What to look out for

[chris91]

Rear is toast in my 99. Just figuring it would be cheaper to find a good used one to throw in it instead of rebuilding for the time being. Anything special I should keep my eye on? Never messed with rears so Im kinda lost. Just wanting to make sure I buy the right one and not a Fox length.

[Dirtyd0g]

I think it is easier to rebuild what you have unless you need axles. Usually it is just a bad bearing, good time to change the gears anyway. Used mustang axles are rarely cheap. If you rebuild it without new axles replacing all the bearings and the gears you should expect to spend $550-$750 depending on who does it and what brand components you buy. I suggest frpp gears only which range about $175 then the bearing kit is about $100 add $20 for a OEM pinion seal (the ones in those kits are junk) and $20 for a solid pinion spacer. Labor should be $250-$400 anybody charging more than that is basically telling you they don't want the work. I charge $250 to do them including bearing changes, add $50 to change axles seals and bearings and $50 to change the clutches if that gives you a good idea of what to expect.

Most guys that do them charge about the same. If you change the clutches add $100 for parts but they aren't often needed unless you race on slicks or good drag radials. The new S-Spring is about $20 from ford and so is the cross pin if you need one. Fluid I suggest breaking it in on standard 75-80w90 with 2 bottles of friction modifier after break in (1000miles) change it to the motorcraft synthetic stuff and add another bottle of modifier.

If the gears are okay you can reuse them, if you need stock 3.27's I am sure I have a set or 6 I will sell cheap. I have some 3.08's and a set of 3.55's but I am out of the numerically higher stuff.
I personally hate changing the entire diff on salt belt cars. It is also hard to know what you are getting with used rear ends too. If the car was wrecked it may be bent.
Alan

[chris91]

My car has 3.73's in it already. Havent cracked open the diff but something is broke in there. And I got a quote from someone for a complete rear end with 3.73's for $250. All I am asking for here is what to look out for in the new rear end when Im checking it out from the seller. Buddy of mine is a tech at Ford so Im sure he will know 95% of the things to check on.Not a story about everything else.

What should I be looking for when I go to pick up this new rear end?? Ill pull the cover off and check things out. New rear comes with everything minus breaks. Was pulled to go with a narrowed setup.

Side story on what mine did. I was pulling onto my street. Heard three loud clunks. Then clunk(sounded like it was missing a tooth, clunk, clunk, clunk.) I pulled it into the driveway and jacked it up. Spinning the wheel didnt feel right. It was clunking in the pumpkin and when I forced the wheel to move it clunked and didnt want to spin anymore. So Im thinkin its fucked and if I can buy a whole new setup thats known to be good for $250 (hes a local banger) than Im good to go. My buddy only wanst $50 to install it for me.

[Dirtyd0g]

First thing to check is backlash. I see differentials that have been built before all the time, more often that not the bearing preload was not set properly which will cause premature bearing failure. Backlash is where you see it and you really don't even need to pull the cover. Grab the flange and twist is side to side if it doesn't seem right it probably isn't. You probably broke the crosspin in yours. Sorry I gave you more info than you wanted I was trying to help....
Alan

[chris91]

No problem man. Been in a bad mood ever since this happened because I just bought the car and had this happen. Im not in the market to get this rear end rebuilt. I found two rear ends for around 250. Just really need to know what to check out when I look at them. The one for 250 already has 3.73's in it and will have the cover off so I can peek in and see whats what.

[Pitbull1052]

That's what I've been telling him Alan not too much to check out either it turns and is smooth or it's not......