kinda the right sport but this is for my truck 82 chev with a built 383 doing a gear ratio calculator and in 2nd gear at 6k i should be doing 111mph


38in tires 4:10 gears 1st 2.48 2nd 1.48 3rd 1.00 3k stall
i know i was in 2nd gear tonight and gps said i was doing 65ish but thats what 1st should be doing at 6k not 2nd this is the calculator im using
http://www.planet4x4.net/forums/calculator.php

thanks for any help

 

Anyone?

 

Did you actually measure your tires? Most off road tires aren't actually the size they say they are. That may be some of it.

 

yea there 38.5 boggers but measure at 38but even an inch difference wouldnt make 65 vs 110

 

I tried another calculator and got the same results as you.
So, one of your assumptions has to be wrong:
1. 4L80E with 2.48 and 1.48 gear ratios
2. 4.11 rear end
3. You know what gear you are in
4. Your tachometer is accurate
5. Your truck doesn't have a "Low range" underdrive unit

You would not be the first person here who thought they had one rear ratio but turned out to have a completely different ratio. You can easily test this with the wheels off the ground and the trans in neutral. Mark a tire and count how many driveshaft turns it takes to turn the tire one revolution.

Have you considered the tach accuracy?

 

the rear end gears say 4:10 right on them iv had the pumpkin cover off and looked its a th400 not 4l80e but same gears i know i was in 2nd put it there manually and i dont have 3rd it slips out i dont have an under drive unit i put this truck together my self tcase wasnt in 4 lo i tested that the next day just to make absolute sure even tho i knew were 4 lo was its not the highest quality tach but i couldnt see it being off more then a couple hundred rpms i guess is there any other way to check rpm exept with a different tach

otherthing i was talking about with a buddy tonight since i have a 3k stall it just doesnt lock up and has that much slip?

 

If 3rd gear is slipping what is the possablity that 2nd is slipping also?

Quote
and i dont have 3rd it slips out

 

Doesn't feel like it 3rd just goes in and slips out fluid didnt smell burnt tell I tryed for 3rd gear trans is fresh rebuilt 3rd has like a line pressure issue

 

I know a small difference in tire size won't make a huge difference that's why I said it could be some of it. Some tires are way worse then 1" some "40's" are actually closer to 37" when measured.

 

yea i know that lol had plenty of buddys wonder why there truck sat so small
like tonight went for a long drive to warm up my truck every time i tested it at 3400-3500 in 2nd i was doing 45 mph but after the drive and using reverse more i may be thinking that it may be sliping a lil cuz i noticed reverse slipping a lil bit

 

If they say 41 10 they are 373 I think ring gears don't read like that 41 10. 41 teeth on ring gear 10 teeth on pinion look online will tell u I think it's 3.73

 

that would make it even more off lol i cant remember if it said that or if i had checked with them numbers or not been over a year since i had the cover off

 

Sorry it's 41 10 is 410 , 41 11 is 3.73