Overdrive

[tirebird]

I'm planning on taking the Tirebird to several events next year(POCO Convention, Hot Rod Power Tour, etc.) and want to make it more highway, high speed friendly. It has a Turbo 400 with 3:42 gears that translates into roughly 2700-3000 rpm at 75 mph.

So, I think I have three options besides driving a lot slower. Option #1 is buy a Gear Vendors unit for about 3k installed. Option #2 is to drop in a modified 700R. Option #3, the least expensive, is to change the differential to 3:23's or even 3:08's. With option #3 I'll obviously lose some performance but with an LS6 under the hood, it would be difficult to notice except in racing circumstances.

So what do you guys think? What would you do in my circumstance?

[Seattle Sam]

I would go with a built 200-4R, with a lockup convertor. THe 200 fits in the same space as a Turbo 350, while the 700R4 requires a shorter drive shaft and you also will need to move the trans cross member back. On my 65 Chevelle I also had to beat the trans tunnel to get the 700R4 to fit.

You can wire the lock-up convertor to turn on with a switch, and have it kick off from the brake switch. Yank makes a nice lock-up convertor that can handle torque.

JMHO
-Sam

[COPO]

I think the gear vendors overdrive may also require some work to the tunnel to fit in the F-body's.

[tirebird]

COPO you may be correct. I'm going to call gear vendors and check with them. I think that is my first choice since I recently rebuilt the TH400 with heavy duty race parts and would hate to pull it out. A local differential shop suggested I swap out the 3:42's for 2:73's. He said it would drop my rpm by over 500 and not hurt the performance that much. I'm unsure even with a torque monster LS6.

[WILMASBOYL78]

If you can swing the GV unit that is the way to go! In fact you should consider moving up to a 3.55 or 3.73 and then add the GV. You will have the best of both worlds....power and cruising comfort.I have the GV in my 68 with th400 and 4.10, 427 BB, the overdrive works great!


wilma