Speedometer Correction Gear

[BillyGoatMTB]

Has anyone come across a 34 or 35 tooth for the FZJ80 (1996)?

My situation is having 4.88's and 35" tires. The speedo reads 62 when GPS confirms actual speed is 57...it reads 8.7% too high.

This appears to be the opposite problem of most folks. Would love to just replace the gear, and skip the whole electric signal modification route.

Afternoon I also have 4:88 and 315's on my 1997 FZJ80. Did you find a good speado correction device?

My other Mud reading has let me to the Lutz

Land Cruiser 70/80/100/105 Speedometer Calibrator | Lutz Auto

Plug and play at the transfer case for compatible Toyota Land Cruiser and Lexus LX applications. The Lutz Auto 70/80/100/105 Series Land Cruiser Speedometer Calibrator corrects the speedometer and odometer after larger tires, gearing changes, or any other modification that affects the factory...

www.lutzauto.com

 

[CycloSteve]

Went with the Marks Speedometer Correction Box from Slee. Not sure if there is a current version available now, as the Marks site shows Dakota Digital converters which are a bit of overkill.

Perhaps the Hypertech unit can be adapted for a Cruiser? Hypertech® - https://hypertech.com/

 

[Diesel-Runner]

I recently installed a LUTZ box. Took 2 minutes and my speedo is now dead on.

 

[florida95fzj]

Just installed the Lutz box as well. Did anyone find a good way to make the new connection water tight? Mine did not come with a boot.

 

[BillyGoatMTB]

Just installed the Lutz box as well. Did anyone find a good way to make the new connection water tight? Mine did not come with a boot.

View attachment 3055459View attachment 3055460

Awesome
I'll order with confidence knowing other 80 series guys are happy with the lutz.

I'm thinking tessitate not waterproof but water resistant, are the connectors sealed like standard Toyota connectors?

 

[jaymar]

Do any of these devices also affect your odometer, correcting it to reflect true mileage with the new tire size? If so, do you enter speed and odo corrections independently, or is this all automatic? And how is it they alter shift points for the tranny downstream?

 

[SpenserAK]

It's all connected. The devices offset the pulse signal to the computer to counteract larger tire size. Your odometer & trip meter count slower because they think the truck is moving slower than it is, thus covering less distance than it really is. Of course, they won't correct the current odometer reading if it's been run without correction for some time, just corrects the speed at which it actively counts mileage. With 315s and stock gears, mine was off by 10-11%. I was able to learn the mileage when the lift & tires were installed, then calculated with the offset, and concluded that my odometer is somewhere around 4,500mi low. At ~230k I don't think it really matters

I'm not sure about shift points. Didn't seem to do anything to mine, at least not noticeably. But on that note - say mine previously went into top gear when speedo said 50, but now it does it when it says 55. The shift point is the same, it's just that the speedo is now showing correct speed. I'm not well versed in all that though, so someone else should have the answer.

 

[Ali SC3]

Okay, so the stock FZJ80 driven gear is 32 teeth. Slee offers a 31 tooth driven gear but that will only make it 3.2% faster. I need about 7% correction. Anybody find a source for a 30 tooth? I already called the dealer and they don't carry it or Toyota doesn't make such a part. I'm trying to find a less costly solution than the Superlift Tru-speed Calibrator.

I am exploring the option of getting a custom Ratio Adaptor. The cost is $90 from
http://www.speedometershop.com/ratio.html

Anybody try this?

Update 1/2025
The diameter is a little smaller apparently and the speedo stopped working randomly after a while. Put the stock gear back in and it works fine now. So probably will just keep the stock gear and get the speedo correction box.
-----------------------------

Just wanted to add to this, I found a 30 tooth gear that is used on older pickups, 4runners and some early tacomas.
Didn't want to wire up a digital correction, and couldn't find the info for a 30 tooth on Mud.
So I took a chance on this one and tried it today, and it's very accurate for my 35's, pretty much what my gps says now.
Looks identical to the one I took out except 30 teeth versus 32 teeth.
Part number is 33403-29105. Tires are new 315/75/16 Falken Wildpeak at3w's for reference.

Enjoy

 

[06reg4x4]

Update 1/2025
The diameter is a little smaller apparently and the speedo stopped working randomly after a while. Put the stock gear back in and it works fine now. So probably will just keep the stock gear and get the speedo correction box.
-----------------------------

Just wanted to add to this, I found a 30 tooth gear that is used on older pickups, 4runners and some early tacomas.
Didn't want to wire up a digital correction, and couldn't find the info for a 30 tooth on Mud.
So I took a chance on this one and tried it today, and it's very accurate for my 35's, pretty much what my gps says now.
Looks identical to the one I took out except 30 teeth versus 32 teeth.
Part number is 33403-29105. Tires are new 315/75/16 Falken Wildpeak at3w's for reference.

View attachment 3643119

Enjoy

Is that stock 4:10’s?

 

[Ali SC3]

Yeah stock gears in the front and rear diffs.
The teeth on the speedo wheel were just a hair too short on the 30 tooth one I listed above, stopped working when they wore down some. If someone can find or make the right diameter 30 tooth wheel it does correct for 35s perfect with stock diff gears.

 

[BillyGoatMTB]

Yeah stock gears in the front and rear diffs.
The teeth on the speedo wheel were just a hair too short on the 30 tooth one I listed above, stopped working when they wore down some. If someone can find or make the right diameter 30 tooth wheel it does correct for 35s perfect with stock diff gears.

Looking forward to seeing how this one works out. I have been running the Lutz Controller for a few years now, no issues, works great.

I am curious on a solid gear alternative.

I'm running 35's 315/75/r16 BFG ATKO2 and geared 4:88, the Lutz has been great

 

[06reg4x4]

Yeah stock gears in the front and rear diffs.
The teeth on the speedo wheel were just a hair too short on the 30 tooth one I listed above, stopped working when they wore down some. If someone can find or make the right diameter 30 tooth wheel it does correct for 35s perfect with stock diff gears.

I make have to do this. But don’t u have base gears too? So that would affect the ratio too

 

[06reg4x4]

I make have to do this. But don’t u have base gears too? So that would affect the ratio too

Fully nerding out on this. Found this list that’s helpful. Pull your vin on partsouq to find the oem gear your truck uses. Then make sure you use the correct part number for your installed worm gear in the case.

 

[Ali SC3]

I did underdrive gears in the transfer case but those don't affect the speedo since it runs off the transfer case output shaft worm gear.
Basically only different gears in the front and rear diffs throw off the speedo, along with of course tire diameter changes. For 35" tires and stock diffs, 30 tooth was perfect. I may just try the 31 if it's the correct diameter as i didn't find a 30 tooth the right size but not even sure the 31 tooth is a perfect match yet either. Some have been tried in this thread already I need to read back through from the start just going off memory right now.

What's your setup, may be able to guess how many teeth will get you close.

 

[06reg4x4]

I did underdrive gears in the transfer case but those don't affect the speedo since it runs off the transfer case output shaft worm gear.
Basically only different gears in the front and rear diffs throw off the speedo, along with of course tire diameter changes. For 35" tires and stock diffs, 30 tooth was perfect. I may just try the 31 if it's the correct diameter as i didn't find a 30 tooth the right size but not even sure the 31 tooth is a perfect match yet either. Some have been tried in this thread already I need to read back through from the start just going off memory right now.

What's your setup, may be able to guess how many teeth will get you close.

Stock gears and 315’s mine factory has

33403-69235 N=32, MARK 32:12

When I ran the vin. I think I need.

33403-69225 N=31,MARK 31:12

The one u used is for a 11 worm drive. I think that’s why it chewed up your last one.
33403-29105 30 teeth (for 30:11)

 

[Ali SC3]

Got it, missed the 12 tooth part. Haven't come across a gear for 30:12 yet which would be good for 35s. 31:12 is probably more right for 33s. Let me know if you do find a 30:12 tooth or I may just get the same 31:12 tooth everyone is using and call it close enough.

 

[BILT4ME]

Got it, missed the 12 tooth part. Haven't come across a gear for 30:12 yet which would be good for 35s. 31:12 is probably more right for 33s. Let me know if you do find a 30:12 tooth or I may just get the same 31:12 tooth everyone is using and call it close enough.

Why not get a Lutz calibrator and be done? (Unless you have a 91-92)

 

[bicycleagent003]

Wow, this is good intel. I'm more interested in the odometer being correct than the speedo, but I guess if one's right the other one is, too.
Does anyone know what gear I would use for the 10% underdrive high range Sumo gears in a 1996 US spec TLC on 33's?
Thanks!