w/r toploader and 2.88

[cobra_dude]

Hi guys

How would a kirkham 427 drive with s/o stroker and 275/60/15 BF Goodrich tyres using a wide ratio top loader and a 2.88 diff.
I dont want to be changing gear all the time and but would still like loads of acceleration. Other ratios i have considered are 3.07 or a 3.31, may be a 3.07 would be a good balance between the 2.88 and 3.31. How many mph/1000 would i be getting with these ratios? thanks

[Bob Putnam]

According to my calculations, you'll have roughly 10.4 mph/1000 rpm in first gear - 62 mph at 6000 rpm. The original street car was geared to about 8.7 mph/1000 rpm (wide ratio w/ 3.31 dif) so you're about 15% higher. That'll be partially compensated for by your extra 5% displacement.

It's a bit high for smooth stop-and-go driving but with the stroker, starting torque shouldn't be a problem. Just make sure that your engine is happy under 2000 rpm.

[decooney]

cobra_dude,

here is my thought on it. I had 3.08s in my last car and 3.31s in my current car with a wide-ratio TL; however my rear tires were shorter than yours. If you plan on driving around town, and less on the freeway most of the time, I would say 2.88s are going to be a wee bit too tall and especially with those 275s on back. Taking off from a stop will be noticeable, even with a stroker. I really like my 3.31s now, and my tires are shorter than yours. 3.08s are great if you spend more than 1/2 your time on the freeway for sustained speeds... your cam has a bit to do with it too, as I noticed between three different cam changes. The bigger cams sure like the deeper gears, and fight back a bit at the tall ones during takeoff; even in a 2500lb car. It really comes down to what you will do with the car and what you expect given different situations. Good Luck.

[Anthony]

A w/r toploader ( 2.78 first) with a 3.07 rear would be comparable to using a c/r toploader (2.32 first) with a 3.68 rear. So, I think it would be OK, fine. With 2.88 rears, it would be comparable to using 3.45's with a c/r toploader. I think the original cobra's equipped with c/r toploaders came with 3.54 rears, and sometimes 3.73's.

One thing to consider is that with the 3.07 gears, I think you are still using the same dif carrier as used in higher number ratio's, so if you ever in the future wanted to put in 3.31's, 3.54's, 3.73's, etc, you only have to replace the gears. I think the 2.88's require a different carrier, so if you want to cahnge to other gears in the future, you may have to replace the carrier as well as the gears.

[Cal Metal]

Anthony:

The 289 Cobras came with Borg Warner T-10 not Toploaders. There was a difference between the Chev and the Ford ratios, despite the fact that they both used the T-10; but I don't think that the w/r Ford T-10 or the c/r Ford T-10 had the same ratios as the Toploader.