4.88s on the highway??

b0bbymc · 07-14-2009, 08:36 PM

I have been calling around trying to find a reliable mechanic in my town that can set up my gears for me at a decent price. The guy i would have gotten to do it killed himself friday.... He was the best at 4wd stuff in the Ark-la-tex. Anyways now im pretty much stuck with a shop that some say "dont take anything to them" and others say they are good. I talked to another mechanic that has been in business for as many years as i am old. He told me that 4.88s are not going to work running down the interstate everyday and that i should rethink my plans. He said that 4.88s will just tear up and it will end up being regular maintenence to replace them if i use the jeep as a dd...

Can anybody confirm this or not. I just want to regear and be able to go wherever i want without worrying that this will happen....Sorry so long...

iceman123187 · 07-14-2009, 09:08 PM

First off what set up are you running? I have a 99 tj 2.5l with 33s d30/d35 4.88 yukons and detroit trutrac. i can run 80 mph down the highway and never shift up and down. if done right they wont mess up. I do most highway driving. avg 18 mpg. My buddy running 95 yj 33's 4.0l 4.56's and detroit trutrac and it also does great. I would def. get a GOOD 4wd shop. Most places will only do the rear if not a 4wd shop. The shop i go to in NC, their guy is the regearing man for 25+ years and do them everyday that is what you need to find. For the money you dont need to go cheap you need right.

sijeep · 07-14-2009, 09:09 PM

I'm running 33" tires with the 4 speed auto... I could not be happier with the 4.88. Jerry rec. them to me due to the trans, he was right on the money, my rpm's are about 2200 at 65 mph, if you have 33's go for it!

jutgin · 07-14-2009, 09:13 PM

Your vehicle specs show your running a 31.5" tire, unless you go bigger you would be crazy to regear. 488 is overkill for that tire size.

**newbs** · 07-14-2009, 09:20 PM

It will be fine because of your deep overdrive (42rle) and you can confirm it with http://www.grimmjeeper.com/gears.html a great gear calculator

redjeepguy1 · 07-14-2009, 09:30 PM

Quote:

Originally Posted by sijeep

I'm running 33" tires with the 4 speed auto... I could not be happier with the 4.88. Jerry rec. them to me due to the trans, he was right on the money, my rpm's are about 2200 at 65 mph, if you have 33's go for it!

works well in that combo for me too.

b0bbymc · 07-15-2009, 07:23 PM

Quote:

Originally Posted by jutgin

Your vehicle specs show your running a 31.5" tire, unless you go bigger you would be crazy to regear. 488 is overkill for that tire size.

I will be putting the RE 4.5" SF w/ 3.5" springs on, 3/4" front spacer, RE Monotubes, Jks 1.25" BL. 315/75R16 KM2s on stock moabs with 1.25" spidertrax spacers, Tom Woods Driveshaft, 1" Currie MML, and superior 4.88s.

robncar · 07-15-2009, 07:38 PM

Quote:

Originally Posted by b0bbymc

I will be putting the RE 4.5" SF w/ 3.5" springs on, 3/4" front spacer, RE Monotubes, Jks 1.25" BL. 315/75R16 KM2s on stock moabs with 1.25" spidertrax spacers, Tom Woods Driveshaft, 1" Currie MML, and superior 4.88s.

Well, with the 315/75R16 (actually a 35x12.50) 4.88 would be the wrong gear for you! Since you have a Rubicon and the 4-speed auto, the correct gear would be a 5.13. Like said above, the 0.69 overdrive of the 42RLE is the difference. The 4.88's would be great for 33's but not 35's, 5.13 would be better.

**05jeeper** · 07-15-2009, 07:47 PM

Quote:

Originally Posted by robncar

Well, with the 315/75R16 (actually a 35x12.50) 4.88 would be the wrong gear for you! Since you have a Rubicon and the 4-speed auto, the correct gear would be a 5.13. Like said above, the 0.69 overdrive of the 42RLE is the difference. The 4.88's would be great for 33's but not 35's, 5.13 would be better.

I have a 05 Rubi with 35s, auto and 4:88 gears. I am very pleased. I think 5:13 would be to low. I run 1800rpm at 60mph in OD. Without OD I am about 2600rpm. Sometimes I wish I went 4:56 cause with the 4:1 transfer in some situations I am too low.

**Jerry Bransford** · 07-15-2009, 07:49 PM

That so-called "mechanic" is full of crap, 4.88 gearing is perfectly fine for anything you can think of. He's probably just a "car-type" and thinks anything deeper than 3.73 is hard-core nutso. 4.88 is a commonly used ratio for Jeeps, no worries. Me? I"ve been running 4.88 gears on my daily driver TJ for years.

robncar · 07-15-2009, 07:54 PM

Quote:

Originally Posted by 05jeeper

I have a 05 Rubi with 35s, auto and 4:88 gears. I am very pleased. I think 5:13 would be to low. I run 1800rpm at 60mph in OD. Without OD I am about 2600rpm. Sometimes I wish I went 4:56 cause with the 4:1 transfer in some situations I am too low.

Your 1800 in OD at 60 is my point. Believe it or not, you left some gearing on the table. I switch my OD off, on the street, every day. I'd love to be around 2500 in OD at 65.

**lj_wil** · 07-15-2009, 07:55 PM

Find another shop.

**GOLENJEEPTJ** · 07-15-2009, 08:00 PM

Quote:

Originally Posted by b0bbymc

I have been calling around trying to find a reliable mechanic in my town that can set up my gears for me at a decent price. The guy i would have gotten to do it killed himself friday.... He was the best at 4wd stuff in the Ark-la-tex. Anyways now im pretty much stuck with a shop that some say "dont take anything to them" and others say they are good. I talked to another mechanic that has been in business for as many years as i am old. He told me that 4.88s are not going to work running down the interstate everyday and that i should rethink my plans. He said that 4.88s will just tear up and it will end up being regular maintenence to replace them if i use the jeep as a dd...

Can anybody confirm this or not. I just want to regear and be able to go wherever i want without worrying that this will happen....Sorry so long...

Definitly find someone else.It's not going to tear up your Jeep by any means! I would even consider with your trans 5.13s!You should try it with a 32rh if you want to see rpms!

**lj_wil** · 07-15-2009, 08:05 PM

I'm having a difficult time believing that there aren't any truck shops in Texarkana.

VTJeePTJ · 07-15-2009, 08:28 PM

Quote:

Originally Posted by 05jeeper

I have a 05 Rubi with 35s, auto and 4:88 gears. I am very pleased. I think 5:13 would be to low. I run 1800rpm at 60mph in OD. Without OD I am about 2600rpm. Sometimes I wish I went 4:56 cause with the 4:1 transfer in some situations I am too low.

I definitely have to disagree here. I have the 4spd with 4.88s and 35's. They were perfect with 33's but now I definitely am wishing for something closer to 5.38 because of the rediculous OD ratio

. I can't imagine it with 4.56.