Front Drive Shaft Play

I constantly amaze myself with the things I don't know...

'75 CJ5, 304, T15, D20. All wheels on the ground, transfer case in 4 lo, front hubs locked in. If I grab the front drive shaft and twist, how much rotational free play should I be feeling?

 

Assuming an open front differential. And you forgot to mention the transmission. Tranny in neutral, about 1/8 of a turn. Tranny in gear, very little or no play.

 

The way I look at things is if I think there is too much play. There probably is. And unfortunately I am usually right.
Doug/Tucson

 

Thanks guys. Actually, both front and back are locked, and it's a T15 tranny. Still, Doug probably summed it up with "if you think there's too much..."

I think there's too much, so pressure washed the mud off this evening, and into the garage it goes for the weekend for a teardown.

Thanks for the responses.

 

There is actually quite a bit of rotational free play in the driveshafts. It's generated by the backlash setup in the R&P. It feels like a lot in the driveshaft, but it's really not that much at the R&P end. Some lockers can have quite a bit of freeplay as well. Before you tear it apart, check out the freeplay on another vehicle and see what you think. Might save you a lot of unessessary work.

 

I have no experience with lockers, in fact, I'm not even sure what they are the only thing I can think of is they are like posi track. But in any event, I have spent the past week, tearing down front ends and differentials checking for play in oder to find the best one out of 8. And I am allowed to mix and match parts, if that's what it takes. Willys works has been very accommodating In my effort to find or build a decent replacement front axle. It wouldn't be a bad idea to check another jeep. If you're sure it's exactly the same, but keep in mind. The other he could even be in worse condition. after going through 8 axles. You get a pretty good idea what is good and what is not
Doug/Tucson

 

What ever lockers are (again, I'm really not sure what they are). But what I'm finding with a standard front differential, 1/4 turn seems to be a lot for a worn but usable front end, what exactly are lockers. I have watch some videos, where I hear people say (he probably doesn't have lockers.) Exactly, what are they?
Doug/Tucson

 

http://en.wikipedia.org/wiki/Locking_differential

 

My locked dana 30 has 1/4 turn of free play in the drive shaft. It has been this way since it was rebuilt with a lock-right at a reputable shop that I trust. I asked the mechaninc about it and he said the locker does cause more free play in the driveshaft.

 

Chuck, thanks for the link! I only began to read it when I stopped To thank you for giving me a what appears to be all the information anybody could ever want on what exactly lockers are. Thanks again
Doug/Tucson

 

www.precisiongear.com/pgtechdiff.htm gives a great one page explanation of the difference between open diff, limited slips and full lockers. Also has tech calculators for engine RPM with differeent gear ratios and tire sizes.

 

If you have a detroit locker, they seem to have more rotational play than others.

 

To an extent ring and pinion ratio may have an influence on how much drive shaft rotation you see before lockup because it takes diff case rotation to take up all the accumulated slack in spider gears, splines and hubs. You would see less slack in a 2.73 gear set as opposed to a 5.38 gear set.