Bite the bullet or modify?

[Ugly1]

So I’ve had a spare 8.8 housing since June. Plan was to modify it with 9 inch ends, narrow it to G-body width, brace it, and upgrade to 31 spline axles.
BS’ing with my foreman, he brought up just stabbing a 9 inch in it, and after some math, I arrived at these numbers for cost:

Modified 8.8: around $2,500 depending on parts
9 Inch: $2,600 to $3,000 depending on center section

I’ve got a local shop that can narrow the 8.8, so that doesn’t need shipped. But with prices so close, is it just worth it to drop the 9 in it? The car’s intended use is more of a universal setup until I figure out what I like more, so that’ll be mainly many street miles, auto x, possibly some road course, and drag strip time. I’m not running a huge amount of power currently, but that’ll change in the future.

If they can do the 8.8 they should be able to do the 9”.

 

[gnvair]

what upper and lower arms are you running ?

I run Spohn adjustable uppers for the 64-72 A body....they are shorter and I needed the shorter arm to get the pinion down. The G body adjustable uppers would only go to 0.
Lowers are UMI for G body.
You can run any brand adjustable uppers for the 64-72. I just chose Spohn.
I also run the Del Sphere/Roto Joints.

 

[nycutlass]

I run Spohn adjustable uppers for the 64-72 A body....they are shorter and I needed the shorter arm to get the pinion down. The G body adjustable uppers would only go to 0.
Lowers are UMI for G body.
You can run any brand adjustable uppers for the 64-72. I just chose Spohn.
I also run the Del Sphere/Roto Joints.

good to know if anyone wants to do that.

 

[UC645]

I run an 8.8 and have many reasons including all the years I spent setting them up at a shop I worked for. The 8.8 can do anything a Chevy 12 bolt can do as well as most of the things a 9" can do. I agree that any conventional differential on a 9" is going to be inferior because of the smaller gear sizing of the spiders and side gears.
The 8.8 is fairly light weight. Brand new OEM parts can be had cheap....I paid a little over $200 for the 31 spline Cobra Trac Lock and new Ford ring and pinion sets are way under $200 if you look on Ebay. Carrier and pinion bearings and shims are super easy to get and are shared with the 12 bolt Chevy.
My housing was from a 95 Crown Vic as I prefer the upper control arm ear angles better than the Mustang housings. It's been narrowed and has the Moser FM7900 housing ends that use the Ford 9" bearings. It's a street car that is driven on radials so it leads a pretty easy life and my engine is under 600 rwhp.
Realistically I could have probably saved myself a bunch of time and money and just kept my built 7.5
After doing it once I could easily duplicate it again.

That was another rear I was considering after doing some digging. The only issues were the upper housing ears take a larger bushing than the G-body 7.5 and the 8.8, and finding one.

If they can do the 8.8 they should be able to do the 9”.

I had asked about them relocating the lower arms on the 8.8, and they said they needed the car in the shop to do it. Likely to end up with enough money in labor to make it more expensive than a 9 inch doing that.

 

[Ugly1]

That was another rear I was considering after doing some digging. The only issues were the upper housing ears take a larger bushing than the G-body 7.5 and the 8.8, and finding one.

I had asked about them relocating the lower arms on the 8.8, and they said they needed the car in the shop to do it. Likely to end up with enough money in labor to make it more expensive than a 9 inch doing that.

For all the fun a 12 bolt posi from a 68’-72 A-body is almost worth the time and money. Is a near bolt in and same rims fit.

 

[565bbchevy]

For all the fun a 12 bolt posi from a 68’-72 A-body is almost worth the time and money. Is a near bolt in and same rims fit.

The problem with that is they are also 4.5" wider which pushes those rims out 2.25" on each side which means you are probably buying new rims to fit correctly plus the need for conversion control arms to fit the 12 bolt in a Gbody.

 

[Ugly1]

The problem with that is they are also 4.5" wider which pushes those rims out 2.25" on each side which means you are probably buying new rims to fit correctly plus the need for conversion control arms to fit the 12 bolt in a Gbody.

Only the upper arms need an adjustable set. And unless doing a lowering kit is not really much and won’t rub. Will allow for wider tires to tuck in there? I never even noticed the problem with mine other than the adjustable upper control arms would have centered it , but the where not available to my knowledge in the late 80’s early 90’s

 

[gnvair]

That was another rear I was considering after doing some digging. The only issues were the upper housing ears take a larger bushing than the G-body 7.5 and the 8.8, and finding one.

I had asked about them relocating the lower arms on the 8.8, and they said they needed the car in the shop to do it. Likely to end up with enough money in labor to make it more expensive than a 9 inch doing that.

Use the Crown Vic bushing and bolt. Drill the hole in the upper control arm bigger. It's easy and not an issue. If you want to run a rotojoint you would have to make a sleeve like I did.
Personally, I'd send the housing to Quick Performance and let them do the flanges and control arm brackets and spring perches (if you are running stock type springs). They do great work that is VERY reasonably priced and can set you up with matching axles. That's what I did. I have no regrets.

 

[565bbchevy]

Only the upper arms need an adjustable set. And unless doing a lowering kit is not really much and won’t rub. Will allow for wider tires to tuck in there? I never even noticed the problem with mine other than the adjustable upper control arms would have centered it , but the where not available to my knowledge in the late 80’s early 90’s

I believe SSM was the first to make control arms for this swap probably somewhere in the 90's but I don't think they were adjustable. If you are already running a decent size tire in the rear adding 2.25" of width per side is going to be a problem with them sticking out of the wheel well, for me I don't even like the sidewall sticking out

 

[nycutlass]

the more i read what everyone is writing the more i know i made the right decision, in getting my custom ford 9. fits perfect done once done for good with any power plant and i bet cheaper in the long run.