Final Drive Ratio Compatability ??

[AusTex4x4Sport]

I have a 96 SR5 4x4 with manual transmission and elocker with 4.10 gearing. I need to replace the ring & pinion in the rear diff, but a friend has a 4.30 diff that he would give me and he says it is close enough that it won't be a problem with the front diff when in 4x4 mode, but that doesn't sound right to me. I know, this sounds like a stupid question, but this is an area with which I have no familiarity.

Any input from the smart folks of the forum on this. I've had a hard time finding anyone locally that will rebuild my diff if I get the new ring & pinion gears for the old diff.

 

[cashmoney]

Gears have to match or you'll bind the drivetrain and break stuff. You can run the 4.30s but you can't use 4wd until you get the other axle changed.

 

[AusTex4x4Sport]

Gears have to match or you'll bind the drivetrain and break stuff. You can run the 4.30s but you can't use 4wd until you get the other axle changed.

Thanks. That's what I thought, but this guy seemed to know a lot more about the 4Runner than I did. It didn't make sense to me and that's why I came here where there seems to be a wealth of knowledge, in addition to a few diverse opinions.

 

[Msivley]

Cash money. Are you speculating on this or experience? I know alot of people running different gear ratio front and rear. Even east coast gear supply has stated this is an acceptable difference. If you have a different experience I would like to hear it please.

Melissa

 

[cashmoney]

Personal experience. Drag racing 4wds mainly. Be interested to learn how to make a mismatched setup work though.

 

[csp]

A "mismatch" needs one gearset to be within 2% of the other gearset.

You're looking at almost a 5% difference between 4.10 and 4.30.

 

[Msivley]

See and thats why I ask. Thanks for the heads up.

Reading on forums I see alot of jeep guys running different and even over at Toyotaholics running different gear ratios. I wasn't sure what the acceptable differences were.

With so many people running different ratios for different reason's I didn't want it stated you absolutely have to run the same ratio or you will break things. The magic number appears to be 2% ( for off road use less traction situations ) is ok correct?

 

[UnderFire]

Unless you are SASing your 3rd gen, you will never run into a situation where you cannot find gears that match exactly, so you have no reason to run mismatched gears.

Sometimes when you swap let's say a Dana axle under the front of a Toyota and leave the rear end stock, you'll run into situations where you can get, let's say a 5.29 for the Toyota rear end, but the closest you can find for the Dana front is a 5.37, that's the only time where it's necessary to run mismatched gears.