Hey guys. I have a '89 iroc which still has the original gears (2.73 I believe). I was reading on here and it seems 3.42 is one of the best all around gears. I was wondering if it's actually worth it? Will I feel a huge difference? I really want that "pinned in the seat" feel, and the stock gears just aren't going to cut it. Drive ability is some what important to me because I'm still in high school and my car is my only means of transportation. Any help would be greatly appreciated!

 

Should notice the difference but i found a good torque converter makes most difference and more bang for your buck

 

Yes, you will notice a difference. You will need the special thick 3.42 gear set for your 2 series differential. You will also need a good installation kit. Be sure to have it set up by someone who knows how to set the pinion depth, bearing preload and backlash.

 

First let me say that a 2.73 to 3.42 ratio change does make a huge difference.I know because I did it, but there is "allot" to be considered when swapping ratios. First do you have a posi unit and if not do you want one? If so now is the time to do it. Keep in mind that a car without one especially with a higher gear ratio will tend to sit and spin a one wheel peal. That means you will only have one wheel applying torque to the ground instead of two. The posi fixes that.

 

And if you're buying a posi, this is the time for 28-splines unless yours is a '90-up axle.

 

I wanted to know the same thing I have two 89rs 2.73posi and a 92rs 3.23 open diff. the body i'm keeping is the 92 but it is not posi. i'm trying to learn what it will take to make the 2.73 a 3.23 or make the 3.23 a posi. and stick under the 92rs.

 

The 2.73 uses a 2 series differential and the 3.23 uses a 3 series differential, so you can't use the 3.23 on the 2 series posi. Most likely the 2 series posi is just about worn out anyway, so it probably wouldn't be worth it. The Auburn differential can't be rebuilt, so it would need to be replaced. You can get a new 3 series Yukon Dura Grip for around $400, and that is what I would recommend. Put it in the 3.23 rear end and you have something that will lase a long time.

 

Can't you run a ring gear spacer for the series 2 diffs?

 

This is a break down of my build. Some of these parts are necessary for the build and some can be changed to match your personal preference as in brand and style L.S.D./Locker.,etc.

1. 3.42 ring and pinion =$ 200.00
2. master bearing kit = $ 90.00
3. axle bearings and seals = $ 30.00
4. 28 spline Eaton posi. Unit = $ 500.00 ( highly recommended )
5. 28 spline axles = $250.00
6. installation/labor = $ 300.00
7. and if you want ,a LPW Ultimate support cover = $ 160.00 ( also highly recommended )
8. Thats $1,530.00 counting the cover.
9. 3 year warranty on parts and labor

 

No need to run a ring gear spacer with the 7.5. Just use the thicker gears that are made for the 2 series. Factory gears will not fit the 2 series without a spacer, but I DO NOT recommend using a spacer, especially in the 7.5. A spacer is a bad idea in any rear end, but it's even worse in the 7.5. If you want a bunch of trouble out of the rear end gears the go ahead and use the spacer.

 

ron u.s.m.c nice car my man! I am a complete novice and the rs I'm working with is stock. the gears are 3.23 and I just wanted to have posi. (NO RACING) this is just my toy I like to play with it every once In a while but no abusing. 700r4 tranny motor might have 260hp so I just want to have a little more get up and go. thx.

 

Is it also advisable to weld the rear diff. tubes to the "pumpkin" for added strength?

 

Not for our stock 9-bolts and 10-bolts. Other parts will fail first. Like in the 7.625", the ring-and-pinion is the known weak link. And even S-60s don't really need that sort of welding because of the torque arm design.

 

Welding the tubes must be done correctly or it's just a complete waste of time and effort. Welding cast iron is not an easy job and should only be done by someone who is experienced with cast iron. You must use nickel to weld cast iron and mild steel together, and it's not easy to weld with nickel.

I agree that welding the tubes on a 3rd or 4th gen is usually not needed because the torque arm takes most of the torque and not the axle tubes.

 

just swap in a 3.42 rear from a six cylinder car.thats what i did.

 

what about this. http://www.ebay.com/itm/GM-7-5-7-5-8...-/290963439401 or this http://www.ebay.com/itm/GM-10-Bolt-Series-3-7-5-Posi-28-Spline-LS1-LT1-Trans-AM-Camaro-93-02-/141046244001?pt=Motors_Car_Truck_Parts_Accessories&hash=item20d702e2a1&vxp=mtr
http://www.ebay.com/itm/GM-CHEVY-7-625-7-5-8-IROC-CAMARO-FIREBIRD-POSI-TRAC-28-SPLINE-LOW-MILES/190885620802?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D17216%26meid%3D892822270298333893%26pid%3D100005%26prg%3D8039%26rk%3D5%26rkt%3D5%26sd%3D290963439401%26

 

The first one is an Auburn. PASS!!!
The second one would be fine.

 

Both are overpriced by $ 100 each. Keep searching or buy new.

 

If the Auburn was free it would be over priced.

 

thx fellas might ttry to buy 2nd one new. but will keep looking for it in good condition at better price.

 

Nope. I'd give $50 for it if it was under 50K miles of granny driving. They daily-drive really well all year around, they can do twin stripes really easily, they can be drifted, but they just need more frequent fluid changes to slow the wear. And once they wear out, they can be rebuilt if you're smart about grinding the small ends of the cones, plus welding up and grinding the big ends. Auburn will protest this, but it works fine when done well.

 

This is just my opinion, and it's not meant to offend, but a brand new Auburn isn't worth $50 to me. They fill the rear end with powdered metal as they wear, and they do wear quicker than any other limited slip differential. The powdered metal ruins the bearings and fills the housing and axle tubes with metal sludge. As for rebuilding one, I've never heard of anyone even trying it before. I just don't see how it could ever be worth the effort when there are other differentials out there that are so much better.

 

And I was just sharing experience my dad shared with me. He did the work, but I was there helping, and I drove that car both before and after. Besides, GM installed Auburns, but GM never installed true lockers. Even the Gov-bombs have friction plates that can slip, so they never truly lock.
But I'm not attacking, merely explaining my differing from someone who comes across as some kind of expert.
And how much damage can an Auburn do, when the whole rear end was covered under the warranty of the car? Probably more the idea upsetting some people than actual parts damage.
The Auburn we messed with was doing twin stripes at 110,000 miles, but had had 3 fluid changes. By 160,000 miles it never had the fourth change, and was "dead". After dad worked the magic, twin stripes again.
The backlash was around 0.011" so the gears could not have been too worn.