87_gta

Hello,

I'm thinking about upgrading the rear end in my 87 Iroc. Currently it is a Factory 9 bolt BW axle with 3.23 gears (G92).

I have been using the search feature extensively before posting.

Little background on the car. Again its an 87 Iroc. Motor was rebuilt 3 years ago and is now a 4 bolt main, balanced and blueprinted 355 with a big cam, bigger heads. Trans was refreshed as well and i also added a shift kit and 2200 stall converter.

last upgrade i did was convert the TPI to a Mini Ram. The Mini Ram is sweet i must say. definitely complements the motor nicely. Only downside was a slight loss of power in low RPM.

This leads to my question. I want to change the rear gear ratio to counter the loss at low RPM. Parts for the 9 bolt are..well...hard to find. I know about 9bolt.com but i am hesitant to buy from there. Hawks does sell a 3.70 gear but i don't know if that's to much gear as i was thinking a 3.45 would be good.

Also the rear diff has 210,000KM (130,000 miles) and has not been serviced ever. There are currently no issues that i can tell with it. However whose to say that everything in the diff right now is still in good shape (ie: cones). So i don't know if its worth putting money into a hard to find parts for rear end or if its better to replace it with a Ford 9inch, GM 12 bolt, Hawks custom 8.8 etc..
I'm looking for opinions. What route would be best?

cosmick

3.70:1 wouldn't be too much, and you don't need a 9" / 12-bolt unless you go to a power adder with drag radials.

big gear head

Randy's Ring & Pinion, or whatever it's called now, has 9 bolt parts.

87_gta

Both thoughts are true. I checked out randys and I don't see the cones as part of their overhaul kit. Are the cones something that usually wear out drastically?

big gear head

Yes, the cones do wear.

87_gta

That's what i'm worried about. I don't want to spend money on parts (ring gear, pinion, bearing etc) and then find that ohh the cones are worn. I figure the cones must be worn considering the age of the car. Car has never been abused or anything. I figure its inevitable that wear has happened.

From the searching I have done there was a company in BC Canada that had the cones for sale but most people on this forum had bad experiences with the quality of the product. The cones from 9bolt.com are not a direct fit.

I guess that's the real issue i have. I want to upgrade this thing. Assuming the cones are in good shape then i got no worries. I'm just thinking if their not. Then what is the best route.

Camaro86IrocZ

iTrader: (1)

Read this a few months back, could be your answer?

https://www.thirdgen.org/forums/tran...installed.html

UltRoadWarrior9

I have an Eaton TrueTrac in my 10-bolt. I like it on dry road, it's definately got the 'posi' style grip. But it can be tricky on wet/slick roads with an auto trans since it's difficult when to choose shift/amount of torque when accelerating/shifting around corners. Definately something to consider!

EDIT: My tire sizes are 295 35 ZR 18 in the rear and 275 35 ZR 18 in the front on Continental DWS rubber. I mention this because thinner tires may be much more forgiving. The DryWetSnow tires grip like a SOB

87_gta

I read that post. Definitely good work on that one. I dont have the know how to do that myself. It's a good option to keep in mind assuming my mechanic will do that.

Any other thoughts?

rb85TA

GMPP Dana44 true Trac posi (better than clutch type posi's IMO), & 3.73 gears w/28x10.5'

87_gta

I spoke with my mechanic he feels confident that he can rebuild my 9 bolt even without the cones.

I can get every part needed ring and pinion bearings etc..

Is it worth it without new cones?

big gear head

If the differential case is machined correctly and the gears are shimmed correctly then it can be done without replacing the cones.

rb85TA

As long as the cones are in good condition & the power level is not excessive, it will be fine.

mmadden55

98 and up V8 birds and camaros had Torsen rears, which are pretty much the same as a trutrac and a 4th gen rear is a bolt in.

rb85TA

Well. ... yes you can swap, I think that the 4th gen is just a tad bit wider. But most that switch are running 4th gen rims or c5 rims with deeper offsets anyways.

87_gta

Hey,

All true points. Power wise its not too crazy. My mechanic has a machine shop on site. I should be safe with the 9 bolt as long as it's in good shape.

Appriciate the opinions. Keep em coming.

cosmick

If 9-bolt parts are unobtanium, then the 7.625" really isn't any weaker, once you do all the upgrades. Plus it's far more common.

87_gta

Hello,

Thought I would give an update on this.

After much thought I have decided to convert the rear end to a 10 bolt I acquired out of a 02 Camaro. The rear is a 3 series carrier with 3.42 gears. I verified this by the markings on the gear and carrier.

I decided to do this because my 9 bolt after close inspection was close to the end. The posi was still good. Good breakaway on it but everything else was on its way out.

I do have a question. My vette wheels in the rear are 18x10.5. I currently run a 2" spacer and I have no issues with rubbing.

I know the rear is wider than stock but a rear from an 02 Camaro is narrower than one out of say a 95 Camaro.

For good fitment should I run a 1/4 inch spacer with longer studs or should everything fit ok as is? I believe the backs pacing of my rear rim is 7.65.

Thank you.

UltRoadWarrior9

I have 18x10.5 C6 Z06 Corvette replica rims and use no spacers at all on the rear.

UltRoadWarrior9

I forgot to mention after putting in my rear end from an 2002 Camaro SS, I also installed an adjustable panhard bar because the tires were not centered to the body. I chose UMI for the panhard bar, since I got their subframe connectors too and was happy with that... Good luck on the install

87_gta

Thanks for your reply.

That's a good point about the panhard bar. From my extensive use of the "search" feature I have seen some who do use an adjustable one and some that do not use that.

Is this something that I should consider purchasing?

MoJoe

iTrader: (5)

Any aftermarket pan hard bar, fixed or adjustable, will be stronger than the stock one.
If your rear end is not centered under the car, then an adjustable PHB can solve that problem.
They are a relatively cheap, and super easy swap. So, if you are upgrading and/or planning to keep the car for a while, my $.02 says it is a good investment.

87_gta

Ok that's sounds good. They are pretty cheap so I will order one.

Lastly I should be good with fitment of my vette rims with the 02 rear?

Or should I use 1/4 inch spacers?

Thanks

87_gta

Hello,

I got backing plates for my 02 rear. The backing plates have holes for sensors.

Since I don't need the sensors. What could I do to cover the holes.

Thanks.

87_gta

Hello,

I figured I would give an update.

Forth gen rear is installed. The fitment is bang on with my vette wheels.

Haven't driven the car much yet but it definitely feels better with the new rear. (Only drove it home) The rear end definitely has a different feel to it and more pep.

A very noticeable upgrade were the brakes. Much more bite than before.

My old 9 bolt was very loose. The yoke had a lot of play and sloppiness to it and there were clicking sounds coming from the rear. (I know the yoke has some play but this was excessive). Also I don't believe I mentioned this earlier, my 9 bolt was wearing out on the carrier where the axle connects to it on both sides. So I would would have needed a whole new carrier, and the splines on axles were visibably worn as well.

Overall I can say I am happy with the swap. I run vette wheels and have no intentions on changing wheels any time soon. For this reason the swap works for me. From my experience with this, an adjustable panhard bar is a must with the 98 - 02 rear. (Made wheel fitment bang on)

Also when it comes to cost, in my opinion you can't beat going with a forth gen rear, especially if you get one with a 3.42 posi as I did. Brakes are better as well. Cost of rear with brakes cost 1/4 of what a new setup without brakes costs. The rear I got also have a T/A aluminum cover with fill and drain plug on it.

Note: for ebrake cable I ordered a set from Hawks. They have one that goes from the factory thirdgen block to the 02 rear end. The cables were a perfect fit.

Also when it comes to stock rims.....I have not had them on the car for about 10 years so I cannot comment on the fitment.

Anyways I just figured I would give my and share my experience with the swap.

Cheers,

87_gta

Hello,

Figured I would bring back this thread.

I have recently ran into a few rear end issues. I would appreciate some opinions.

My vette wheels tires were recently damaged to the point where I had to take them off the car. They always fit the car but even when I had the 9 bolt on with 2 inch spacers there was some slight rubbing issues. As of right now one tire has a huge gash in the sidewall. My tires are discontinued.

So I put the factory wheels back on. Now I can comment about figment.

I can honestly say the tires are pretty much flush with the fender. They don't stick out, at least in my case.

I do however have a few issues still. Common issue. My factory wheels still do rub on the big bumps (when I don't slow down in time) rub the fender lip. My factory wheels do have some minor cuts but nothing serious at this time. Ohh I have also raised the rear about half inch.

What should I do about this? From my use of the search I figure I have 4 options

1) roll the fender lips, either myself or body shop.
2) get the 9bolt re-built (rather not really)
3) the is more extreme but, narrow the rear end. (I know it's a 10 bolt and nothing special)
4) find a third generation housing and swap parts (if I can even find one)

Last thing to note. I am in Canada and used parts are not easy to find. At least in my area. I drove 5 hours (one way) to get the fourth gen rear.

Thank you.

GeneralDisorder

iTrader: (1)

Just get the Torsen for the 9 bolt from Austrailia. It's great. Mine is setup with the commonly available 3.70 gears . Love it.

GD