Vintage Mustang Forums banner
1 - 2 of 2 Posts

Discussion Starter · #1 ·
I put a new T-5 (from NPD, 3.35 first gear) in last fall, and changed from a 2.8 to 3.55 rear at the same time. I followed the formula in NPD and ordered a 21 tooth driven gear. I'm still reading about 20% high. I understood that the driven gears were interchangeable from C4 to T-5. Is that incorrect? Do I need to get a T-5 gear from the dealer? Or do I need to tear apart the T-5 and put a new drive gear on the tailshaft (no, no NO...)?

Gene Zierdt
'65 Conv.
302/roller cam/valves/ported
T-5 w/3.55
negative roll, progressive front, 4 1/2 rear springs
Front & rear anti-sway bars

2,176 Posts
I have a 23 tooth in my 1990 T-5, i also have 3.55 rear gears. The speedo seems pretty close? The gear
was bought at a local Jeep dealer Part #J3167393. Seems the jeeps have lower gears! Fit's right on the speedo cable...

1966 Mustang Coupe, 302 custom roller cam, holley 650dp,
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.