Mopar Muscle Association UK

Just checked my crank end play. I know it should be a max of 7thou or at a push 10thou.

Mine is 62thou.

The thrust surface on the crank itself is corrogated like ripples in a pool.

The thrust surface of the bearing is so worn it has parted on the upper half and is hanging off!

Is this repairable at reasonable cost or is it a new crank?

Any ideas what would cause this? I don't want to get it fixed and then find it has damaged again in 6 months time.

First, a question Dave, is your car a manual?

Nope. And the converter don't push against the end of the crank either so I am at a complete loss.

That thrust surface on the crank looks pretty bad mate, it could be metal sprayed to build it back up.

It is the rear thrust that has been wiped right, not the leading one? I would have said the cap was not centred but the wear looks equal on both bearings so I am at a loss why it should have done that on an auto, I have seen it many times on 4 speed cars

From that I assume the wear is at the front of the crank and not at the back of the Journal. I know some surfaces can be metal sprayed to build up wear.

Is the Crank +10 & +10 or is the rest of the bearing surfaces more worn ?

If it is a new crank then it is a re-balance of the motor - more money

On the first two photos of the crank the rear of the block is to the left and the front to the right.

The wear looks to have been caused by the crank being pushed forwards. But I can't see anything that would cause that.

The only thing that I can imagine happening is the torque converter being pushed hard forward. I don't see how that could happen though?

There is a place fairly local that might be able to metal spray it. Cost is my main worry.

Is the Crank +10 & +10 or is the rest of the bearing surfaces more worn

Don't know what that means Pete. I will remove the crank completely when I can face going back in the garage again. Right now I am too upset. I just don't have any money left to put this right.

I have never come across a damaged crank before so this is all new to me.
To be honest, in the past with old Ford engines, I used to just bang in new bearings and if the crank spun OK that was that. Big ends we used to check just by feeling for play. That was good enough for those things.

Dave, I meant has the Crank already been ground.

If it has already had a couple of grinds then I would opt for a new one.

I cannot imagine the Gear Vendors has had any impact here.

I assume the rest of the Rod clearances are within tolerence....

Have a word with Mr Billadeau - he has some spare cranks - I recently sold him a +10/+10 freshly ground 6 pack crank and Bearings.

?200 for the re-balance, though.....

You should have to pull the convertor forwards to bolt it up unless it is on the box wrong and that is not a mistake you would make for sure so it makes no sense.

To have that much wear I would have thought the pressure on the bearing must have been pretty constant so you nee to work through anything that would have a crank/thrust relationship effect, i.e. convertor, flex plate, cap alignment, speaking of which, is the damage equal on both bearing halfs? the radial damage on the crank will be constant.

dave is the oilway to that journal clear? i am wondering if a slight lack of oil to that journal could have caused premature wear on the bearing shell, try to get a oil gallery brush down and see what comes out .

The bearing face looks far to good to be oil starvation Trev, something in there is pushing on the crank

Thanks Pete. I will contact Dave B if it comes to that.

Alex wrote:You should have to pull the convertor forwards to bolt it up unless it is on the box wrong and that is not a mistake you would make for sure so it makes no sense.

Yup. For sure I would have noticed if the converter was tight behind the flex plate. There was a suggestion on Moparts about "Ballooning" but although I am not exactly sure what to look for the converter does look normal.

To have that much wear I would have thought the pressure on the bearing must have been pretty constant

I would have thought so too but I noticed the high amount of end play even before i touched a cap or rod bolt. I asked Geof Hauser about this and he says he saw it once on a 383 he rebuilt. He had no idea what could have caused it either.

is the damage equal on both bearing halfs? the radial damage on the crank will be constant.

You can see the other bearing half looks about the same in the top photo but it is starting to part company with the rest of the shell.

If it's any help take a look here, won't fix the problem but might give a reason, it starts off pretty basic but does go into ballooning and also bad earths as a reason ( no i'm not kidding)

http://www.4secondsflat.com/Thrust_bear ... lures.html

My apologies if you know all this already

If the bearings are a couple of thou different in whats left of the thrusts it may be because the cap was off, it only has to be a thou or so and it will break the oil film and starve the thrusts. I always set the crank in, centre the middle cap, rotate the crank a couple of turns the check the end float on both bearing halfs, more than once I have had to re set the cap.

I don't know enough about convertor 'ballooning' to help.maybe Dunc will see this post??

When I spun the crank the other half came with it!

The bit that has come off is on average 3-4 thou thinner. The bearing is a Clevite and is marked .020 which I guess means the crank is 20 thou under?

Sounds like the cap was not centred mate, they are a pest, also if they get a hard shock they can walk, but this is more often a 4 speed trend.

If the shells are 20's that is as far as I would go with the crank..the bearing surfaces look decent so if the others check out I would leave them alone and just get the thrust surfaces metal sprayed and the centre journal re ground to the same spec as before.

Sorry it is bad news mate