I recently installed a GM Performance Parts Fast Burn 385 (385 HP, 385 ft/lbs) Engine into my 1989 IROC and I know I will run into problems. The car still has the stock Borg Warner Rear End in it and the stock driveshaft. I believe the rear in it is the best available rear-end in 1989. It also has Limited Slip. At some point, I know the rear-end will probably blow out due to the HP. In preparation, I have began to think about what type of rear I will put in whenever the old one goes. While my heart says stick with GM and put a 12 bolt in, my instincts tell me to put in the Ford 9''. I was wondering if anyone has any suggestions. Also, could someone tell me where I can find prices on each complete rear-end. Thanks

 

There are LS1 engines putting out that much without blowing the stock rears, which are nearly identical. Put slicks on and you will blow the rear, for the street you should be fine.

That said, forget the GM, The ford is not as efficent but will still be running when the 12 bolt is in pieces. Considering they cost abotu the same it should be a no brainer.

 

I'd take a 9" over a 12 bolt anyday. Wayyyyyyy easier to change gears when you decide you don't like the gear ratio you have anymore. Stronger. Parts can be found anywhere under the sun, and are generally less expensive. More choices on carriers also.

 

I have a Moser 9". It is very nice. Though I am aware of the gear changing easiness, I have never done it since I put the rear in the car. Although, i am going to have to after blowing my pinion seal and ****ing everything inside. Looks like I am going to do a complete rebuild of all moving parts in there.

 

I say 9" too. If you're going to spend the money up front you get better parts interchange and availability with the Ford.

It's BS like that keep your GM car all GM that keeps people from realizing their cars full potential. Every automaker had at least one or two good ideas. All the NASCAR teams that run Chevys all use a 9" Ford and have Honda/Acura rod bearings on the crank. Hows that for all GM?

Parts is parts and fast is fast. Run the best stuff you can afford.

 

I also say 9" for the ease of gear changes & excellent price on parts.

 

the 9" is great if you plan on swaping gears....

BUT the 12bolt is much more effeciant, there is quite a bit of power loss through a 9", the 12bolt has significanly less.

 

a true car guy doesnt care about what the name of the corporation is, and cares only about the actual part and what it does.


get the 9"

 

it seems harder to pick out what u need for the 9 inch bolt in for f-bodies because the when u click on that link u can just buy the housing in that area. unlike if u click onto 12 bolt u have all the options there, seems hard to find out what u need if u want a complete bolt in 9 inch.

www.moserengineering.com

http://www.chevyhiperformance.com/te...les/0304_nine/

 

Have you broken the 9 bolt yet? I'd be surprised if you did, it's fairly strong. Wearing out the posi is another story (I got tired of rebuilding posis and just welded the sidegears in to the case making it a spool… been driving it like that since last fall and am very happy with it).

Yea, a 9" uses a little more power. Will you be able to measure it? I doubt it, the difference is smaller then what could be accurately measured on a dyno.

If I was buying aftermarket I'd go 9", just because of the availability of good parts. If I was doing it myself I'd probably start with a ford 8.8 out of a mustang because parts for them really are dirt cheap (it's just a copy of the GM 12 bolt but many more of them were made) and again, availability of parts. If I wanted to do something trick then I'd either setup a quick change 9" for an f-body or get a mopar 8-3/4 for the drop out center section like the 9" but the geometry advantages of the 12bolt/8.8 and being lighter then the rest and just as strong.

 

my vote is for the 9 in. parts availability and durability.........dont go the brand loyalty route.........i mean even firebirds have CHEVY engines in them (shoulda kept the 400 around).my .02

 

the ford 9" is the like the SBC 350

 

is 385 hp gonna break a 12 bolt? probably not. im going through the same ordeal right now too. the 12 bolt eats less hp. its still GM. and i dont think i will ever break a 12 bolt so thats my choice. Moser engineering sells a complete 12 bolt minus brakes for like 2200.00

 

Tell ya what, when you lose your c-clip and your axle/tires goes rollin past you after screwing up your cars body, I'll go ahead and passs you with my 9" and be sure to send a flat bed for ya. The bad thing about the c-clip eliminators for a 12 bolt, cant run'em on the street as you'll eat up seals left and right, and since they're pressed onto the axle, you'll have to take it somewhere it have it removed and a new one pressed on. The 9" is the best bang for the buck for overall realiability, durability, safety, ease to work on, cost to change out parts ie. gear swaps!

 

I've tried to stay out of this as everybody seems to love the 9" while the 12 Bolt is deemed no good.

The Moser rear that plumminfool speaks of does not have c-clips or c-clpi eliminators but rather used big ford housing ends just like a 9"

I have yet to break the 12 Bolt in my street car(that runs better than some racecars )after thousands of miles and several hundred runs with 60fts in the 1.47-1.49 range and ET's in the mid to high 10's.

 

If losein 2 cylinders and adding a turbo has you runnin in the 10's, just hink how fast you be if you ran a twin turbo 2.2L -more boost and yet another 2 cylinders lopped off

 

First, the BW 9 bolt uses axle retention just like the 9" (no c-clips) and for that matter, all of these places are making you what is essentially a custom axle, if you want a 12bolt with 9" ends then that is what they'll build you…

 

fortunately, i am old enough now to have a race car and another car to drive on the street. im not building a car to race on the street. thats why a full spool 12 bolt is the rear for me.

 

What do you consider "significant" it is supposed to be 10% , now this is 10% more than the 12 bolt. So say a 12 bolt sucks 10% of the total drivetrain loss, (witch it doesnt) so 10% of 10% isnt that much when you look at the big picture, availabilty of parts, aftermarket support, and the strength of a 9".
Just my .02

 

the diff in loss at the 600rwhp level is still inmeasurable in real life.


so the whole argument is pointless.

 

didn't I say that already?