Regear the diffs or the tcase? (1 Viewer)

[62LostInMn]

I asked this question buried in another thread and never got an answer so thought I'd try again. I have a stock 62 with 31's and would like to go to 33's, but the performance with 31's is about as low as I'd like to go with the auto tranny. I can't maintain speed in OD up moderate hills with an empty vehicle.

Is it possible and/or does it make any sense to regear the tcase for running larger tires instead of doing diffs? Can you get to similar ratios this way with gears that are available?

 

[Kynot62]

The only way to get the auto to run correctly with 33's is to regear the diffs. I changed my 62 over to 4.88's and everything started to work properly again. Including the lock up in the torque converter. The difference is night and day. Try this link if you want a little more about gear changes and options in our wagons http://thewagonway.com/?p=169

Regearing the tcase wont do it. The only gears I know of are by Marks and the underdrive high range is only an 8% difference compared to stock. 33's are about 20% larger than the stock 29's that came on 62's from the factory. So you need more of a gear change (lower) to get back to stock specs.

People will tell you you can run 33's just fine with an auto but all you have to do is drive a 62 with 33's and the 4.88's and you will see the difference.

Tony

 

[Ducks]

Autos definitely need the correct diff gears in order for them to function properly. It's also true with 80s. Ditch the auto and put in an h55! Then that 3FE will blow your socks off.

Chad

 

[Mark W]

There are no T/C gears to do what you want. Regearing diffs is a straightforward undertaking.


Mark...

 

[Benjaman]

I asked this question buried in another thread and never got an answer so thought I'd try again. I have a stock 62 with 31's and would like to go to 33's, but the performance with 31's is about as low as I'd like to go with the auto tranny. I can't maintain speed in OD up moderate hills with an empty vehicle.

Is it possible and/or does it make any sense to regear the tcase for running larger tires instead of doing diffs? Can you get to similar ratios this way with gears that are available?

Good time to buy some Toyota electrics in 4.88.

 

[PF]

I'm running an FJ62 with 4.88s, 33s and an AutoTrans. If you do more hwy then off road driving AND you don't have to crest a lot of high altitude mountain passes you may want to consider 4.56 gears. The 4.88s are just a shade toooooo low for the highway. Revs over 3000rpm at 80mph. Just my 2cents.

 

[62LostInMn]

I've read that before, go 4.56 if more on-road than off, 4.88 if the other way around. What rpm do you get at 70-75 mph? I typically don't drive faster than that with the old girl. I pull a trailer with a couple of wheelers during hunting season and my brother's boat once in a while. That makes me lean toward the 4.88 when I make the switch. I have a tranny cooler on it and a Rodney Stage I valve body will be going in this spring.

Thanks to all for the feedback.

 

[PF]

70-75mph ends up being a bit over 2600-2800rpm.

Before you spend $2000 on a valve body and 4.88s be sure you never want to convert to a 5speed manual. You'll be switching the gearing back to 4.11s like I am.