Possible to exchange gears between 98 Limited & 98 SR5?

[CarolinaCowboy]

So I have a 1998 SR5 which I think has a 3.58 gear ratio, but I'm not sure about this. My dad has a 1998 Limited which I think has a 4.56 gear ratio with RR diff lock. I'm not definite about either gear ratio but I know, just from driving both, that the Limited gear ratio is higher. So my question... is it possible to completely switch these differentials, including the rear locker? I don't have enough know-how to do it myself so I'd take it to my mechanic but just wanted to double check that it was possible.

Also, anybody have an educated guess as to how much that would run me if it can be done?

 

[brian2sun]

So I have a 1998 SR5 which I think has a 3.58 gear ratio, but I'm not sure about this. My dad has a 1998 Limited which I think has a 4.56 gear ratio with RR diff lock. I'm not definite about either gear ratio but I know, just from driving both, that the Limited gear ratio is higher. So my question... is it possible to completely switch these differentials, including the rear locker? I don't have enough know-how to do it myself so I'd take it to my mechanic but just wanted to double check that it was possible.

Also, anybody have an educated guess as to how much that would run me if it can be done?

To clarify, the higher the number the lower the ratio so 4.56 is a lower ratio than 3.58. No 3rd gens (at least 4x4s) ever came with 3.58s - 3.90 was the highest ratio offered. Almost if not all elocked 3rd gens have 4:30s so you have about a 99-100% chance that's what your Dad's is. Most of the unlocked V6s are 4.10s so that's what yours probably is. To know for sure, jack up one rear tire and have a buddy spin it exactly 20 times (open diff)while you count driveshaft revolutions. 41 = 4.10s, 43 = 4.30s, etc.. Make some marks with white-out or something so you can count the tire and driveshaft revos.

The entire rear axle assemblies can be swapped, but keep in mind you must swap front diffs too because the ratios must match to use 4x4. And you will need to wire the locker to your truck. I don't know what a shop would charge since most people that do this are DIY kind of guys. I would guess a full day of labor to swap axles, another to swap front diffs, and possibly another 1/2 day to wire up the locker in yours.

 

[CarolinaCowboy]

To clarify, the higher the number the lower the ratio so 4.56 is a lower ratio than 3.58. No 3rd gens (at least 4x4s) ever came with 3.58s - 3.90 was the highest ratio offered. Almost if not all elocked 3rd gens have 4:30s so you have about a 99-100% chance that's what your Dad's is. Most of the unlocked V6s are 4.10s so that's what yours probably is. To know for sure, jack up one rear tire and have a buddy spin it exactly 20 times (open diff)while you count driveshaft revolutions. 41 = 4.10s, 43 = 4.30s, etc.. Make some marks with white-out or something so you can count the tire and driveshaft revos.

The entire rear axle assemblies can be swapped, but keep in mind you must swap front diffs too because the ratios must match to use 4x4. And you will need to wire the locker to your truck. I don't know what a shop would charge since most people that do this are DIY kind of guys. I would guess a full day of labor to swap axles, another to swap front diffs, and possibly another 1/2 day to wire up the locker in yours.

Right yea I understand the higher the number, the lower the ratio. Which in essence means the higher the number (lower the ratio), the more power... which is what you generally want when installing larger tires. But I didn't know that the front diff would need to be swapped as well so I appreciate that. Knowing it would be that much work (and hence money) lessens my incentive to have them swapped out vs. just installing new gears and an ARB air locker. But I appreciate the tire/driveshaft tip, I'm gonna have a buddy hopefully help me with that tonight so we'll see. If I have the 4.11 gears, instead of the 3.91s I'd be less tempted to do anything with the gears. But I'll report back with what I find. Thanks Brian!

 

[CarolinaCowboy]

So I was able to check myself just now using your method Brian and as suspected I have the 3.91s. Which means with 35s (as I'd like to do) my gas mileage will likely plummet... I have 265/70r16s (30.5s) now and get about 18mpg. So I think upgraded 4.88 gears followed by an ARB air locker at a later date is more likely. That is probably cheaper, and more effective, than completely swapping axles, diff locks, & wiring... correct?

 

[cj80cruiser]

Your mpg are gona plummet either way. LOL! But lower gears would be the way to go on 35's. Why not go with some tall skinnys? I'm thinking about some 255's for gas mileages sake and IMO 4runners pull off the skinnys better than most SUVs. just throwing something else out there to spark some new thoughts.

 

[brian2sun]

So I was able to check myself just now using your method Brian and as suspected I have the 3.91s. Which means with 35s (as I'd like to do) my gas mileage will likely plummet... I have 265/70r16s (30.5s) now and get about 18mpg. So I think upgraded 4.88 gears followed by an ARB air locker at a later date is more likely. That is probably cheaper, and more effective, than completely swapping axles, diff locks, & wiring... correct?

I would strongly suggest 5.29s with 35s on an auto w/ a V6. On a manual, 4.88s/35s/V6 would be good. I would expect gears and ARB locker installed would run ~$2500-2800. If you're going to 35s, swapping for the 4.30s would hardly be worth it anyways IMO since it's still not a low enough ratio to really push 35s well. I 2nd cj80's suggestion for 255s, I like mine a lot and 4.88s/255s/auto/V6 is a great combo

 

[CarolinaCowboy]

I would strongly suggest 5.29s with 35s on an auto w/ a V6. On a manual, 4.88s/35s/V6 would be good. I would expect gears and ARB locker installed would run ~$2500-2800. If you're going to 35s, swapping for the 4.30s would hardly be worth it anyways IMO since it's still not a low enough ratio to really push 35s well. I 2nd cj80's suggestion for 255s, I like mine a lot and 4.88s/255s/auto/V6 is a great combo

Well you've talked me out of switching F&R axles/gears/diffs... is it possible to pull just the rear e-locker out of there? He never uses it and has no plans to mod at all.

And I have heard that most people recommend slightly lower gears for auto vs. manual trannys but whenever I get around to switching out gears I would make the choice based on whether I'm running 33s or 35s. For the tires, I wouldn't mind 255s other than the fact that I'll predominantly be running sand & mud, which warrant the wider 305 or 315 for me. You guys think there would be a sizeable difference in mpg btwn 305s(~33x12) and 315s(~35x12.5) at my stock gear ratio(3.91)? Because total price point difference for a set is less than $50 when I was quoted...

 

[cj80cruiser]

Well you've talked me out of switching F&R axles/gears/diffs... is it possible to pull just the rear e-locker out of there? He never uses it and has no plans to mod at all.

And I have heard that most people recommend slightly lower gears for auto vs. manual trannys but whenever I get around to switching out gears I would make the choice based on whether I'm running 33s or 35s. For the tires, I wouldn't mind 255s other than the fact that I'll predominantly be running sand & mud, which warrant the wider 305 or 315 for me. You guys think there would be a sizeable difference in mpg btwn 305s(~33x12) and 315s(~35x12.5) at my stock gear ratio(3.91)? Because total price point difference for a set is less than $50 when I was quoted...

If you're going to do the gear install anyway and are aware of what mods you will need to do to get 35s on your truck then I say go for the 35s. Just to be clear though. You do realize those lower gears aren't gona recoup your mpgs though right? so you're still gona have worse mpgs with 35's vs. 33's but that would be the worst part of the deal. If you're wheeling pretty hardcore then I may have a 2nd thought about going as big as 35's.

 

[CarolinaCowboy]

If you're going to do the gear install anyway and are aware of what mods you will need to do to get 35s on your truck then I say go for the 35s. Just to be clear though. You do realize those lower gears aren't gona recoup your mpgs though right? so you're still gona have worse mpgs with 35's vs. 33's but that would be the worst part of the deal. If you're wheeling pretty hardcore then I may have a 2nd thought about going as big as 35's.

What mods, other than ~3.5" coilover/LC lift, 2" BL, & maybe 1.25" wheel spacers, would I need to clear 35s? And yes I know lower gears won't totally recoup mpg but they will help some, as well as restore a good bit of the power band. I don't foresee wheeling really hard like some of the guys out in Colorado & Cali, so I if I do run 35s it will be for both form & function. The roughest stuff I'll run into will probably be at Uwharrie OHV park, and I don't think that quite measures up to the toughest stuff out west. Never been but I'm taking an educated guess.

 

[brian2sun]

If you're wheeling pretty hardcore then I may have a 2nd thought about going as big as 35's.

You must mean if you're not wheeling pretty hardcore, then you may have 2nd thoughts about going as big as 35s, right? The bigger the tires with the least amount of lift possible is best for the trails.

 

[brian2sun]

What mods, other than ~3.5" coilover/LC lift, 2" BL, & maybe 1.25" wheel spacers, would I need to clear 35s? And yes I know lower gears won't totally recoup mpg but they will help some, as well as restore a good bit of the power band. I don't foresee wheeling really hard like some of the guys out in Colorado & Cali, so I if I do run 35s it will be for both form & function. The roughest stuff I'll run into will probably be at Uwharrie OHV park, and I don't think that quite measures up to the toughest stuff out west. Never been but I'm taking an educated guess.

I personally wouldn't go to 35s on a DD. My 255s look the almost the same height as my neighbor's 35s on his Jeep Willy's and unless you break out the tape measure it's hard to tell the difference by eye. Mine are 33.5, his "35s" are in reality only 34.5".

 

[CarolinaCowboy]

I personally wouldn't go to 35s on a DD. My 255s look the almost the same height as my neighbor's 35s on his Jeep Willy's and unless you break out the tape measure it's hard to tell the difference by eye. Mine are 33.5, his "35s" are in reality only 34.5".

Yea I've seen some 34.5s next to 33s and I can definitely tell just by eye that the "35s" are bigger but if they weren't next to each other I'd have to check the tire to see what size they were. You really can't tell whether people are running 33s or 35s on here either unless they tell you, most of the pictures look similarly. I kinda know that 33s is the smarter call but my "bigger is more badass" side of me still wants the 35s :hungry:

 

[brian2sun]

Yea I've seen some 34.5s next to 33s and I can definitely tell just by eye that the "35s" are bigger but if they weren't next to each other I'd have to check the tire to see what size they were. You really can't tell whether people are running 33s or 35s on here either unless they tell you, most of the pictures look similarly. I kinda know that 33s is the smarter call but my "bigger is more badass" side of me still wants the 35s :hungry:

If you don't regear right away, the 255s won't suck your power near as much as the 35s will and with 3.91s you will really be bogging down on 35s.

 

[CarolinaCowboy]

If you don't regear right away, the 255s won't suck your power near as much as the 35s will and with 3.91s you will really be bogging down on 35s.

Yea I definitely understand that. Before actually figuring out my gears today I had just hoped that I had 4.11s, but I won't go with 35s at least until I regear even though I'd like to haha. Between the 33s though, you think the 3.91 gears would struggle pushing 305s vs 255s? As of now, I just don't see myself w/ 255s cause of what I'll be running in... I feel like 285s & 305s are better compromises w/ power & mpg.

 

[brian2sun]

Yea I definitely understand that. Before actually figuring out my gears today I had just hoped that I had 4.11s, but I won't go with 35s at least until I regear even though I'd like to haha. Between the 33s though, you think the 3.91 gears would struggle pushing 305s vs 255s? As of now, I just don't see myself w/ 255s cause of what I'll be running in... I feel like 285s & 305s are better compromises w/ power & mpg.

Wider is better for sand. There isn't a big difference between 305s, 285s, and 255s as far as power-wise. I ran 305s for about a year and they rubbed bad in the front on the firewall and the back against the fender flares (the flares/body would sit on the outer edge of the rear tires and prevent it from stuffing and acted like a brake on the tires).

 

[cj80cruiser]

You must mean if you're not wheeling pretty hardcore, then you may have 2nd thoughts about going as big as 35s, right? The bigger the tires with the least amount of lift possible is best for the trails.

No, I was suggesting that going 35's and giving it hell might break things. That is opinion from another member but he breaks stuff all the time so maybe it's just him, lol.

 

[cj80cruiser]

What mods, other than ~3.5" coilover/LC lift, 2" BL, & maybe 1.25" wheel spacers, would I need to clear 35s? And yes I know lower gears won't totally recoup mpg but they will help some, as well as restore a good bit of the power band. I don't foresee wheeling really hard like some of the guys out in Colorado & Cali, so I if I do run 35s it will be for both form & function. The roughest stuff I'll run into will probably be at Uwharrie OHV park, and I don't think that quite measures up to the toughest stuff out west. Never been but I'm taking an educated guess.

That would be the mods I'm referring too.

 

[CarolinaCowboy]

Wider is better for sand. There isn't a big difference between 305s, 285s, and 255s as far as power-wise. I ran 305s for about a year and they rubbed bad in the front on the firewall and the back against the fender flares (the flares/body would sit on the outer edge of the rear tires and prevent it from stuffing and acted like a brake on the tires).

Wow I'm surprised your 305s rubbed like that... did you have the same lift as you do now? With what I'm putting on I expect to clear 305s no problem... ~3.5" coilover front lift & ~4" LC rear lift + 2" 4crawler BL. I kinda built the lift to be able to squeeze 35s if I went that route, so I don't foresee any rubbing with 255s, 285s, or 305s. If I have any rubbing problems at all though, I'd either throw some wheel spacers on right away or just save up to buy the wheels I want with less backspacing. And I would expect that either method would solve most of the rubbing.

Anyways, the plan as of now is the lift goes on next weekend, tires ordered and ready by the following day. Once we're there I can quit talking and show you guys results :banana: Until then I'll just be wishing I was :fishing:

 

[brian2sun]

Wow I'm surprised your 305s rubbed like that... did you have the same lift as you do now? With what I'm putting on I expect to clear 305s no problem... ~3.5" coilover front lift & ~4" LC rear lift + 2" 4crawler BL. I kinda built the lift to be able to squeeze 35s if I went that route, so I don't foresee any rubbing with 255s, 285s, or 305s. If I have any rubbing problems at all though, I'd either throw some wheel spacers on right away or just save up to buy the wheels I want with less backspacing. And I would expect that either method would solve most of the rubbing.

Anyways, the plan as of now is the lift goes on next weekend, tires ordered and ready by the following day. Once we're there I can quit talking and show you guys results :banana: Until then I'll just be wishing I was :fishing:

You shouldn't rub on 305s with a 2" BL. I only had the sus lift when I had them on, not even my 1" BL.