which rear end,need honest answers

ok i need professional advice here guys,none of this i heard this or ths guy said that..i need sound advice,this is a big descision.heres my ?,im finishing up my 87 with a stoker 400,424 cid trick flow heads ,roller cam the works,dyno should go easily past 500.so now its rear end time.i know the stock one i have is just.i was looking to get a 9 inch setup,but have been discouraged by price,horsepower loss and used availabilty.id hate to loose 3 percent just from a rear.a 12 bolt is posing the same dilema.i know the some rears were of the "9 bolt" bw design and are sought after for extra strength.my real ? is can a 9 bolt be built up enough to last,and if it can,will it cost an arm and a leg to do it,or if im going that route should i just go witht the 9 incher?..its going to be stret car,minor strip and no slicks ever

I'm no professional, BUT, I'd say that if you DON'T run slicks EVER, you'd probably be "ok" running the stock 10-bolt. However, for obvious reasons, you probably don't want to risk that, so then a 12-bolt or a 9" is a wise move:thumb:. I know there are guys running into the 11's and even 10's on the 10-bolt, but I doubt they'd last long;). There are also the odd case of a 12-bolt breaking in a ~12 second car:rolleyes:.

Making upwards of ~500 HP like you're planning on, I wouldn't be overly concerned about losing ~3% here or there, considering the fact that you don't plan on running slicks, so you'll over-power ANY set of street tires you put on the car anyways:rolleyes:. SO, either a 9" or 12-bolt is a good option, just go for the one that will suit your price range better, because I think that either one will be better than the 10-bolt (in case you ran with drag radials or something like that?).

That's my $.02:cool:.

thanks pete.but i will add 3 percent loss is still aloss,,,

hey

How about an 8.8?

well, here's my story. I bought a used rear end (disk instead of drum) and rebuilt it. New gears, bearings, moser axles, support cover, solid crush sleeve, will weld axle tubes. All the parts ran a little over a grand and I didn't even get a new posi unit, which would not have been a bad idea. If you add the cost of the posi and labor (I did everything myself, but I know some people would not do that), you are looking at something in the range of 1600-1700 bucks and in the end you still have a rusty, old 10-bolt with same design flaws.

For $2100-2200 you can get a nice, shiny 12-bolt that will be bullet proof and it would be build by best professionals out there, not the local tranny shop (and this job I would definitely not trust to your every day mechanic).

Plus 10-bolt also has some kind of a loss. You are not looking at the 3%, you should only consider the difference between 10-bolt (1-2%??) and the good rear ends.

something to look at: http://www.ws6transam.org/10bolt.html

thanks,that kinda answers my ?.gues ill be buying the 9 inch

if you want to be sure you'll never break it-

9 inch
33 spline axles (i have 31's and wanna move to 33's)
spool- get nothing less... you'll end up getting a spool if you do anyway
iron nodular 3rd member
aluminum yoke
ARP wheel studs are a MUST

You probably don't need the extra weight... and yes, the 9-inch has been proven to lose 3% more power than the 12-bolt (5% for a Dana 60, 7% for a GM 12-bolt, 10% for a Ford 9-inch). I would suspect the power loss through the 12-bolt would be very similar to the 10-bolt... same pinion centerline geometry, and that is a major contributor to mechanical effciency. My Strange 12-bolt seemed to be within 10-15# of my stock 10-bolt. The 9-inch will add at least 30#.

Then there is a potential issue with the torque arm and driveshaft. The larger body of the 9-inch, and the cobbled up TA mount that they bolt on to it often causes problems with the TA mount/bolts hitting the DS tunnel in the 4th Gens... I suspect the 3rd Gen may be similar. The TA mount also pushes the TA off the to left, requiring a 9-inch specific TA mount. And, the pinion shaft of the 9-inch is 3/4" lower than the 12-bolt, meaning your DS has to make a sharper angle = additional wear and power loss, plus the need for a really good adjustable TA to get the correct pinion angle.

Finally... how strong do you need it? I have an 800HP nitrous setup, and the car used to be an M6. The 12-bolt had no trouble with 5,000rpm drops. A buddy of mine took his Strange 12-bolt to a shade under 1,000HP before he decided to move up to a "premium" (not your basic) 9-inch, that eventually was fine at the 1,350HP level (8.6@160+MPG in a 3,550# convertible). If you are only talking 500rwHP with your setup, the 9-inch would seem to be overkill.

you were asking about the borg 9 bolt, its actualy quite a strong rear. miles, the fella i get my parts from is running a 427 in front of his with no probs. they are rumord to be as strong as or stronger than the dana 44. reason they quit making them? cost, they were quite spendy as a new carrier last i price one a few years ago was $1100 and GM is one of the only2 places to get borg parts. miles is the other as he bought the rights.
i have 2 of them and love it. after i get my other T-5 tranny case sent to
G force to be built i can hammer with no worries of grenading anything.
the borg rear is 7.75 where the 10 bolt is 7.5 or the revised version is 7.625. they were avail from 85-89 and some early run 90 models got the last of stock.

imjuneer,you say dont waste cash on a 9 inch?if so what would u recommend?
chicken ,are you saying build th esnot out of a 9bolt and ill be good?

my buddy has a turbo ta that has a 9-bolt in it the car is full body,3.27 gears the car 60's in the 1.40 range and has no problems.

imjuneer,you say dont waste cash on a 9 inch?if so what would u recommend?
chicken ,are you saying build th esnot out of a 9bolt and ill be good?

theres actually not much to build, they are pretty much ready to go from the start. only thing thats going to be modded is a girdle which miles has been working on and on some of the third gen forums "i think" its T/A creations thats working on one pending general intrest.
i will say this, if you can get lucky , score a rear out of a 89 or early 90 model as those years got the PBR brakes. the 10 bolt plate WILL NOT fit as i have physiclly measured the plates on 2 ocasions. now drilling is not out of the ques though. so hopefully your iron calipers work or you know how to scervice them. the calipers are the same from 89-97 but the only diff is the mounting plates where it mounts to the tubes.

anthony, 12-bolt is about $300-400 less than a 9 in. And like guys here said, they weigh less and have less power loss than 9 in. 12 bolt got my vote.

as far as I remember GM 12-bolt is about as strong as ford 9 in (although when people talk "bulletproof" 9 in is usually the one everyone thinks about, that's my experience).

be sure when describing a rear be sure your describing it corectly as 9 BOLT, 9 IN or 12 bolt.
not flaming anyone directly for the record just reminding of clearity. :cool:

I personally would just build a 9inch they are so cheap. You could buy a housing, TA mount, and 31 spline axles from moser for $900. Then i would just to a salvage yard and buy a 31 spline posi center section out of a ford pick up with the gear ratio of your choice. Some guy was selling the center sections on ebay for $150 for a 31 spline 3.50 9 inch posi. So for about $1200 you have a damn strong rear that would be tough to break. JMHO. If i could do it over again thats what i would do.

be sure when describing a rear be sure your describing it corectly as 9 BOLT, 9 IN or 12 bolt.
not flaming anyone directly for the record just reminding of clearity. :cool:
The original post clearly asks about the relative merits of all three configurations.

I am running alot more than 500 rwhp I run BFG Gforce on the 10 bolt with soft gears, hard axles and a eaton posi. So far so good? Im not saying it wont break tomarrow but I beat on it pretty hard. But out of the whole It will smoke the tires before I hurt the rearend.

i hear you chicken,my orginal ? was ref a 9 inch or a 12 bolt,but later i nquired if building the gm 9 bolt worth it

i hear you chicken,my orginal ? was ref a 9 inch or a 12 bolt,but later i nquired if building the gm 9 bolt worth it
no sweat all is kool :)

The answer is ..........................

Strange 12 bolt

Lighter than all others - some may weigh 50 Lbs more
Lower loss than a 9"
You absolutely will not break it footbraking an automatic even with slicks
Torque arm bolts go thru entire arm and center casting - bolts tend to come loose on other styles.

Steve

I have a 9 inch just because I never wanted to worry about it EVER! It's also slick to be able to slip in a different gear whenever I want (highway gears vs. drag gears). As for the weight, an aluminum center section is available and is only 150 dollars more than the nodular case. Saves almost 30 lbs. Fit the package with a lightweight spool and lightened gears and the losses aren't a major concern.

I can only tell you my experience. I've broken several 7.5" 10 bolts in a few 4th gen F-cars. For our 95 we put in a Moser 12 bolt with 33 spline axles and a posi unit. I have had no problems and have fed it 700+ ft/lbs of torque at the rear wheels and made several 10.4x passes. It seems to be holding up fine. If you're going to the trouble to build that motor you owe it to yourself to build the rest of the driveline to take it. You won't notice a 3% power loss if you never knew you had it but you will notice broken gears, axles, etc...

12 bolts are NOT bulletproof! Why do I say? Cause my Moser broke the posi and bent the pinion on my first track pass and i'm not even pushing 500hp. About 400 at the wheels and that pass was a 1.64 60ft with a 3000rpm launch on ET streets and it's a 6spd. And I got nothing but hell from Moser trying to get a new ring and pinion after they sent a new posi. Very unhappy with them. If I were you, go with a 9". By design, I think they have much better pinion support then a 12bolt. Don't use a spool if your ever gonna drive it on the street. If you do go 12bolt, go with Strange and definitly go with a solid pinion spacer. Even if they can't build you one, take the rear apart and put one in before you run it.

Ken R.