RPM at 70 mph?

[rtarh2o]

I am in the process of a diesel conversion. I am going with the 6.2 diesel, I can either use my existing trans or swap to a 700r4. I would really like to keep the toyota trans but not sure if the ratio will work. I have also heard that the 91-92's were a different ratio? Just wondering what rpm everyone is turning at 70. I also need to know your year and tire size so I can figure out which route I want to go.
Thanks
Rusty
94 FZJ80 on transplant list

 

[Downey]

Simple math Rusty. Tranny output shaft and drive shaft turns one rpm to one rpm of engine crank shaft when in high gear. Now determine gear ratio. 4.88 gears will have drive shaft turn 4.8 turns to one turn of the tire. Now determine circumference of tire(i.e. how far down the road did you go on one turn of the tire)

 

[rtarh2o]

I have done the math but I have found in the past that things aren't always what they are suppossed to be, I am hoping for a few real numbers so I can be sure I am going the right way. For instance, the ratio on the early 80's I have heard are different than the later? If that is the case I could swap out an earlier trans instead of the 700r4
Thanks for the formula though
Rusty

 

[corsair23]

Rusty,

Working from memory here but in my '97 LX with 285/75/16 Toyo MTs (fairly new), stock gears, running @ 70 with OD off I believe my rpms are in the 2400-2600 range. Toyo site will tell what the true circumference of the 285s are but not sure what they are as they sit on my truck loaded down. I run 40-42psi in them, not that that will help you though

 

[Lka1988]

I am in the process of a diesel conversion. I am going with the 6.2 diesel, I can either use my existing trans or swap to a 700r4. I would really like to keep the toyota trans but not sure if the ratio will work. I have also heard that the 91-92's were a different ratio? Just wondering what rpm everyone is turning at 70. I also need to know your year and tire size so I can figure out which route I want to go.
Thanks
Rusty
94 FZJ80 on transplant list

The only real difference I know of is that your trans (A442F) is electronically controlled, while the earlier trans (A440F) is hydraulic. IIRC, of course.

HTH
_lane

 

[MSGGrunt]

1997, 4.88 gears, 38.5 tires, 2200 or so RPM's at 70 MPH with a cutsom turbo.

 

[rtarh2o]

The only real difference I know of is that your trans (A442F) is electronically controlled, while the earlier trans (A440F) is hydraulic. IIRC, of course.

HTH
_lane

I thought the same thing until I found this on another site. It is supposedly from CruiserDan on this site. A440F Produced January, 1990 through July, 1992 on U.S. spec FJ80s 1st gear: 2.950 to 1 2nd gear: 1.530 to 1 3rd gear: 1.00 to 1 overdrive: .717 to 1 reverse: 2.678 to 1 Fluid capacity: 16.4 US quarts A440F Produced August, 1992 through December, 1994 on U.S. spec FZJ80s, production continued on non-US. spec LC80s 1st gear: 2.950 to 1 2nd gear: 1.530 to 1 3rd gear: 1.00 to 1 overdrive: .765 to 1 (approximately 6% lower overdrive than previous model) reverse: 2.678 to 1 Fluid capacity: 16.4 US quarts. I would like to hear from some 91-92 owners to see what rpm they are turning with 33" tires so I can see if this is true or not? If it is true it would be nice to swap an early A440F into my 94 instead of a GM unit Rusty

 

[Lka1988]

I thought the same thing until I found this on another site. It is supposedly from CruiserDan on this site.

A440F
Produced January, 1990 through July, 1992 on U.S. spec FJ80s
1st gear: 2.950 to 1
2nd gear: 1.530 to 1
3rd gear: 1.00 to 1
overdrive: .717 to 1
reverse: 2.678 to 1
Fluid capacity: 16.4 US quarts

A442F
Produced August, 1992 through December, 1994 on U.S. spec FZJ80s, production continued on non-US. spec LC80s
1st gear: 2.950 to 1
2nd gear: 1.530 to 1
3rd gear: 1.00 to 1
overdrive: .765 to 1 (approximately 6% lower overdrive than previous model)
reverse: 2.678 to 1
Fluid capacity: 16.4 US quarts.

I would like to hear from some 91-92 owners to see what rpm they are turning with 33" tires so I can see if this is true or not? If it is true it would be nice to swap an early A440F into my 94 instead of a GM unit Rusty

(cleaned up a bit)

That's news to me. Cool.

 

[rtarh2o]

Thanks, couldn't figure out how to clean it up like that Rusty