Crankshaft end float

[Cannon Cocker]

Not talking about end play at the moment. I have the bare crank(reconditioned) with properly sized new bearings installed in the block and torqued down. I'm able to move the crank from front limits to rear limits over a distance of .039. I believe this is called "end float". Is this excessive? Thanks in advance.

[Wolfman]

That is too much !!
A lot too much.
Should be more like .006 to .008.
Do you have all the components bolt up tight on the front of the crank ???
Washer, pulley. All the parts that would normally be there ??
That will make a difference.
If you do, you will have to take the crank back to the machinist and have the front face of the front crank journal machined to take up the slack.

[Joe Gopan]

Did you follow the Crankshaft installation instructions in the Army TM or the Jeep factory service manual? End Play is 0.004" to 0.006".

[Cannon Cocker]

At this point I've only installed the crank and not the lead components yet. I'm familiar with end-play and how it's achieved. But while checking out the machine shop work on the crank, measuring, etc., I noticed, while with the main caps torqued down, that I could move the crank from one extreme to the other for a total distance of .039. I believe this is called end-float but I've noticed many interchange this term with end-play. The term is not important. It seems that by setting the end-play iaw the manual, after final assembly,the "end-float" wouldn't make any difference, in that the crank can move no more than the established end-play. Am I right? But what the heck do I know? That's why I ask. Block work consisted of decking, installation of valve guides, and cylinder boring. The crank was turned under also. Does this help?

[Joe Gopan]

Best get thhe Army TM or Civilian manual for the jeep engine, it will give you details on setting end play with feeler or dial Indicator, and instruction how to correctly install front main bearings, correct installation of the thrust washer, etc..

[Cannon Cocker]

I've reviewed and followed the manuals. I honestly think the machine shop took too much material from the crank thus creating lateral slop in the rotating assembly. An expensive error that'll likely cost ME. Thanks for responding.

[Joe Gopan]

Are you positive that they removed material from the front of the crank shaft? Normally this would not be done.
Did you arrive at the 0.039" end play with the Pulley, Oil Slinger, Drive Gear Spacer, Timing Gear, and Thrust Washer in place with the Nut Tightened?

[Cannon Cocker]

No I didn't. I'm hopeful that once those components are installed with the requisite number of shims to achieve the end-play of .004-.006, the .039 end-float will be a "so what?" Presently, I'm inspecting and measuring machine work performed before I go forward with assembly of the engine.

[dpcd67]

Hey, while you are looking at your crank, could you measure the distance from the gear to the end of the threads, please. There is not enough room for my nut to screw on fully, and all the components seem right. (spacer, oil slinger, pulley and nut)
I have two M38 crankshafts and both of them are 1.9 inches from the gear to the end.
thanks.

[Cannon Cocker]

Sorry for the delay, I've been indisposed. I've already installed the crank and it's buttoned up. Getting an accurate measurement will be difficult but I can try.

[dpcd67]

Ok, good. I don't need a measurement now; just tell me if your nut is flush with the end of the crank threads, or is one thread protruding? I checked a friend's M38 and his is the same as mine, one thread is sticking out; one nut thread I mean. And his engine is original.
I already buttoned it up and will set it on the frame later this week.

[Cannon Cocker]

The nut I have which is original has a bar thru the center on the leading edge to enable hand cranking with a crank. As such, threads of the crank have to be recessed within the nut. Before installing the nut, I had approximately 5-6 threads of the crank extending beyond the face of the pulley. Hope this helps.

[Joe Gopan]

The nut I have which is original has a bar thru the center on the leading edge to enable hand cranking with a crank. As such, threads of the crank have to be recessed within the nut. Before installing the nut, I had approximately 5-6 threads of the crank extending beyond the face of the pulley. Hope this helps.

_____________________________________________________________________________
Your Pulley Nut is the type installed on MB/GPW, the pin is for the hand crank. M-38/M-38A1 has the short thinner nut.

[Cannon Cocker]

Interesting. Wonder what the corresponding hole in the front bumper is for?

[dpcd67]

I think the cranking nut was left off because now we have 24 volts instead of 6; always marginal in cold weather and of course, not enough for a big radio.
They kept the hole in the bumper but that was as far as it went; maybe leaving the door open for a cranking nut. If we could see the prototypes, they might have them. IDK.