I plan on doing the SAS on my f-150 (1991) and i was wondering what would be the maximum tire size on the 8.8? The rear end has a welded diff, its on 33s and see's a lot of street duty.

SVT ran 37s and a welded diff for some time with 3.55

it broke the spiders / case into a lot of peices

then he had 4.88s and a welded diff and 38.5s

same thing

the factory case is very thin ( for a LS diff ) near the ring gear so it will distort and break - we tried an open diff to - it was thicker but broke in the same place - the shafts are the same size as a factory 9" 31 spline -

now he has a built 9" 39.5s














and he did it with a SIX cylinder :flipoff2:

SVT ran 37s and a welded diff for some time with 3.55

it broke the spiders / case into a lot of peices

then he had 4.88s and a welded diff and 38.5s

same thing

the factory case is very thin ( for a LS diff ) near the ring gear so it will distort and break - we tried an open diff to - it was thicker but broke in the same place - the shafts are the same size as a factory 9" 31 spline -

now he has a built 9" 39.5s














and he did it with a SIX cylinder :flipoff2:

yes, i did. And, the thought of knowing there is a 1.5" C clip holding in my tires didnt make me very happy. I would run a detroit if i did it again and had to keep the 8.8, but i should have done the 9" swap the first time it shattered...

The idea I don't like about the 8.8 is how thin the housing is. The thickest truck 8.8 housing is .188" wall tubing while all truck 9's are .25". That adds up to 1/8" less material and it does tremendously effect the strength of the housing in shear and in bending as compared to the 9". I ran the numbers awhile ago, I'll see if I can dig them up, if not I'll just run them again.

Then you have the pressed in tubes and rosette welds. I got rid of my first 8.8 when my truck was still a 4x2 since I twisted one of the tubes with a 300, NP435, 3.08's, and 235/75-15's on a hard launch (got some wheel hop and then hooked solid on tar and chip)

Weak housing, weak centerpin/carrier, and c-clips....FUCK THAT.