i have a th400 with a 3800 stall and it seems like the top speed is 80 mph. do th400s shift at a different rpm? why does it basicly max out at 80?

 

What is the gear in the rearend

 

Are you sure your shifting into 3rd. I have a 4.11 rear gear and I'll top out at 135-140

 

4.11 it shifts at 5500rpm and yea its in third.

 

What rpm is it pulling at 70mph?

 

5000 range

 

4.11 in 3rd gear should be near 3900ish

You're still in 2nd gear...

http://www.kabamus.com/garage/gears.html

based on a 1st gear - 2.48, 2nd gear - 1.48, 3rd gear 1.00

 

Do you have a ratchet shifter in the car? That would easily cause the problem without you knowing

 

i swear im in third i did a dig and it shifted twice. no i fabricated a bracket to where i can use my stock shifter

 

i went to that website. see what you find out? i have 305/45/18 drags and its saying at 6500 rpm my mph is 84 something?

 

yes, 84.5 at 6000 rpm in 2nd gear!
125.1 at 6000 rpm in 3rd gear

RPM - 8000 7500 7000 6500 6000 5500 5000 4500 4000 3500 3000 2500 2000 1500 1000

3rd Gear 166.8 156.4 146 135.5 125.1 114.7 104.3 93.83 83.41 72.98 62.56 52.13 41.7 31.28 20.85
2nd Gear 112.7 105.7 98.62 91.58 84.53 77.49 70.45 63.40 56.36 49.31 42.27 32.22 28.18 21.13 14.09

 

I have a stock motor but it is procharged and running 7 pounds. I don't get what's wrong. I did hit 100 just recently and that was at 6500 rpm

 

Man you going to hurt that motor doing that. I think too you are in second gear!

 

What is the fluid condition? It could easily be that you're blowing through the converter. Was the converter built specifically for your combination?

Is the tranny equipped with a brake? What is the max stall speed of your converter?