which of our cars came with a 9 bolt rear and which came with a 10 bolt rear? was there a difference in strength/performance or what? Also if i wanna switch my2 series carrier gears to 3.73 or 4.10 do i just need the little spacers or is there more involved?

 

look here for some info. All the gear ratios like 3.45 and 2.77 are 9 bolts.

The 9 bolts are 7.75" in diameter. 10 bolts are 7.5" or in 4th gens 7.625".

Difference in strength: none really. 10 bolts snap easier under a lot of torque if you have good traction. because the 9 bolt is a bigger diameter the car can get moving easier and can take more abuse.

Upgrading from 2.73 to 3.73 all you need is a spacer.

 

9bolt.com has info on the 9 bolt rear end. the 9 bolt came in the GTA and I believe some Iroc camaros.

 

so more than likely i have a 10 bolt in my 91 Z?

 

'89 was roughly the last year. mostly an opt. for the higher end cars (z28,formula,TA,GTA ,TTA and IrocZ) many of these had the 9bolt but, not all.

 

the 9 bolt was avail starting in 85 and came in mostly firebirds they were offerd in camaros. 2.77, 3.08, 3.27, & 3.45 were the common borg ratios. the borg was rumord to be a strong as or stronger than the dana but cost is what mostly killed the 9 bolt. the 9 bolt you want is out of the 89 and mid year 90 models. they have the PBR brake plates.
some of the 90 year model cars got the 9 bolt because they were dumping their stock of the rears.
hte 9 bolt is far stronger than the 10 bolt. miles (www.9bolt.com) is /was running one behind his 427 camaro. cant say that about many 10 bolts. the 3.45 came in stick cars and are more rare than other ratios. i know of about 4 borg rears in my area and im the only one with a 3.45 AND i have a spare in storage.

 

so what do you think a 9 blot would handle, more than a 10 bolt?

 

this is gonna be an asumption, being miles has a 427 i would assume they could handle up to atleast 450 hp. i can always ask miles but not sure how long it would take for a reply. if you are ready to purchase he usually answers PDQ but slow on general ques.

 

ok, i just crawled underneath my 86 iroc, and i do have a 10 blot, which is better for racing, you see, i am building a 406 for mine abnd i really wanted to see if i could get away with a 10 blot, or if a 9 blot is better, i would switch it out, i am trying to avoid buying a 12 blot.

 

you can build a 10 bolt to handle quite a bit. stright out of the box a 9 bolt is better. TA creations is now making a girdle for the 9 bolt so now that i think about it i dunno WHAT it can actually handle.
go buy yourself a good set of gears, carrier, and axles. im pretty sure there is a girdle aval for 10 bolts. hit up summit, Jegs or thunder racing and see what they offer. the good thing about a 10 bolt is you can get the brake mounting plates from a 93-97 F car rear and mount up PBR rear calipers. to mount PBRs on a 9 bolt ya need the 89-90 year brake mounts. anything before wont work as they are the old style.

 

alright i will check that stuff out. thanks for the help.

 

i found a 9 bolt 3.45 disc rear back in the day to put in my 89 trans am

i wined and posi was shot so i sold it and built a 3.73 posi 10 bolt

posis are way to expensive to be worth anything other then the cool factor of havin one

a new posi is almost 1000 dollars you can rebuild them though

the dana 44 is a great rear though

 

actually a NEW carrier from Miles is $475 and thats shipped !!

 

wow thats cool man

makes me almost wish i kept the 9 bolt but i may have found a dana 44 in a half finished project camaro

the car has an lt1, richmond 5 speed and a dana 44 and its going to real cheap so im going to pick it up and part out what i dont want and maybe use the body for a derby car because it has the cage it it already plus its a berlanetta haha

 

bro if you can get your hands on a dana that came in our cars id be all over that if i were you!!!!!!!!
id almost give up my 9 bolt for a dana being the parts avail is easier.

 

I sent Miles an e-mail asking a few Qestions, and haven't heard back from him. I have the 9-bolt in my car and I need to know if I should replace the axles, i know i should get the rebuid kit and have rear gone through. I also wanted to find out about the 4.10 gear ratio.....

 

what do you need to know about yuor axles Birds?

 

I just want to know if I need to replace them with stronger one's (car has well over 200k on it) and if he has every thing that I will need to overhaul it. I also would like to go with 4.10 gears if possible....

 

unless your axles are warped at the shaft, warped at the stud plates, or your splines are toast you shouldnt need another set.
plus as far as i know there arent any upgrades for them.
Miles carrys all the seals, gears and install kits. brake plates and axles are the only thing he dosent have.

 

Stock for stock the 9bolt is better (no c-clips either), but I actually prefer the 10 bolt because more parts are available and they're cheaper. Alot cheaper. If you're gonna be making alot of power and you want to consider the car reliable I would definately look to go aftermarket.

 

i hafta agree with crazy. if your car came with a 9 bolt its easier to deal with. if your getting things together to install one it takes more effort as ya hafta do your homework.
for example, the only way to have PBR brakes is if you found a 89 or early 90 year model and robbed the brake mount plates. if you have a stick your pretty much SOL unless ya wanna pay the $520 as cocacolakid mentioned in a previous thread and then pay the shipping for the 3.45s from aussie land.
as i said a 10 bolt can be built strong and like crazy said parts are very avail for them and from the aftermarket.
my car came with a 9 so im sticking it out. as for my 83 T/A, it has a 10 bolt with 3.42 gears. all i want for it is PBR brakes. i had considerd popping in my other 9 bolt but im passing on that as i see no need in having to dig for even more parts for another 9 when needed.
also all in all when ya get done building a 9 bolt you will have spent a lil bit more than if you built a 10.