Well i just ordered a new rear end yesterday from strange engineering. I ordered the s60 with 3.73's. Im kinda having 2nd thoughts about this. i will be running a 383 with around 500hp, a 700r tranny. Just wondering if i should of got 3.9's or something. What do ya'll think.

If you want to drive much at highway speed stick with the ratio you purchased. I am looking at purchasing the same strange s60. let me know how the install goes. Jb

I'd stick with 3.73s. I believe the 4L60-E has the same final overdrive ratio. Well, I had some 3.73s installed in the '94 Impala SS I had and about a year later I had the stock 3.08s reinstalled. I wanted to cruise, not rev.

All depends on how highway driving you will be doing. If I had your setup in my Chevelle, I'd put 3.55s, maybe even 3.42s. But, I do more highway driving in my Chevelle than cruising around town.

DWJ,

What's the purpose of the car, how much highway dirving, etc. At what speed will you be driving most of the time? Do you plan on hitting the drags and how often? All of these questions and more really need to be asked before a solid answer could be given. 3.73's are great for the street, especially if you need to do a lot of highway driving. Unless you plan on going with an overdrive?

Fred.

SS,
Car is street only, (maybe drag 1-2 times just to see what she'll do when i'm done) Not alot o f highway use, but just want to make sure that its not reved through the roof when i do. Plan on (right now at least) using a 700r tranny, but seams like i change my mind on everything several times anyway.
Thanks for the help
Dave

700R-4 has .7 O/D which means the 3.73 will cruise like a 2.61 on the highway.

I've got 4.10s which will be like a 2.87 with my 4L60.
80mph should be <3000 rmp with 27" tires.

Use this to calculate your RPM... play with tire heights, gear ratios, etc. If the trans has lock-up, factor converter slip @ 2%... not sure how much slip if no lock-up, but RPM will be ~200-300 higher.
http://www.tciauto.com/tech_info/calculators.htm#7

Dave, what tire size are you going to run?

I'd decide what RPM you would consider acceptable going 70mph (or whatever mph you want to drive on the freeway) and match the tire, gear ratio, trans overdrive, etc. to achieve that RPM. If you don't drive much on the freeway, 3.90s would be fine.

I'd be more concerned about 500 horse with a 700R.

If your not going to race it a high gear ratio (lower number) may be better.

The 3.73-1's are gonna be very nice with the 700R4! :thumbsup:

Huh guess this is all part of the "learning expience" That i get with building my 1st car. Didn't even know that all these came into factor. Ohh well guess thats why you always build others. Anyway to answer the question i plan on running 17's or 18's with a 50 series tire. So whetever that comes out to be... Love the site though, have learned alot from the people on here
thanks for the info
dave

The 3.73-1's are gonna be very nice with the 700R4! :thumbsup:

What he said

Here's a tire-height/width calculator

http://www.wallaceracing.com/tire-aspect-calc.php

pick your size example: 275/50/17

put
275 in the "width"
255 in "Aspect Ratio"
17 in "wheel diameter"

and submit to get your tire's height.

Thanks for the link Derek. Looks like the tire will be 28.83 inches tall