I know this has been debated many times before, but my 12 bolt blew up 2 months ago. I have a 66 chevelle with a 454 and a turbo 400 with a transbrake. I am going to make this car less of a street car and more strip oriented. Is your 12 bolt holding up against all your big blocks out there? Or have you guys switch to a f#$d nine inch. What posi unit's are you guys using? Gears? Axles? Sorry about all the questions. I wanna do it right the first time. Thanks,Erwin.

always used a 12 bolt check out the pic. of the white car, that thing had thousands of runs on it most of them with the transbrake and it NEVER failed. But it did have a spool, which may be ok for you if your gearing up more for the strip.The main thing is to set it up right most guys slap them together, they don't check the pinion depth and then it grenades graemlins/sad.gif
john

my friends 3000# 67 Camaro has ran 8.90's in the 1/4 with a 12 bolt. 496 BB with a lot of NOS.

i have a 12 bolt...many runs in the low 10's and mid 9's all day long in the 1/4, i am afraid to push it harder cause of my tranny problems(d**n cheap import rebuild kits). if you knew how crazy a driver i was, you would understand how much abuse a 12 bolt can handle if built properly and set up is key just like everyone else will tell ya. for axles look at the profile

The durability of a 9" is not much different than a 12 bolt GM until you get into the high dollar nodular iron cases. The 9" does have a couple of basic design advantages in the removeable case and the second pinnion bearing. But the standard cast iron 9" case is horsepower limited just as is the 12 bolt. Either one will do for what most guys run. For a high dollar car, you could go with an aftermarket housing and an aluminum case and an endless array of axles for the 9". But I wouldn't consider this for anything less than a 9 second car.

DTS 12 bolt. 3.08 with eaton posi.
Just installed and only less than 100 easy miles so I cannot speak for durability yet. Upgraded from 10 bolt 3.70 posi to support a Ramjet 502.

Hey Erwin, I was wondering why I wasn't seeing your car around town, sorry to hear about that :mad:

Anyhow, I'm running a 9" in a braced carrier, mini-spool, Mark Williams axles, and 4.56's.

Time for another cruise, isn't it? graemlins/hurray.gif

Another option would be to contact Strange about their Dana 60 rear ends. They are a little heavy, but they are really strong with a 9.75" ring gear. All of the early pro-stocks ran them with the added abuse of a 4-speed.

I'm taking the nine inch route, for what I can sell my restored 12-bolt for I can run the nine inch and have two sets of gears ready to go. Heck I'd need to replace the 12bolt axles and buy c-clip eliminators anyway just to stay with the 12bolt. I already have one nodular case donated from a big block Torino. I just picked up 5 1957 ford rearends for free! I'll be building up one of these for my Son's 70 Nova which has a 4.56 geared 12-bolt in it now. I've seen these 12bolts go on ebay for over $1500! Just makes sense economically and serviceability wise to run the nine inch. I'll let the numbers matching crowd have my 12bolts. JMHO graemlins/beers.gif

12 bolt,Eaton posi, Richmond 3.73's,stock axles,disc brakes...when posi was replace a couple years ago,no evidence of axle twist so far.

If I ever find time to finish the El Camino, I'll be able to try out my 9" I built last year. Big bearing truck housing with 1/4" wall tubes, Alston billet ends (late big bearing style), narrowed to 58 3/4" wms, Currie axles, FMS Explorer disc kit, FMS N case with steel caps, billet adjusters, Detroit locker, Richmond 3.89's, aluminum Daytona pinion support, and Daytona 1330 yoke. I think it'll live. ;) Early 12 bolts are basically non-existant around here, but I've been able to scrounge plenty of free F*rd truck housings in the past, pass them on to friends in need.

Go with whatever costs you less to setup for your needs. Both are very strong when properly setup: 12 bolt = 8.875" to the Ford 9". Without going into all the design details the 9" does have a strength edge - but it comes at the cost using more horsepower in the process. An interesting thing that has been underway for a little while now is that a lot of racers who had Ford 9" differentials are switching over to the Ford 8.8". What makes that so interesting is that the Ford 8.8" is a close copy of the Chevy 12 bolt!

Thomas

Are any of you guys running 12 bolts with 9 inch housing ends? The c-clip thing kinda got's me a little paranoid. Thank's for all the reply's. Keep the reply's coming.

Kinzli- I hope to be back on the road in a couple of months.

I am running a 12 bolt with 9" inch ends on it. I dont have many miles on it yet, but it went together fine and seems to work ok too.

Erwin, I have a 66 as well. I went with a 9 inch. I also used the Ladder Bar kit from Morrision and coil overs.

Here is a few pics of the 9 inch installed.
web page (http://home.comcast.net/~larry.macdonald/new_frame.htm)

Larry

Originally posted by Dcairns560:
I am running a 12 bolt with 9" inch ends on it. I dont have many miles on it yet, but it went together fine and seems to work ok too. Same here. Upgraded from a 10 bolt to a 12 with the 9" ends. Only a couple hundred miles on mine, too and no track time yet.

I'm running a 5 speed so we'll see if the rear can hold together. graemlins/thumbsup.gif

Tim.

12 bolt, powertrax, Mark Wiliams axles and c-clip eliminator kit. welded tubes, and girdled cover.

Larry your car looks great. Thank's for all the reply's guys. I'll let you guys know what I go with when I decide to build the rear end.

Well I'll chime in as well here since I have run both a Ford 9 and 12B (and a BOP and a 10 bolt).

Well first off... anyway you go it is gonna cost you some bucks! Secondly what kinda shock to the tires are you giving her? You run nitrous? You have a stock style suspension? 4 link? Lader bar? Or plans for them?

Nothing from a stock Ford 9 will handle much abuse. Nodular cases are tough to find and I managed to break mine. A stock housing needs to be braced or else you will most likely twist it. If you plan to run ladder bars or a 4 link you can use a 9" from a early 70's Torino or Ranchero. These are a heavy duty housing with stronger tubes and are the correct width assuming you are running a 68-72. Figure to go with and aftermarket case and daytona style pinion support if you plan to race it with a trans brake or hit hard. A third member will cost you a grand easy with those mods. More if you want to steep up to a 35 spline. In the end, the 9" will weigh a bit more, it will suck about 5% additional power through friction and the cut of the gears then a 12B will, but the way the teeth are cut and mesh it will give you a stronger mesh then the 12B setup. Brakes for the rear can also cause minor issues.

I will be running a 12B this time around... one simply beacuse I scored one for a good deal and I wanted a bit less weight and less power loss. I'll take my chances with good caps or reinforcing cover. The biggest down side to the 12B is axle retention. Most c-clip elims like to leak and are not designed for side loads if you do much street driving with your car. Strange has some safety hubs that supposedly can handle turning regularly and seem to have good reviews. Other then that the 12B is pretty plug and play. If you have a 12B now I don't see whay not just beef it up a bit with stronger aftermarket gears, a reinforcing cover or stronger caps, better axles.

I will second the comments about twisting the stock 9 inch. It needs to be beefed up if you are going to use it in competition..

I used the nine inch because I had it. It came out of my drag car. It was a 3000lb 10.7 second car. The tubes were twisted and needed to be replaced before I could use it in the Chevelle.

Larry

Fab 9,fully braced,Moser axles,Detroit locker,CE four link,Strange coilovers,Baer disc brakes

Full Moser equipped 12 bolt, welded tubes and Ford style axle bearings.
The guy that built it for me told me to try and break it. ;)

What do you guys mean by welding the axle tubes? I have my 12 bolt out and I want to send it out to get powder coated and have 9 inch ends installed. Can I run my stock drums and backing plates with 9 inch housing ends? I am thinking of a eaton posi from tom's diff's. Probably moser axles. Not sure about gears. I hear richmond's are noisy. I have a stock rear suspension in my 66 at this time. I have ssm lower lift bars, and hotchkis upper adjustable control arms. Stock rubber bushings with moog replacement big block springs. Any suggestions or comments? Thanks, Erwin.