Fox Thunderbird Rear Control Arm Upgrade and Pinion Angle Check

Originally Posted by bassman97

The latter ones went to IRS, maybe the 88+ is IRS? I'm not really an expert on T-Birds but I know they switched to IRS after the Fox platform.

88s were not IRS. Coil springs with the 4 link kinda rear. Upper and lower control arms. They used a straight axle 8.8 with either 3.55 or 3.73 gears, depending on trans. Im only speaking for turbo coupes here but Im sure the other models used a standard rear for that year. in 89 they changed over to the different body style and started running v6s with superchargers.

Nice article.

I am glad to hear that the Lakewoods only moved the rear forward 1/4 inch.

If someone uses a Southside type lower bar (commonly refered to as "lift bars") from a Mustang on a Fox T-Bird, it lowers the attachment bolt centerline further away from the centerline of the axle. This geometry in conjuction with a Mustang shorter control arm has the effect of moving the rear forward more than say the 1/4 to 3/8 inch difference in arm length.

I have owned over 24 of the 83-88 T-Birds and all of the lower arms are the same length including 87-88 Turbo Coupes. (of which I have owned 17 of those)

The pic above with the TRX wheels is my 87 TC with Southsides and yes I measured before and after and the Southsides moved the rear forward exactly 1.0 inch. Did the same thing on our 83 460 Gray Bird as seen in the pic.
Just informing of my experiences.

Also, we run our T-Birds pinion angle at 2 degree down as well....

Here is a couple of pics of the Birds after I "fixed" the problem with a little streching of the Southsides: