4.88 vs. 4.56 in a 2006

[Redline]

Funny you ask this question today. Tomorrow the major surgery begins.

I spent today running errands, doing some testing and prepping the car for the transplant.

I purchased some mineral gear oil for the break-in oil changes I plan.

Cleaned the car inside and out (even a good shop takes more care with a clean/nice car).

Did some 0-60 and 1/4-mi. testing for the modified/5,500-lb wet-weight baseline, and did a 65-MPH fuel economy test using cruise control. It will be a while before I do the 'after' tests, and I won't even think about doing them until I'm confident the gears are worn in nicely.

At 5,100-ft 0-60 was about 10-seconds and 1/4-mi. was in the mid 17s. Fuel economy test was 18.56-MPG.

Watching the RPM today on my economy test I won't be too surprised if I loose a bit of MPG, but performance will be better. There is also the possibility that MPG will stay the same, or improve because unlocking of the torque-converter and shifting our of overdrive should be greatly reduced on grades.

I didn’t want to spend the time/money doing a towing test, but I would not be surprised if towing economy improves.

anything new to report, James?

 

[Redline]

Progress Update

We had hoped that the lockers and gearing would be finished after the last two days and I would have my 4Runner to start the gearing wear-in process. But, there are almost always 'issues' and the issues have caused some delays.

The good news is that the delays don't have anything to do with lockers/gearing installation. The mechanic at the shop I'm using has done hundreds of gear/locker installs and has that part of the job completed.

But, the company that shipped the ring & pinions and install kits didn't include a couple items I ordered and paid for. One was the rear crush sleeve elimination spacer and the other was the new rear yoke. I did open the shipping boxes containing the install kits but didn't really know what the crush sleeve elimination looked like and I completely missed the yoke. Part of this was my own ignorance about what parts were needed for this job, but I should have had the technician confirm we had everything (like the yoke!) before late yesterday afternoon when he was trying to put the rear diff back together. I supplied these parts, not the shop, so it was my error/problem.

The crush sleeve elimination spacer is not required, just an upgrade I wanted and was willing to pay for. It was too late yesterday afternoon to get one shipped overnight to arrive today, so I had to settle for a the normal crush sleeve on the pinion. Not having the correct yoke was a bigger problem as the splines on the new pinion are different than the original. Luckily a nearby driveline specialty shop had the correct yoke on the shelf. This yoke, Toyota part, cost me $135.00 instead of the $42.00 for the one that was not shipped. I'm receiving a credit for the missing parts, but it was a bit frustrating. It's a good reminder to check your parts before a project and if you don't know exactly what you're looking for ask someone who does.

ARB Compressor:

I think I will be happy I decided to use the ARB (larger) compressor and switches for the lockers. As others advised, the ARB is designed to work with the lockers/solenoids. The ability to 'clock' the compressor to meet the needs of the install already proved beneficial during mock-up this afternoon. The compressor fits nicely behind the stock air-box on the passenger side fender.

There is another delay, not related to the lockers/gears install, a suspension issue, which is why the 4Runner is not back on the road tonight. It’s a problem with my aftermarket A-Arms. New thread liked below.

http://www.expeditionportal.com/forum/showthread.php?p=218117#post218117

 

[Scott Brady]

So... are you a happy dude now

 

[Redline]

So... are you a happy dude now

I'm generally a happy dude... but Oh Yeah! :smiley_drive:

On my initial drive I thought "4.88s Good Call"

I got the Mall Crawler back from the shop the night before last. Drove it home about 15-miles and parked it over night to cool (initial wear-in). Yesterday afternoon I put another 100-miles on the gears (not all at once) and I'm about to go out for another 100+ of break-in miles on them. By the end of this weekend I hope to have most of my careful break-in miles (400-500) behind me. Hopefully a little towing of the Chaser around town for wear-in on Sunday, then the first oil change and the front skids will go back on. If I get to 500-mi. and have the time I might even hook-up my 30-ft travel trailer and tow it 10-15 miles for a serious towing load wear-in (6,000-lbs).

4.88 Initial Impressions

From what little I have driven the car I can confidently say I'm VERY happy I decided on 4.88s over 4.56s. I don't have a Scan Gauge (yet) but using the tachometer and speedo/GPS the calculations I did regarding RPM and MPH seem to be right-on. About 2300 @ 64-65 MPH.

Yesterday I drove up and down a twisty mountain road (power and coast side of gears both seeing use). I was able to run at least one gear higher on grades and the engine would easily pull the weight of the car. Downhill a taller gear also worked for engine braking. Gradual accelerations from a stop is effortless, close to stock, as the torque of the gears motivate the weight with relative ease.

Our weather is unseasonably cool right now and the mineral/dino break-in gear oil is having an easy time of it. The diffs are only warm to the touch when I stop for a cool-down, not hot.

Torque Steer or alignment?

I had an alignment done yesterday but the car is pulling to the right. I think it is the alignment and I'm going back for a re-do this afternoon. I have checked the tires pressures and even changed to a different set of tires last night (Toyo MT to Cooper ST) to eliminate tires as a cause. Still pulls to the right occasionally. Seems sensitive to the crown of the road (alignment) but also seems to pull more under acceleration. I would be surprised if the added torque of the lower gears induced some FWD torque-steer on this all-wheel-drive car, but is it possible? 100 Series guys with low gears?

Slightly off topic (suspension)

Possibly related to the alignment are other changes that occurred at the same time as the gears/lockers.

The guy I had install my OME suspension a year ago had the lower/front strut spring cups up-side-down. I was present during the install so I'm to blame too, but the fact is they were on wrong. The four wheel drive shop that did my gears has run into this before, and said it was a fairly common problem.

The strut spring cups were corrected and lucky me, I got some lift in the front that the car badly needed. Over an inch! Now the rear is sitting about 1/2-inch low. I don't like a rear-low attitude for appearance and visibility, and think it can/does also affect how the car drives. Tomorrow I will get 1.5-inch spacers for the rear springs, which should put the rear about 1-inch higher. I also plan longer shocks in the rear for more travel.

Not sure how much adding the rear spacers will affect the alignment, maybe slightly as a nose high car generally has more caster than nose low. Think I will need another alignment just because of the rear 1.5-inch spacers?

The testing and miles continue

 

[ntsqd]

snip..........
Not sure how much adding the rear spacers will affect the alignment, maybe slightly as a nose high car generally has more caster than nose low. Think I will need another alignment just because of the rear 1.5-inch spacers?

What's the wheelbase?
I doubt it though. Just as a guess I'll go with 105" WB.
Tan X = 1.5"/105"; X = Invtan(1.5/105) = .000249*

I'll also guess that your install guy told you that for, at the worst, the price of a new pinion seal, some gear lube, and some RTV or a diff gasket that the solid spacer can be installed after the fact.
I've 'relaxed' a Ford 8" crush sleeve (same part as the 9" sleeve) and a Toyota 8" crush sleeve. I went with solid spacers on both. I'm not much for drag strip launches, so I don't know why I'm so hard on them.

 

[spressomon]

James,
Post higher front lift where's the caster at? Sounds like either an alignment issue and/or not enough caster. Who did the alignment?

1.5" rear coil spring spacers? Are you sure you want to go with such thick spacers rather than new coils altogether?

 

[p1michaud]

Gears, alignment and lift.

On my initial drive I thought "4.88s Good Call"

...The testing and miles continue

James,
I'm happy to read that the gears are in and you are working on the break in. Well done. I noticed you have not mentionned playing with the lockers yet. Are you waiting for the gears to be broken in?

I'm sure with a bit of tweaking, you will get the mall crawler dialed in. You have to take me for a spin in that sweet machine the next time we meet up. :smiley_drive:

Cheers:,
P

 

[Redline]

Les Schwab did the alignment. Today I went back and a different guy, a young kid with one year experience/fresh out of school, fixed it up. He drove and I rode with him before and after. There was plenty of caster, but it still had a slight pull to the right, he felt it too. He said that sometimes vehicles with much larger than stock tires will need more caster on one side (the right) than the other to help compensate for the crown of the road. He set it up that way and it drove well.

I'm pretty sure there is some additional steering/torque sensation through the steering wheel with these lower gears (separate from the cater issue). There certainly is more torque and it drives/steering a little different/heavier, not bad, but I notice it. Still analyzing it. For those that don't know, the V8 4Runner is all-wheel-drive, it can't be put into 2WD.

I will have the rear spring spacers tomorrow and was going to put them on immediately. But this evening I played with the coil-rite air bags I have in the rear. Newer coils would be nice but I'm not sure there are taller ones available, I will have to double check. There is a firmer OME rear to replace my medium duty spring, but I already have the ability to increase the spring rate with my coil-rites. I'm also concerned I could lose the adjustability of my coil-rites with the spacers because it could make the air bags too short.

I will continue to research and play with things. I'm not too concerned about adding a spacer as they are easy to remove. I ran them on my LJ for a while until I needed a stiffer spring for all the weight I added. The front spacers on the LJ were never a problem, the rears did get squished and compromised a bit. I later added a metal spacer in the rear to boost up the OME springs that had lots of weight on them.

James,
Post higher front lift where's the caster at? Sounds like either an alignment issue and/or not enough caster. Who did the alignment?

1.5" rear coil spring spacers? Are you sure you want to go with such thick spacers rather than new coils altogether?

 

[Redline]

I will get it dialed, it is very close right now, just not perfect

Before one of my cool-down breaks yesterday I was in a large dirt shoulder and briefly tested both lockers for function. They work! I will 4x4 with them soon as I can after the initial break in miles. I should have over 400-mi. by tomorrow afternoon. 300+ currently.

You can ride with me any time Mr. P :rally_guys:

James,
I'm happy to read that the gears are in and you are working on the break in. Well done. I noticed you have not mentionned playing with the lockers yet. Are you waiting for the gears to be broken in?

I'm sure with a bit of tweaking, you will get the mall crawler dialed in. You have to take me for a spin in that sweet machine the next time we meet up. :smiley_drive:

Cheers:,
P

 

[Redline]

Wheelbase is 110-inches.

No he didn't say I could add the solid pinion spacer later but makes sense. He agreed it was a good idea to have the solid spacer but also seemed to think that the crush sleeve was fine as that is what they have stock. I'm pissed the parts guys didn't send it. Maybe I will upgrade later, now you've got my attention as you have 'relaxed' a couple some how?

What's the wheelbase?
I doubt it though. Just as a guess I'll go with 105" WB.
Tan X = 1.5"/105"; X = Invtan(1.5/105) = .000249*

I'll also guess that your install guy told you that for, at the worst, the price of a new pinion seal, some gear lube, and some RTV or a diff gasket that the solid spacer can be installed after the fact.
I've 'relaxed' a Ford 8" crush sleeve (same part as the 9" sleeve) and a Toyota 8" crush sleeve. I went with solid spacers on both. I'm not much for drag strip launches, so I don't know why I'm so hard on them.

 

[ntsqd]

Wheelbase is 110-inches.

No he didn't say I could add the solid pinion spacer later but makes sense. He agreed it was a good idea to have the solid spacer but also seemed to think that the crush sleeve was fine as that is what they have stock. I'm pissed the parts guys didn't send it. Maybe I will upgrade later, now you've got my attention as you have 'relaxed' a couple some how?

I simply lost the pinion bearing pre-load. Most diff guys think they're fine and few people have trouble with them. The first was in a '67 Ranchero w/ a 302c.i. V8 and an AOD trans. I used it to flat tow my ~2k lbs glass dune buggy to the desert. I sometimes have a slightly exaggerated view of what a machine should be able to do without crossing into abuse of the machine, but I very, very rarely abused the diff.
The second one to relax and loose pinion bearing preload was in my '84 Yota Xcab. Those diffs I have abused. Detroit x Lockright & 4.88's. Same thing, the spacer relaxed (though not nowhere near as much as the Ranchero's) and pinion bearing preload was lost.

I find it interesting that older Toyota 4wd mini trucks came stock with a solid spacer and shims. It is only the newer trucks and install kits that do away with this feature. The first diff I ever set up gears in was this car, a Zagato bodied Fiat 8V:


and it has a solid spacer, as do the 6 of it's brothers that I set up at the same time. In those cars even the front wheel bearings have such a spacer!

(pic links to short blurb on car if interested)

 

[slooowr6]

James,
Any update on gas mileage change with the 4.88? You are using 33" tire with 4.88 right?

Alex

 

[Redline]

Peaches and Nectarines

Funny you should ask, I've been wanting to post an update.

Monday I did my first 'after' test with the 4.88s. The data is probably close and a good representation of the 4.88 vs. 3.73 gears, though conditions were not exactly the same as the before test.

One thing that will never again be the same is the front end lift. While having the gears done the shop noticed the front springs were installed incorrectly. This was corrected but the front of the truck is higher, 2-inches higher at the front skid plate!, so instead of nose low the car now sits level and is a bit less aerodynamic.

I'm still running mineral oil, not my normal synthetic in the diffs, the outside temps were warmer, and there were stronger winds on the 4.88s test. Only moderate wind on the 3.73 test (we have lots of wind).

Testing was almost all freeway, a repeatable test very similar to other tests I have performed with other vehicles.

3.73 Test 5-21-08

Temps 59
Wind moderate
GPS MPH 65
A/C On
Cruise control used
Trip Odometer 51.3 x 10% slow = 56.43-miles
3.039 gallons of regular unleaded.
18.56-MPG

4.88 Test 6-22-08

Temps 84-87
Wind strong
GPS MPH 65
A/C On
Cruise control used
Trip Odometer 51.2 x 10% slow = 56.32-miles
3.327 gallons of regular unleaded.
16.92-MPG

Comments:

On the 3.73 test the was more traffic and I needed to slow a couple times. There was likely little to no effect on the MPG numbers. To maintain speed the tranny did shift into 4th on some grades, even to 3rd a few times, to maintain 65-MPH. The gearing was so tall that on downgrades the 4Runner would almost coast, I think this helped fuel economy at the cost of uphill acceleration and torque.

With the 4.88s the tranny only unlocked 5th once briefly for a grade, but never shifted out of O/D and then went right back to 5th-locked.

Based on the data above there was a 1.64-MPG loss of fuel economy. This may always be, or possibly with synthetic oil and less wind I can get closer to the 3.73 MPG. My guess is that the fuel economy may improve up to 1/2-MPG, making the wet/unloaded freeway MPG loss about 1-MPG.

The improvement in drivability is tremendous, the rig feels much closer to stock, but I can still feel the weight and other changes, it is not the same truck.

I towed my Chaser a bit for some gearing wear-in, and even my 30-ft, 7,000-lb Avion travel trailer! But I have been driving the car mostly empty. Next week I will go on a camping trip for about 5-days and it will be interesting to see how it pulls on and off highway in both high and low-range.

James,
Any update on gas mileage change with the 4.88? You are using 33" tire with 4.88 right?

Alex

 

[slooowr6]

:bowdown: Thanks for the detail update. The true benefit of the 4.88 should be even more obvious when you hook up the trailer in full travel mode.

 

[tdesanto]

Thanks, James, for the update. I am definitely interested in your feedback after towing your Chaser next week. I'm watching this thread closely as I'm seriously considering going to 4.9's to get back to stock power in much the same way that you are. Again, many thanks for sharing all this important info.