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That Regular Guy
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Discussion Starter #1
Hey guys, just bought some 3:73 gears. And I'm gonna install them myself with the help of my friend. And I wanted to know how hard is it really to install them? Is it something somewhat easy if you pay good attention to. Or something extremely hard no matter what? Any input helps!
 

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Rockin the "letter" cam!
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easy to do. Just mark the main caps and watch for the spacers when you remove the carrier. Everything needs to go back in same place.
You will need to press off the pinion bearing and press it onto the new pinion.
 

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That Regular Guy
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Discussion Starter #3
easy to do. Just mark the main caps and watch for the spacers when you remove the carrier. Everything needs to go back in same place.
You will need to press off the pinion bearing and press it onto the new pinion.
Alright. Do all cars shim the same?
 

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its a PITA! get a tool to measure the backlash
 

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That Regular Guy
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Discussion Starter #5

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its not horrible you just need to measure back lash and if you are just putting on gears the selective shims should all stay in the same spot. if you change the case you will have to remeasure everything. you are going to need a new crush sleeve for the pinion and those can be tricky, the trick is to take in baby steps dont want to over tighten because you could put to much pre load on then have to take it all apart and get a new crush sleeve.
 

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That Regular Guy
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Discussion Starter #7
its not horrible you just need to measure back lash and if you are just putting on gears the selective shims should all stay in the same spot. if you change the case you will have to remeasure everything. you are going to need a new crush sleeve for the pinion and those can be tricky, the trick is to take in baby steps dont want to over tighten because you could put to much pre load on then have to take it all apart and get a new crush sleeve.
Alright that's what i thought. I got am install kit so I have all the extra part we need. It seems really hard. But it also seems like one of those things you just gotta open up and do.
 

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Yes it is a PITA but if you don't mind the work and you have the tools you can prob pull it off. I recently installed some 410's in my 91 GT. It took me ALL day and that is with a machine shop right around the corner swapping bearings for me.

I would count on some downtime though. Let the rear end drain the first day. The next day pull your drain pan out and spray the crap out of the pumpkin with degreaser and let it set for a little while. Then spray it out with brake cleaner. That will dry up the inside for you so your not getting oil all over you (gear oil STINKS).

Warning for you now...the pinion nut with a new crush washer is NOT easy to tighten down. It takes about 400 ft. lbs. to crush that washer. My brother in-law and I did it by putting a pry bar between two bolts on the pinion flange and bracing it against the concrete. I then put a 1/2 ratchet drive wrench (strong snap-on tool) with a 27mm socket and attached a 3 foot cheater pipe on it. We tightened the pinion nut 1/8 turn each time. It took probably 20 minutes just to do this because you have limited room under the car. You will want to go slow though because you'll pass up the 16-28 in. lbs. real fast if not paying attention. Also DON'T use the old crush washer for the mock-up test. Some say they use it but after trying a few times and never getting the same pattern my local racing shop told me not to use it. Once I quit I started getting consistant patterns. With or without the old crush washer the inside bearing (closest to pinion head) isn't going to seat deeper than the race anyhow so really no point in having it. Once you do get to the point where you are going to crush the new crush washer, make sure you spin the flange a lot because it will loosen up some. Spin it until it loosens up and then recheck the pinion drag until it reads consistantly at 16-28 inch lbs.

Tools I believe are a MUST have for this job

1.Strong socket set (mostly metric) 12 point 12mm required to remove driveshaft
2.Either air impact for pinion nut or a long piece of pipe.
3.Jackstands
4.INCH lb torque wrench and a FOOT lb wrench.
5.Magnetic base with a dial indicator for measuring backlash.
6.Bearing splitter and press (or pay a machine shop to do it)
7.Lots of brake cleaner. I went through prob 6 cans.
8.BEER or a drug of your choice :D

J/k on the last part but it left me feeling that way.

If you got a local shop that will charge a cheap enough price I'd take it to them but if their too high I can understand why you would want to do it. I thought all my local shops were charging $400 and up but it wasn't until after I started the job I found out there is one local racing shop that has everything to do the job and they only charge $150. If I had known I'd have let them do it. :p
 

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That Regular Guy
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Discussion Starter #9
Yes it is a PITA but if you don't mind the work and you have the tools you can prob pull it off. I recently installed some 410's in my 91 GT. It took me ALL day and that is with a machine shop right around the corner swapping bearings for me.

I would count on some downtime though. Let the rear end drain the first day. The next day pull your drain pan out and spray the crap out of the pumpkin with degreaser and let it set for a little while. Then spray it out with brake cleaner. That will dry up the inside for you so your not getting oil all over you (gear oil STINKS).

Warning for you now...the pinion nut with a new crush washer is NOT easy to tighten down. It takes about 400 ft. lbs. to crush that washer. My brother in-law and I did it by putting a pry bar between two bolts on the pinion flange and bracing it against the concrete. I then put a 1/2 ratchet drive wrench (strong snap-on tool) with a 27mm socket and attached a 3 foot cheater pipe on it. We tightened the pinion nut 1/8 turn each time. It took probably 20 minutes just to do this because you have limited room under the car. You will want to go slow though because you'll pass up the 16-28 in. lbs. real fast if not paying attention. Also DON'T use the old crush washer for the mock-up test. Some say they use it but after trying a few times and never getting the same pattern my local racing shop told me not to use it. Once I quit I started getting consistant patterns. With or without the old crush washer the inside bearing (closest to pinion head) isn't going to seat deeper than the race anyhow so really no point in having it. Once you do get to the point where you are going to crush the new crush washer, make sure you spin the flange a lot because it will loosen up some. Spin it until it loosens up and then recheck the pinion drag until it reads consistantly at 16-28 inch lbs.

Tools I believe are a MUST have for this job

1.Strong socket set (mostly metric) 12 point 12mm required to remove driveshaft
2.Either air impact for pinion nut or a long piece of pipe.
3.Jackstands
4.INCH lb torque wrench and a FOOT lb wrench.
5.Magnetic base with a dial indicator for measuring backlash.
6.Bearing splitter and press (or pay a machine shop to do it)
7.Lots of brake cleaner. I went through prob 6 cans.
8.BEER or a drug of your choice :D

J/k on the last part but it left me feeling that way.

If you got a local shop that will charge a cheap enough price I'd take it to them but if their too high I can understand why you would want to do it. I thought all my local shops were charging $400 and up but it wasn't until after I started the job I found out there is one local racing shop that has everything to do the job and they only charge $150. If I had known I'd have let them do it. :p
Well I'll be using my friends shop, his mechanic brother and him. And American Muscles write up on how to do it. That way sounds the easier way out of most the write ups I've seen. I have a feeling it is gonna be an all day ordeal. Not just a 5 or 6 hour thing.
 

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Well I'll be using my friends shop, his mechanic brother and him. And American Muscles write up on how to do it. That way sounds the easier way out of most the write ups I've seen. I have a feeling it is gonna be an all day ordeal. Not just a 5 or 6 hour thing.
The American Muscle write up, which I've read, is a good starting point. But I would ignore the part where he says to use the old crush washer. As I mentioned it just caused me more pain than it was worth. My local racing shop was a huge help on this. It was great having some experienced racers nearby.

If your using a shop with a lift I suspect your going to find this job much more tolerable. There is a lot of torque involved in this mod so more room under the car helps a lot.
 

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That Regular Guy
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Discussion Starter #11
The American Muscle write up, which I've read, is a good starting point. But I would ignore the part where he says to use the old crush washer. As I mentioned it just caused me more pain than it was worth. My local racing shop was a huge help on this. It was great having some experienced racers nearby.

If your using a shop with a lift I suspect your going to find this job much more tolerable. There is a lot of torque involved in this mod so more room under the car helps a lot.
I'm using a different washer. I bought an install kit with em. So that will help a little.

Edit: I'm confident we can do it. It's just the fact that if something happens it could be real bad. I'd pay a shop to do it. But 400 dollars is a little too much for my taste.
 

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I'm using a different washer. I bought an install kit with em. So that will help a little.

Edit: I'm confident we can do it. It's just the fact that if something happens it could be real bad. I'd pay a shop to do it. But 400 dollars is a little too much for my taste.
Hehe yep money makes me a bit more patient as well. I'd say if you think you can do it you probably can. If someone has doubts I'd say stay away from it. As for something happening it's really all in making sure you get it right. If your a little off on something you may get some gear whine which you might be able to go back and correct. If your really far off on something you could end up chipping teeth on the gear. I think that would be your worst case. But this can be avoided by simply paying attention. When I first did mine I ended up with a whine or whirring noise and it turned out the pinion nut had loosened up on me. Fortunately my pattern was so close though that the wear on the gears was almost perfect. From the sound of your caution though I think you'll make sure its done right before trying to drive it.

The one who is new at this but attempts to try it without a care in the world is asking for trouble.
 

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That Regular Guy
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Discussion Starter #13
well my buddy helping me has done a PI head swap, taken out trannies, and engines. by himself. and his brother like i said is a mechanic. i trust em. but things can still go wrong. im not gonna rush it either. i want it done right the first time. Just to make sure though. im calling around town and getting estimates on how much it'll cost. im hoping for some one to say round 100.
 

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im getting ready to do the same thing. this sounds intimidating lol.
 

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That Regular Guy
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Discussion Starter #17

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That Regular Guy
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Discussion Starter #19
25 dollars?! not worth it.
 

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I drove my car a lot yesterday to further test the 410's. They are still quiet so after having to go back and double check some things I got it all right. Kind of wishing I had went with more gear though...like 430's or 456's.

I'm so glad I didn't go less. The 410's from the stock 308's weren't as much of an improvement as I had hoped. Maybe I'm just setting my hopes too high and its time to get busy with making some HP.
 
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