4.56 or 4.88

[Rock Hound!]

Hopefully soon I will be investing in new gears for the TJ. I just am not sure what to run. I have 35" tires, and this is my daily driver. Under the hood is the bad a** 4.0 . I am currently running 3.73. Any help with the pro's and con's of either would be greatly appreciated.

 

[mbryson]

stick or auto?

For me, I'd go with the 4.56 and stick to 35" tires. I regeared my XJ to 4.88 and daily drove it with 35" tires. It was more gear than I really wanted on the road. Great in low range, though.

 

[Rock Hound!]

stick or auto?

For me, I'd go with the 4.56 and stick to 35" tires. I regeared my XJ to 4.88 and daily drove it with 35" tires. It was more gear than I really wanted on the road. Great in low range, though.

Stick

 

[Jeremy]

stick or auto?

For me, I'd go with the 4.56 and stick to 35" tires. I regeared my XJ to 4.88 and daily drove it with 35" tires. It was more gear than I really wanted on the road. Great in low range, though.

realy? i thought that 4.88's and 35"s was equivelant to the factory overall ratio. (3.55 and 235/75/15) i had no complaints with my 4.88's and 35"s highway speeds with out over working the motor. enough to keep me moving up hills without slowing down.

 

[mbryson]

realy? i thought that 4.88's and 35"s was equivelant to the factory overall ratio. (3.55 and 235/75/15) i had no complaints with my 4.88's and 35"s highway speeds with out over working the motor. enough to keep me moving up hills without slowing down.

Yep, didn't like it at all. I'm running 4.56 with my 37" tires and a worn out small block and kinda wish I had 4.88s, but not enough to change gears yet.

Just my opinion. I was a banker at the time, though. Maybe I thought it should be a lot like a BMW or Benz?

 

[BioNuke1]

I think my friend wishes he used 4.88 instead of 4.56 on his same setup...

 

[Contagious]

same setup for me and I used 4.88s - very happy with them. Plenty of speed on the freeway and I'm in good shape if I want to go up to 37s

 

[shrubeck]

I think my friend wishes he used 4.88 instead of 4.56 on his same setup...

That's me and yes. 4.88

 

[DaveB]

If the stock tires were 235 (roughly 29 inch tire) with 3.73 gears the new ratio math looks like this:
3.73/29xPI = X/35xPI X = 4.50 So 4.56 would get you back to stock with 35 inch tires.

 

[BCGPER]

4.88's and 35's on my daily driver LJ with the AOD. I like it. Ended up being slightly lower than stock (4.11) gearing which helps in the power department, but not so low that I can't maintain 75 mph all day if need be.

 

[Tacoma]

Yep, didn't like it at all. I'm running 4.56 with my 37" tires and a worn out small block and kinda wish I had 4.88s, but not enough to change gears yet.

Just my opinion. I was a banker at the time, though. Maybe I thought it should be a lot like a BMW or Benz?

That works out to around 3.73 effective. Just did nearly the same calc's for the Blazer: from 30-31ish that were on it to 38's and 4.56's. Calculator said I would need to run 4.57's to stay at a 3.73 equivalent. I was hoping to get more like 4.10-ish effective....

 

[Shawn]

I would do the 4:88's. You may pay a tad more at the pump but you will pull hills much easier.

 

[Jeremy]

I would do the 4:88's. You may pay a tad more at the pump but you will pull hills much easier.

and your spedo will be acurate.

 

[GOAT]

You do not want to install anything larger than 4.56s in a LP30.

 

[RockMonkey]

You do not want to install anything larger than 4.56s in a LP30.

He's got a point there.

I did 4.88s with 35s in my XJ, but I'm not planning on driving it on the road much.

 

[benjy]

I wish I had 4.88s instead of 4.56s on my TJ with 35s

 

[Rock Hound!]

You do not want to install anything larger than 4.56s in a LP30.

What's the harm

 

[RockMonkey]

What's the harm

Tiny little itty bitty pinion gear. This small gear is much weaker than a numerically lower ratio gear. Plus a low pinion front axle is already pushing on the coast (weak) side of the gear when driving forward.

 

[RockMonkey]

Here's a picture that illustrates the point. This is a 4.10 vs. 4.88 so not quite the exact comparison we're making, but you get the idea. The higher (numerically) ratio you go the smaller and weaker the pinion gear gets.

 

[Brett]

Tiny little itty bitty pinion gear. This small gear is much weaker than a numerically lower ratio gear. Plus a low pinion front axle is already pushing on the coast (weak) side of the gear when driving forward.

Isn't even the HP30 only 2 teeth engaging at a time?

EDIT: with 4.88's