4:10 or 4:30 gears for me

[82 GT]

Originally posted by Ieatcamaros
I don't use any of the formulas online, I have my own. I have it on a spreadsheet if anyone is interested in it. I got 100 rpm difference in what crazypete posted. At 65, I got 3495. At 75, I got 4032 RPM. Not enough difference to matter, but it is the sole reason I use my own formula. Your rpm's at 68 mph(65-70) with a 4.10 gear is 3656. If you want to drive the car on the street but optimize at the track, I would go with 4.10's since you are going to be putting in an 8.8 anyway. Me, I would put 4.30's in and trailer it to the track. You got your 88gt for the street. IMO, your only other option (besides the high rpm's on the highway) would be to get a 4.56'd 8.8 and put a lentech aod in. That would be the SH1T!

I went to the analyzer on here and used the TOP SPEED calculator to find my rpm/mph but I only used the 4th gear column since that is a 1:1 ratio I need for my C-4 calculations.

With a 4:10 gear and 25.6" tire(225/60) I would be at 3500rpm at 65mph and I would be at 111mph in 3rd at 6000 which is my shift point.
With a 4:30 gear and same tires I would be at 3700 at 65 and 106 at 6000 in 3rd gear.
Using a 26' slick is only 200rpms less.

Ok, here is what I discovered which kind of changes things a bit for me.
Judging from that calculator, I don't have 3:73 gears like I thought I had or was told I had at one time. Instead, I have 3:27 gears!!
My best time on street tires is 13.78 at 105mph with traction problems.
When I get slicks, that's only going to get better. So I guess I need either 3:73's or 4:10's