1999 Montero Re-gear?

[speedtre]

I'm still debating on what size tires to get. It would be good to save some money now, but ultimately I'd like to get 33s or 285/75s so in the long run it may be cheaper if I get them now. The one issue I'm worried about with the taller tires is gearing. The stock Montero already seemed sort of anemic (admittedly I'm comparing it to a 2002 Tundra V8), but I'm sure after increasing the tire size it would feel that much more lethargic. In addition, I will likely be pulling either a trailer full of camping equipment and a RTT or a small pop-up camper and some of that will be in the mountains, so if I go with the larger tires, a re-gear will be needed in short order (if not immediately).

So, what is the conventional wisdom for gear sizes if you go up to a 33 or 285/75 and you want to maintain stockish acceleration and towing ability? Any idea on typical cost for re-gearing if you pay a shot to do it? I have the ability, but not the space or tools to perform a re-gear myself right now unfortunately.

 

[off-roader]

I'm still debating on what size tires to get. It would be good to save some money now, but ultimately I'd like to get 33s or 285/75s so in the long run it may be cheaper if I get them now. The one issue I'm worried about with the taller tires is gearing. The stock Montero already seemed sort of anemic (admittedly I'm comparing it to a 2002 Tundra V8), but I'm sure after increasing the tire size it would feel that much more lethargic. In addition, I will likely be pulling either a trailer full of camping equipment and a RTT or a small pop-up camper and some of that will be in the mountains, so if I go with the larger tires, a re-gear will be needed in short order (if not immediately).

So, what is the conventional wisdom for gear sizes if you go up to a 33 or 285/75 and you want to maintain stockish acceleration and towing ability? Any idea on typical cost for re-gearing if you pay a shot to do it? I have the ability, but not the space or tools to perform a re-gear myself right now unfortunately.

Well, there are only a couple of "affordable" options depending on model Montero you have. You're looking at 4.62, 4.9 or 5.29 from Mitsu.

If you have the smaller difs then all are options. With the larger difs, then the 4.62 and 4.9's are available. Iirc 4.2's are the stock gears for your year.

 

[speedtre]

Well, there are only a couple of "affordable" options depending on model Montero you have. You're looking at 4.62, 4.9 or 5.29 from Mitsu.

If you have the smaller difs then all are options. With the larger difs, then the 4.62 and 4.9's are available. Iirc 4.2's are the stock gears for your year.

Is there an easy way to determine my diff. size?

Thanks!

 

[off-roader]

Is there an easy way to determine my diff. size?

Thanks!

Which engine do you have? If it's the 3.5L SOHC engine, then do you also have the rear locking differential? If so, this is the 9.5" dif versus the normal rear diff. I'm not 100% sure if the non locking rear dif is a 9.5" dif or not. The front will be an 8" in either case.

Also, there are discussions that the 5.29:1 ring gear for the smaller 8.5" rear diff will also fit the 9.5" diff but will simply be weaker than a 9.5" ring gear but you do get the lower 5.29:1 gear ratio.

 

[speedtre]

Which engine do you have? If it's the 3.5L SOHC engine, then do you also have the rear locking differential? If so, this is the 9.5" dif versus the normal rear diff. I'm not 100% sure if the non locking rear dif is a 9.5" dif or not. The front will be an 8" in either case.

Also, there are discussions that the 5.29:1 ring gear for the smaller 8.5" rear diff will also fit the 9.5" diff but will simply be weaker than a 9.5" ring gear but you do get the lower 5.29:1 gear ratio.

It's a 99 so I BELIEVE it's the SOHC engine. It has the cold weather package, including the locker rear diff.

I'm looking to maintain stock acceleration and towing capability with 33s or 285/75s and keep MPG as high as possible.

 

[GrassCat]

Is there an easy way to determine my diff. size?

Thanks!

Look under the hood and you will see a sticker located on the fire wall. Your ring gear information is noted there. If you have a full size 1999 Monty than it will be 4.27.

An easy swap will be from an 1994 - 1996 Monty SR with the 4.62's or 4.90 from a later model Montero Sport. The SR swap is real easy. just replace the third member on the rear and on the front just swap out the carrier and short axle housing.

I have never done a Montero Sport swap, but I would think they would be the same as above.

Hop on over to the Mitsubishi 4x4 wire forum. You will find more information there. If you don't have the winter package, now is the time to add that locker as all the SR's have them.

 

[off-roader]

iirc those came with 31" tires right? If so, an upsize to 33's equals a 6.5% increase in diameter. If they came with 30's then that's a 10% increase in diameter.

Based on my calculations, going from 4.27 to 4.62 equals 8.2% increase in gearing reduction (4.62/4.27=.0819 or 8.2%).

Oh, in case you weren't aware, a larger gear number = a lower gear ratio which is what you want if you put on larger tires.

HTH.

 

[speedtre]

iirc those came with 31" tires right? If so, an upsize to 33's equals a 6.5% increase in diameter. If they came with 30's then that's a 10% increase in diameter.

Based on my calculations, going from 4.27 to 4.62 equals 8.2% increase in gearing reduction (4.62/4.27=.0819 or 8.2%).

Oh, in case you weren't aware, a larger gear number = a lower gear ratio which is what you want if you put on larger tires.

HTH.

It came with 265/70/15 which is equivalent to 30s. So going with 33s and 4.62 would be pretty similar to stock...just very slightly taller...hmmm.

Thanks.

 

[tdesanto]

I have a gen III, but I have 285/75 tires, like you suggested you'd like to switch to. Mine came stock with 4.3 R&P gears and I swapped to 4.9s. I couldn't be happier with it. It gave me just a bit more power over stock, which turned out great for when I tow a trailer (which you also mentioned).

So, it sounds like it would be a good fit to go to the 4.9s The front diff is the same in all of these models.

 

[speedtre]

I have a gen III, but I have 285/75 tires, like you suggested you'd like to switch to. Mine came stock with 4.3 R&P gears and I swapped to 4.9s. I couldn't be happier with it. It gave me just a bit more power over stock, which turned out great for when I tow a trailer (which you also mentioned).

So, it sounds like it would be a good fit to go to the 4.9s The front diff is the same in all of these models.

Just out of curiosity, what did that do to your MPG?

 

[tdesanto]

It didn't really change much. I have a 5-speed A/T; so, I believe it had something to do with the fact that it can stay in overdrive more often. Even though the vehicle now runs a little higher RPMs, it's in 5th more often. Before the re-gear and after the larger tires, the A/T would shift to 4th at even the slightest hills. Now it climbs the hills in 5th and sometimes 4th. When I'm in CO or UT in mountainous terrain, it still needs 4th or occasionally 3rd. That's all without towing.

While towing, it was horrible without the re-gear. With towing, it's now comfortable. Sure, with only a 3.5L V6, it doesn't have a ton of power. So, it still needs 4th and 3rd, but it can tow the trailer up those mountains all day long.

When my truck was mostly stock, I got 18 MPG easily. After adding the tires both before and after the re-gear, MPG seemed to be around 15. While towing, it depends on the terrain. On flat ground in TX, it's about 12-13 MPG. In the mountains, it's around 10-11.

 

[Coolio]

Do you know which Montero models the 4.9 or 5.29 gears came in? I'm wondering which ones to look out for in scrap yards.

 

[speedtre]

It didn't really change much. I have a 5-speed A/T; so, I believe it had something to do with the fact that it can stay in overdrive more often. Even though the vehicle now runs a little higher RPMs, it's in 5th more often. Before the re-gear and after the larger tires, the A/T would shift to 4th at even the slightest hills. Now it climbs the hills in 5th and sometimes 4th. When I'm in CO or UT in mountainous terrain, it still needs 4th or occasionally 3rd. That's all without towing.

While towing, it was horrible without the re-gear. With towing, it's now comfortable. Sure, with only a 3.5L V6, it doesn't have a ton of power. So, it still needs 4th and 3rd, but it can tow the trailer up those mountains all day long.

When my truck was mostly stock, I got 18 MPG easily. After adding the tires both before and after the re-gear, MPG seemed to be around 15. While towing, it depends on the terrain. On flat ground in TX, it's about 12-13 MPG. In the mountains, it's around 10-11.

Did you do the re-gear yourself or did you pay someone to do it? If you paid someone, how much did it cost?

 

[off-roader]

Did you do the re-gear yourself or did you pay someone to do it? If you paid someone, how much did it cost?

Last time I checked here in the Silicon Valley (San Jose, CA) it cost ~600-800 for both front and rear diff's. Make sure they know the rear is a 3rd member design so It's much easier to work on. The front's a pain either way you look at it though. Easiest would be to replace the entire carrier assembly with a good one.

 

[jp1985]

I know its an old old thread, but i was wondering about re gearing my 02 limited.
Would a carrier assembly just swap right over into a limited?

thanks guys.

JP