Author Topic: Worth swapping from 4.65 to 4.90 with 33"'s?  (Read 11559 times)

Cosmos99

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Worth swapping from 4.65 to 4.90 with 33"'s?
« on: February 01, 2018, 01:34:59 PM »
So I just picked up my 3rd Montero. This time a 1999 Gen 2.5. It is very well set up and has 33" along with 4.65 gears. I picked it up in Huntington Beach and it felt great at see level. I live in Boulder ( 5400ft above sea level ) and routinely drive to the mountains. I know the altitude hp loss is pretty sever at 10-12k. The monty is fine off road but the long highway passes at that elevation are still a pain with the 4.65's.  My question to the experts is will there be enough of a difference to the 4.9's to justify the cost? I usually do all my own work but I no longer have garage space to work and also gears are a little out of my realm. Thanks in advance guys!

-Ed
Gen 1 1987 Radier 2.6 ( sold )
94 Montero LS with 93k miles
99 Montero overland ready.

Shovel

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #1 on: February 01, 2018, 02:23:26 PM »
That's a tough call,  so that truck already has had its gears swapped from the original 4.27 to 4.65?  (More likely 4.636 as that's what DOHC Gen 2's had..)

I'm going to assume you have a locker too,  so that means there's no such thing as a junkyard drop in 4.90 (which is what you can do with an open 4.90 3rd member..)  -  you'd be spending some significant money obtaining the gears,  paying somebody to swap them around etc. 

So with a stock 4.27:1 gear ratio going to 4.636 that's about 8.5% more wheel torque while your 33" tires are about 12" larger..    in other words you have around 4% less effective torque than stock?      If you had 4.9 gears that's about 14.7% more wheel torque and therefore in the vicinity of 2-3% more torque to the ground than stock everything or around 6% more than you have now.

Maybe instead get a shift kit to tighten up the transmission a little, and ensure the engine is in peak tune.   


concealer404

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #2 on: February 01, 2018, 02:30:00 PM »
For 33s i'd go to 4.90s if i had 4.27s.  Probably wouldn't bother if i already had 4.63s.
1998 Montero Winter Package (For Sale)
1994 FZJ80 Land Cruiser (Wife's)
2006 V8 4Runner Sport Edition (Mine)

Cosmos99

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #3 on: February 01, 2018, 02:53:21 PM »
That's a tough call,  so that truck already has had its gears swapped from the original 4.27 to 4.65?  (More likely 4.636 as that's what DOHC Gen 2's had..)

I'm going to assume you have a locker too,  so that means there's no such thing as a junkyard drop in 4.90 (which is what you can do with an open 4.90 3rd member..)  -  you'd be spending some significant money obtaining the gears,  paying somebody to swap them around etc. 

So with a stock 4.27:1 gear ratio going to 4.636 that's about 8.5% more wheel torque while your 33" tires are about 12" larger..    in other words you have around 4% less effective torque than stock?      If you had 4.9 gears that's about 14.7% more wheel torque and therefore in the vicinity of 2-3% more torque to the ground than stock everything or around 6% more than you have now.

Maybe instead get a shift kit to tighten up the transmission a little, and ensure the engine is in peak tune.

Thanks for the info. I just asked the previous owner and you're correct. 4.636.  Engine is in very good tune even with high miles. Can you please enlighten me on the trans shift kit?

-Ed
Gen 1 1987 Radier 2.6 ( sold )
94 Montero LS with 93k miles
99 Montero overland ready.

Cosmos99

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #4 on: February 01, 2018, 03:00:57 PM »
For 33s i'd go to 4.90s if i had 4.27s.  Probably wouldn't bother if i already had 4.63s.

I was thinking the same thing as far as keeping the 4.63's....Damn altitude is a killer.
Gen 1 1987 Radier 2.6 ( sold )
94 Montero LS with 93k miles
99 Montero overland ready.

concealer404

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #5 on: February 01, 2018, 03:18:38 PM »
For 33s i'd go to 4.90s if i had 4.27s.  Probably wouldn't bother if i already had 4.63s.

I was thinking the same thing as far as keeping the 4.63's....Damn altitude is a killer.

Right after buying my truck, i immediately drove it over the Continental Divide.  It had 33s and 4.27s. It wasn't awesome.
1998 Montero Winter Package (For Sale)
1994 FZJ80 Land Cruiser (Wife's)
2006 V8 4Runner Sport Edition (Mine)

Shovel

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #6 on: February 01, 2018, 03:34:08 PM »

Engine is in very good tune even with high miles. Can you please enlighten me on the trans shift kit?


Transgo makes two different shift kits for your transmission and I have to confess I have not yet installed one in this application.   Ernest has,  and his experience with it matches my experience with a different transmission.

I have installed Transgo shift kits in 45RFE transmissions,  the result is a cleaner and quicker hand-off when changing up or down gears which they claim makes the transmission wear parts last longer and produce less heat - from my perspective in driving the vehicles it made them feel more powerful than they had before.    It doesn't slam into the next gear,  it just takes less time building up to the shift - if you've driven a newer vehicle with a ton of speeds (like a ZF-8HP in a RWD Chrysler)  it's about like how they zip through gears without drama or drag. 

I wouldn't say to expect a transformative effect from it,  you still have the same gear ratios and horsepower as before but if you're looking for a little extra to make up the deficit between the gears you have and the next notch up - that's the way to go in my opinion.       I'll be installing a shift kit in mine soon as well (on the list.. such a long list!)

Crumb

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #7 on: February 01, 2018, 04:43:35 PM »
 OR get 5.29's for the high altitude package.

Cosmos99

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #8 on: February 01, 2018, 09:05:16 PM »
For 33s i'd go to 4.90s if i had 4.27s.  Probably wouldn't bother if i already had 4.63s.

I was thinking the same thing as far as keeping the 4.63's....Damn altitude is a killer.

Right after buying my truck, i immediately drove it over the Continental Divide.  It had 33s and 4.27s. It wasn't awesome.

Yeah it's rough up there.
Gen 1 1987 Radier 2.6 ( sold )
94 Montero LS with 93k miles
99 Montero overland ready.

Cosmos99

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #9 on: February 01, 2018, 09:10:07 PM »

Engine is in very good tune even with high miles. Can you please enlighten me on the trans shift kit?


Transgo makes two different shift kits for your transmission and I have to confess I have not yet installed one in this application.   Ernest has,  and his experience with it matches my experience with a different transmission.

I have installed Transgo shift kits in 45RFE transmissions,  the result is a cleaner and quicker hand-off when changing up or down gears which they claim makes the transmission wear parts last longer and produce less heat - from my perspective in driving the vehicles it made them feel more powerful than they had before.    It doesn't slam into the next gear,  it just takes less time building up to the shift - if you've driven a newer vehicle with a ton of speeds (like a ZF-8HP in a RWD Chrysler)  it's about like how they zip through gears without drama or drag. 

I wouldn't say to expect a transformative effect from it,  you still have the same gear ratios and horsepower as before but if you're looking for a little extra to make up the deficit between the gears you have and the next notch up - that's the way to go in my opinion.       I'll be installing a shift kit in mine soon as well (on the list.. such a long list!)

Thanks! I will look into it. This is only my second automatic out of 30+ cars and trucks in my time so I am new to them.
Gen 1 1987 Radier 2.6 ( sold )
94 Montero LS with 93k miles
99 Montero overland ready.

Cosmos99

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #10 on: February 01, 2018, 09:23:31 PM »
OR get 5.29's for the high altitude package.

That would probably be the best bet but I have a good deal lined up on a full set of 4.90's.  You know anyone selling 5.29's?
Gen 1 1987 Radier 2.6 ( sold )
94 Montero LS with 93k miles
99 Montero overland ready.

Crumb

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #11 on: February 02, 2018, 03:11:02 PM »
 You need to buy them brand new, Ernest just sold his. there are very few stateside but they're not crazy expensive like they used to be.

kalieracer

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #12 on: February 03, 2018, 11:07:22 PM »
Quote
Message from Shovel:  Oh crap..  I have just accidentally misused my moderator powarz.... I'm really sorry Kalieracer!    I thought I had clicked quote,  and then when I submitted it I had trashed  your message.

Lesson learned by me.      Please edit this back to what you had said before (I can't change it back, there's no edit history) or if the forum won't let you, tell me and I'll edit it back.    Again very sorry!   :(

Shovel

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #13 on: February 04, 2018, 09:48:44 AM »
Quote
In this message,  Kalieracer had offered that there might be some power to be gained by improving intake and exhaust.    I was a fool and clicked the wrong thing and ruined his response.. - Shovel 

If I were to do any intake modifications on the 3.5SOHC I think the most promising path there would be to try to adapt an endeavor plastic intake manifold to our engine.    Velocity plays a huge role in making power and that intake clearly is built for charge velocity - plus it's sure to keep the intake charge cooler & it weighs a few pounds less.      I don't think anybody's done that swap yet - I just need to get the parts together so I can be that guy if nobody else beats me to it. 

On the exhaust side I'm pretty confident there's a little power to be had,  probably above the butt-o-meter threshold even.     My money's on going  2.5" from the catalytic back,  with either a straight through type muffler or at least a "turbo" type.     I'm not convinced that chambered or delta mufflers actually flow better I think they might just be louder. 

jaccox

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Re: Worth swapping from 4.65 to 4.90 with 33"'s?
« Reply #14 on: February 05, 2018, 07:04:46 AM »
There was a member on the Facebook that used the diamanté intake and he claimed he felt nothing different other than louder intake noise. Shovel go to the facebook page and type in "Josh Moe" and it should pop up. The fwd intake would be really great if it it had the throttle body on the passenger side rather than driver side. The member went with an electric fan conversion and ran his intake pipe across the front of the engine bay in front of the accessory belts and behind the electric fans (which seems it'd just be more time for intake air to absorb heat in my train of thought)
1999 Montero. 33x10.5x15 General X3's. 4.90's w/rear locker. Full armor. ADD idler arm. ADD 1.5" complete lift. Siberiean Bushings everywhere. 150W alternator with upgraded 4 AWG leads and grounds. 2nd Battery in the rear for camping stuffs to come.