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No More Lugging - Re-Gear to 4.88's and Front ARB Locker

No More Lugging - Re-Gear to 4.88's and Front ARB Locker
December 6, 2017.

Over the last 17 years, the truck has been amazing. Truly a joy every time I get in it, work on it, or even just get all googly-eyed looking at it.

But, as we've started bigger and longer adventures, and turned it into an adventure truck as much as an around-town-mobile, the truck has slowly gotten to a point where it was time to do something about the drive train.

Big Tires = Big Problem
…and by slowly, I mean it was about like this:

And that cliff, right there at the edge, was the installation of bigger tires. See, before that, even with all the extra weight from bumpers and sliders and bed racks and CVTs, the gearing was OK - so I could get rolling easily in first gear, climb up a rocky road without going into 4L, and my gas mileage was still pretty reasonable.

But those tires screwed all that up. I was lugging as I'd start from a stop light, and simple hills would require downshifting to third gear, from fifth. And my gas mileage dropped from ~19 to 14 mpg.

Such is the slippery slope of vehicle modifications, I guess. To more easily go on the adventures, you need the bigger tires, so those weren't going away. Instead, the discussion of what gears to get, and how to get them began.

There were really two choices I had to make:

  1. What gear ratio to go to?
  2. How to get those new gears installed on the truck.

Choice 1: Gear Ratio
From the factory, the truck came with a 4.10 gear ratio. Of course putting on larger tires meant that the gears were pushing the truck further down the road (since one rotation of the wheel is now a larger circumference), and so at any given speed, my RPMs were lower by about 6-7%.

To bring those RPMs back up into the power zone (between 2500-3000 RPM on a 1st Gen, V6 Tacoma), I'd need to change the gearing. My choices: 4.56, 4.88, or 5.29 ratios.

5.29's were out - that would be too much gearing for my 33" tires, especially since the truck is still my primary vehicle. Driving around in town would feel like being in 4L, and I didn't want that.

4.56 vs. 4.88 was a tougher decision. For "around-town," 4.56 might be better - it'd get me back to (essentially) stock gearing, but when the truck was loaded for adventure, it might still require downshifting into 4th on hill climbs, and there might be places where I'd have to go into 4L that I may not otherwise. For adventuring, 4.88's would provide that lower gearing and power, at the expense of some "around-town" efficiency of 4.56's. In the end, I decided that the direction the truck is going is towards adventure - and so 4.88's would be the best fit.

Along with that decision, everyone I talked to recommended that I get a front locker as well. I already had the OEM rear locker, and putting an ARB air locker in the front at the same time would be the obvious, economical choice. And of course, it wasn't their money! Lucky for me, I already have an ARB compressor, so much of the work was already done.

Choice 2: How to Install?
In the early days of the truck, the only real work it needed was "regular maintenance" - which for me meant an annual oil change since I drove it so infrequently. With a coupon from the dealer, it made little sense to do any of this myself. But now, I try to do most of the modifications and maintenance myself - both so I can learn more about the truck and so that should something break on the trail, I have a better sense of how to fix it or what it "should" look like.

So, I initially thought I'd partially install the new gears and locker myself. Really, I had several options:

  1. Order some gears (perhaps through a group buy) and install them myself.
  2. Order some new, assembled differentials with the gears already installed, and replace the diffs myself.
  3. Pay a shop to install new gears in my existing differentials.

As I researched thought about it more however, I very quickly realized that #1 was way out of my league. Being one of the more finicky items on the truck, I knew that I didn't have the tools or the know-how to do the actual gear install myself. I also talked to some guys who did have the know-how and did install their own gears, only to hear them say that they wouldn't do it again - they'd pay someone.

Well, hearing that also made me question #2. There are really two reputable places to get gears - ECGS (East Coast Gear Supply) and Zuk in Arizona (Toyota Gear Installs). I liked the Zuk was using Nitro gears, and a quick email exchange with him netted a lot that I liked hearing - he was happy to do both the gears and the locker, and he'd do it for a totally reasonable price. But, there was a problem - he didn't do the actual install on the truck, so I couldn't drive it down for a couple days and "be done." Instead, I'd have to take out my diffs, ship them down, get them rebuilt, and then wait for them to get shipped back so I could reinstall them.

That would mean two weeks of "truck on jack stands" - longer than I wanted (or could really pull off given the lack of a shop). I was also unsure that the front diff removal/install was in my wheelhouse - at least alone.

So that left option #3. It was the most expensive option, but it was also the one with the highest success rate, and the shortest timeframe. I had a great recommendation from Mike (@Digiratus) for a semi-local shop - JT's Parts and Accessories - and so I gave them a call.

Communication was great with Carl and we worked out a mutually agreeable time and price - I'd bring my truck in when the shop opened on December 6, and I'd drive it home when they were done the evening of December 7. Not too bad, especially since it meant a night in Leavenworth with @mrs.turbodb while we waited. Win win.

Install Day
I was up early on install day, leaving Seattle by 4:15 am. With a fuel stop, that got me to JT's Parts & Accessories just before they opened at 7:00am - perfect timing. I headed in to say hello.

A couple guys were there and let me know that Jared and Chris, who would be doing the work would get started around 8:00 am or so. They suggested I take the short walk into town and grab some breakfast, and then that I was welcome to hang out and take pictures of the work once it got started. Sweet.

At 8:00 sharp, Chris and Jared arrived, and it was time to get started. Into the shop we went, and as they got the truck up onto the lift, I was immediately jealous. I need a shop like this.

Not losing any time, the wheels came off first, and then the truck went higher.

Next, out came the rear diff oil (apparently "weird" on my truck because the drain plug is on the wrong side), as well as the rear axles. Watching Jared work, it was clear to me within the first 15 minutes that I'd made the right call - while I could have wrestled these things myself (though much harder without a lift), it was great watching an expert do it the first time.

It's not every day you see your drive shaft up between the gas tank and exhaust…

As the rear diff was disassembled and drained, Chris got to work opening the new parts to be installed, and doing the final machining on a solid spacer for the rear diff. Even though these guys do this all the time, it was nice to see Chris excited to open everything in the same way I'd have been - "Oooo, a new ARB!"

In the end, the newly installed parts were a Nitro 4.88 front and rear gear package (with Nitro rear ring & pinion, Nitro front Master Install Kit, Nitro rear ring & pinion, Nitro rear Master Install Kit, Front pinion pre-load solid spacer, Rear pinion pre-load solid spacer, and Front Yoke) and an ARB 7.5" RD90 air locker for the front diff.

Within 20 minutes of the truck heading up on the lift, Jared had separated the clamshell of the rear diff and was ready to take it off. There was a bit of wrestling and help from Chris at that point - something in the diff had gotten hung up - but Jared remarked that they were still on record pace, as he masterfully disassembled the stock diff on the bench.

I was impressed by the fact that after each step, he'd lift up whatever part he'd been working on, and essentially clean up the entire bench surface. Through the entire procedure he kept the entire area very clean. Definitely something I liked seeing - that attention to detail indicated great things in my mind.

Everything disassembled, it was only mid-morning when they got to work on the final cleaning of the old parts - suffering most with the paper seal around the diff clamshell (which I'm sure had been in place for 17 years)!

And then, it was time for assembly of the new rear diff. Boy, how I wish I'd been able to ask questions every few minutes of this process - because there were so many bearings that were pressed on, tolerances that were checked, and bolts that were torqued down to specific specs that I was once again glad that I hadn't tackled this myself (though, I'd never really considered assembling the internals) - it was clear that Jared and Chris were doing a better job than I'd have been able to do, and much faster since they had all the right tools!

By 11 am, the new 4.88 rear gears were installed, and it was time to see if everything had gone together "just so," so out came the yellow paint and Jared cycled the gears a few times to see the wear pattern. After a couple minor adjustments, he was happy.

Chris had been getting the rear diff and axle housing cleaned up during this time, and had just laid down a bead of silicone as the new clamshell was read to be reinstalled. It went on without a hitch, and then they quickly got the rear end buttoned back up - except for throwing the wheels back on.

So, at 11:15am, they started on the front. There was a bit of armor to remove first - the @RelentlessFab skids were a hit, getting a few complements about beefiness - and then draining, hoses, clamps, and other miscellaneous bits to disconnect from the front diff before pulling it out.

Oh, and there were lower ball joints to remove. Pulling these made me think of all the lower ball joint issues I've heard of in the last few months. Definitely a part I'll be keeping a close eye on, especially now that they have been "mucked with."

Everything disconnected and out of the way, it was time to remove the diff, which can be a pain when the truck isn't up on the lift and there are two guys who do this for a living. For them, and in that situation, it pops right out, leaving a nice big "OMG something seems to be missing" hole under the truck.

The front diff was apart just as quickly as the rear had been, and by 11:45 am, I was cringing as Jared nonchalantly chucked up a step bit and drilled a hold in the diff cover. This of course was for the ARB air locker, but that didn't make it any less traumatic.

Working in tandem as they had all morning, Chris had been pressing bearings onto the new front diff/locker assembly as Jared disassembled the stock components. He then stepped in to tap the hole for the locker with the "nice new sharp tap" that they'd broken out of the box just a few days earlier.

And then it was time to assemble and test the front - both for tolerances and wear pattern, as well as ensuring that it held pressure.

The pressure test went fine…

But the yellow paint and wear pattern wasn't perfect, and it was 12:15 pm - time to break for lunch! We all split up at that point to grab a bite to eat, and Jared made an off-the-cuff remark that he'd been hoping to finish by lunch…

Of course, I'd been prepared for two days, and I'm sure he could see the surprise on my face - because he said, "it'll probably be 3:00 pm now." When I mentioned the two-day estimate to him, Chris piped in to give me the low down - it seems that most "normal" customers don't show up on time, and usually there's a bunch of "extra" stuff that takes time - like installing the air compressor for the front locker, which often requires fabrication of a custom mounting bracket.

Well that rang true for me, having spent several hours fabbing up my own bracket for my Bussmann, and a day figuring out how to mount my ARB CKMA12 air compressor to the firewall. Plus all the time it takes to run wiring cleanly (which they also weren't going to need to do, since I was going to wire up the solenoid for the locker).

Of course, I was happy to get the truck back early. Unfortunately, the cost was still the same! 🙂

After lunch the final tolerances and contact patterns were quickly achieved, and the front diff was reassembled, hoisted back into place, and secured. Finally, the air lines were run up to the compressor using some "new, less flexible but probably better" hose supplied by ARB.

With that, and the reinstallation of the wheels, it was time for a test drive.

Now, normally the test drive is something that Jared or Chris would do, but given that I was there and obviously interested in the process, Jared offered to ride shotgun while I took it out on a 10-mile maiden voyage. Naturally, I was game, so we opened up the shop doors and headed out!

Not really knowing what to listen or feel for, I left analysis of the work to Jared. And he was happy - there was no significant whine to either differential (that we could hear), and while there was a little bit of drive-line shake, he assured me that it was well within the normal range, especially after increasing the gear ratio (thus making everything spin faster at a given speed). He didn't think I needed to do anything about it unless it bothered me - at which point I could start by getting my drive shaft balanced.

Right now, my tires being out of balance is much more annoying, so once I get that resolved I'll decide whether I can even notice the driveline vibration.

With that, instructions on break-in, a lightening of my wallet, and many thanks, we were done. It was 3:17pm.

Dang, those guys were good!

I was a happy camper - though I hadn't even really driven the new gears all that much to get a feel for them, I knew that the work done was quality work, and that made me feel great.

Little did I know just how happy I'd be once I had a chance to drive the truck a bit more and experience the awesomeness of the new gears…

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