above check the size of the hole 1" x 1" sounds correct so that you can install the bearing in the end of the crank. Also the id size as also mentioned.:)
Bence as mentioned above check the size of the hole 1" x 1" sounds correct so that you can install the bearing in the end of the crank. Also the id size as also mentioned.:)
Race Director
Joined: Jun 2000
Posts: 10,037
Likes: 668
From: FL
Re: Pilot Bushing Help (74vetteman)
Check the back of the crank. If it is machined in the center, you should be good to go. Go to the parets store and get a pilot bushing (they are cheap and you need it anyway) and you will see the size of the hole you are looking at.
Agree with 74vetteman on the clutch linkage. The hole you need tapped is the forward one about 6" in front of the other. GM has stopped including this on new blocks so the guys doing 502 swaps are having to fabricate brackets.
Agree with 74vetteman on the clutch linkage. The hole you need tapped is the forward one about 6" in front of the other. GM has stopped including this on new blocks so the guys doing 502 swaps are having to fabricate brackets.
Thread Starter
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: Pilot Bushing Help (SteveG75)
Steve:
Yes, the rear center of the crank is machined. Is it ok to use a pilot bushing from NAPA? redvetracer said that he gets all of his from NAPA.
Yes, the rear center of the crank is machined. Is it ok to use a pilot bushing from NAPA? redvetracer said that he gets all of his from NAPA.
Pro
Joined: Jun 2001
Posts: 683
Likes: 0
From: Calgary
Re: Pilot Bushing Help (bence13_33)
I would use the GM roller bearing pilot bushing. They came on the 6.6 liter diesel engine and are recommended for performance use in the Chevy power book. Moroso sells on as well. GM part # is 14061685.
I have seen the brass bushings cause the input shaft to become blue where the two mate. probably not a good thing.
Nice camera work paso, and nicely detailed engine. What digital camera do you use?
[Modified by 74vetteman, 12:55 PM 4/6/2002]
[Modified by 74vetteman, 12:56 PM 4/6/2002]
I have seen the brass bushings cause the input shaft to become blue where the two mate. probably not a good thing.
Nice camera work paso, and nicely detailed engine. What digital camera do you use?
[Modified by 74vetteman, 12:55 PM 4/6/2002]
[Modified by 74vetteman, 12:56 PM 4/6/2002]
Melting Slicks
Joined: Dec 2000
Posts: 2,635
Likes: 0
From: Union Ontario
Re: Pilot Bushing Help (paso)
71coupe and redvetracer,
The same thing just happened to me too with the one I got from Napa.
I didn't think it was a problem.... I guess I'll pull the tranny and clutch out again and get the GM one.
The same thing just happened to me too with the one I got from Napa.
I didn't think it was a problem.... I guess I'll pull the tranny and clutch out again and get the GM one.
Drifting
Joined: May 2000
Posts: 1,573
Likes: 1
From: Ga.
Re: Pilot Bushing Help (bence13_33)
If you plan on doing alot of high rpm shifts, I would go with the GM roller pilot bearing. The pilot bearing supports the input shaft of the transmission and you want this to be smooth. The GM unit is about $12 and well worth it. You don't want to get a cheepie piece..... :smash:
Melting Slicks
Joined: Apr 2000
Posts: 3,341
Likes: 6
Just because there is a machined bore in the center of the crank does NOT mean it is set up to accept a pilot bushing - they machine bores in cranks meant for automatics, too! The bore, at about 1.705" in diameter, is where the pilot is placed when the torque converter is put in position.