LS Pilot Bearing Size
LS Pilot Bearing Size I am wanting to put an LS in my 70 vette. I am trying to gather info and parts as I go along to try and make this as painless as possible. I have a few questions. First one is, is the pilot bearing in the LS motors the same size as in the old small block chevy? Also, what about the flywheel? The reason I ask is because I now have a Keisler 5 speed in my vette and would like to be able to reuse that transmission as it only has around 5K miles on it or so.
Any help you can give would be greatly appreciated.
Any help you can give would be greatly appreciated.
TECH Apprentice
Joined: May 2006
Posts: 360
Likes: 1
From: Kansas City metro area
Take a look in the Stickys for at least some of what you are looking for. I put a Muncie 4 speed behind my LS1 and it certainly works but there are some tricky items to consider, the pilot bushing/bearing being one of them. Your Keisler is probably like a Muncie dimension-wise. It would be easier for you since you can use a standard Chevrolet bellhousing. Beautiful car by the way.
My car had an M20 in it when it came from the factory. All I really had to do was make sure the bell housing was going to allow the input shaft center line and crankshaft center lines were in line.
Did you reuse the stock bell housing in your installation? I know Keisler makes some hybrid bell housing but I do not know if they have accommodations for the stock style clutch linkage.
I will check out the sticky for the pilot bearing stuff and post my findings here.
Did you reuse the stock bell housing in your installation? I know Keisler makes some hybrid bell housing but I do not know if they have accommodations for the stock style clutch linkage.
I will check out the sticky for the pilot bearing stuff and post my findings here.
Originally Posted by Novas Forever
This is when I read a posting about the pilot bearing being short. The Muncie input shaft started in the stock bearing but did not engage far enough. The back of the LS1 crank has 2 different bores. The deepest one is where the stock bearing sets. The one closest to the clutch is much larger. The posting said that you could either have a longer pilot bushing machined (which is sweet) or get a special bearing that fit in the larger bore. I went with that bearing and left the original bearing there. It did not fit tight in the crank so I used some shim stock to tighten it up. Everything fit great then and was well supported.
TECH Apprentice
Joined: May 2006
Posts: 360
Likes: 1
From: Kansas City metro area
I used the GM bearing and it worked OK but the extended bushing would be my choice now. Since a Chevy II has the clutch fork at the 5 o'clock position I couldn't use a stock regular bellhousing not the stcok Chevy II housing since it would only allow a small flywheel. I went with a Lakewood scattershield to use as an adapter, didn't need the protection. I had to modify the block plate because there are parts that stick out beyond the mating surface in the area between the block and flywheel. I would probably just leave the block plate off next time. It bolted right up minus 1 bolt that is not used. I have got to fabricate the clutch z-bar mounts, they mount on the block from the factory. It will all work it just takes some patience to figure it out.
Keisler responded to me that they make an extended bearing for the LS motor. That should help quite a bit. They also make a bellhousing that will adapt the LS to the Muncie, of course at a price.
I think I read that you just used the standard bellhousing and had to leave one bolt out. How is that working out now that you have had a chance to add a few miles to the car?
I think I read that you just used the standard bellhousing and had to leave one bolt out. How is that working out now that you have had a chance to add a few miles to the car?
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Originally Posted by 69blackwidow
eddie70, i used an extented pilot bushing from day motorsports. i think it was like 10 dollars mike
Sweet deal. I will look into it and get me one on order since it seems I am going to need one.
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Joined: Sep 2004
Posts: 3,148
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From: Downers Grove, IL
Originally Posted by Eddie 70
I think I read that you just used the standard bellhousing and had to leave one bolt out. How is that working out now that you have had a chance to add a few miles to the car?
Thanks for chiming in Patrick. Good to know I can get away with the stock bellhousing.
I believe I will just use what I have.Now if I can come up with a solution to my clutch linkage. I want to use the stock stuff if I can.
I believe I will just use what I have.Now if I can come up with a solution to my clutch linkage. I want to use the stock stuff if I can.
I got some good pilot bearing/bushing information here when I installed the Tremec TKO600 behind my LM7 Gen 3 truck motor. I lined everything up (trans to block) and measured how much engagement the input shaft would have into the crank by measuring how far the input shaft surpassed the front edge of the BH using a long straightedge. I then measured from the face of the block to the crank hub to see how far it stuck out. I drew all this up to scale and determined an extended bushing by about .5"" would be ideal. Unfortunately, all the drawings I had for this were lost when my computer crashed last fall, but I see I attached it in my post on the above thread.
The closest I could come on this was an old school "extended" pilot bushing (it is like 1/4" longer, for a total of about 1") on eBay. It was a real tight fit in the crank. I used a stock LS1 flywheel and LS6 pressure plate with an "eBay special" clutch disk along with a mid 80's GM truck bellhousing since the pattern was the same for the 4 bolts on the tranny and as mentioned above all but one bellhousing to block bolts.
I don't have much time on the combo, still working the bugs out, but the clutch setup has not been an issue other than neededing a larger bore MC over what the Toyota had.
The closest I could come on this was an old school "extended" pilot bushing (it is like 1/4" longer, for a total of about 1") on eBay. It was a real tight fit in the crank. I used a stock LS1 flywheel and LS6 pressure plate with an "eBay special" clutch disk along with a mid 80's GM truck bellhousing since the pattern was the same for the 4 bolts on the tranny and as mentioned above all but one bellhousing to block bolts.
I don't have much time on the combo, still working the bugs out, but the clutch setup has not been an issue other than neededing a larger bore MC over what the Toyota had.
Last edited by V8 Supra Builder; Feb 25, 2007 at 11:47 AM.
Originally Posted by V8 Supra Builder
I got some good pilot bearing/bushing information here when I installed the Tremec TKO600 behind my LM7 Gen 3 truck motor. I lined everything up (trans to block) and measured how much engagement the input shaft would have into the crank by measuring how far the input shaft surpassed the front edge of the BH using a long straightedge. I then measured from the face of the block to the crank hub to see how far it stuck out. I drew all this up to scale and determined an extended bushing by about .5"" would be ideal. Unfortunately, all the drawings I had for this were lost when my computer crashed last fall, but I see I attached it in my post on the above thread.
The closest I could come on this was an old school "extended" pilot bushing (it is like 1/4" longer, for a total of about 1") on eBay. It was a real tight fit in the crank. I used a stock LS1 flywheel and LS6 pressure plate with an "eBay special" clutch disk along with a mid 80's GM truck bellhousing since the pattern was the same for the 4 bolts on the tranny and as mentioned above all but one bellhousing to block bolts.
I don't have much time on the combo, still working the bugs out, but the clutch setup has not been an issue other than neededing a larger bore MC over what the Toyota had.
The closest I could come on this was an old school "extended" pilot bushing (it is like 1/4" longer, for a total of about 1") on eBay. It was a real tight fit in the crank. I used a stock LS1 flywheel and LS6 pressure plate with an "eBay special" clutch disk along with a mid 80's GM truck bellhousing since the pattern was the same for the 4 bolts on the tranny and as mentioned above all but one bellhousing to block bolts.
I don't have much time on the combo, still working the bugs out, but the clutch setup has not been an issue other than neededing a larger bore MC over what the Toyota had.
Originally Posted by 69blackwidow
hey eddie, the part #for the long pilot bushing i used from day motorsports is pb-6500. its $10.99 mike
Thanks for the help Mike. Great help like you guys are giving sure does help make a project like this go a whole lot easier.
Originally Posted by jeepinpete
Per the GM Racing LS1 Installation Guide, use pn 12557583 pilot bearing. This is a sealed ball bearing that fits in the larger counterbore in the crankshaft.
Originally Posted by Me
I did some measuring today, and according to the specs at Rock Auto (parts house), the GM 12557583 pilot bearing (listed as fitting a 2002 Avalanche 2500 and other late model trucks) is 22.7mm ID (or .894 inch), 43.3 OD, and 13mm thick. I measured my crank (2003 Avalanche 5.3 LM7 originally an automatic) and TKO input shaft, and the OD is fine, but the input shaft is only about 15mm (or .590 inch)- way smaller than the bearing's stated ID.
You should go by your Chevy dealer & see if they have one on hand that you could measure.
Originally Posted by V8 Supra Builder
This may not fit with what you want to do. Per my research in the other thread:
I suspect your Keisler tranny is a Tremec series similar to my TKO600, if this is the case, the 12557583 inner diameter is way too big for your input shaft. The 12557583 appears to be used in truck applications that use a larger input shaft diameter than the T56 or old school style trannys. The LS1 T56 pilot bearing is shown to be .600 inch ID, 1.096 OD, .720 inch thick.
You should go by your Chevy dealer & see if they have one on hand that you could measure.
I suspect your Keisler tranny is a Tremec series similar to my TKO600, if this is the case, the 12557583 inner diameter is way too big for your input shaft. The 12557583 appears to be used in truck applications that use a larger input shaft diameter than the T56 or old school style trannys. The LS1 T56 pilot bearing is shown to be .600 inch ID, 1.096 OD, .720 inch thick.
You should go by your Chevy dealer & see if they have one on hand that you could measure.
