im going to put a 383 stroker and a 700r4 in my car and was wondering what gears i should put in my rear end. my car will just be a street car and maybe go to the strip every now and then. i dont really care about gas mileage because it wont be a daily driver.

 

Either 3.73's or 3.42's. Since its an auto...I'd put 3.42s. But I'm guessing you're using the same stock tconverter?

 

if you want street/strip i would use 3.73's

if you want strip and performance only i would use 4.56's

4.10' and 4.11's are best used with 5spd and 6spd combos, so dont use those.

 

When it comes to rear ends its best to ask yourself exactly what kind of performance at the strip are you looking for. With a 383 even with a auto. trans you will be putting down enough power to shatter a 10 bolt. Gears are broken primarily on launch with sticky tires that “hook”.Some of the guys here are using a modified 10 bolt for street/strip but only “with out” sticky tires that do not “hook”.Bottom line is for aggressive hard launching with sticky tires requires a Ford 9” or a 12 bolt. The 10 bolt is not strong enough for that kind of punishment.
That being said I have the modified 10 bolt on my DD with street tires that will not see the track,at least not with this engine. I switched from a 2.73 open differential with 26 spline axles to a 3.42 with Eaton Posi. And 28 spline axles using a L.P.W. Support cover. I love it and would recommend the 3.42s to anyone using the 700r4 trans.

 

thanks for info
really helped

 

This is also helpful for me, I have a 355 in my 86 iroc, and have had a carb on it for the last couple of years, but am going to put the tpi unit back on. (with the necessary upgrades of course.) But I would like to change out my rear end gears too. I have 2.73 now, I was thinking of 3.73, or 3.42. What kind of RPM would I be turning at 60mph with 3.73, or 3.42s? Also, do you need to make modifications to your chip when you change your rear end gears? Thanks for any extra help you guys can give!

 

What would 4.56 be like with a T56?

 

Stock intake use 3.42:1. HSR use 3.73:1

 

First gear would be near-useless, sixth would be like a 700R-4 / 3.27:1 with the converter locked.

 

What the?!!!?!! First, it somewhat depends on tires. With a 28" tire, like a 275/60R15, you can go up one gear from whatever you'd use with a 26" tire, which most of us use. The following is for 26" tires: With the 700R-4 having that 3.059:1 first, there aren't many engine builds that'll love a 4.10:1 axle, true enough, But going to a 4.56:1 axle? Maybe if you have a legit Nascar engine, but not a 6000-RPM ( or less ) street SBC. If you want an automatic, and need the 4.10:1 gear for the dragstrip, to get the engine to it's HP peak at the finish line, then seriously consider a 200-4R swap.