thrust bearing on big block ford

Im running a 572 big block ford procharged engine ...i am having trouble with the center main thrust bearing...i have to replace it after every meeting..it flattens it out...i run it pretty hard 8800rpm @42lbs boost,could it be crank flex?all the other bearing look mint...i am looking at changing the crank to a better brand maybe a crank with center counter weights?...anyone have any ideas?

this was an interesting read, maybe it can help you, http://www.motor.com/magazinepdfs/082010_09.pdf

lenco and clutch...the bearing is squsing downwards

What kind of crank??

did you check crank end play after bolting up trans,and what about clutch ped going over center,and pushing forward on crank? have seen this more then once

BOSS 429 wrote:did you check crank end play after bolting up trans,and what about clutch ped going over center,and pushing forward on crank? have seen this more then once

how does that work? I'm thinking it'll have a cross shaft type setup? I will be dealing with this so I'd like to learn something.

What block are you using? What brand?

Charlie

procharger 528 wrote:Im running a 572 big block ford procharged engine ...i am having trouble with the...thrust bearing..it flattens it out...i run it...8800rpm @42lbs boost,could it be crank flex? all the other bearing look mint...any ideas?

Which crankshaft do you have (brand/stroke) and where do you set your thrust clearance?

the cross shaft has a stopper on it the clutch can open 60 thou max...i have widened the thrust bearing to 12 thou that's putting a feeler blade in between the bearing and the crank..that's seems to have solved that problem...the bearing is still crushing on the bottom side...the block is a eliminator block with billet caps...the crank is a scat 4340 steel 4.3 stroke 4.6 bore...i know not the best crank but was the only one available at the time....we only have one meeting left so the plan is to get a billet crank with center counter weights on it hopefully that will help,i was trying to sort it out before then..

I have seen a couple setups on highly boosted 429-460 applications that were converted to use a Torrington roller thrust bearing that goes between the front crank coubterweight and the rear of the front main bearing bulkhead. The builder machined the crank and block to accept the large roller bearing.
Later this week I will try to add pictures of the setup.
Keith

I don't know how much torque you're making to deform the crank but, I have seen with a camera, while happening on the dyno, the crankshaft actually shorten by almost .060"  with a 5.300"  stroke and around 1,500 horsepower with a 2.200" crank-pin and 2.75" main sizes.

We needed to open up the rod side clearance to .080" being sure the crankshaft main surfaces were wide enough and piston guide the rods to keep a thrust bearing in it.

what everyone's thoughts on full grove bearings verses half grove bearings?..i have been running full grove, i am going to try a set of king half groves and see if that changes the crush on the bottom bearing....

The reason I asked what block you were using, is because I thought you may be using an Eliminator block.
The difference between the Eliminator block and a Ford SVO A-460 block is, that the main caps are not dowel pinned with the Eliminator blocks, whereas with the Ford SVO A-460 block they are. That doesn't cause too much of a problem with #'s 1, 2, 4, and 5 main caps. But I have seen the number 3 main cap move fore and aft even when fully torqued, and that's where your thrust bearing is. So what typically happens is that only the thrust surface that's on the upper shell in the block, does the actual job of carrying the thrust load. Furthermore, once the thrust surfaces are offset relative to each other, it creates a scrapper effect with the oil that is on the thrust surface, causing a lack of oil to that upper shell.

Hope this helps.
Charlie

cool40 wrote:

BOSS 429 wrote:did you check crank end play after bolting up trans,and what about clutch ped going over center,and pushing forward on crank? have seen this more then once

how does that work? I'm thinking it'll have a cross shaft type setup? I will be dealing with this so I'd like to learn something.

Have seen  many guys do this in the last 5 years , 1 guy who overbuilt everything was killing the thrust ask me to look at his after he had just tore his up again. For what ever reason I leaned  over the front of the car to look at something while he was pushing  in the clutch to start the engine and I FELT THE FRONT BUMPER MOVE forward,lol . He then told me he was having a problem shifting the car also. It was pushing the presser plate over center,and forcing the clutch into the flywheel.

One of the others had a custom pilot bushing  that stuck out too far, bolting the trans down it just shoved the crank forward and killed it.

another one has asb the trans wrong ,with the wrong bearings, this one stuffed the input into the crank


converter guys kill them pretty easy also, just have to check clearance, most it seems don't , if its a new combo check everything twice.

1 thing that is common with the converter cars is the thickness of the HEAD of  flex plate bolts , have seen a lot of witness marks on the converter where its not going into the crank all the way, but is being push back into the trans,and thus pushing forward on the crank . It was so bad on 2 engines that it was throwing the belts off after the thrust was gone,  They killed 2 crate engines. There  have been a lot of times I have to cut the heads of the bolt down which doesn't hurt a thing .

cool40 wrote:

BOSS 429 wrote:did you check crank end play after bolting up trans,and what about clutch ped going over center,and pushing forward on crank? have seen this more then once

how does that work? I'm thinking it'll have a cross shaft type setup? I will be dealing with this so I'd like to learn something.

call me sometime if you want, we could go over your build

procharger 528 wrote:Im running a 572 big block ford procharged engine ...i am having trouble with the center main thrust bearing...i have to replace it after every meeting..it flattens it out...i run it pretty hard 8800rpm @42lbs boost,could it be crank flex?all the other bearing look mint...i am looking at changing the crank to a better brand maybe a crank with center counter weights?...anyone have any ideas?

seening 2500 hp + engines not having this prob in other ELM blocks, The tq that they make and running them up the rpm chart, I cant see it being the block.

BOSS 429 wrote:

cool40 wrote:

BOSS 429 wrote:did you check crank end play after bolting up trans,and what about clutch ped going over center,and pushing forward on crank? have seen this more then once

how does that work? I'm thinking it'll have a cross shaft type setup? I will be dealing with this so I'd like to learn something.

Have seen  many guys do this in the last 5 years , 1 guy who overbuilt everything was killing the thrust ask me to look at his after he had just tore his up again. For what ever reason I leaned  over the front of the car to look at something while he was pushing  in the clutch to start the engine and I FELT THE FRONT BUMPER MOVE forward,lol . He then told me he was having a problem shifting the car also. It was pushing the presser plate over center,and forcing the clutch into the flywheel.

One of the others had a custom pilot bushing  that stuck out too far, bolting the trans down it just shoved the crank forward and killed it.

another one has asb the trans wrong ,with the wrong bearings, this one stuffed the input into the crank


converter guys kill them pretty easy also, just have to check clearance, most it seems don't , if its a new combo check everything twice.

1 thing that is common with the converter cars is the thickness of the HEAD of  flex plate bolts , have seen a lot of witness marks on the converter where its not going into the crank all the way, but is being push back into the trans,and thus pushing forward on the crank . It was so bad on 2 engines that it was throwing the belts off after the thrust was gone,  They killed 2 crate engines. There   have been a lot of times I have to cut the heads of the bolt down which doesn't hurt a thing .

I had to cut the flex plate bolts on my first build, sure glad my buddy caught it in time

procharger 528 wrote:Im running a 572 big block ford procharged engine ...i am having trouble with the center main thrust bearing...i have to replace it after every meeting..it flattens it out...i run it pretty hard 8800rpm @42lbs boost,could it be crank flex?all the other bearing look mint...i am looking at changing the crank to a better brand maybe a crank with center counter weights?...anyone have any ideas?

Sounds like it's in the bell housing. Check the end play in the input shaft to pilot bearing. Make sure the radius on the pilot is not so large as it will cause it to contact the pilot bushing or inner race of a bearing and push the crank forward.

Insure that you have a clutch pedal stop to prevent the fork from going over center. Check all your geometry in this area. Use the stop to set your air gap for the disk to pressure plate donut.

Never seen any cap movement on any Eliminator block or A-460 either.