Differential ratio and tire sizes...

[4x4Hunter]

Alright, I got all the parts for my lift in today and will be recieving the brake lines in the mail soon. What I was thinking today was if I would be ok using the 3.55 factory diff ratio with 32 X 11.5" M/T's for about a year. I probably won't do any off roading till things start to get really rebuilt, but I want to be sure that I'm not going to damage any of the parts by running that large of a tire with that ratio. If any of you guys who have switched over your diff's have a suggestion on what I might want to consider... I really like the diff' skid plates that are out there, and prolly will get some of those eventually. I wanted to switch over to like a 4.56 ratio, but I've heard that its something that probably should be done by a professional shop, and can be quite costly. Let me know what you think about the factory ratio and the tires please..

Thanks

 

[TexExplorer]

I'm wondering the same thing...

I'm sharing the same worries... only I've got a stock 97' Sport. Any opinions are welcome...

 

[briantf]

Acceleration / torque will suffer, but...

For the 91-
The 8.8 is a strong rearend, esp. on Explorers. The D35 front should be OK as well, but you're going to need to watch your wheel bearings. Heavy/tall tires can cause problems.

I repacked my Ranger's front bearings at 25K, I'll replace them at 50K. Cheap preventative maintenance.

Your performance (acceleration) is going to go down, it's like running really tall gears (from 235 to 275's, what is that, 3.08 effective ratio? something like that). The torque on the OHV isn't overwhelming to begin with. Might want to look into some of the board's performance enhancements.


Getting gears is expensive, no doubt. I looked into 4.10's for my Ranger, since that's a factory ratio I thought it would be less expensive. It's not. I'd go for 4.56's too, since it's the same $$. Figure on $5-600 per differential for parts and labor. More, if you put a TrakLok or some other limited slip in your rearend (cheaper to do it all at once, though).

As for the 97, pretty much the same applies. I know a Ranger guy that ran 33's with 3.55, he survived. You probably will to.

Best,
Brian in CA