right now i have the 2.77 gears. i want to go to 3.4x - 3.73 which do you guy recomend?

also where is the best place to find a 3 series posi carrier? 9bolt.com has them but the price is kind of steep. i was thinking i might be able to find a complete rear at a salvage yard.

 

usualy a junk yard rear end is cheaper.

by the time you buy all the parts, and tools needed. it can get rather expensive.

you would need a pinion depth checker, magnetic base dial-indicator, in/lbs torque wrench, the gears, posi, install kit, ect.

unfortinatly you can't just toss a set of gears in, getting the pinion depth , and backlash set right, has to be done perfectly, or you will chew through the gears in a hurry.

 

I got a set of 3:73's installed into my 10 Bolt. I went from a 2:73 to the new gears, it is a totaly differen't car. I like the 3:73 because I feel that 3:42 my have left me wishing for more gear, but a 4:10 would have been too much.

With the 3:73's installed the car pulled much harder out of the hole and I could do burnouts (LG-4 305) with my new locker. It is a lot of fun. I think that the 3:73's are a good choice, especialy once I get the 355 that has a bigger cam in it installed next month.

 

3.42 is about as far as you want to go with a stock TPI. THere isn't enough rev capability in it to make the car go any faster.

Correct gearing is different for a TPI car as compared to a carb car; the torque vs. RPM curve is different. You need to pick gears that keep the motor in its optimum power range as much of the time as possible. With TPI, that's 3200-4200 RPM.

3.27 is a good TPI/auto gear. 3.45 was used in the hottest TPI/5-spd cars, but is borderline too much for a stock 350 TPI.

Try to find a 89 9-bolt or a 90-92 10-bolt with disks. You have the PBR brake system, wihch is far far superior to the old cast-iron caliper system. You don't want to downgrade that.

 

Setting up the gears yourself isn't really all that hard. though a lot of people are intimidated by it. You don't really need a pinion depth checker, though it will make your life easier. You can set the pinion depth by trial and error and by reading the pattern. You will need a dia indicator that reads in .001" increments with a magnetic base, but these can be found fairly cheaply at places like Harbor Freight Tools (that's where I got mine). An inch pound torque wrench will only set you back about $35 from Sears, just make sure you get a good one that reads down to 5 in/lbs.

If you need a carrier and everything it may be cheaper to buy a rear. On the other hand any rear you get from a yard will most likely need a complete rebuild, including new axels. The newest rears in these cars are still 12 years old, and most of the ones in a junkyard will have significant mileage on them. In the end it may be simpler to just build what you've got. Or price out a bolt in 9" or 12 bolt. I bet you'll find the bolt in rear is about the same as a full rebuild with good parts. I found this out only after I fully rebuilt mine...

 

yes, it can be done with trial and error.

and in fact, most of the defects and diffrences are in the housings, not the gears. so the shim that is currently there is likely going to be the right one. but i tend to give people the advice that is most fool proof. and how many people without a pinion depth checker have a press to go through trial and error of getitng the pinion depth right.

 

see this is my same exact problem....Install the gears, or get a rear. and when i think of a used rear, im thinking, it sat in the junk yard for HOW many years...uncovered, un ran....rusting...and if you have to go all out and rebuild the rear, which the kit is about 100 bucks. itll be better to do your own rear and cheaper.

now i have seen a GOOD rear end rebuilt with eaton posi , disc brakes, and 3.73s going for 500 or so....but...thats 500 bucks...ontop of the proportioning valve you need for discs, dunno how much that is, and IF the calipers and discs are good, if not, another 200......

so what i came to is this. you have a rear, that works, brakes that work.....

i got my GM 3.73 OEM gears from ebay for 89 shipped.....KILLER deal. getting the slp posi for 99. rebuild kit ..100. so alittle under 300 i have everything needed. and its mostly new, and i know its good. seeing the gears in hand is an important factor to me when i hear *used rear*

a used rear might have had the gears installed wrong? might be rusted? youll have to do about the same thing to rebuild the rear , as you would with a gear swap. also, im more worried about going fast , than stopping fast ...or at least thats what i tell myself when i want discs lol....

its your call though, im just helping lay down some facts.....now IF you dont feel very confident in putting in your own gears, gear installs vary from 200 to about 400 depending on where you look...its 350 here in sc, so im going to TRY to install mine....lucky my gears have a slight wear pattern on them already as well as a pinion bearing pressed on....im going ot try to get away with matching up the wear patterns as much as possible....then checking for backlash and wear pattern with gear paint....

in my opinion, and just mine....at least when you install your own gears, you know what was put in, and you know it was good. a used rear might fall apart 30 miles down the road, After all, its still sitting in the junk yard for a reason.