waste of money on a 7.5" 10 bolt

29x9 on a the same wheels

 

Does any other brand make a direct fit 9", that's looks mean but I can't afford 1200 on a housing and axels

 

I thought you were talking about building a 9".

Agreed, wasting money of a 7.5" if you plan to go fast.

 

There are several other companies. I can't think of their names right off. I know currie makes one. A quick Google search of "fbody 9"" will net you a lot of info

 

So if I get 4.11 gears with 28 spline trans am axels it would be a waste with the 7.5?

 

How much HP?

Are you going to run slicks?

Are you racing or street driving?

If you have a TPI engine, 4.11's will be too low.

 

Not sure on exact hp. I know it's over 500 hp, I am gonna run slicks, mostly street use but I'll go to the track every once in a while. Its a Pontiac 462 so it's got quite a bit of torque.

 

Then yes, you are wasting time and money with a 7.5.

Also, I think you will want less gear behind that big indian.

 

Like 4.56?

 

I mean 3.73?

 

Without knowing the details of you engine, I'd say 3.73 at the lowest. You could probably get away with 3.42/3.55

I have seen some big inch cars run 11's with 3.55 gears.

 

Do you know what the best car would be that has a 9" to swap into mine that would be fairly easy?

 

dont waste the money on the stock rear. it will go to pieces even with good parts if you are hard on it.

 

I promise you will have more in a homebuilt rearend than a Moser housing....between brackets and ends and labor....

 

No.

They all will require major fabrication. Breyer off buying a new one.

 

I have also heard about people using 4th gen rear ends? Are they direct fit? If so, is it worth beefing up or a waste?

 

4th gen still uses the same puny 7.5" ring gear

 

not trying to sound like an a55hole, but this is one of those things...... if you have money to build a 500hp motor, you should be able to save up some money for a rearend to support it.

having said that, you can probably make the stock rear last for a little while with an automatic. i would go have some fun with the car, but be somewhat easy on the rear. keep the 60' times in the 1.6's or slower. pay yourself $100 or so every 2 weeks or so towards a new rear. dont worry about trying to fab one up, its just not worth it. once you get done building one you will wish you had just bought one instead.

 

Thanks man, I think that's what I'll do. And if I make the car more powerful I might just mini tub it in the future. Thanks for everyone helping me out. I'm pretty new to this forum stuff.

 

i agree with diggler whole heartedly. don't spend more money on that 7.5 than you have to to keep it going down the track until you have enough to spend on a pre-fabbed 9".

my car had band-aided 7.5" 10 bolts for a long time. i put a solid pinion spacer in it, and an ebay eaton posi. i always used gm pull out gears (i could get them for almost nothing from ebay) and a set of 89-92 28 spline axles. i had a second rearend that i picked up out of a parts car for zero dollars that i'd swap in whenever i hurt the "good" rearend. once i filled the "good" rearend back up with more ebay parts, i'd swap it back in. the 9" in my car was actually in my dad's racecar. after he quit racing on a regular basis, the car just sat and sat. i had picked up an 89 iroc as a daily driver/rolling project for $1000. shortly after i got that car running well, i traded it to + my "good" 7.5" from my car for my dad's 9".

keep your eyes open on www.racingjunk.com, www.ls1tech.com, www.yellowbullet.com and here for a 9" that someone might be selling. they go for $.50 on the dollar used all the time.

 

quick performance also sells a housing and axle package thats inexpensive and you can source a stock center and posi to get you by. you can find used chunks for as little as 100 bucks, but plan on spending 350-450 for a decent unit. budget rear for about 1500 bucks or less.

 

Look for the 12 bolts as well. Just as strong for what 99% of people out there are doing. Plus the use a bit less power to the wheels and weigh less.
I will run either but prefer a 12 bolt.

 

I prefer the 9" for 2 reasons. The first is given the option I will chose the stronger part every time. I would rather be as reliable as I can make it vs chasing every possible 10th. The second reason is the ability so set up gears in the comfort of my house rather than laying under the car the whole time.

 

i agree with 1320 for the most part. if you are starting from scratch and have the funds, a 9" strange 12 bolt drop out housing is the best of both worlds, IMO.

why do you prefer the 12 bolt? if it wasnt a torque arm car, id go for it.
once you start making power, the case flexes. youll get geasr whine, broken torque arm or driveshaft or all of it before its over. LOL.

 

I have hear of noisy hears in all rears pretty much. But after seein LMR stock suspension run deep 7s in the quarter mile for a long time, I have no reason to run anything but unless it is cheaper. If I find a 9 inch, cheaper or it is all I find, I'll use it. But folks talk about swapping gears easy, sounds good, but I never have to mess with them. I see a 9 inch as a in between, the 12 bolt uses less power and the Dana 60 punks them both in the strength department. So any three are great for us street guys even in you run 7s.

 

Everyone has ther own reasons for using one part over another, use what you like. If I remember right 87_ta went 10s with the 7.5 and a t56. I broke one with a stock 305.

 

if i ran a 12 bolt in my race car, it would have to be one with 3" axle tubes and strange/ford ends. the small tubes with stock gm ends/eliminators suck. i could not keep the one in my 4th gen from leaking. i redid the seals about 4 times, and i think i finally had them sealed up shortly before i sold it.

i still like the 9". super trick parts are plentiful, and i dont think the efficiency is that big of a difference, honestly.

 

Now a stock GM 12 bolt...border line junk.

 

Another issue with the 12 bolt in our car, is some of the aftermarket rear covers and panhard bars will interfere with each other.


Wait, isn't this thread about Matt painting his wheels?

 

Yep. A year ago.

 

lol, yup. looks like i may have found a buyer for the wheels too...which means even more awesome things to come! hello M/T Pro-5 ET's!

 

Ya, I would like to get a set for my car.

 

Matt always has the newest coolest wheels. Lol i just blew my money on shocks and a rack conversion....and my new sfi firesuit....

No cool wheels yet...still 15x7" rears too. Lol

 

Oh yea...and my car came with a 12 bolt so thats what i use.

 

Cannot beat that, I would live to buy a car I did not have to swap the rear in. Putting a 4th gen rear in my 91 RS pretty soon. Mainly because the brakes are better and I will not need spacers for the rear with 4th gen off set. Sure the limited slip works better in a 00 rear than the OE 91.

 

lol, yeah...since i'm a wheel *****, i never have money to go fast, lol

 

But at least you look good doing it!

 

I have a 12-bolt in the camaro. Been 1.1x 60ft on the rear tires for more passes than I can remember, never had any issues with it.

GM housing, moser 35 spline axles/spool, strange solid pinion spacer & billet carrier caps, 9" housing ends.

 

how much does your car weigh again?

 

I considered beefing up a 7.5" when I was planning my 350 build. Once that got bumped up to a 385, the 7.5" idea was out the window. Putting in a 9"

 

Was 3050. - There are a handfull of SS/DR & X275 class cars running 12-bolts as well, more than most realize holding 1.1x 60fts @ 3000+ w/o any issues.

 

9" vs 12 bolt is really splitting hairs when it comes to most cars.

 

Yep, stock for stock 12 vs 9 inch is different, the 12 bolt had casting flaws in the carrier caps and what not that made it not so strong. But aftermarket vs aftermarket, they are pretty close in strength. One uses less power and weighs less and the other weighs a bit more and uses a bit more power. The 9 inch is just a touch stronger. Like I say, not enough for it to make a difference for most of us. People always play the "easy" gear swap card, but the few people I know that have 2 carriers are making so much power that if they break it, they need another for back up, not usually a numerical change.

 

****, do you have any bracing on that rear?

 

All rear end banter aside....the fabricated m9 rears are the coolest looking rears ever. Lol

 

Looks like a part to the death star.

 

Fab housings in general look awesome!

Diggler - Just the typical cross pipe below the housing between the 4-link plates, but mine is only 42" wide to the ends of the tubes.


*I will say there comes a point where I wouldn't want a tq arm attached soley to the housing on a 12-bolt; just not a spot I'd want to add addition stress to. One could do something like I have with the 8.8 swaps & span the load out into the axles tubes to help though.

Lots of people relate the 12-bolt as being problematic with a manual trans, thinking the added stress of the clutch shock + the tq arm is causing deflect. IMO, it mostly comes down to the gears themselves & the set-up. A 9" has a very low pinion height & correspondingly high helix angle. The longer helix makes for a larger tooth contact area(thus the strength of a 9") which means more surface to distribute load through but also means more friction/drag(thus "robbing" more power). With a typical 8620 "street" gear that's set-up to be relatively quiet(as little gear noise as possible), the abrupt shock from a clutch car(especially one on radials) just doesn't hold up as well with the smaller tooth contact on the 12-bolt vs the 9". Once you go to a 9310 "pro" gear, not only is the softer material better at handling shock loads but most people also set the back-lash much tigher as decel gear-whine really doesn't matter in a race car; those two things combined exponential multiple the load handling of either rear.




For note of my crazyness, I am putting a custom tq arm in my car to try vs the full 4-link; simply removing the upper links. Be interesting to see how it works in a 10.5outlaw trim car with the blown combo.

 

Unless they've upgraded their TA mount to prevent side-to-side movement, I wouldn't recommend them if you're using an aftermarket adjustable TA. That's scar tissue talkin'.

Nobody mentioned the Strange S60. Talk about bullet-proof...

 

Branding says that qp offers a side brace now to help stop side to side movement.

 

Yep, ah did.