Rear end gears and lockup on Highway

I just got the gears in my 87 Mustang changed to 3.73's and on the way home from the shop the rear end locked up about 15 minutes from the shop. I was on the highway, going about 50 about to exit, and both of the rear tires completly locked up. It was quite a miracle that I kept control of the car and actually managed to get it off the road where it would not block traffic, and all of this in 5 o-clock traffic. I called the shop today and they told me that there is no way what they did to the rear end had anything to do with it. Is this true? He said it was probably the posi unit in the rear or the bearings. This car has been driven daily since i got it and I have never heard or felt anything coming from the rear end. The shop seems to very reputible in my area, and I wanted to see what you guys err.. people thought. After I got the car stopped I got out and looked at the rear end and it was smoking very badly. Please let me know what you think, as I had to pay 40 bucks to get it towed to my house and it is going to cost me about $150 to tow it back out to the same shop I had it done at.

Regards B

Reply to
btothec
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Have you even seen the inside of the rearend since it happened? Sounds to me that the rearend fluid level could have been low or that the shop, regardless of how reputable, didn't even put the fluid in. The smoking could partly be the residue from old fluid in the housing and pinion and/or carrier bearings carving their way into the races. You only had gears installed and nothing else done, right? How many miles are on the trac-lock?

Helmut Roner

1988 GT
Reply to
HELMUT RONER

It just happened last night. So I haven't had a chance to get into the rear end yet. The car has about 120K on it and as far as I know that is the original trak-loc in it. Right when I saw it smoking I thought to myself that they probably forgot to add fluid.

Regards B

Reply to
btothec

It's bullsh*t IMO. They just were inside the diff and it fails 15 minutes later....

The limited slip would simply stop working, I've not heard of one locking up the wheels.

Failed bearings come on slow and likely wouldn't lock, just destroy themselves until the wheel and axle decided to pull out of the housing.

IMO they had to set up the gear spacing wrong or damaged a seal that caused it to leak out all the fluid. (or maybe forget to refill it)

Reply to
Brent P

Yes, changing the gears improperly could have caused the real axle to lock up. If it wasn't what they did, it sure is some bad timing for it to happen!!

Steve

Reply to
Steve Marshall

That is kind of what I think too. I also don't understand why they didn't just rebuild the posi unit while in there. Hell the kit is only about $40 and isn't that hard to rebuild.

Reply to
Joe Cilinceon

The smoke has me wondering but I'm gonna put my money on an improperly installed spider pin - this is the only thing I can think of that will cause a sudden lock up. Failure to put oil in the diff would give some kind of warning......

Reply to
Jim Warman

OK. I sat down there with them today to watch them take it apart. Looks like the pinion bearing went out. They said that they reused the old one's and that is what they usually do as the bearings are usually still good. Is this true? I figured if I am paying $400 to put a set of gears in the thing, and most of that is for labor that they would put a new bearing in. They said I had to pay for the bearing and the labor was free so I went ahead and had them replace all of the bearings while they were at it. I started to get somewhat aggitated when I found out they used the 16 year old bearings in it, and the guy there didnt seem to know why I was upset as all I had to pay for was the new bearings, but what he doesn't realize is that I paid $40 to tow it to my house, and then $60 to tow it back to the shop, and then wasted 4 hours sitting around there today. What does everyone in here think? Keep in mind that this thing made no noises ever, and has been driven daily for over a year by me and appears to have been driven daily for the 15 years before I got it. Do the pinion bearings just go out with no notice like that?

B

Reply to
btothec

Yea,

There was fluid in there, but it didn't look like a whole lot. And as I was sitting and waiting for them to get to my car they were doing another rear end on a Mustang, and they did use an impact.

B

Reply to
btothec

It's very easy to go too far with an impact...also, if you go by the book you should never use an impact to torque a bearing as it could mar the race or roller on impact. They should check the bearing preload after they do it to make sure it is'nt too tight...And fluid levels should be enough to flod the pignon bearings...

Hope they fixed it right this time.

Doing gears stupidly is like russian roulette, it will go well 5 times out of six...Bet ya they did'nt set the pignon depth either and simply re-used the pignon shim they found in it from the factory gear...

I guess now you know where not to go next time. Too bad you had to be the one to discover they are a sloppy bunch...

Hope your car is ok now.

Serge

Reply to
Serge

This is scaring the sh#t out of me! I'm doing 4.10 gears as my next mod, but to be honest, after reading this, I'm starting think not.

Cindy '96 laser red auto GTS

Reply to
C. Olofsson

Serge, I am having 4.10's put in my car in a month or two. Should the shop pay for all these replacement parts if I tell them I want them replaced? Or should I buy them from another source?

Thanks.

Cindy '96 laser red auto GTS

Reply to
C. Olofsson

The shop should have most of the bearings and seals in stock if they are specialized. It's a good idea to do at least the axel bearings and seals. The other bearings could be kept if good, but replacing them at that time is cheep insurance. A complete kit with all the hardware you need is about $100 from Ratech...

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Just make sure you go to a specialty shop (transmissions and rear ends or reputable speed shop) so they know how to set it up properly.

Serge

Reply to
Serge

I do many of them Cindy with no problems. It's actually the most fun mod you can do to the car...you won't recognize your car after it, you'll think it's on steroids or something....Just find someone who know what they are doing.

Serge

Reply to
Serge

You're going to have the rearend taken aprt for the gears regardless so your best bet is to buy the Ratech (RAT-305K from Summit) rebuild kit. I has everything except the axle bearings with it. Check your auto parts stores to see which ones offer a lifetime warranty on axle bearings. This is why I bought mine separately. I ordered this kit from Summit and it came straight from Ratech. It was missing the crush sleeve and carrier shims, but I got shims from Musttanguy and my new gears already had a new crush sleeve with them. If you get the kit MAKE SURE that the shop that does the work REPLACES the front & rear bearing races for the pinion. Most shops will not do this and keep the races and other small unused parts.

Helmut Roner

1988 GT that just had the 8.8 rebuilt with new everything except lowmileage trac-lock.
Reply to
HELMUT RONER

I am planning on doing this sometime this month or next also. Can anyone recommend someone " who know what they are doing." in the Cleveland, OH area?

Going from the stock 2.73 to 3.73's. Then will put in the trans-go shift kit for my AOD

Thanks!

Matt

89 5.0 GT Vert
Reply to
Matt

:-) You lucky dawg! I envy you!! Thanks for the info. So how does it FEEL?? Much quicker? Did you ever take your car to the track before the gears? I'm hoping to knock off a little less than a second from my 1/4 ET. :-p As long as I'm in the 14's, I won't feel like I'm competing with the Civics anymore at least. *puke*

Cindy '96 laser red auto GTS

Reply to
C. Olofsson

Never did get to the track before the change. I've been once since. My biggest problem was lighting up the tires through the first sixty feet. As best as I can determine this was costing me about a 1/2 second (2.45 second

60' time instead of say a 1.8 second) in my ET.

How does it feel? It feels great. Now bear in mind that I do have a high stall torque converter and shift kit installed which is set for a hard shift. So if I'm accelerating at more than 1/4 throttle the tires will chirp on the 1-2 shift.

-- Richard

Reply to
Richard

Where is the shop and what is their name? If they are doing this kind of work then it would be a good warning to others.

Dan

Reply to
Dan

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