Pilot bearings - BIG vs small
08-20-2009, 03:28 PM
#1
Pilot bearings - BIG vs small Ok. Since there seems to be alot....ahem ALOT of confusion about which pilot bearing to use, we figured an actual picture and somewhat of a vehicle list would be a good idea to help you identify what pilot bearing should go in your application.
First off, just because the pilot bearing comes in a corvette/ctsv does not make it high performance and therefore can be used in liew of the regular pilot bearing. GM has this part listed as "Used in high-performance manual transmission applications" but lists nothing else. This can be very misleading.
So here is the skinny on it.
Also in this thread i will refer to the GM pn 14061685 as the small bearing and the 12557583 as the BIG bearing. Of course due to their difference in physical size. Both sizes will fit into the LS crank. The only difference is the larger bearing will fit into the first bore step that the crank has and the smaller one fits into the second bore step in the rear of the crank. This is due to the different lengths of the main shaft aka input shaft of the transmissions through the different gm platforms. IF you try to use the BIG bearing in an application where it is not needed and try to FORCE the transmission to bolt up to the engine, you can do one of a few things.
1. it will not go together at all
2. it will go together after many curse words, alot of sweat, and impact and longer bolts, but not start
3. it will go together, you run the car and it makes a funny noise all the time. exploring this further leads to this conclusion. The main shaft is thrusting against the pilot bearing so hard that it pushes the crankshaft forward, completely wiping out the thrust bearing, and ruining your brand new (insert price here) LS engine.
4. it will go together, possibly start, run ok, act like it is down on power, and repeat what happened in #3 just not as soon
5. You will break the ear off of the engine trying to pull it on with the bolts.
6. any combination of any of these problems PLUS ALOT MORE.
The BIG (pn 12557583) bearing started being used in a few diff vehicles other than the LS platforms, but for now we will stick to only the LS based platforms. In the cars it was originally in the CTS-V circa 2004. From then it went on to be used in all C6 vettes and yes still of course in the cts-v. It is also used in the new 2010 Camaro with manual trans. It is possible that the G8 uses this same bearing, but i cannot confirm that at this time. A little more investigating will find out. Those are actually all of the (american) RWD LS cars that gm has from 03 and up.
The small bearing (pn 14061685) was used in the Fbodies and C5 vettes. ALL Fbodies and ALL C5 vettes. Also ALL GTOs. That would sum up all of the RWD LS V8 cars that GM made from 97-04 in the Y body, 98-02 in the F and 04-06 in the GTO.
To my research, the BIG bearing was used in all GM M/t LS trucks, including both the 5spd and 6spd manual transmissions from 99 and up.
So....the bearing is not specific to the engine, more specific to the trans that is being used. IF you have a C6 and are using the C6 trans/drivetrain, then it must use the BIG bearing. If you are dropping an LS3 into an Fbody then you must use the small bearing.
Notice this does not cover alot of the hybrids that come about such as using a diff transmission other than the normal GM 5spd or 6spd car or truck trans that would normally come on an LS engine such as the T5/T10/Muncie/Saginaw etc. I believe the hybrid guys have most of that figured out.
Get it?
ok now pics.
questions?
First off, just because the pilot bearing comes in a corvette/ctsv does not make it high performance and therefore can be used in liew of the regular pilot bearing. GM has this part listed as "Used in high-performance manual transmission applications" but lists nothing else. This can be very misleading.
So here is the skinny on it.
Also in this thread i will refer to the GM pn 14061685 as the small bearing and the 12557583 as the BIG bearing. Of course due to their difference in physical size. Both sizes will fit into the LS crank. The only difference is the larger bearing will fit into the first bore step that the crank has and the smaller one fits into the second bore step in the rear of the crank. This is due to the different lengths of the main shaft aka input shaft of the transmissions through the different gm platforms. IF you try to use the BIG bearing in an application where it is not needed and try to FORCE the transmission to bolt up to the engine, you can do one of a few things.
1. it will not go together at all
2. it will go together after many curse words, alot of sweat, and impact and longer bolts, but not start
3. it will go together, you run the car and it makes a funny noise all the time. exploring this further leads to this conclusion. The main shaft is thrusting against the pilot bearing so hard that it pushes the crankshaft forward, completely wiping out the thrust bearing, and ruining your brand new (insert price here) LS engine.
4. it will go together, possibly start, run ok, act like it is down on power, and repeat what happened in #3 just not as soon
5. You will break the ear off of the engine trying to pull it on with the bolts.
6. any combination of any of these problems PLUS ALOT MORE.
The BIG (pn 12557583) bearing started being used in a few diff vehicles other than the LS platforms, but for now we will stick to only the LS based platforms. In the cars it was originally in the CTS-V circa 2004. From then it went on to be used in all C6 vettes and yes still of course in the cts-v. It is also used in the new 2010 Camaro with manual trans. It is possible that the G8 uses this same bearing, but i cannot confirm that at this time. A little more investigating will find out. Those are actually all of the (american) RWD LS cars that gm has from 03 and up.
The small bearing (pn 14061685) was used in the Fbodies and C5 vettes. ALL Fbodies and ALL C5 vettes. Also ALL GTOs. That would sum up all of the RWD LS V8 cars that GM made from 97-04 in the Y body, 98-02 in the F and 04-06 in the GTO.
To my research, the BIG bearing was used in all GM M/t LS trucks, including both the 5spd and 6spd manual transmissions from 99 and up.
So....the bearing is not specific to the engine, more specific to the trans that is being used. IF you have a C6 and are using the C6 trans/drivetrain, then it must use the BIG bearing. If you are dropping an LS3 into an Fbody then you must use the small bearing.
Notice this does not cover alot of the hybrids that come about such as using a diff transmission other than the normal GM 5spd or 6spd car or truck trans that would normally come on an LS engine such as the T5/T10/Muncie/Saginaw etc. I believe the hybrid guys have most of that figured out.
Get it?
ok now pics.
questions?
Last edited by Beau@SDPC; 08-20-2009 at 03:35 PM.
08-21-2009, 11:49 AM
#4
small. the aftermarket cranks are going to be exactly like the stock crank as far as the pilot bearing bores and how they are fitted. so as per the writeup, the fbody using a trans with the fbody input shaft will use the small bearing with any crank
01-08-2010, 03:53 PM
#5
I know this is bringing this back up after a few months... I know a few people have put F-body t56 transmissions behind truck 5.3 and 6.0 engines. The offset of the back of the crank should be the same as the ls1 correct, thus meaning I need the small bearing (14061685)?
01-08-2010, 10:24 PM
#6
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I know this is bringing this back up after a few months... I know a few people have put F-body t56 transmissions behind truck 5.3 and 6.0 engines. The offset of the back of the crank should be the same as the ls1 correct, thus meaning I need the small bearing (14061685)?
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02-22-2010, 12:23 AM
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joyridin' (03-28-2020)
03-29-2010, 09:31 AM
#20
ok i have a f-body with a manual. so that would be a small bearing. but i am using a t56 magnum. (tr6060) so is that still a small bearing.
can you give me a length to measure the imput shaft.
if the stock t56 imput and mine are the same it should be a small bearing correct?
thanks, and sorry for the ramble of questions
D
can you give me a length to measure the imput shaft.
if the stock t56 imput and mine are the same it should be a small bearing correct?
thanks, and sorry for the ramble of questions
D