[Probird]

I've haven't seen a thrust bearing do this before, I'm sure some of you have though. What would cause this? It looks like maybe it got pounded pretty hard? This is the 2nd season on this seat of bearings. I was lazy last winter and didn't tear it apart so I'm not sure when it started. I replaced them the season before that and they didn't look anything like this at that time. The pic is of the rear lower half of the bearing. The rear top half has one real small area that looks like this. Could it be a bad set of bearings?

I measured the crank endplay and with this set of bearings it is .011. With a different set of used bearings I had lying around it was .009. I don't remember for sure but I think when it was put together the first time it was .007. The thrust surface on the crank is very smooth and doesn't look like it has any wear at all. Any ideas???

[Probird]

Oops, I meant to say it is a pic of the upper rear half of the bearing, block side.

[harry k]

transbrake use?
do you have anti-ballooning plate ?
torque converter ballooning
th400 trans reduce converter feed limiting the amount of converer pressure. this is the converter feed passage in the stator body.

[Probird]

Yes transbrake
Yes 8" convertor with anti-balloning plates.
Same convertor has been used for 5 seasons (hundreds of passes),
Not using a th400, using a glide that's been in the car for 15 years.
It doesn't look to be wearing the bearing, it just looks like it's falling apart.

[70 lucerne lemans]

My last set looked like that,I figured it was the Eagle crank....I wonder if being on the transbrake on the two step has anything to do with it...

[Goat-Racer]

If only one of the shells looks like that then the two halves were not aligned with each other when the engine was assembled. The one half that was the most rearward took all of the load until it wore enough material away to meed the second half. Then the wear will slow down/stop. The half that was taking all of the thrust load (with poor lubrication because of the misalignment) gets all of the heat and the surface will be all heat cracked and start to pit.

Mine looked the same way when I took it apart.

So, back to basics. When the crank first gets set into the block with the upper half bearings and no main caps, check the crank end play. When the #4 cap goes on, if you have any less thrust clearance than without the cap, you aren't there yet.
I used to leave the cap loose and tap the crank front and back with a dead blow hammer. I'm not a fan of whacking the crank with a hammer, not do I like the idea of prying front to back with screwdrivers. I'll probably try to lever the crank somehow this time as to not mar things up.

Maybee we can get some input from guys who do this for a living on how they align the two halves.

[dda72]

Rick, how much clearance between the flex plate and converter when it's pushed into the transmission?

[harry k]

it should be min .075" & .125" high side.

[Probird]

Originally Posted by dda72

Rick, how much clearance between the flex plate and converter when it's pushed into the transmission?

Dwight- When I bolt the convertor to the flexplate I shim it to get 3/16" of pullout from the tranny. So when it's all the way in there it's probably 1/2" to 7/16" total. I haven't taken the transmission apart yet to see if there is any wear on the back half of the pump but I'm guessing it's ok. If there isn't enough pullout that will wear the back half of the pump and cause low pump pressure. Since the car doesn't rock backward when the transbrake is applied I'm guessing the pressure is still good and there was plenty of pullout. I'll check the tranny out good though just to make sure there isn't a problem there that would cause any problems.


Goat-Racer....The upper half pictured was much worse then the bottom half. The bottom half only had one small spot that had come apart like that. I totally see what you are saying. What would cause the two halves to not line up? There's only one way to put them in there and this is probably the 4th or possibly the 5th set of bearings that have been in this block with none of the other ones having this problem. Do you think it's a manufacturing defect in the bearings themselves that would cause them to not line up properly?

[Goat-Racer]

Well, I don't think that it was a bearing defect, at least not from what I saw on my engine anyhow.

Those two halves of the thrust bearing should be able to slide front to rear a few thousanths in the block and the cap. Measure the distance between the two thrust flanges on each of the two bearings. Next, measure the thickness of the main cap and of the block where the bearing would sit. The bearings should be a touch wider than the web and cap are thick.
If the block and cap are the exact same thickness and are indexed properly to one another, and the bearings measure out the same, then there should be no trouble getting the two halves lined up. If they don't line up, then you may have to get a little creative.

Levering the crank back and forth a few times before the #4 cap is torqued should force the thrust surface of the crank to align the two halves of the bearings. The last push should be forward.

[Goat-Racer]

I would still install the crank and check the end play with only the block half bearing in place, and record the value. If you have any less thrust clearance with the cap installed, then the two halves are not lined up.

[screamingchief]

Looking @ the bearing pic,my guess would be oil contamination.

You run methanol right?

Those alky engines can be kinda hard to get warm enough to burn off moisture and such,and that moisture can easily turn into acids if said moisture us left in the crankcase for any length of time,and those acids like to do nasty things like that to engine bearings.

How often are ya'll changing the O&F on this?

What oil are ya'll using??

Any visible signs of moisture build-up in the crankcase or such???

I would probably start changing the O&F more frequently myself regardless.

Also,if too much methanol gets into the oil,that too can cause the oil to breakdown as well.



Bret P.

[Probird]

Originally Posted by screamingchief

Looking @ the bearing pic,my guess would be oil contamination.

You run methanol right?

Those alky engines can be kinda hard to get warm enough to burn off moisture and such,and that moisture can easily turn into acids if said moisture us left in the crankcase for any length of time,and those acids like to do nasty things like that to engine bearings.

How often are ya'll changing the O&F on this?

What oil are ya'll using??

Any visible signs of moisture build-up in the crankcase or such???

I would probably start changing the O&F more frequently myself regardless.

Also,if too much methanol gets into the oil,that too can cause the oil to breakdown as well.



Bret P.

That's a good thought Bret. It doesn't get changed but a couple times a season.

You can smell it in the oil as I use the fragrance in the alky.

The last two seasons I've been warming the car up and driving around
the pits on 93 octane gas. I switch it over to alky to make the pass
then switch it back driving back to the trailer.

I don't really see moisture in the oil at least not like it has been in the past.
I used to get alot of alky and water in the vacuum pump catch can. I don't
much anymore using the primer plus system. That's why I don't change it all
that frequently. I know there is some in there though.

I'm using Castrol full synthetic this year.

Do you think I would see it on the rest of the bearings too or just the thrust?
That's the only place I see any damage.

[Half-Inch Stud]

Cap wafting? Cap zigs while the crank zags?

[cfmcnc]

Originally Posted by Goat-Racer

I would still install the crank and check the end play with only the block half bearing in place, and record the value. If you have any less thrust clearance with the cap installed, then the two halves are not lined up.

This is the CORRECT way to check thrust clearance.Bill C

[Goat-Racer]

Bill, what is your method of aligning the two halves?

[Cliff R]

Over .010" is too much clearance, IMHO. In all these years, I've lost one thrust bearing. It was the only engine that had over .010" when assembled. Since it was my own I took the risk, and it failed pretty quickly.

It measured right at .012".

To line them up, I gently drive a wedge in between one of the counterweights and the block to push the crank forward, then torque the cap and measure the end play.

I also remove a tiny amount of material from the oil groove out to the edge of the bearing at the parting line on one upper shell, to provide positive oiling.......Cliff

[Half-Inch Stud]

Originally Posted by Goat-Racer

Bill, what is your method of aligning the two halves?

Ditto on method , and that will require money.

Otherwise..."meta-amphetamine engineering...heck yea".

[67cruiser]

There was a great article someware here all about thrust bearing halfs and what to do with them plus pictures, I ground a 30 degree edges on my Thrust Bearings plus as Cliff Stated ground or opened oil groove up. So far no issues.

[Goat-Racer]

Originally Posted by Half-Inch Stud

Ditto on method , and that will require money.

Otherwise..."meta-amphetamine engineering...heck yea".

I don't understand????