Topic: 4.88 gears question

[Dittrich31]

I have a 95' 2.5 with 31" tires I am about to have installed 4.88 gears and all new bearing kit.  One of my questions is do i need to change my speedometer gear, and if so where can I find the speedo gear that I need because I cannot find one for 4.88 and 31's.  Also What should I expect as far as driving on the highway because I am going on a trip from chicago to colorado and am expecting a big help from the new gears to get me there happily.  Anyone with experience with this please chime in and let me know what to do. Thanks all

[Torch_Ind]

or you could go to 33's woot woot

[sma97tj]

i run 488 with 35s and i am one mile per hour off from factory with gps  i would say with 31s you would be screaming your rpms

[FourbangerYJ]

http://www.grimmjeeper.com/gears.html

According to this link the factory 4.10's with a 27 inch tire (stock size 205-75-15)  3024 RPM's at 70 MPH.
4.88's with 31's 2922 RPM's at 70 MPH.

I'd say 4.88's and 31's would work just fine!

[Torch_Ind]

http://www.grimmjeeper.com/gears.html

According to this link the factory 4.10's with a 27 inch tire (stock size 205-75-15)  3024 RPM's at 70 MPH.
4.88's with 31's 2922 RPM's at 70 MPH.

I'd say 4.88's and 31's would work just fine!

I have driven with stock size tires with my 4.88's and my big t/b and full exhaust and it was awesome !!! "was doing body work and didn't want paint and what not on my muds"

[Torch_Ind]

I think its time for a new paint and get rid of those rusts...

yup still working on it.  even bough a new windshield frame

[knotts89]

i run 4.88s and 33s on my tj with an air raid intake, tb spacer, 4.0 tb, and exhaust and its about right. my speedo is 5mph slower than wat im doin so its pretty close. I would think those gears with that size tire would be a little much espically if ur gone to be doing a lot of hwy driving

[chrisfranklin]

That's what I'm thinking with my setup -- 4:88s on 31s for the time-being.  And while I'm at it I'll throw in an 8.8 rear end... 

I figure I'm going to like the 4:88/31s combo so much that if I ever move to 35s, I am probably going to want to regear again to get the same drive-ability. So, I'd probably drop to 5:13s with the 8.8 and find a front end that'll handle 5:13s also.   

[Dylan]

http://www.grimmjeeper.com/gears.html

According to this link the factory 4.10's with a 27 inch tire (stock size 205-75-15)  3024 RPM's at 70 MPH.
4.88's with 31's 2922 RPM's at 70 MPH.

I'd say 4.88's and 31's would work just fine!

When I check the numbers at that link I can get the stock data to match, but the 4.88 and 31" combo at 70mph shows 3174rpm, not 2922... the closest I can match your second figure is to punch in a tire with a true diameter of 33.4 inches (for 2921rpm).

[sharpxmen]

When I check the numbers at that link I can get the stock data to match, but the 4.88 and 31" combo at 70mph shows 3174rpm, not 2922... the closest I can match your second figure is to punch in a tire with a true diameter of 33.4 inches (for 2921rpm).

maybe one of you looks at 5th and the other at 4th gear 

[neale_rs]

That's what I'm thinking with my setup -- 4:88s on 31s for the time-being.  And while I'm at it I'll throw in an 8.8 rear end... 

I figure I'm going to like the 4:88/31s combo so much that if I ever move to 35s, I am probably going to want to regear again to get the same drive-ability. So, I'd probably drop to 5:13s with the 8.8 and find a front end that'll handle 5:13s also.   

Yeah, always do the gear change after the tire change.  That way you will be happy with it!  LOL
I did the gear change first and then the tires and it is a bit disappointing.

[jfrabat]

Yeah, always do the gear change after the tire change.  That way you will be happy with it!  LOL
I did the gear change first and then the tires and it is a bit disappointing.

Tell me about it!  After going with 31's and 4.88, 33's and 4.88 felt SO SLOW!