DIY 4.3 Re-Gear (1 Viewer)

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After using 4.88 for about a year now, I don't see any drawback to this ratio. The mild increase in high speed (80 mph+) RPM over say a 4.56 or 4.33 (maybe 100 rpm?) isn't enough into the RPM range to increase engine noise at all (and at those speeds there are other noises that are louder). But the torque available low in the RPM range is much improved. I see the concern about the Nitro gears, and did have some wear in shavings at the 500 mile break in change. There was also some 'gear noise' for a few thousand miles. I'm up around 8000 to 10000 miles on the gears (I'll go double check that) and now they are silent as the factory drivetrain was (or at least my recall of that drivetrain). I certainly don't notice anything out of the ordinary in use.

I know OP has locked in on 4.33 for many good reasons, just putting this here for the ratio discussion.

@TeCKis300 Nitro was selling an alternative eLocker when I geared up. It locks up good. Can't find it on their site, but if you want a second option you could reach out to them. It's an Auburn part, in the eCTDMax line, and runs open/locked.

From my assessment, 4.88s are a pretty large jump in gearing to 4.3s, ~300rpm in the tallest gears at highway speeds, almost a full transmission gear difference. At least for me with stock aero, almost stock weight when not towing, and other considerations, 4.3s were the ticket putting things right back to stock overall gearing. I could definitely see 4.88s as the right choice for heavier built rigs.

More data crunched here:

I did look into the Auburn locker. Not much feedback to be found. From the minimal commentary from jeepers, seems to have a marginal track record.

How available is a e-locked rear on the salvage market? I would assume tough to get as they were pretty limited in the US market. Harrop is a better design although significantly more expensive plus additional setup.

More than I initially thought and seems reasonably easy to source. car-part.com

It’

I think that’s the beauty of the 4.30 ratio diffs. Other than swapping the part time actuator on the front I think they’ll drop right in. That’s what I would do personally, and I’ve considered doing that. If you’re going to the trouble of rebuilding the diffs, I’d jump right to 4:56 with new gears/bearings, etc.
Where did you source your parts? Ebay? Local wrecking yard?

Yes and yes. My go to for recycled grade A parts is car-part.com. Lots of stuff on Ebay too. Craigslist less so for a niche vehicle but probable as well. I have used car-part.com for decades, successfully every time. As with anything, especially in the used market, your experience may vary.
 
I did look into the Auburn locker. Not much feedback to be found. From the minimal commentary from jeepers, seems to have a marginal track record.
Good pull on the link. I wasn't able to relocate it on their site. Carl recommended it, I haven't had any issues. It is for sure not widely installed, at least on this board, but gears and lockers in general aren't particularly common on here.
 
^Got more info and any pics? It is USA made. Perhaps an opportunity that hasn't been highlighted enough?
 
Well, it's inside the 3rd ... Comes with the basic jeep style switch. I didn't install that and run it via my Bluetooth relay. Nothing in any of this different from how a Harrop could be implemented. The pics at nitro show a larger carrier diameter and larger pins, how much this matters in practice is probably theoretical. It is less $.
 
Want to thank Georg ( @orangefj45 ) with Valley Hybrids / Cruiser Brothers. He's been providing me with excellent consultation. Just as I previously experienced working with him on my LRA subtank install -

Looking to do the same DIY journey for the Harrop rear e-locker.
 
Plenty of guys have gears so this may be common knowledge but I haven’t seen it yet... and this thread will have a lot of eyeballs.

Do our 200s derive vehicle speed/distance for the speedo from the sender on the transmission (VSS aka vehicle speed sensor) or the ABS wheel sensors? Does regearing, which would alter the driveshaft revolutions per wheel revolution, introduce any issues due to a new disagreement in ABS vs VSS measurements?

Will this fix a speedometer that reads low due to larger than stock tires, assuming you gear to the ratio correct for those tires?

(Yes, I know the name VSS implies it is for the speedo but it could also be more for transmission control and feedback.)
 
Plenty of guys have gears so this may be common knowledge but I haven’t seen it yet... and this thread will have a lot of eyeballs.

Do our 200s derive vehicle speed/distance for the speedo from the sender on the transmission (VSS aka vehicle speed sensor) or the ABS wheel sensors? Does regearing, which would alter the driveshaft revolutions per wheel revolution, introduce any issues due to a new disagreement in ABS vs VSS measurements?

Will this fix a speedometer that reads low due to larger than stock tires, assuming you gear to the ratio correct for those tires?

(Yes, I know the name VSS implies it is for the speedo but it could also be more for transmission control and feedback.)
I can report that 4.88s with 35s (35.1" diameter) reads about 10% slow. So 59 on the speedo is 65.

Aside from that, I haven't had any other issues. On the plus side, all my miles since tire install are 10% low. Making bank on low mileage insurance deductions.
 
I can report that 4.88s with 35s (35.1" diameter) reads about 10% slow. So 59 on the speedo is 65.

Aside from that, I haven't had any other issues. On the plus side, all my miles since tire install are 10% low. Making bank on low mileage insurance deductions.

My Math tells me that this means that the speed input is on the tire side of the diffs. 31.5" stock tires = 98" traveled per revolution. 35" tires = 109" traveled per revolution, which would be 11% slower than stock. Given that the stock speedo reads fast by a few percent by most accounts, the gears seem to not be affecting displayed speed because all of the difference in @grinchy 's displayed speed is accounted for in his tire size change.
 
95% sure for modern vehicles, that the speedo is derived from the ABS system. Meaning wheel speed sensor.

As opposed to output shaft on the transmission from back in the day.

My 2002 Lexus IS300 manual use to derive from the output shaft of the transmission. Auto variants of the IS read from the ABS system. After swapping to a Getrag transmission, I re-wired it to read from the ABS system.
 
These are straight from Eaton, Harrop is not involved with their design or manufacture. Part number for the rear is 14213-1... it should hopefully a be larger unit, whereas the Harrop units were all based on the older Eaton Dana 44 center carrier.

E-locker 4? Do you know when the new design ships? Seems the current Harrops are back-ordered.
 
From my assessment, 4.88s are a pretty large jump in gearing to 4.3s, ~300rpm in the tallest gears at highway speeds, almost a full transmission gear difference. At least for me with stock aero, almost stock weight when not towing, and other considerations, 4.3s were the ticket putting things right back to stock overall gearing. I could definitely see 4.88s as the right choice for heavier built rigs.

More data crunched here:
chart has 3.9 with 31s vs 4.8 with 35s as 200 rpm difference. Lots of ref points for diff tire sizes and diff gears so maybe I’m looking at it wrong. I can say in practice it just has more get up and go, and I’ve yet to find a car or driver that didn’t like these things.

as for 4.3 it’s fine and I’m not saying it won’t be worth the upgrade, particularly the route You’re going reduces cost significantly and risk too. Plus new rear wheel bearings ftw.
 
Wife let me put a couple hours wrench time in on fathers day. Delivered the front axle carrier baby. Wasn't too bad of a job. The 200-series specific side axle extension and mounts should swap right over based on earlier comments. I thought I might try adding the Tundra ADD front axle disconnect mechanism but I'm not feeling motivated enough to do that.

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While it's fresh in my mind, some tips and shortcuts to removing the front diff carrier

1) Remove driveshaft - FSM calls complete removal. I only removed the end connected to the front diff. Once the front carrier is separated from its mounts, there's enough play to get the driveshaft off the studs
2) Remove CVs - FSM call for significant disassembly of the suspension. None of that is necessary as there's no need to pull the CV off the hub side. I just pulled the 2 big bolts holding the lower ball joint to the steering knuckle to have enough room to separate the inner CV.
3) Separate inner CV - this takes some good force. With the pry I had, I couldn't get the right leverage against the carrier lip, and without confidence I wouldn't damage it. Used a large bearing separator plate in the gap around the axle and against the carrier, as a flat solid protected surface to pry against. Made quick work once I had that.
 
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Are the Tundra front third and 100-series rear third direct bolt-in or do you need to modify?

What are you going to do with the ADD actuator? Remove it and put a cover on?
 
The rear third member is a direct bolt in swap. If you want to use the factory locker version, a small notch has to be ground into the housing to clear the locking fork.

On the front the side extension with the ADD gets removed and the cruiser parts have to be used.
 
The rear third member is a direct bolt in swap. If you want to use the factory locker version, a small notch has to be ground into the housing to clear the locking fork.

Sounds like essentially the same swap and notch I had to cut on my 100 series swap. I thought I read somewhere that the factory elocker actuator won't clear the KDSS bar. Is that true?
 
May have read it from my post. The factory electronic actuator wont clear the sway bar. The bar hugs the third member pretty close.
I found a thread in the 80 section detailing how to convert the factory electronic actuator to an air operated unit.
It's pretty straight forward. Just need a machine shop to fab a couple parts.
 
Would a 200 with a factory rear locker need a special axle shaft with long splines like the 80-series setup?
 

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