I have a 1990 4runner with a automatic. I want to put 33x12.5 tires on and need to change the gearing to do this. How can I tell what my stock gear ratio is?

 

yotatech.com has provided a calculator to help figure it out.

I think you have a 4.10 gear ratio at the axel (ifs)
Some may have less like a 3.73.

https://www.yotatech.com/~corey/tire...tt_offroad.htm

 

The 3.73 gear ratio was used in the 2wd automatic trucks from 85 to 95?
Your 4runner proabably has 4.30 gears in it. (check your vin plate on the drivers door and decode your axle code ). For 33's, I'd go with 5.29 gears to keep your RPM's a little higher than stock.
I go higher so the motor has an easier time pushing the heavier tires and taller truck around.
These motors may not have much low end grunt, but they do like to rev. Good power to be had from 2500 to 3500 RPM.
My highway crusing RPM's are about 3K at 70MPH. That's with 5.29's and 32" tires.
Hope this helps,
Todd

 

so with 33" tires 5.29's would be wiser than 4.88's, how would gas milage and acceleration be for 33"s with 5.29's, becuz my gas milage and acceleration have gone bye bye

 

Todd E,

Do you have an automatic or stick? The link you provided is very detailed, Thanks. I'll check it out today. At the moment 5:29's seam a little low. But then again I got the overdrive.

 

Mines a 2wd auto.
Even worse tranny gearing than the 4wd
My overdrive gear is a crappy .688:1 ratio.
I think the 4wd auto is about .7 or so.
You may notice a slight improvement in acceleration because of being slightly overgeared compared to stock.
Gas mileage will vary depending on how much you press that right foot
Todd

 

thanx todd, i think im gonna go with 5.29's and i someday might get a wild hair and get 35"s so i'll already be set up for them
oh ive also heard though that the 5.29 is kinda brittle, its not too bad is it?

 

I have 4.88's, but almost wished I had went with 5.29's. Now I'm glad I didn't since I just got a crawl box! With 4.88 your gearing on the street will be a bit tall with 33', with 265/75x16 my GPS and my speedometer are within a 1/2 mph of each other.. I have a second set of rims that I will use exclusively for offroad play with 33'.

 

where's a good place to buy gears, i looked at 4wheelparts and it's like 150 for the rear and 160 for the front, also should i get the master installation kit, im probably going to have a shop do it for me

 

Don't buy your gears from 4WP, they aren't of good quality and will give you problems, a local 4 wheel shop has done many gear changes due to premature life.

Use Yukon or Motive, either are of the best quality sets out. You won't need the full master install kits, most likely your bearing are just fine. I had aprox. 60,000 miles on mine when I had it done and the bearing were in excellent shape.

The 5.29's have a smaller pinion gear, therefore they are a bit weaker than the 4.88's.

 

Todd E.

My stock gear code is G254.

G = 8"
25 = 4.556
4 = 4 pinions

As per my calculations moving from the stock P225 tire to a 33" tire. I need to go to 5.19 ratio. So, this means the 5.29 would be the best for staying as close to the factory performance. I then compared this to the NORS inc. catalog and it tells me the 5.29 is good for 33"to 36" tire.
I'm going for the 5.29 gears and thinking of using Detroit TrueTrack differential.

Thanks for the help.

 

I have used a detriot soft locker. It has both road manners and a good off-road grip.

I have also used Lock-rite. It had very poor road manners and a great off-road grip.

food for thought.

 

I'll check into the soft locker. Thankx

 

Sounds like you've got youself setup well with info
Occationally you can find someone selling used 3rd's already setup with the right gears and maybe even a locker (that's what I did).
I saved a few bones going that way.
Search here, Pirate, Wild Yoats, 4x4wire, even Marlin Crawler's board and see what you find.
Todd

 

this is jason. do you have the lift kit on in the picture? i'd stay away fron the detroit true trac i heard alot of bad stories about them braking. since you have the 4.56 now the 5.29's should be no problem on the street. ......... i gave a guy your number who has a 3.0 v6 that he'll sell parts from it has a good upper intake.

 

I am hearing allot of good things about the Detroit Soft lock. I think I'll go that way and I'm taking Todds advice and going with Yukon 5.29 gears. I just posted my rims on e-bay to raise some cash to finnish this job.

Jason, Let me know what you think of this posting.
See if I did it wright.

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2450890203

 

that listing should be good how you worded it for the rims. i would have waited till sunday to list it. that way it will end on sunday when people have all weekend to look at your stuff and they don't have to work. those rims look in good shape. you will probably will get alot of questions from people wondering if they will fit there year truck good luck. that swap meet is on sunday see you there later.