thakmfb

O.k. So as a lot of you guys that have helped me know I am doin a complete over haul of my 92' XJ 4.0 H.O. Got the reman crankshaft today. Put all my bearings in got the crank in, everything tourqed, spins very nice. I measured my crankshaft end play and I am at .009. Spec on ALLData is .0015-.0065.
I have seen some reports of a standard spec. and preferred spec.
Front what I have gathered the preferred spec is .002-.0025, But I cannot find anywhere that will confirm this. Can anyone verify this "preferred" spec. and if not is the .009 of endplay that I have going to be o.k. for me to run, or should I bring it to within the .0015-.0065 spec? Thanks for all the help!

thakmfb

Nothing from the engine guys ?

lngliv3

I would adjust endplay to within the .0015-.0065 spec. Thats what the manual I have says spec is..Are you really pryin hard on it to move it or are u being gentle with it ....it looks like its a lil bit much for me....

thakmfb

Nope...just moving it with a screw driver until it stops. Not prying hard at all. Im at .009 and spec is .0015-.0065 , I am tight by .006 to meet spec.

5-90

I'm given to presume you're talking about "axial endplay" (end-to-end movement,) which is more commonly called "thrust."

There are two primary causes for excessive thrust:

1) Wear or damage to the thrust bearing (the #3 main for us, as I recall. It's readily distinguishable by having the flanges on the sides.) Typically corrected by bearing replacement.

2) Wear in the crankshaft thrust surface (far less common) or a grind error where the grinding wheel is allowed to remove material from the thrust faces of the crankshaft (how'd it look when you got it back?) Typically corrected by crankshaft replacement.

I do not know of "oversized" thrust bearings (akin to the common "oversized" main bearings used for ground crankshafts - the bearings are oversized, the crankshaft is undersized...) and I can't think of a good way to fix it offhand, apart from the weld-and-grind approach (which means you'd probably have to take the crank and block into a crankshaft specialty shop, I'd think.)

For measuring crankshaft thrust, it is not necessary to prise against the crankshaft cheek with all your might - doing so is likely to compress - and therefore deform - the soft alloy that makes up the bearing, and you'll need a new set. You just just enough force to firmly butt the crankshaft to the limit of its motion, after having firmly butted up the other way and zeroed the dial indicator (or noted well the reading on the thing.)

I am not really familiar with a "preferred" setting for crankshaft thrust, particularly since you can't really do anything about it (you can try various tricks to alter main/rod bearing clearance slightly - but only one or two thousandths of an inch - without major work.

Crankshaft thrust is not, that I've noted, generally subject to wear. The only real adjustment I can think of would involve installation of Torrington bearings, but there's no way to get them on the shaft in the proper place (a Torrington bearing is a roller bearing in a flat circular arrangement, used for thrust applications. I can't think of an effective way to retain split Torrington bearings on a flat surface - you'd end up having to run them in a counterbore, which might work.)

5-90

You may wan to recheck your numbers - 0.009" is nine thousandths of an inch, and the spec is one and one-half to six and one-half thousandths of an inch. As I'm reading it, you're loose on thrust, not tight...

0.0015 - minimum axial endplay
0.0065 - maximum axial endplay
0.0090 - your measured axial endplay...

thakmfb

No i have 9 thousands. Spec is read as 15 thousands to 65 thousands. Im tight

mocXI

no the spec you posted in the original post from alldata was 15-65 ten thousandths so if you have .009 you would have 90 ten thousands which is way past spec.
if you are talking about thrust as 5-90 has pointed out which i believe you are, then from what ive always come to know the only way to fix that is with a new crank and new main bearings. also from what ive learned and everything ive ever seen when a vehicle has a problem with thrust it is due to a transmission problem.

thakmfb

The engine is out of the truck. Reman crank with new bearings. And also why does my dial indicator go to .0090?

5-90

What sort of dial indicator are you using?

My larger units (1" travel and 2" travel) do not read down to the ten-thousandth, they merely do thousandths. I have to use a "test indicator" to read the next decimal place - and they only do 0.050" (+0.0250" to 0" to -0.0250") of travel.

And 0.009" is a good deal more than 0.0015"-0.0065", in mechanical terms, because it should be read as 0.0090".

The transmission problems being referred to are transmission mechanical issues that transfer thrust to the crankshaft, and this can also be found in reman cranks (since remans aren't typically checked for thrust on the grinder. You need an in-spec block or a purpose-built gage set for that.)

Thrust is not easily correctable - and it's typically either weld-and-grind or outright replacement, as I mentioned before. It would take a very good crankshaft shop to do a proper weld-and-grind job to bring thrust back in spec, as it is not a standard operation. Most machine shops I've known would merely scrap a crank for having loose thrust, as it's easier (and so would I - and I've been building engines for about 25 years, and I'm no stranger at all to performance work.)

thakmfb

I smell what your stepping in now. Correct me if Im wrong but if I were between 2-6 thousands I would be o.k.?

5-90

Correct - 0.002"-0.006" is perfectly acceptable, given a spec range of 0.0015"-0.0065". You're just hacking off half a thousandth off of each end and ignoring it.

thakmfb

Cool, thanks for settin me straight. I will update the post and let you know how this plays out.

thakmfb

Got is all sorted with a new crank and bearings. I am right in the middle of the spec now. Thanks for everyones help!