Building a 7.5"

[DSM]

I am wanting to build my 7.5" that is currently in my Regal and I am looking for a good outlet for parts.
-aftermarket axles
-posi unit
-3.42 ratio ring/pinion
-installation kit
I priced out the parts through summit and I would be looking at like $1000 :shock: Have any of you built a 7.5" with aftermarket parts and what did you end up spending? Is it necessary to do the C-clip eliminator kit?
I don't really want to use anything that is used

The two most important things you need are a solid pinion spacer and a cover with a girdle, followed closely by 28 spline axles. My rear end guy also strongly suggested ARP fasteners for the ring gear. Here is how my 7.5" axle is built:

solid pinion spacer - Ratech 4111 $16.95 (Summit)
Diff cover w/girdle - Jegs $150
3.42 R&P - Moser - $160
28 spline axles - Moser - $225
extra long metric wheel studs - Moser - $15
Torsen diff - 98 Firebird take-out $100 (it was a new take-out from SLP back when they were still avail)
axle outer bearings BCA5707 - $26 Rock Auto
axle seals BCA/National 8660S $4 Rock Auto
differential bearing kit BCARA320 $77 Rock Auto
ARP ring gear bolts 230-3002 $77 Summit
Labor $175
TOTAL: $1026

Disclaimer: I have an 8.5 in my G-body!

The axle above is in an 84 Camaro that has a TPI 350, manual trans, and puts 365 ft-lbs to the tires (which is about 430 ft-lbs at the crank.) I use it mainly for open track and autocross (with a 295/35-18 BFG KD) but it also sees the dragstrip with 255/60-15 drag radials. I'm not looking to get involved in the strength debate, just offering a data point for what a properly built 7.5 axle will cost you. No, it's not cheap. Yes, it will survive a pretty fair amount of abuse. The stock axle in this Camaro (with 3.73 gears, no girdle, and 26 spline axles) survived 20 years of drag racing, autocrossing, and street abuse, and the 350 has been in the car for 15 of those years. Yes, it broke eventually (sheared 3 teeth off the ring gear). I built it as described above 5 years ago and it's been bulletproof so far and I have no worries that it will take whatever I throw at it.

 

[79malibu]

Since your using new parts you might as well upgrade to 28 spline axles IMO. A little bit stronger i would imagine. I am using a Zexel Torsen LSD out of a 02 Camaro SS and used 28 Grand National axles. I scored the whole Camaro SS axle with Summit Girdle for a good price a while back. As for the eliminators i have heard they leak oil if used for street duty but i haven't any experiance with it. When i rebuild mine i'm using the above mentioned parts along with a Strange rebuild kit.."Thanks BeerMonkey!" Solid crush sleeve, and welding the axle tubes to the housing. I will be using the original 3.73 gears to save some $$. If I add everything i think i will have under 600 after the welding and gear set-up. And it will be as strong as it could ever be... :lol:

how did you weld the tubes to the cast iron center section? like a nickel rod? i am looking to do this just for added insurance but i don't wanna screw it up and have sh*t cracked or go inside the diff!? anyone have any pics of this or done it that can help out?

 

[dogsht]

Great post DSM

 

[85GPLef41]

how did you weld the tubes to the cast iron center section? like a nickel rod? i am looking to do this just for added insurance but i don't wanna screw it up and have sh*t cracked or go inside the diff!? anyone have any pics of this or done it that can help out?[/quote]

I haven't gotten around to start my rebuild..But for the welding i was going to ask a buddy who is a welder to do it for me. I have seen the mod done on a few rearends though it didn't dawn on me to ask how it was done. I will ask my buddy and see what he recommends.

 

[86Cutlass383SR]

Here's the way I tend to look at things. This is for a street application. On a working man's budget.

I have a car with a stock 7.5/7.625 rearend and a beefed engine/transmission and I want my rear end to hold up to my newly built power. My current rearend is chattering and won't hold up much longer, or, it won't move when I put it in gear.

Not included in the price is an installation kit, new bearing and seals, and gear setup by a professional who knows how to set these up correctly. I need a set of gears. Ratio doesn't matter much as they are close enough in cost in each rearend family. I need a posi diffential carrier. And lastly, I need a set of beefier axles. Looking quickly thru SummitRacing.com, most posi differential carriers are in the $400 - $500 range, gears are in the $150 - $200 range.

My options are:

(Re)Build my 7.5/7.625. I already own the housing or I can pick one up for next to free.

Build an 8.5 rearend. Since my car came with the *lowly* 7.5 I need an 8.5 in housing. I'm not bolting in a rearend into my car of unknown condition. I have bad luck and the only 8.5 I find needs a total rebuild. Great! :shock: I've just paid $600 - $800 for a rearend that I get to put in the same new gears, posi, and axles. You may luck out and find a rebuilt 8.5 that is ready to go for $1000. It is stronger than that 7.5 but, if I'm going to upgrade, I can get even more strength for about the same cost or just a bit more.

Build or buy a 12 bolt or 9" Ford. The Ford housing is cheaper than the 12 bolt housing but remember to add the extra cost of the center section to hold the differential into the housing if it's needed.