Drive train "slop" - 39 PU
 

I have two questions, and I think I know the answers, but hope I'm wrong.

Put the drive shaft, rear axle ass'y, drums and rear wheels on my 39 PU chassis a couple of days ago. After tightening things up, I noticed I can rotate each rear tire through about 2" of free play before the drive shaft (through the speedo hole) or the other rear wheel moves.

Or, in other words, I have about 7.5 deg free play.This is considerably too much, isn't it?

I had this a part a few years ago, and put in new bearings, but I don't remember what splines, backlash, gear contact looked like - guess I'm gonna find out.

Second question...... I pulled out another rear axle while thinking about this. It didn't have a drive shaft, so I can't see how the pinion input shaft fit's in the drive shaft, but it looks to me like the input splines are shot. They are not supposed to have a "step" in them are they? I've attached photos.

Thanks, as always!

Gordon

Re: Drive train "slop" - 39 PU
 

Here's a story probably not many have heard. THis was back in the early 50's. I had a 47 ragtop with a stock 59AB. My wife had it one day, drove into town, stopped at a stop sign, went to take of, it wouldn't move. I towed it home, pull the rear end, removed the torque tube. I could slip the drive shaft right off the pinion. The pin that holes the couplen or sleeve had sheared off and the pinion had cleaned off all the theeth in the sleeve. It was just like you had put the sleeve in a lathe and turned out all the splines half way through the sleeve. Almost unbelievable. Walt

Re: Drive train "slop" - 39 PU
 

Walt, guess your saying I got some junk..............

Thanks,

Gordon

Re: Drive train "slop" - 39 PU
 

Gorden

Your truck is 74 years old. Most moving parts are worn to some degree. Consider how your truck is used, and then decide if the whole drive train is good enough for the service you will expect.

Bruce

Works good
Lasts long time

Re: Drive train "slop" - 39 PU
 

Bruce,

I appreciate the input, and that's a very good point. I'm sure all splines have some wear, ring and pinion a bit, and maybe a little in hubs as discussed in this forum. I've wondered sometimes about how good is "good enough".

It won't be driven a lot. I do want to take a trip now and then, though, and don't want to have an experience like Walt's wife. I've replaced head gaskets and darn near everything else on old cars on the roadside , and can fix a lot of stuff in an emergency (if I can find parts), but doing a Ford rear end/drive shaft would be easier with the body off.

Another factor is that I'll leave this truck to my kid some day, and he's got brains enough not to tear into a project like this. Maybe he's got brains enough to sell it.

Gotta keep reminding myself, as one signature on FB says: "It's just a hobby"!

Thanks,

Gordon

Re: Drive train "slop" - 39 PU
 

If the rear was quiet, the axles good just replace the spline coupler, then maybe in another 50 years it will have to come apart again for worn splines.

The 46 I had in high school was much worse, I just put in a used coupler, drove it 30K more, burned off several tires, it's probably still going.

Re: Drive train "slop" - 39 PU
 

Kurt,

Glad to get your opinion. I'm building what I want to be a dependable "occasional driver", and often wonder if I'm being too particular or not particular enough. Some discussion on the Barn makes it seems like everything's got to be "gnat's butt".

That spare rear end in my photo is shot, is it not? Cant imagine it 'posed to have that step in the splines.

Thanks,

Gordon

Re: Drive train "slop" - 39 PU
 

I can tell you my 39 had 4-11 ratio and a 10 spline pinion. Torque tube had no center bearing. Time to upgrade to 3-54's.

By the picture, a six spline pinion and assuming someone has changed the rear out maybe to 3-54's which I had someone do to my 39. I also got the needed later torque tube with center bearing/drive shaft with the six spline shaft coupling to work with the new pinion on my upgraded ratio.

No slop and Nice story Walt:D

My ring/pinion kit came from Mac's #48-4209-E. It's made in Italy so it's got to be fast

Re: Drive train "slop" - 39 PU
 

Portlander,
Thanks for the info. Hadn't noted the 6 spline/10 spline difference. Sometimes I read so much on this forum my retention goes away! Does the torque tube setup with center bearing also have short radius rods that attach to the torque tube? Have one of those around here somewhere.

I may have confused folks with my post. The rear end and splines pictured were not in the PU - they are just a spare.

I believe the one installed is 4.11 like yours was. Can't find any numbers so will have to check it out.

Looks like the bottom line is the drive train in the truck is sloppy AND what I thought was a spare has worn out splines - and would need different components.

Thanks for the reply,

Gordon

Re: Drive train "slop" - 39 PU
 

No no no! Not a body off job at all! Body off is all by itself a much more complicated job than any differential job, and yes, many jobs can be done at the side of the road with minimum tools.

Re: Drive train "slop" - 39 PU
 

Our rear radius rod's will work. The #'s are stamped into center pinion/ring case. Scratch around near the top plug. If you think you found some #'s use a soap stone over them and wipe it. You'll see'um then.

Do not remember my stamped #, but was told that the # specified 4-11.

Re: Drive train "slop" - 39 PU
 

My 39's going to my grandson, who will be two next week. As soon as that bugger starts talkin and spelling, the first word's he's gonna learn from me are Flathead Ford.

Developing the early V8 brain @ a young age:D