What is my R&P ratio supposed to be?

[2damslow]

I have a 94 4runner with the overdrive 5sp stick shift and V6. I spin the tire and I figure that the ring and pinion ratio is about 4.88
It is clearly lower than the 4.11 ratio that I expected to find. When I cruise down the highway I spin the motor about 3400 rpm's at 70 miles an hour, which seems a bit high to me.

What ring and pinion ratio is it supposed to be? I plan to swap a v6 into it and if it's really 4.88 ratios than I just might go with an automatic OD trans for the swap...

 

[WristPin]

One way of determining your axle type and stock gearing is to look for an Information Plate on your truck, on the firewall (prior to 1989) or door jamb (1989-current). It will look something like this:

C/TR/A/TM 138 HR11 G282 A130H or C/TR GJ7/KQ41 A/TM G251/R150F

These numbers are the Color (paint) code, Trim Code, Axle Code, and Transmission Code. You will also need to check the first few digits of you VIN #.

The first position of the Axle Code is a letter which identifies the diameter of the ring gear. Toyota trucks and 4Runners have always used the 7.5" and 8" diameters, but the others are listed here for completeness. The first table applies to Japanese-built Toyotas, which have VIN numbers beginning with "JT". The second smaller table applies to North American vehicles with a VIN beginning with "4T".



You need to check out this page.

 

[WristPin]

also, if you have the rear shaft unbolted, the end of the pinion should have been painted. this page will help you decode it

 

["N8"]

or you can yank out the diff and count the teeth =p

 

[ih8seals]

3400 rpm's at 70 miles an hour

i'm also very interested in this thread, here is my question: what size of tires you are running on???? i have almost the exact rig just don't know the gear ratio. 70mph@ 3000rpm in 5th gear according to the speedometer. on the doorjam sticker, the tire size shows 225/75/15, but with this size tires, i clocked the actual speed(with my handheld GPS which proven very accurate) 63mph @3000rpm(speedometer still showing 70mph).

interestingly, if you go to the major online tire vendors' website to check on the tire size of this vehicle, the all show 31/10.5/15. i switched to this size tires, now everything matches.

does it mean the previous owner swapped out the gears?

 

[2ndGenToyotaFan]

I noticed that with 31's and 4.10 gears, was pretty close to actual speed in my old pickup, but now with 33's and 4.10s I'm right were the math says I should be, when I pass the police radar signs. That's 1.16 times what my speedo says.

What everyone needs to remember is the speedo will show the same speed compared to RPM's no matter what gears and tires you have, the trick is getting the gear to tire ratio close to stock, then the speedo will be close to correct.

 

[2damslow]

My speedometer checks out with my GPS speed. The truck has plain jane all terrains. 31 inch street tires. I am conviced the PO changed out gears, because I can see little spooges of blue RTV around sealing surfaces.
Sweet!
I guess I can go to 33's or 35's with no major headaches...

Thanks for the info

 

[Bob_Garrett]

A 94 with a 5 speed and the 31" tire option should have come from the factory with 4:56 gears. The autos had 4:88s. If the gears have been swapped, the PO may put in gears from an automatic equipped truck. Not sure why he would do that with all the power from that mighty V6.