4.88 Gearing, Will I Be Glad/Regret? (1 Viewer)

[tenmile]

I am just a week away from some major overhaul work on my 97. I am adding a TRD SC, Lift, and lockers while having my axels services as well. I currently run 285/75/16's BFG', I may move up to a true 33-35 in the future, but for now am happy. I have been told that this is the time to re-gear, if I am going to re-gear due to the axel service, but my LC is my DD and I hesitate due to lack of understanding. It's clear from the forum that 4.88 is ideal for my potential tire size, however what are the down sides if I just stick with my current BFG's? And is my SC going to provide that extra-something that I've been looking for on the steep grades? We do plan to tow a camper and boat quite a bit as well. Any feedback- to regear or not to regear?

Thank You

 

[ppc]

Everybody has different expections of what they need. You need to determine the things your asking yourself IMHO. I would only do one modification at a time. Yes if you regear it should be done at the same time as axle service. Installing the SC gives you that extra-something but depending upon what you are towing, where and how often the SC might not be the ideal solution. I would suggest you do more research and also make sure the engine, trans and cooling systems are up to the added stress.

 

[locrwln1]

If you are even thinking about bigger tires, considering your location, gear it. Look to Romer and others in your area. They have the SC, 35's and still geared it. And yes, 4.88's, especially if you plan on towing.

Jack

 

[tenmile]

Good insight, I've been doing 4 years worth of investigation, and had not considered the re-gear to 4.88 until the shop brought it up. I live at 9000 ft with a pas at 11,500 on every side, the SC is a must for me at this point, I just do not know if the re-gear would be a welcomed addition as well.

 

[tenmile]

Thanks Jack, I did not realize others in my area had completed the same

 

[7schulz]

If you do re-gear and don't go up to 35's I think you will be reving a little high at speed. play with the calculator to see where you will sit at your driving speed.
4x4 related Calculators, Crawl Ratio, Gears Tires Sizes, etc..
I re-geared to 4.88's before I did any mods and don't have 35's yet but I broke my R&P so gears was a have to. I run high rpm's on my stock 31's if I were to drive faster than 60. 2400-2500 rpm is the 60 mph range for my set up. If you got the change$$ I would do it and put on 35's

 

[tenmile]

No $$$ for 35's at this point, I believe my BFG's are close to 33. I like to travel around 70-75 on I-70, around 65 w/ trailer.

 

[7schulz]

Looks like you will be around 2850 RPM at that speed. Up to you if that is acceptable or not.
MPH:
Axle Ratio: 4.88
Transmission Ratio: .765
Transfer Case Ratio: 1
Tire Diameter: 33
RPM: 2851

about 3700rpm if you have to down shift to 4th.

 

[tenmile]

That seems kind of high, I've read that the 4.56 may not be a useful regear really?

 

[TCH2FLY]

Drive around for the next couple days with the O/D off. While it isn't exactly the same as going to 4:88s it will give you an idea of what to expect in terms of highway RPM. If you can't live with it ... don't do it.

I ran 285s with 4:88 for several weeks and I didn't mind it BUT I have also owned and driven lot's of cars with high numerical gearing. After the switch to 315s I wish I had gone 5:29.

 

[7schulz]

That seems kind of high, I've read that the 4.56 may not be a useful regear really?

Sorry I edited my last statement for correct numbers. Yea I heard the same about 4.56. A lot of people told me 4.88 for my flatland alititude but recomended 5.29's at high altitude.
https://forum.ih8mud.com/80-series-tech/368126-re-gear-1fz-fe-sweet-spot-mpg.html

 

[tenmile]

Ok, I may be able to live with that, I just ran out and meassured my 285's and cold they are 31.5 in, why does BFG say they are 33?

 

[landtank]

if you aren't going to to a 35" tire I'd consider 4.56 gears with the 33" tires you have.

 

[Trapper50cal]

285's are 32 point something (32.6-32.8) plus, as they wear, obviously they get shorter. Overall Diameter is also reliant upon rim width.

 

[Grench]

315/75R16 with 4.88 gears and a supercharger = my own personal nirvana.

 

[Trapper50cal]

315/75R16 with 4.88 gears and a supercharger = my own personal nirvana.

That IS about perfect!

 

[CycloSteve]

315/75R16 with 4.88 gears and a supercharger = my own personal nirvana.

Running exactly that with my rig, and it moves up the hills at altitude (over 7000') quite well. If you are considering going with 315's in the near-future, do the gears now when everything is out for the axle service. Heck, try and sell your 285's if they are in decent shape and use the money for a set of 315's.



Steve

 

[tenmile]

Steve.
Good idea. Will the 315's run on an OME 2.5 without rubbing?

 

[thumper]

Yup, 315s will fit fine on OME 2.5. That is what I have and what Steve has also. I have 5.29s with mine though. I also have a supercharger. I run about 2800 rpm @ 68 mph or thereabouts. Truck is happy, I am happy, all is good in the world. I will eventually go to bigger tires when I get a bigger lift.

Jon

 

[tenmile]

Thanks John, good to know, what brand tire do you run?