With a 700R4 (2500 stall, shifting at 6k when racing) and a 26" tall tire, what would be the best gears to go with for the rear end...
Im currently in the TH350 w/ 2.73 open category, but looking to change it.
Car is not a daily driver, but does get a lot of cruise/track miles.
I was thinking 4.11s, but would a higher (numerically) gear hurt me? I know the first gear in a 700r4 is really short to begin with, and going with the shorter gear would make first gear next to nothing.
Anyone like to chime in on this?

I would go with 3.55's
You don't need 4.11's with a 700R4

Especially considering the 26" rear tires - first gear will be useless.

Dan

Especially considering the 26" rear tires - first gear will be useless.

Dan

Its not useless....you could pull stumps out for people. LOL

double post

I had 3.42's with my 200-4R, and swapped to 4.11's. While I can't say the car ET's any quicker, first gear is not "useless" or whatever. With 225-60R15 street radials, the overdrive and lockup converter make a nice street package with the 4.11's. At the track, I use a 26" tire, 26X10.5X15 ET Streets, and it all works fine. I also use a 2500 stall. I cross the finish line at 98-99mph and about 5700rpm.

Bottom line, for street driving I liked the 3.42's a little better, but for the track I like the 4.11's a little better.

But I think 1st gear in a 200-4R is 2.75, and in a 700R4 I think 1st is something like 3.06, so yeah, maybe 4.11 would be overkill. Maybe a 3.73 gear would be a good compromise.

I have a 700 w/ 4:10's. A little much for normal crusing, your out of first real quick. But on the track I like it. Pulls real hard in first and I shift right under 6 as well. I'm not to experienced at the track so I don't know if the 4:10s are hurting or helping me. However 4:10's with the 700's 3.06 first gear can make for some traction problems on a street car. In my combo I ease into the throttle to avoid spinning, makes for crappy 60 ft times, in a car thats at best a mid 13 sec street car.

My car is a driver so if I were to do it again I would opt for 3.73's

With a 700R4 (2500 stall, shifting at 6k when racing) and a 26" tall tire, what would be the best gears to go with for the rear end...
Im currently in the TH350 w/ 2.73 open category, but looking to change it.
Car is not a daily driver, but does get a lot of cruise/track miles.
I was thinking 4.11s, but would a higher (numerically) gear hurt me? I know the first gear in a 700r4 is really short to begin with, and going with the shorter gear would make first gear next to nothing.
Anyone like to chime in on this?
I have a 700R4 in my 65. I also used 26 inch tires and shifted at 6000 RPM. The rear end is a 4:11. The one differance is that I had a 3000 lock-up converter. I wouldn't reccommend anything less than that. One thing I would caution you about is that I was forced to full throttle shift into 4th gear before going through the traps. (which required some modification by my trans guy) Ideally a 28 inch tire would help that situation a lot. The 1st gear in the 700R is a short gear, but the 4:11's are not too short. I have been able to launch with 1.5 and 1.6 60 ft times on a track that is far from prepped.
I have now just re-built my 383 and should be firing it up for the 1st time today. I plan to race tomorrow night so I'll post my results. I will be on the 26 inch Hoosier QTP's for the race, but now that I have a solid roller and race valvetrain I'll be shifting at around 7500 RPM. I have also changed to a 4500 RPM lock-up converter. I am going to try and get over and chassis dyno the car this afternoon as well. The old motor was about 425 HP... I am hoping the new is close to 600. I know I rambled a bit, but I hope this helps.

Bottom line: I think the Ideal setup for an engine only turning up to 5500-6000 RPM is a 700R with 4:11 gears and a 28 inch tire. You get great driveability with a great race setup when you want it.

Steve

on a 700-R4 1st gear is 3.06:1

on a 200-4R 1st gear is 2.75:1

On a TH350 (or TH400) 1st gear is 2.52:1

You need to take this into consideration when picking your rear end gears. If you are shooting for a 10:1 ratio on launch you need the following rear end gears for these transmissions.

For a 700-R4 you would need a 3.42 gear. This makes a 10.46:1 "launch" gear ratio

For a 200-4R you would need a 3.73 gear. This makes a 10.25:1 "launch" gear ratio

For a TH350 you would need a 4.11 gear. This makes a 10.35:1 "launch" gear ratio

A "launch" gear ratio in the 10:1 range is very good and typically pretty safe for most street-size tire combos (say 26-28" tall). When you start getting into back halved cars and bigger (taller, like 29-31") tires you will want more gear ratio and the bigger tires will help get it to the ground.

Thanks guys, that was quite the array of answers...
I think the 4.11s are sounding about right in my book. The track i race at is professionally prepped (Gateway International), and I will be street driving on M/T ET streets, so we will see how this lil 400hp small block likes it...

Bottom line: I think the Ideal setup for an engine only turning up to 5500-6000 RPM is a 700R with 4:11 gears and a 28 inch tire. You get great driveability with a great race setup when you want it.
Steve

I've got a '72 with a 400 hp/413 lbs-ft 350, 700R4 @2500-2800 stall, 8.5" w/4.11s and 275/60R15 tires, SSM upper and lower bars, Delco shocks.

I have only put on about 200 miles since the gears and SSM bars went in. I can say that I still have some tire spin in 1st, but the raods here aren't the best, so I haven't gotten a chance for a real good street launch.
Cruising is pretty nice, acceleration at 65 to pass does not require the 4bbls, and maxing out the speedo doesn't require 4th gear either.

I've got a '72 with a 400 hp/413 lbs-ft 350, 700R4 @2500-2800 stall, 8.5" w/4.11s and 275/60R15 tires, SSM upper and lower bars, Delco shocks.

I have only put on about 200 miles since the gears and SSM bars went in. I can say that I still have some tire spin in 1st, but the raods here aren't the best, so I haven't gotten a chance for a real good street launch.
Cruising is pretty nice, acceleration at 65 to pass does not require the 4bbls, and maxing out the speedo doesn't require 4th gear either.

Your combo sounds VERY much like where i am heading. I cant wait to feel the first good launch with them gears in it... it will be great!

In my combo (see sig), I went from 3.42 - 3.73 - to now 4.10's. From my own experience I'm happy with the 4.10's. There's more than just starting line improvements with 4.10's vs lets say 3.42. At any speed the vehicle is snappier. On the street I use 28" tires and at 60 mph the engine turns 2100 rpm.