Hi Topher,
Some questions/observations:
1.) Is the 8.8" Ford rear stronger than the 8.5" GM rear? And if so, how is that known?
2.) You mention that the rear was a bolt-in swap, but you seem to have CA's with spherical races. The UCA's for example, don't form a 90-degree included angle as they do in the GM configuration, but (eyeballing your pictures,) maybe only 60 degrees (which reduces lateral stiffness location for the rear, incidentally.) There are similar uncertainties about the LCA's. In short, if someone has OEM bushings or simply bushings without spherical races, this doesn't look like a bolt-in swap. Also, the suspension geometry is changed in ways which may or may not improve handling - for example, what about pinion angle, rear roll center height, and anti-squat behavior?
3.) Related to (2.,) how is the fore-aft position of the rear relative to the chassis changed? (I supect it gets displaced aft.)
4.) What is the compatibility of the Ford disc brakes with the GM brake system?
5.) You already mentioned the incompatibility of the bolt circle pattern between Ford and GM.
6.) You already mentioned the difference in width between the two rears.
7.) How does the weight of this rear compare with the 8.5" GM, aside from the brakes proper? This Ford unit looks heavier.
8.) What is the vertical pinion offset of this rear relative to the 8.5" GM unit?
9.) What is the lateral pinion offset of this rear relative to the 8.5" GM unit? Or better, where does the lateral location of the center of the pinion yoke U-joint fall upon installing this unit into the car, relative to the GM rear?
The conclusion I get is that this is hardly a bolt-in swap (although not trying to knock your efforts by any means, Topher! It looks like you did a great job.) On the face of things, this seems like a lot of trouble to go through for an improvement in strength, presumably. Speaking for myself, this difference would have to be very large to merit correcting all of the other differences between the two rears.
Best,
MAP
Wow thats alot of questions. I will try to answer them all.
1) car originally had a 7.5 as it was not a turbo car
2) the 8.8 has been deep into the nines in 3-3300 lb mustangs
3) a good 8.5 costs between 750-900 same for a 12 bolt
4) 8.8 has same size ring gear and pinion as a 12 bolt
5) I hate seeing turbo cars cannibalized for their rear ends there scarce already
6) The arms are from TRZ motorsports and are the same double adjustable arms as they sell for g bodys
7) the lca attaching points an the rear are 1" wider per side creating an angle less than 90deg which will triangulate the rear suspension (increasing strength and lateral stability)
8)most 4 link setups are triangulated esp in a performance app anyway
9) the arms can move the wheel position fore or aft which can give clearance for larger tires near the front of the wheel opening (where it sometimes gets tight)
10)also lengthening or shortening the lca WILL change instant center so lift can be added or taken away from the front of the car
11) also pinion angle can be adjusted
12) I was concerned about the pinion offset on this rear before I installed it but found it to be identical with the 7.5 I removed
13) Brake lines actually bolted right up to stock t-block
14)parking brake took a bit of work
15) TRZ sells this kit and has done the R&D on it already in fact it has been used on many cars before mine You could visit their website trzmotorsports.com
they have a stock style suspension g-body (a pink bu I think) running 8.18 with a strangely similar setup (not sure what diff but arms are the same)
16) I just did my own R&D to make sure the vehicle will function properly
17) If your going to buy uppers and lowers anyway why not get ones that allow adjustability of the suspension rather than hoping the standard arms you get will achieve desired affects (unless possibly someone is intimidated by 4-link suspension tuning)
18) the wider rear also allows for more wheel options since a different bs will be used (a plus in my book)
I hope I answered all your questions. Believe me I did plenty of research before and during this swap and it is extremely well designed and laid out.
I realized I forgot to post a link to the other thread with all the info (including prices) so here it is
My G-Body 8.8 Rear End swap complete w/pics