i am about to get a 9" rear end for my camaro. i cant decide what rear ratio to get. the most i drive it around town is to work sometimes and to local cars and coffee. farthest one way is usually 15 miles. when i take it to the track it is on a trailer. not much highway driving at all. here are the details:

gen 1 350 non roller (around 400 hp to the wheels at 6200 rpm)
700r4 trans with yank 3600 stall converter.
cam specs- comp cams 12-246-3 (intake at 050 lift-230, exhaust 236)
car weighs around 3300 with me in it
255-50-16 tires

if you want any other specs let me know

current rear is the stock 10 bolt with a limited slip, 3.73 gears

i cant decide between 3.7, 3.89, 3.91 or 4.11

 

considering the stall speed of yer convertor, and that you have an od trans, no highway??? I'd go as steep as you can. the nice thing about the 9" is that all you have to do if you don't like it is buy a pumpkin.... if u had a bit more motor 4 n a halfs….

 

4.11 if more strip and you dont plan to spray.

 

i guess i should have said, no long distance highway. just figure if i am going to take the car somewhere far i would just load it on the trailer,


no plans to spray. or any power adder for that matter

 

I run a 4.11 and have no problems on the highway

 

I've used a built 700R4 with 3.91's and 3000 stall, no drag racing, just liked to go fast... If you are not "speeding" on the highway a 4.11 might even be a bit tall for you, especially if you want to drag race it. Also use a custom 3000 stall behind a TH400 with 3.75's, works great for cruising...

 

id run 4.11s with that set up. its whats in mine and I love them. also a very similar combo. 383 with that cam, through a 700r4 with a yank 700r4. car traps at 115mph right around 6k on a 28" tall tire. I drive the car on a stock tire size turn about 2k at 60mph. 2800 at 80.

 

91 camaro racer - have you taken your car to the track before?
What et and mph?

Gear it for that.

http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php

Use this calc to figure it out

 

so the last time i went to the track was 3 years ago. best run was 14.083 @ 101.58. i have since made some pretty decent changes. (cam, LCARBS, rear control arms, front 70/30 struts, 50/50 rear drag shocks, umi torque arm, yank 3600 torque converter, subframe connectors, panhard bar and some weight reduction)

hopefully i will be heading back to the track soon and will have some updated numbers.

 

@6200, assuming 7% converter slip, this is top end speeds (in 3rd gear)

4.11 is 109mph
3.91 is 114.6mph
3.89 is 115.2mph
3.7 is 121mph

Hope this helps you decide.

 

finally got to go to the track.60 foot was horrible but, ran a best of 13.44 @ 107.88 mph. so if i went to 4.11's i would pretty much be maxed out with no room for faster speed. but i would have quicker acceleration and should still run faster right? i was crossing the stripe at about 5600 rpm with the 3.73's.

 

Put a better tire on it

 

60 foot was my doing. was coming out slow. didnt go wot till half way thru 1st. could have done much better but getting used to the new combo.

 

You could go with a taller tire, instead of gears.
A steeper gear will have a better 60ft and ET(provided traction isn't a problem), but the mph(indicative of HP), usually doesn't change much.

Why couldn't you go WOT off the line?
You using a trans brake?

 

I'd get more seat time in the car before making decisions about changing gears.

 

so with 26" tires, 4.11 gears, 7% slip and 110 mph my rpm in 3rd would be 6254

with 28" tires it would be 5807

i could have gone WOT off the line but i didnt want to spin, i knew i would only get a few runs in so i was being overly conservative with the starts. no trans brake. only foot braking it.

i am probably over thinking the whole rear gear decision. have only changed gear ratios once when i went from 2.73 to the current 3.73's. i got 3.73 because the car was still a daily. now it is track with some random cars and coffee meets. i trailer it to the track.

 

i agree that i need more seat time. i am also worried that if i run the 10 bolt hard off the line that it will break. hence why i want to swap to a 9"

 

I think the 10 bolt will be okay if it was healthy in the first place. Maybe slap one of those structural covers on it.

 

the rear is still the stock 91 housing. i put in the posi and gears quite awhile ago, maybe 10 years?? i do have a main cap support cover on the rear that i put on a year ago. looked over everything at that time and it still looks good in there. no noises or anything from the rear and the posi works good.

if i keep the 10 bolt that would save a lot of money! i guess the worst thing is, if it breaks i end up putting a 9" in it anyway.