gear ratio questions

[adistler1]

I recently posted about my 79 FJ40 that I just bought. It's got the 36" super swampers on it. Probably the 1st thing I want to take care of is having the right gear ratio.

I read that 3.70 is great for highway driving (I use mine as a daily driver), but it's better to have something higher for larger tires. The problem is, when I get up to 50 mph, I get a really loud rumble and it really doesn't want to go any faster than that. It doesn't necessarily strain, but I don't really want to push it either.

What would you suggest that I do? And how hard of a job is it--as I'm a total newbie when it coes to working on cars/trucks, but it's something that I want to do... and hey, everyone's gotta learn sometimes.

Thanks in advance!

Aaron

 

[78 One owner]

Can you tell where the rumble is coming from?

 

[Mace]

what motor? tranny/tcase?
50mph on 36" tires can easily be spun in 3rd gear. perhaps you are just not in the RPM band..

 

[adistler1]

Can you tell where the rumble is coming from?

the rumble doesn't seem to be coming from the engine, more like something in the transmission, like right below me.

what motor? tranny/tcase? 50mph on 36" tires can easily be spun in 3rd gear. perhaps you are just not in the RPM band..

It's the original 2f, 4 speed, but I'm not sure about the tcase.

 

[CruisinGA]

check to be sure your driveshaft is in phase. Each universal cross needs to be lined up.
Before you put it in phase check to be sure all your joints are good, drop the shaft and flex each u-joint by hand and feel for any binding or looseness.