Grandpa Builds A 2000 Montero

[grandpa]

Oh i wonder if i was thinking about something else. If front is bolt in, rear should just be a simple r&p swap then, right? I wonder what i was thinking of, thought some hybrid stuff necessary.

Yes, the rear is a standard ring and pinion install. I'm waiting on those parts now. It's all factory parts without any custom fabrication. I sourced the front axle from a 2003 Montero Sport with the 3.5L engine and 4.90 gears. I'm install a new ring and pinion in the factory locked rear axle.

 

[BOPOH]

what parts are you replacing or keeping? Any bearings, gaskets or seals?

 

[grandpa]

In the front I replaced the axle seals. The rear will get new pinion bearings and seals.

 

[SONICMASD]

Great thread and truck!

From what I can gather, a lot of people seem happy running 33/10.5s on the stock 4.2 gears, did you find it too slow or are you moving up to 35s?

 

[grandpa]

I'm not planning on taller tires but the stock gears create a lot of down shifts on longer hills especially when carrying a load. I'm hoping to get some acceleration back and better passing ability. Hopefully it will be worth the expense and labor. I'll certainly report the results.

 

[mr_ed]

Sweet build. Just curious, if you aren't moving to 35s, why did you go all the way to 4.9s vs swapping in 4.6s from a SR?

Just trying to make up my mind as to whether I go 4.6 or 4.9 with my 31s (possibly 33s in the future). I'll be interested in how your revs are on the freeway.


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[Swank Force One]

Here's some data for 70mph.

With 31" tires:
4.272 = 2444
4.636 = 2652
4.90 = 2803

With 33" tires:
4.272 = 2296
4.636 = 2491
4.90 = 2633

With 35" tires:
4.272 = 2165
4.636 = 2349
4.90 = 2483


Personally as long as i'm keeping the 6g74, i'd maybe want something even higher than the 4.90s, but that starts to get a bit more expensive i'd imagine.

 

[BOPOH]

i assume that gear ration is equal to some kind of revolutions?

 

[mr_ed]

Here's some data for 70mph.

With 31" tires:
4.272 = 2444
4.636 = 2652
4.90 = 2803

With 33" tires:
4.272 = 2296
4.636 = 2491
4.90 = 2633

With 35" tires:
4.272 = 2165
4.636 = 2349
4.90 = 2483


Personally as long as i'm keeping the 6g74, i'd maybe want something even higher than the 4.90s, but that starts to get a bit more expensive i'd imagine.

This is some dope info! Thanks!


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[grandpa]

Sweet build. Just curious, if you aren't moving to 35s, why did you go all the way to 4.9s vs swapping in 4.6s from a SR?

Just trying to make up my mind as to whether I go 4.6 or 4.9 with my 31s (possibly 33s in the future). I'll be interested in how your revs are on the freeway.


Sent while on the toilet using Tapatalk

I was thinking that if the stock tire was 29" tall and I went with my current 33" tires that is a 15% increase. So if I increase the 4.27 gears by 15% that is 4.91 and should return the truck to near stock gearing. And 35's are not out of the picture in the future. I'm sure that if I went with the 4.6 I would have regretted it later.

 

[PacS14]

Here's some data for 70mph.

With 31" tires:
4.272 = 2444
4.636 = 2652
4.90 = 2803

With 33" tires:
4.272 = 2296
4.636 = 2491
4.90 = 2633

With 35" tires:
4.272 = 2165
4.636 = 2349
4.90 = 2483


Personally as long as i'm keeping the 6g74, i'd maybe want something even higher than the 4.90s, but that starts to get a bit more expensive i'd imagine.

I have a 99 with the 3.5 and 33" tires and at 70 mph I'm at 2750 rpms. I also live in flatland houston, maybe that math is lab math (perfect scenario) meaning they did not take wind resistance and aerodynamics into account. I'm looking into moving up to 4.90 gears in the distant future as I'm attending school and I also have a full time job.

 

[Swank Force One]

Wind resistance and aerodynamics cannot change gearing. More likely you have an inaccurate tach and/or aren't verifying via gps. My 98 with 33s and 4.27 hits the given rpm.

 

[PacS14]

Wind resistance and aerodynamics cannot change gearing. More likely you have an inaccurate tach and/or aren't verifying via gps. My 98 with 33s and 4.27 hits the given rpm.

Im using the GPS to go by since I have not upgraded to the Dakota digital yet, my tach seems to work just fine so I doubt is inaccurate, I will double check with a scanner what my actual rpms are, the day I did it was kind of windy, but even then it was in the same place I normally see it.

 

[grandpa]

The 4.90 gears are in and I'm doing the break-in miles. I'll update with speed vs rpms soon.

 

[PacS14]

Sweet! Let us know how they work out for you I'm very interested on this. Also an expense list, labor included.