Lock Only the rear? ARB Kit for all ratios?

Redline

Redline

Likes to Drive and Ride
4.88s?

I'm giving a bit of thought to 4.88s (spending plenty of time punching numbers into the gear calculators).

4.56 import gears are 630.00 a set, where 4.88 are only 240.00. $800.00 difference for about 150-RPM less in overdrive?

In overdrive/5th RPM would be 2325 w/4.88 at 65-MPH. Stock was around 1900.

Crawl Ratio would be 43:1 !!!

Anyone think that 4.88s is far to low for my 4Runner on 33s/255/85R16? It is very heavy, 5,500-lbs wet/empty. It would surely accelerate well. Wonder if the torque on the axles would be way too much? Fuel economy could be better, worse, or the same, hard to know.

I will lock both the front and rear if I change the gears.
 
p1michaud

p1michaud

Expedition Leader
Redline said:
I'm giving a bit of thought to 4.88s (spending plenty of time punching numbers into the gear calculators).

4.56 import gears are 630.00 a set, where 4.88 are only 240.00. $800.00 difference for about 150-RPM less in overdrive?

In overdrive/5th RPM would be 2325 w/4.88 at 65-MPH. Stock was around 1900.

Crawl Ratio would be 43:1 !!!

Anyone think that 4.88s is far to low for my 4Runner on 33s/255/85R16? It is very heavy, 5,500-lbs wet/empty. It would surely accelerate well. Wonder if the torque on the axles would be way too much? Fuel economy could be better, worse, or the same, hard to know.

I will lock both the front and rear if I change the gears.
Click to expand...

Redline,
With the additional weight of your rig and that sweet AT in tow, I'm sure that the 4.88 would work fine in your application. The only thing is I know you like to cruise a bit faster than 65 on occasion. Have you looked at your RPM's for the higher speeds? Are there any other newer 4Runners out there currently locked front and back that you know of?
Cheers,
P
 
Redline

Redline

Likes to Drive and Ride
Unfortunately I don't know of any newer 4Runners that are locked at both ends. I'm sure there are a few out there but the closest I personally know is the ARB 4Runner that Scott B. tested a few years ago. I think the ARB 4Runner was running stock gears, 32-in tires, and not nearly the weight I have, but it was locked front and rear for sure.

You pose a valid questions regrading RPM at higher speeds. In general I don't drive much over 70-mph, 65-70 is typical for me on the freeway. But there have been occasions when I have disregarded fuel economy and dropped the hammer for hundreds of miles to make some time on a ling trip. Returning from the ExPo trophy last year is one good example, where I did 800-mile in one day. On trips like that the stock higher gears are possibly better, though again the lower gears would pull better on grades.

My thinking is that with 4.56 or 4.88 gears I will rarely have to drop out of overdrive at highway speeds, probably only for very steep hills, the same ones that now occasionally require 3rd when pulling the Chaser.

With 4.88s @ 80 in O/D = 2,860-rpm
@ 70 = 2,500

2,860 sounds kind of high for an extended time but this would be the exception. The engine would be louder, but the little V8 spins nicely and makes plenty of power above that RPM. 2,500-rpm at 70 w/ 4.88s really doesn’t sound too high except it is very close to me losing my overdrive. Currently in w/3.73 I’m spinning about 2,660 in 4th/direct at 70-mph.

This is a tough call and I will have have to give it lots more thought. Even without my Chaser the tall overdrive doesn’t have much zip up here at 5000-ft (and above) when there is a good grade. If I shift down to 4th it is fine.

Thanks for the input and comments P.


p1michaud said:
Redline,
With the additional weight of your rig and that sweet AT in tow, I'm sure that the 4.88 would work fine in your application. The only thing is I know you like to cruise a bit faster than 65 on occasion. Have you looked at your RPM's for the higher speeds? Are there any other newer 4Runners out there currently locked front and back that you know of?
Cheers,
P
Click to expand...
 
L

Life_in_4Lo

Explorer
if you don't strongly feel the need to regear, I would skip it. I don't think it's worth it as it is heavily dependent on a good installation and you just don't want to be going back in there. jmo

rear locker only is perfect on the 4R. I had the ARB rear locked on my old 03 4Runner and it was sweet. I think RD23? You can always take a different line if the rear locker isn't cutting it at an obstacle.

Now if you are going big, than all bets are off and yes, get the front locked. However, the rear locker is more than enough if you are running 32's and near stock-ish.

I think the only fully locked IFS rig Toyota makes is the Megacruiser... ? and that has portals so 50% less stress at the wheels.
 
Redline

Redline

Likes to Drive and Ride
I agree about 'felling strongly about needing gears' that's why I'm still studying my driving patterns, etc.

FYI, I'm running tall 33s, 255/85R16, and probably always will on this car.


Life_in_4Lo said:
if you don't strongly feel the need to regear, I would skip it. I don't think it's worth it as it is heavily dependent on a good installation and you just don't want to be going back in there. jmo

rear locker only is perfect on the 4R. I had the ARB rear locked on my old 03 4Runner and it was sweet. I think RD23? You can always take a different line if the rear locker isn't cutting it at an obstacle.

Now if you are going big, than all bets are off and yes, get the front locked. However, the rear locker is more than enough if you are running 32's and near stock-ish.

I think the only fully locked IFS rig Toyota makes is the Megacruiser... ? and that has portals so 50% less stress at the wheels.
Click to expand...
 
toy_tek

toy_tek

Adventurer
Slightly different application (3rd Gen) but I went through a similar decision process last year when I installed the new suspension and 285's (33's).

I was worried 4.88's would be too tall, since 4.56's would have brought me back to stock gearing.

I wanted to "get it all done at once", ie: gears & lockers, and I wanted to get it right the first time.

So, looking at your RPM calculations with your tire size and weight concerns (which were similar to mine - I pull a 2000 lb atv trailer frequently) I think you'd be very happy with 4.88's. I cruise at 65-70 and my RPMs are in the 2500-2600 range. Downshifting on hills is greatly reduced, as well as the transmission "hunting" on gradual grades.

Crawl ratio advantage is surprising, I can idle down a 35 deg (or so) incline in low/1st without touching the brakes.

I realize our trans ratios are probably different, but just for comparison here are my GPS readings:
60.0mph @ 2250rpm
70.5mph @ 2600rpm
76.5mph @ 2800rpm

I often wonder why I didn't re-gear sooner...
 
Redline

Redline

Likes to Drive and Ride
Yep, different application but still interesting data.

4.10s would put me back to stock so 4.56 is still lots lower.

111db said:
Slightly different application (3rd Gen) but I went through a similar decision process last year when I installed the new suspension and 285's (33's).

I was worried 4.88's would be too tall, since 4.56's would have brought me back to stock gearing.

I wanted to "get it all done at once", ie: gears & lockers, and I wanted to get it right the first time.

So, looking at your RPM calculations with your tire size and weight concerns (which were similar to mine - I pull a 2000 lb atv trailer frequently) I think you'd be very happy with 4.88's. I cruise at 65-70 and my RPMs are in the 2500-2600 range. Downshifting on hills is greatly reduced, as well as the transmission "hunting" on gradual grades.

Crawl ratio advantage is surprising, I can idle down a 35 deg (or so) incline in low/1st without touching the brakes.

I realize our trans ratios are probably different, but just for comparison here are my GPS readings:
60.0mph @ 2250rpm
70.5mph @ 2600rpm
76.5mph @ 2800rpm

I often wonder why I didn't re-gear sooner...
Click to expand...
 
Redline

Redline

Likes to Drive and Ride
4.88s?

I thought I was going to be able to talk myself out of re-gearing (and spending $$$) but the reality is that with the altitude, mountains, weight, and wind the little 4Runner loses speed on even mild inclines in overdrive.

I'm very close to biting the bullet and doing gears and lockers front and rear. Other than some lighting, this is the last major modification the rig needs.

I was pretty convinced that 4.56 was the way to go, but I'm now giving very serious consideration to 4.88s. The lower the gears the less I will have to shift out of overdrive, and staying in overdrive is better for fuel economy. (Wind resistance hurst MPG more than RPM anyway.)

Currently I can avoid a downshift from overdrive to direct with a very light foot, but the car looses speed on even mild grades.

The difference in RPM in overdrive is about 150-RPM between 4.56 & 4.88, which really isn't much.

With 4.88s I would be about 400-RPM higher at 65-MPH than I was when stock; 2300 vs. 1900 back then.

Arguments for and against please.
 
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