1989 mustang rear axle

I have a 1989 mustang gt I installed a new 31 spline axles with new bearnings and seals I believe its a 8.8 rear end all books say 31 spline axles only for 8.8 I have side to side play but no other noises any ideas  

C clip type axles always have some side to side play...

you might be able to reduce side to side play by asking the axle manufacturer if there are any variations in C clip thicknesses.. so the axles are pulled in slightly tighter to the cross shaft..

how is the side gear clearance in the differential... there are shim kits available for them from some manufacturers..

this is only going to effect you .. if you have rear disc brakes... if you have rear  drum brakes .. the problem is nil...

just curious... what kind of POSI do you have????

i did have one friend about a decade ago... who did a disc brake swap on the rear.. he also had what he thought was too much end play... he made a thin but very tough sleeve to slip onto the cross shaft to push the axles slightly tighter to the side gears...


check for worn carrier ends... where the side gears and thrust washers have eaten away at the inside of the differential case...  check for worn thrust washers...  check for worn spiders gears..

this can all be done without pulling anything but the rear cover the cross pin and axles out..  

inside the differential.. non posi
4228  Washer-Differential Pinion Thrust behind side gear.
4230  Washer-Differential Pinion Thrust behind pinion differential gears

posi
4947 Rear Differential Clutch Kit


the C clip
4N237  Axle Shaft Retainer

these are basic ford part group numbers... the complete part numbers vary by which rear end you have...

and after market gear suppliers may have shim kits for the spider gears..


i am hoping that you still have the METAL ID TAG thats bolted on with the rear end cover...

without it.. you might have some issues getting stuff..  

I have drum brakes and the tag is missing I will check with the axle manufacturer thank you  

If thats the only clunk you hear then I wouldn't be to concerned of that noise. You do want atleats .250 or 1/4" between the axles when it is assembled... Anything closer then that and you run the risk of the (2) axles banging each other, and then creating a really big problem.

You do have self adjuster's on the rear shoes.Sometime they can make a clicking sound when you back up and touch the brakes.  

You didn't mention if it was a posi rear? When I first purchased my '68 Galaxie back in the day. Ford fitted the front calipers so loose they actually banged when you backed up. Then if you were going slow enough when you allied the brakes it would calipers would bang then also..My 2 cents...

Bob  

Thats a pressed on bearing you have. You should hear the clunk on a General Motors rear when you go over a small bump. It's scary..

I ran a 9" Ford rear with 6:30 rear gear in my ChevyII. When I was just coasting, and no engine power you want to hear a scary noise. The whine in the rear gears even set-up correctly would scare you. It's a sound you have to hear. It's louder then a noisy gear drive for the cam...  

Bob  

is the diff new or was it used ?  

Welcome aboard Wap55:

Does the wap55 stand for anything else then a slure word to us Italians
Because Ima Graduate of Whatza matta u...LOL...

Do you remember when you where installing it if the bearing had a retainer ring over the bearing. I'm wondering if the retainer ring was not pressed on all the way or retainer ring I.D. is is too big, and is sliding causing that clunk.

1.Remove both sides down to the AXLES and brakes.
2. Look at those retaining clamps that has the 4 holes in it
3.Are any bolts loose?
4.if they are tight.
5.Grab the Axle at the flange.Do a push pull test. Is there alot of end play in the axle bearing? If there is go to the other side axle and do the same test.
6.Did you physically measure the axles and then the amount of axle room inside the houseing.
1.I think you either have a lose bearing retainer.
2.The axles are too long and butt against each other
3.Look to see if the axles are hitting each other

Bob