How far can you twist a driveshaft by hand?

[zerfetzen]

My wife bought a '69 Mustang from a lady who doesn't know anything about the car.  The lady says she thinks the 9" rear end has 3.70 gears and a detroit locker in it, and it's believable, given how the guy she bought it from built the car.  And let me say I'm sorry to ask a stang question here, she always wanted one and I can't seem to get on any stang forums.  I'll figure that out.  But anyways...

I can turn the driveshaft somewhere between more than an eighth and less than a quarter turn by hand before the rear end engages.  That's not right, is it?  If not, what do you think is wrong?  Could that be the yoke or crush sleeve?  Is it safe to drive it like that, for example to a tranny shop to get fixed?  Thanks.

[The70RT]

That's the rear gear. Auto trans right? If manual it could be either. Gear just may need adj.

[zerfetzen]

Toploader 4-speed, so it could be the trans. too?

[The70RT]

I would check both. I don't think you should have that much play in either one. Maybe someone on here can chime in.

[l8rg8r]

your right that is to much play in either one imo but that doesn't mean its junk just time for some attention wait the blue oval means it junk lol couldn't resist a little fun at your  expense

[zerfetzen]

It's all good, I'm going to look into the rear end first and hope that solves it, but if not, she wants a Tremec TKO 600 anyway, so no harm no foul, eh?

The real crime here is just halts my 69 Charger project, but hey, it's my wife, so I guess it's time to learn a little Ford for her.  Cheers.

[l8rg8r]

better you than me so heres to ya

[zerfetzen]

Now I'm wondering if this is actually normal, because it is a detroit locker.  I'm reading in several places online that this much slop in the driveshaft is, maybe, normal with a locker.  I can live with some loud noise when it engages here and there, but it happened once and was pretty loud.

[FLG]

Yea there loud and some of them are quite aggressive. I have a very mild locker in the chebby truck, ill see how much slop there is in the driveshaft. Some of them are LOUD like a damn iron gate closing. The one in the truck is mild, you get some noise when pulling out of a spot slowly but thats about it.

[zerfetzen]

Thanks FLG, please let me know what you come up with. 

[zerfetzen]

I went to Eaton online and found a pdf download of the owner's manual for the detroit locker.  Here's what it says on page 4:


"Backlash or slack between the driving and driven clutch teeth is an inherent part of the NoSPIN and necessary to permit
automatic operation when driving in forward and reverse. The total backlash in the driveline is increased by the amount of the
reduction between the ring gear and pinion. If the ring gear-pinion ratio is 5 to 1, the total backlash in the driveline with the
NoSPIN would be about 30°. This in turn is increased by clearances between planetary gear, sliding splines and the ring and
pinion gear. We feel that the total driveline slack can amount to as much as 1/4 turn of the driveline without being abnormal,
but if it exceeds 1/4 turn, other parts in the drivetrain could be checked."

If that's right, and if a 3.70 gear allows proportionally less slop in the driveshaft, then the rear end is perfectly normal having slop between 1/8th and 1/4.  Whew!  I hope that's right, and if so, problem solved!

[FLG]

I would say i can rotate it by about the same so i think your all good 

[FLG]

woops, forgot i responded LOL

Had the page up but it was from when you posted so i didnt refresh and forgot i had posted already