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Diff rebuild

M

Mustang_Charly

Member
I love it when I actually find out why some part has failed...

I am in the process of rebuilding my 8 inch differential. First time, never done that before, but hey, I bought the "how to" video, (thanks Ken, at Badshoe Productions) so why not?

I always have had a loud "clunk" when shifting manually from first to second (C4 automatic) at low load; suspected bad u-joints. Upon closer inspection, the u-joints looked and felt fine. However, I did notice that the diff had a lot of backlash at the pinion input, so I figured I would be rebuilding it soon.

Then, this summer I put in new leaf springs, and in the process of moving the rear axle housing around and putting it up on blocks to clean it off, of course it swung around nose down once in a while, as they tend to do, being nose heavy and all.

Soon after putting it all back together I began to notice a "rattling" noise coming from the rear, but only in "float" conditions. I put up with it through the fall, and firmed up my plans for the rebuild once the snow started falling.

Well, now I am in the middle of it (both snowfall and rebuild) and found the problem:The pinion pilot bearing was completely empty; no rollers at all. The bearing had fallen apart at some time in the far past, all of the rollers falling out of the race. Then I have to assume when the axle housing dropped nose down during the leaf spring change, some of the rollers found a new location inside the diff. After reinstalling and driving, they then proceeded to do their damage to the pinion gear. Photos attached:

Overview:
case6.jpg


Close up of pilot bearing:
case5.jpg


"Empty" pilot bearing race:
case2.jpg


Broken pinion gear tooth:
case4.jpg


Stuff I found in the bottom of the axle housing:
case3.jpg
 
Good job, its nice when you discover your not crazy, and there actually was an issue. Plus the added benefit of doing it yourself, and not being beaten over the head by paying someone else to do it. Congrats!
 
Congrats. Hate to see it happen but it definitely feels good to do it yourself. Can't say I'd try to tackle that job myself.
 
"blue65coupe" said:
Congrats. Hate to see it happen but it definitely feels good to do it yourself. Can't say I'd try to tackle that job myself.
Click to expand...

Duane, we got you through the carb, now you could do anything. Have no fear....

:lol :lol :lol
 
There are quite a few suppliers for Mustang parts over here, it all depends on what they keep in stock. Usually I order from the US, but then shipping and customs adds about 50% to the cost.
 
I have heard about the shipping charges from members on other boards but I didn't know there was enough of a demand for there to be mustang suppliers. I have traveled to a lot of countries and I have not seen much in the line of American muscle cars.
 
"lethal289" said:
Duane, we got you through the carb, now you could do anything. Have no fear....

:lol :lol :lol
Click to expand...


Yeah well, he's still not qualfied to touch my rear end...... :rp
 
Let me know what you think of the video and make a thread about your rebuild. I'll be doing a rebuild of my 9in this year. I have excessive backlash as well and makes quite the thunk shifting from reverse to drive. I'll be going with a Richmond rebuild kit (bearings, gear, etc) and likely the Detroit TrueTrac differential. It'll be my first time rebuilding a third member as well.
 
Buening, the Bad Shoe video is EXCELLENT. It not only walks you through a 9" open, but a 9" traction-lok and a 9" 4-pinion. He also shows a few shortcuts and explains in detail the particular tools you'll need.

I'd never built a rear end before, and used that video. I couldn't be happier with the way it turned out.

I used Richmond gears and Timken bearings.
 
where do you get the video? I plan to swap the 3.73's I got from Rick into my 4.11 traction loc 9" and that would be helpfull.
 
Not only is the DVD great, Ken ("Mr. Badshoe"?) is very helpful. He personally answered all of my questions and gave me some good advice.

The places I had problems:
1) Removing the two carrier bearings: Don't even mess with a cheap puller, you need a heavy duty bearing puller. I had to "modify" the claws substantially, and you need to stabilize the arms by clamping in a vice:

difc.jpg


I ruined my original carrier messing around with a cheapo puller and trying to "weaken" the bearing race with a cutting wheel.

2) Torquing the nut to set the crush sleeve: I nearly pulled my vice out of it's anchor. Instead, I made a tool to hold the input yoke while tightening the nut:

difa.jpg


difb.jpg
 
Good write up on the diff. procedures, you should put it into the tech article section when you are finished. I do have a question for when I do mine. I had my 8" diff w/ 2.8 ratio rebuilt about 5 years or so ago and don't have too many miles on it. If I change to a 3.5 ratio, will I have to remove the bearings or just replace the pinion/diff ring gear and set the backlash? I am wondering how far into this I would have to go since the bearings etc. were replaced earlier? Thanks, gary.
 
On a year old rebuild, I wouldn't bother with the bearings (they'll normally last a good 200k miles). You may have to replace the pinion bearing, if they can't pull it off the pinion and not damage it.

I had all my bearings pressed off and on by a machine shop ... cost about $35.
 
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