Rear end questions

[oldtimer]

I'm in the process of changing transmissions and noticed what I thought to be excessive play in the rear pinion flange when I pulled the driveshaft out. It seems to have about 3/8" rotation before turning the crown gear.

Then I noticed a ratchet kind of action/feeling through the pinion flange when I turned the wheels with the flange.
Should this be, with a properly working Auburn unit ?

There also seemed to be ( what I thought was ) a little too much rotational movement in the rear wheels. They each rotate about a 1/2" without moving the side gears.

After taking off the rear cover for inspection, the crown and pinion are in excellent shape. No chips or broken teeth and a very nice wear pattern.

I have an Auburn posi unit, 30 splined axles and a support cover and run 10 1/2" slicks. The rear end has not seemed to be causing any problems up to now but I would like to prevent a future problem from occuring .

Am I being too fussy or should I be concerned about anything.

I've been launching off a T Brake at about 4500 RPM an I am amazed that I haven't broke something up 'till now.

How much play should there be in the axle/side gear splines

Any help or opinions would be appreciated. I'm thinking about going with a spool. Car gets very, very limited street use.

 

[oldtimer]

Help guys,

someone has got to be able to guide me here

 

[my86turbot]

I HAD THE SAME TROUBLE WITH MY Auburn posi unit
AND IT FAILED I ALSO CHECKED MY GEARS LOOKED GOOD
CHANGED THE POSI TO AN ETON UNIT NO MORE PROBLEM







86 T TYPE BLACK GN1 ALU HEADS ROLLER CAM T63E TURBO
ELE

 

[Buzzard]

Lets try this in the chassis forum, maybe you will get more replys.

 

[oldtimer]

Originally posted by my86turbot
I HAD THE SAME TROUBLE WITH MY Auburn posi unit
AND IT FAILED I ALSO CHECKED MY GEARS LOOKED GOOD
CHANGED THE POSI TO AN ETON UNIT NO MORE PROBLEM


Thanks my86turboT

Do you recall if there was a ratcheting feeling in the pinion flange while you were turning it by hand with the driveshaft disconnected ?






86 T TYPE BLACK GN1 ALU HEADS ROLLER CAM T63E TURBO
ELE

::

 

[mayosmechanic]

You need to check the backlash on your gears.I like to see about .012" to .016 on used gears.The ratcheting concerns me.Is it with both wheels off the ground or just one.There should little to no play in the side gears.You should also check the cross shaft for play where it goes through the case.No play allowed!HTH

 

[oldtimer]

Thanks again for the replies.

The ratcheting feeling I get when I turn the pinion flange by hand is with both wheels off the ground. They of course turn in the same direction.

With the cover off, I can see that there is play in the axle shaft splines and side gears. I know that there must be some clearance or the axles wouldn't slide in, but just how much clearance should there be. Presently, the wheels can move approx. 1/2" ( at the outside diameter of the wheel ) rotation before the side gears move. Seems like a lot to me, but the rear end hasn't caused me any problem up to now. I was just inspecting the rear end as a precautionary measure while I had the driveshaft out.

I'd prefer to fix whatever is wrong, if anything, at a standstill rather than have it come apart at the 1000 ft. mark on the track.

I've heard good and bad about the Auburn units. This is my first experience with this unit, so I continue looking for experienced help

 

[mayosmechanic]

Pull your axles and look at the splines.There is clearance for the axles to slide in but it is minimal.The side gears should be snug.The 1/2 inch doesn't bother me as much as the ratcheting.If both wheels are off the ground it has to be in either gear set or bearings as the posi is not slipping at no load.Is the cross shaft tight?

 

[oldtimer]

I'm suspicious of the pinion bearings. Have to go out of town on business for a few days. When I get back, I'll check further and keep you posted. Thanks for taking an interest

 

[Rickracer]

Here's how to check the pinion bearings

With the driveshaft, wheels/tires, and drums removed, you should have about a 15 inch pound preload (breakaway torque) to turn the pinion (use a socket on the pinion nut), and it should turn smoothly. If it is much less than this, it is probably time for some new bearings. Preload should be about 25 inch pounds with new bearings. If the bearings look good, no pitting, galling, or scoring, you could reassemble with a new crush sleeve, setting preload at 15 inch pounds, but since lots of parts places now carry differential bearing kits with shims, gear marking compound, new pinion nut, and new bearings for $75 to $85, I'd just freshen it up anyway. You will have some rotation of the wheels with no movement of the side gears, that is relatively normal. As was mentioned before, make sure there is very little play in the pinion cross shaft. I have used Auburn posi units many times, and they are satisfactory for the money, but IMHO, the Eaton units are superior, as they should be, they are more expensive.

 

[oldtimer]

Rickracer

Thanks for the help. I'm doing just that. I'm replacing all the bearings and installing a spool.