8.8 specs for a 79 Monte

[pontiacgp]

7.5's have been know to survive abuse with a few upgrades..

84 elcamino , 464 Big block buick, th400 w stg 3 kit , 9" 3300 stall , 275 M/T drag radials, 3.42 7.5 posi . 11.80's in the 1/4 . Goin on 4 yrs now. Just build ya a cheap 7.5 .

 

[richp85elco]

richp-I completely agree with you when you say you know what you're getting when you rebuild a 7.5 for the same price as a shot-in-the-dark 8.5. That's why I was originally tempted to rebuild my current rear, especially since my LS1 isn't going to be a beast; thanks for the rebuild run-down. However, you said the used 8.5 and a rebuilt 7.5 would be close to the same price. By the same token, for close to or less than that price, albeit with slightly more guess work, I'd have an 8.8. To me, it's a good compromise in the long run, especially if I win the lottery and decide to go crazy with HP upgrades. While I have no intentions of doing that right now, a 7.5 would nonetheless limit my options. Plus, it sounds like an interesting challenge.

jrm-Awesome info. I was talking to one of my Marines that's got a few fox bodies and a lightning and that was his recommendation as well. I will admit, his expertise with Fords is definitely a factor for me in this swap. I know he'll be able to help me out on sourcing and rebuilding a rear if necessary. I'll probably use the baseline kit for the control arms, since I'm upgrading the suspension anyways, so it's almost a sunk cost. Any idea when you're planning on doing the swap?

yea buddy i was defending your reasoning for not wanting a shot in the dark 8.5, but to clear things up by no means am I saying you have to do all the upgrades I suggested for it to survive behind your current powerplant. Those upgrades are for something like pontiac gp just posted a car that will see some real abuse.

for what your planning on, if you dont have a posi in there already just find a stock one in the junk yard ($100) set it up correctly and your good to go for a alittle more security get the girdle($130) and weld the axle tubes ($50) for less than $300 it will be solid, no messing with geometry, suspension brakes, etc.

if you upgrade in the future then you can do the upgrades i mentioned so there is your room to grow. But i understand your reasoning behind the 8.8 its always good to have help and if you choice that route i admire your innovativness..Good luck!

 

[jrm81bu]

jrm-Awesome info. I was talking to one of my Marines that's got a few fox bodies and a lightning and that was his recommendation as well. I will admit, his expertise with Fords is definitely a factor for me in this swap. I know he'll be able to help me out on sourcing and rebuilding a rear if necessary. I'll probably use the baseline kit for the control arms, since I'm upgrading the suspension anyways, so it's almost a sunk cost. Any idea when you're planning on doing the swap?

It should help to have some Ford guys on your side. I may end up with the Baseline kit or maybe something homemade eventually, but I want to get it in and running then see what traction issues arise. I had hoped to do it this summer but it looks like it won't be until at least spring time now.

 

[tntracecars]

we use the 8.8 out of ford explorers. the axle is 59 1/2" wide. comes with 31 spline axles. disc brakes with emergency brakes. only comes in 3:55, 3:73 or 4:10 gearing. check the rearend tag for a "l" between the gear ratio on the 3:73 and 4:10 will have tracion loc "posi". if using a 8.8 rearend with bigger HP engines, be sure to weld the axle tubes to the center housing. they are only plug welded from the factory. if you prefer the 9" ford rearend, you can get one with axles (no center section) for $750 from rearend vendors.

 

[79CMC]

tntracecars: Thanks for the info-that's exactly what I was looking for. Which year ford explorers? What do you do for control arms? Any modding required to the driveshaft?

 

[hurst1979olds]

I planned on doing this swap as well. But I think I'm going to keep my GM car all GM. But I did buy a 3.73 posi gears and carrier off a guy that I dont need anymore. It has less than 5,000 miles on it. Its a Ford Racing carrier and Ford Racing gears. Let me know if interested. All it need is new pinion bearing.....The guy over preloaded it and wiped out the bearing and just replaced everything new. PM me if interested.

 

[Bar50]

Well, the cheap way out on the 7.5 is to use the aforementioned 28 spline posi unit from an F-body car '93 and later. Axles from a GN, 28 spline, spring for Mosers or Yukons or what you prefer. Most of the time the F-body donor will have a good driver gear ratio like 3.23-3.42-3.73. The donor may also have discs if you want them...

I ran one hard for three years in a slicked up bracket car mid to low 11's with a used posi unit from the salvage yard. The posi broke, they are not rebuild-able. I have bought used take outs from GN guys in the past, you just gotta search the turbo forum classifieds or post a 'want to buy' ad...

By the way, the 8.8, 8.5, and 7.5 are all c-clip axles. If you go 8.8 (I picked on up for my BBC grudge/street race car) I am going with the Baseline Suspension kit. I am going with a bolt in axle swap upgrade, and the new axles come with whatever bolt pattern you want. Mine is a disc 5 lug, and a guy at work has a quick Fox car and wants the axles to make his five lug so that eased the pain of new axles.


If its a driver, weekend warrior without slicks, I'd use the 7.5, uh, they came in LS1 cars, right? With the bigger axle that all the 7.5's went to in '88 or so.

hurst1979olds,

How much for the 3.73 set up?