legacycentral bbs

What is the design dim. for crank thrust? I am concerned that my engine has crank walk. Which would certainly be excessive thrust. Thanks team.

Small. So small you really shouldnt be able to visibly notice it.

That said.....

I have seen two perfectly running motors with 1/16th " or more crank walk, that were running perfect.

And my current crazy motor where I stuck the ej257 crank in the phase 1 block with EXCESSIVE crank walk..... And as far as I know, no issues due to the excessive thrust.

I believe I was told mine was .052", which is less than a 1/16". It has been running fine, so it is going to be something to be corrected later.

Specs from the FSM are 0.0012" to 0.0045" new with a wear limit of 0.0089".

Gary

My motor has a ton of crank play...but it runs great...so no biggie in my book

Thanks for the info. Will be addressed in a rebuild , which is not planned in the near future. FSM sure is small numbers.

You guys with a lot of crank play ever find metal bits in your oil?

Seems like our engines will still run well, but is there a little internal damage?

What happens with crank play is the thrust bearing wears. But slowly. This wear is not the same as a bad bearing. AFIK, the only time the thrust bearing sees wear, is when the clutch is pushed in. So don't ride the damn clutch!

Anyway, this kind of wear is SLOW, so if you change your oil regularily, then the metal is very slow to see, if at all.

The damage that actually happens is first the bearing collar wears out. Then the crank itself sees wear. If you were to do a rebuild using a worn thrust bearing crank, you would have some play to start with, but with 100% thrust bearing collar. And if you stay off the clutch( dont ride it at stop signs), the bearings should run another 50-100k in my mind..... I am not saying this is better than just getting a new crank, but our motors do live with excessive crank play.

Right, good explanation.

I'm wondering if anyone has worn the bearing collar to the point that the crank got worn. And how much crank play did it have?

That'd be cool to know the amount of crank play that can occur before the thrust bearing is shot. I guess it would be about the same as the thickness of the bearing collar.

I blew the timing belt last night and replaced it today and discover my crank is walkin' about.

I then also realized that it is causing my mystery clutch issue.

I noticed about a year ago that after hard braking my clutch pedal felt like somebody had pushed the clutch slave cylinder into its bore, it would good nearly to the floor.

I just realized my crank slides forward when I hit the brakes(hard).

http://www.youtube.com/watch?v=jpCQx-UmOjE

Well if your crank moves forward with braking, it's going to move forwards with the clutch pushing on it anyway.

The real danger with worn thrusts is that the rods can get their bearings worn out of flat, that and the rods rub the crank if it's really got a lot of wear.

You can get over-sized(that's thicker) thrust washers.

I'm worried. I had no idea it was that bad, the engine leaks NOTHING so I never bothered to really mess with it. That seems like A LOT of movement. I'd say a 1/8 to 1/4 in..

Yeah well there's not much to be done about it, you have to do the whole motor to cure it.
If it's possible don't hold the clutch in when you are starting it, they wear most at startup when they have no oil to them and you have your foot on the clutch. Put the car into neutral at the intersection or lights where possible.

All_talk wrote:Specs from the FSM are 0.0012" to 0.0045" new with a wear limit of 0.0089".

Gary

I second these numbers, I've always said no more than .005". BUT I have seen a K20A motor with .050" run a 25 hour race and not go wizz-bang. So.....yeah....

Well luckly the neutral switch was disconnected when I bought the car(thanks Dave!). So no clutch on startup, but I won't be able to tear into this thing for a few months so I'm crossing my fingers.

my cranks been walking for a while now with a noticeable amount of play. my a/c belt used to squeal when pressing the clutch down. ahah gonna rebuild when snow melts.