Z06 FAN

I have a 1987 iroc with a 9 bolt rear end (3.27 posi) with some problems. Took it to the local rear end, transmission guy who is the best in our area. He's retired now but he listened and said I definitely have problems in the rear end ( which I already kind figured). I also have a 10 bolt non posi rear end with drum brakes out of a Camaro that's sitting behind my garage. Im not sure which one I should rebuild and use. I was also wondering if I could rebuild at home with the right tools if I can get ahold of them. Im mechanically inclined but not a mechanic. In the end I want lower gears 3.55 or 3.73, posi and I want disc brakes which my original 9 bolt has. What route should I take and can it be done in my garage? Or is the a better option?? What would you do?

Roblaza

iTrader: (1)

Anything is possible if youve got the drive to get it done.

I regearred my 10 bolt in my basement at home with a few tools and the couple specialised ones you'll need. Dial indicator, beam type torque wrench ect. I'm am a lisenced tech though, so I had access to a shop with everything I needed but decided I wanted to take it on in the comfort of my home at my own pace. The only thing I needed closer the end was a shop press to put the pinion bearing on the pinion, otherwise it can be done.

GeneralDisorder

iTrader: (1)

Depends on what tools you have or are willing to buy. I am a mechanic and own a shop - but did my 9 bolt in my home garage on my mid-rise lift. Did the work with the rear end in the car. But again - very accomplished mechanic here so zero learning curve. Personal evening project car and daily driver so it's easier to do jobs that can take multiple days at home where it can stay on the lift indefinitely.

You will need some relatively expensive tools. An inch/pounds dial type torque wrench, and a quality pinion depth gauge for starters. Plus the usual hand tools and a 1/2" impact would be highly recommended.

Ring and pinion setup is not something an amateur should start with really. It's pretty involved.

GD

big gear head

The 9 bolt is actually a little better rear end, but it will probably be more expensive to rebuild. The Borg Warner differential in it can be reconditioned, but requires some machine work. There is a better differential available for it that General Disorder can tell you about.

You will probably have to replace just about everything in the 10 bolt that you have, so in this case the 9 bolt might be cheaper. As far as rebuilding it at home, you can do it, but it won't be easy. You will have to be patient and be willing to assemble and disassemble it many times to get everything shimmed correctly. You will probably need to post pictures of your contact patterns so that we can help you read them and give advice on what to do next. You will need to get a few special tools for this job.

Drew

iTrader: (58)

Falls under the category of "if you have to ask on a forum, you probably shouldn't attempt it". Not impossible by any stretch of the imagination, but there are plenty of things that can catch a person up... There's nothing special about a thirdgen rear end. Get on the Google and start reading and viewing photos and videos of gear install and setup. Once you have a working knowledge of how shimming pinion gears and the carrier alters the gear pattern, and how bearing preload plays into the equation, you can start looking more closely at the 7.5" 10-bolt or 9-bolt specifically.

Knowing and doing are two different things. If you don't know you surely can't do it right. If you do know, you can still make mistakes in judgement that will leave you with whiny or grindy gears, and a differential full of metal shavings. Go forth and learn, then decide if it's something you want to get involved with.

As far as gear ratios, with the 9-bolt you're limited by the market. You won't have many options if you want new gears. Last I looked the only new gear set available was a 3.70 gear, but things could have changed.

GeneralDisorder

iTrader: (1)

Nope - it's just the 3.70 for aftermarket. But they did make other ratios stock so it's not totally impossible to find good used sets.

It's a lot more attractive to rebuild the 9 bolt now that there exists a Torsen carrier option. They give pretty good performance and are fairly strong for a mild third gen combo. The 3.70 and Torsen is a nice setup and can be done for around $1000 in parts. Compared to axle swap options that often require brake upgrades, etc and typically cost $2000-$3000, the 9 bolt can be the right answer for price/performance if you already have one.

GD

ironwill

You'd probably do well to have a pro set up the rear. As with building an engine, tight clearances and proper assembly require experience, skill, and expensive special tools. Any mistake made along the way will prove to be very costly in the long run. Not trying to discourage you, but this isn't a good job to tackle for a beginner. Maybe you can persuade your retired pro to be hired to do one more job if you agree to help do the heavy lifting for him, and in return, he shows you how to do the setup.

Z06 FAN

I Have a friend that has a parts car the same as my car, I'm going to talk with him about buying the whole rear end tonight. They are both 87 Irocs with 350, 700r4 rear disc brakes and I will double check to make sure it still posi. Im pretty sure its all stock as he bought it from someone he knows that's owned it a long time. And he himself has had it as a parts car for his 87 Iroc for the last 5 years. What my plan will be is put that rear end in my car. Then pull mine out and rebuild it with help of members on this forum and or help from the retired tranny/rear end guy and a mechanic he recommended to me which I do know personally. I just didn't know he would be into doing a rear end rebuild. So hopefully I can get a hold of this rear end!

TransamGTA350

iTrader: (2)

I rebuilt and set up my 9-bolt in my basement. Like others have said, it’s not all that hard, but you need some special tools and it has to be done right.

2 tricks I used for the pinion bearing. One was that I bought an extra inner bearing and had the inner race machined a few thousandths to eliminate the interference fit so I could easily remove and install multiple times with different shims between the bearing and pinion. Once I got the pinion depth right, I removed the shims, installed the new unmodified bearing and then installed shims behind the pressed in bearing race in the housing.

The 2nd trick with the pinion bearing was when I did the final install on the bearing, instead of pressing it on, I used the hot/cold method. I put the pinion in the freezer overnight and I put the pinion bearing in the oven at 300 degrees for about 20 minutes. Set the pinion gear side down on a table and drop the hot bearing down onto the pinion shaft. It will slide right on and then when the 2 temperatures equalize, it will have the required interference fit.

Aviator857

So many of the TV shows make building the rear seam so scary that the default answer for anyone that hasn't every attempted it is "don't do it it s too complicated"... if you are good with detail, have the right tools, and understand how to do the gear engagement test (yellow grease paint) then its not that hard to do, if its a toy/project then I would say give it a try if failing doesn't mean financial hardship for you (AKA no one likes to blow a grand but that means different things to different people). If its a daily and or messing up the rear would cause you a lot of pain then pay someone to do it and get a warranty, you can save some money by just taking them the rear not the entire car.

There are alot of youtube videos on how to do this.

Also may be worth a look at building a ford 8.8 or something better than the stock 9 or 10 bolt out of the junkyard etc.

TransamGTA350

iTrader: (2)

Completely agree with this, and also the time component. The first time you will end up taking it apart and putting it back together many many times to get the pinion depth, gear mesh and backlash correct. Adjusting one affects the other 2, so it's very iterative. Guys who do it all the time get a feel for it and their first stab at the rough setup is usually very close. Without the experience, it's just very tedious and will take more time and even have to walk away and come back to it when it just doesn't seem to be working out. I spent probably 4 or 5 nights for a couple of hours each session after dinner just working on getting the setup right. This is all good if its a toy and you don't need to drive it to work the next day.