Spf with BBF, tremec, and 3.73 rears.

Anthony · #1 (**permalink**) 05-23-2005, 09:32 PM

I'm thinking about doing some gear/tranny changing, and I was wondering if someone could tell me how hard/easy is it to start out using second gear, not first, with a BBF, tremec ( TKO / 600 ) , and 3.73 rears, as I think many Spf's come with 3.73 rears ?

terry251 · #2 (**permalink**) 05-23-2005, 10:03 PM

Anthony, as a new guy in a 418W SPF, I can tell you there have been more than a few occasions when I inadvertantly started off in 3rd!! It is pretty obvious in a few feet that the "oops" is on me, a few more revs and away we go. Not really a problem. I've talked to quite a few drag racers that use 2nd as a start line gear all the time. In roadracing, 1st gear is for real slow corners and pit work. Your BBF has pleanty of torque...why not consider a change to a higher rear end ratio (3.23?) instead of doing away with 1st?

Terry

Anthony · #3 (**permalink**) 05-24-2005, 03:49 PM

Terry, I'm currently running a wide ratio toploader, 2.78 1st, and a 3.07 rear. Runnning the car on the track, the gears are just a tad too wide spaced I think, and I'm tinking on changing to a close ratio TL , 2.32 1st, and keeping the 3.07 rear. I figured that even with the 3.07 rear, I'd still be OK with this set up. 1st gear ratio with this set-up woild be similar to a car with a 3.73 rear, and a tremec tranny starting out in 2nd gear. The 3.07 rear is good for cruising.

I was just trying to find out if it seemed OK witrh this gear set-up / ratio for starting out from a stop, before I made the purchase / change.

Thanks.

terry251 · #4 (**permalink**) 05-24-2005, 05:26 PM

Anthony, got the concept now! I think you will be fine with the slections you are contemplating, especially the top gear cruising in a relaxed mode. I have the .65 5th gear in my Tremec; great on the highway, but a bit of a hole from 45 to 70 mph.

Good luck!

Terry

DonC · #5 (**permalink**) 05-24-2005, 05:50 PM

Anthony:
My TKO w/0.82 fifth and 3.07 rears with 17" rims gives me 22-23 hundred turns @ 70 MPH on my 450CI 428. Good cruising numbers if you're into cruising. Bottom end will still break it loose in 1st and 2nd coming up through the gears if I lean on it.
Depends what you want to do with the car. The 600 ratios are a little far apart for the ultimate in road race gears but doable.
DonC

Anthony · #6 (**permalink**) 05-24-2005, 06:41 PM

Don,

Yeah. The wide ratio TL is a little too wide for me, but you can still have alot of fun on the track, and I bet the times are not much slower with the wide ratio trans, but when you come out of a turn, accelerate, and shift, it just seems like the split is a tad too wide, but hey, what do I know, just an amateur wannabe racer.

I get about 27-2800 rpm's @ 70 mph, although I do most of my cruising on local roads, 45-50 mph, with an occasional highway cruise.

I think you picked the perfect rear ratio, the 3.07, for your set-up, that is using the TKO600. The only other ratio I would consider using would be a 2.88.

Terry, with the close ratio TL, 1st is 2.32, and with a 3.07 rear, 1st gear multiplication is 2.32 x 3.07 = 7.12, overall gear multiplication. With a tremec, 2nd gear is 1.98, and with a 3.73 rear, 2nd gear multiplication is 1.98 x 3.73 = 7.39, and with the TKO600 with 1.89 2nd, 2nd gear multiplication is 7.05 . A little tall, but I don't think it would be a problem.

I think I'm going to give it a try. Maybe this fall or next year.

Thanks.