3.73 swap gone bad

sweet93hatch

New Member
Apr 21, 2004
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Well, I had a local automotive shop fix my trans, install my king cobra (while they were in there) and install my 3.73's. I went to pick it up tonight and when I was cruising home, my whole friggin rearend locked up and nearly killed me. Seriously, I almost died. Hehe. Anyhow, I took it back to them and there was noise coming from the rearend back to the shop. What the heck is wrong?????? Any guesses??????? The tech at the shop said he wasn't sure if there was supposed to be play after he crushed the sleeve or not. I have no idea what he is talking about.
 
If it completely locked up I would suspect there was a carrier bearing failure or possibly a pinion bearing failure.

When your backlash is out of spec you can get howling or whining coming from the diff. Basically backlash is how much play is between the teeth of the ring gear and the pinion gear. It can be adjusted by the carrier bearings.

check out this website for answering your questions about gears and the various terms associated with differentials and great info on install procedures

http://www.angelfire.com/theforce/5ohcpa/cpa5ohtech001.htm
 
sweet93hatch said:
The tech at the shop said he wasn't sure if there was supposed to be play after he crushed the sleeve or not. I have no idea what he is talking about.

There should be no play at all. It sounds like he didn't get the crush sleeve crushed and he doesn't have a clue about what he is doing.
 
Maryland Stang said:
he doesn't have a clue about what he is doing.

That is always a possibility. I took it down the road and banged through the first three gears, grinning from the SOTP and then clank, crunch, squeal and not necessarily in that order. Maybe he can just get it drivable and I can get it to a gear shop.
 
It turns out that the bearings were bad and seized up my rearend from extreme heat. I am supposed to pick it up Monday afternoon. We will see how she runs. Despite the bad initial experience, the difference from the stock gears and the 3.73's was rather cool. She pulls noticably harder.
 
when you get it back,take it easy on it for a 50 or so miles and give the gears time to wear in and let the bearings get lubricated first.the shop should have told you this.you don't do a burnout or power shift as soon as the gears are in.
 
First, your an idiot for driving anything hard right after it was installed. That goes for motors, clutches, tranny's, and rearends. And didnt you have like 3 of those done at the same time? Secondly, regardless of how it failed, your mech didn't know how to finish the job correctly and he didnt tell you how to drive it after the install. The problem is definetely their fault and I hope they are paying to fix the problem. I personally wouldnt be using the gears after all that happened, I dont care what anyone says.
 

While I appreciate your input, I really wouldn't go around calling people idiots. Perhaps I need a lesson in mechanics, but by the sounds of things you need a lesson in tact. Its too bad you live in Cally cause I would love to give it to you.
 
Actually I'm in Illinois and feel free to stop by. I've been out of the Marine Corps for 8 months now and I could use a good brawl. I personally don't care for tact. I love helping people out, but I don't pull punches. People, not necessarily you, do stupid things with their cars all the time, and sometimes it gets really old hearing about it and having to fix the problems. I also don't like stupid mechanics working on cars and screwing over the customer. If your not sure what you are doing, then dont touch it, thats a good motto to go by. I'm sure you've heard of break-in periods before so next time you'll know. But I'd be fuming if someone did my rearend and the next thing I know, the whole thing locks on me as I'm driving. That could have killed you. As for the crush sleeve, I believe off the top of my head, it gets 160 ftlbs. It'll hover at 145-150 as the sleeve is crushing, and after its done crushing, it'll reach 160 and your done with that. There are shims on each side of the carrier, and by changing those, you adjust how close or far the gears are to each other. Then use the supplied yellow paint to see where the teeth are engaging each other. They should be meshing in the middle of the gears, and the instructions should have some images of right and wrong markings. Its an easy process, but most people dont have access to a large enough torque wrench to crush the sleeve. Make sure if its a posi, that they also added the friction modifier with the gear lube. It helps the posi work and keeps chatter noise down.
 

In Flint we don't brawl, we find the problem and eliminate it . I appreciate your input, I just didn't appreciate how you went about it. Just the same, thanks.
 
Idwitheld-1` said:
...more like 600 ft. lbs to crush that sleeve.

And what generated "extreme heat"? Sounds like there was no oil.

I'm not sure as of yet. I will find out more tomorrow when I go pick it up. Hopefully everything is fine. This is the first gear swap I've ever had done. I've had turbo cars in the past and just stuck with stock gears. I hope that I am happy with my choice on the 3.73. Time will tell.
 
Sucks about your gears man, I hope they get fixed and your out on the street again in no time, you'll love the gears.


sweet93hatch said:
In Flint we don't brawl, we find the problem and eliminate it .

I usually dont get involved with the "internet fight" thing, but I think you're being a little immature this go round. SmockDoiley was just putting forward his opinion and you had to play big bad internet man (My money is on the Marine) when you could have just said you didn't like his remark.

sweet93hatch said:
I appreciate your input, I just didn't appreciate how you went about it. Just the same, thanks.

That would have been just fine if you said it first.