What rpm would my car be if I'm driving at 55-65 mph or 70-80 mph ( 3.23 or 3.42 gears)

I know that there is a calculator somewere, but I can't find it!

leo

Does anyone actually do it in their 4th gen?? (I'm thinking most of you only go for the th-400 or the th-350 for race-car only )

 

It sucks on the interstate. I've got 3.73's so its about 3200rpm at 65MPH. When I get a new rearend I am going to 3.23's or 3.42s. With the ET Streets on its a little better because they are taller.

http://www.gafba.com/calculators/ringgear.asp?mode=calc

 

I'm running a TH400, with a non-locking convertor, and 4.10's...... . At 70mph in top gear it was running a shade under 4,000rpm. I added a Gear Vendor 0.78 O/D unit, and it dropped it down to a shade over 3,000rpm. I don't drive it on the street much any more......

And 28" slicks help at the track......

The GV essentially doubles the cost of the install.

 

That's why I can't go that way....

I think I'm gonna stick with the 700-R4 for my daily driver

leo

 

i have an s10 blazer with a 305 and th350 trans, at 70mph i turn about 3000, it would be higher but i have 30" tall tires so that helps. i get 14mpg on the highway

 

I am installing a TH400 this year. Originally, I was going to buy the GV up front. But the project has gotten a bit out of hand cost-wise. So I was looking for ways to cut down the cost. When I thought about it, I realized that when I was a kid (early to late sixties) nearly all cars had a 1:1 top gear. I had a '68 Charger 440 wedge that originally had 3.23's and I drove that thing from Cleveland to San Francisco without giving it a thought. Later, I swapped in 3.73's and drove it all over.

So with my 3.42's I decided to give it a try. The car is in no way a daily driver, but I do plan to put my usual ~4,000 street miles on the car this year along with track use. With my street tires, 3,500rpm is ~80mph and top speed at my 6,400rpm redline will be ~145mph (which I hope to see in the traps!). This sounds pretty useable. I also had cars with 4.10's when I was a kid, and that was pretty annoying even then. But if it's an occasional driver, I think even 3.73's might be tolerable. Most likely I will get a GV OD for next year, but I think it's worth a try without it.

Rich Krause

 

I drive 70 miles every day, city (Philly) / highway... and my MPG is bad alredy with 3.23s

Besides I usually go around 80mph on the highway... I don't think it's worth to now drive 55-65mph just becuase of it


I think I'll stick the 700-r4

leo

 

If you want to see your RPM's with the gears you have now, put the transmission in 3rd gear and see. The 3rd gear on the 700r4 is the same as third in a TH350 or TH400

 

my TH350/3.73 1976 Skylark was quite annoying to drive on any highways...not only does the gas mileage suck, but the engine keeps wanting to pull you down to a lower RPM, so if you don't have the cruise on its easy to slow down and not realize it. IMO unless your running 10's or something that the A4 just can't handle, stick with the overdrive.

 

I wish I could
http://web.camaross.com/forums/showt...threadid=93190

 

My 90 454SS truck came with a TH400 and 3.73 gears. Do you want to talk about poor fuel mileage? The factory EPA sticker reads 10mpg City and 11mpg Highway! I installed a built 700R4 a few years ago. The mileage improved, but 700R4s don't do well behind modified BBCs. I've rebuilt the oem TH400 and I plan to reinstall it with one of those GV OD units.