Speedo Correction - What do you use? (1 Viewer)

[LC4LIFE]

More info in this thread:

Speedo drive gear options?

I'm nearly finished changing my diff ratio to 3.7 and just wondering if anyone knows the part number for the speedo gears to suit 3.7? I currently have the 32:12 speedo gears which suit the 4.1 diff ratio but I know the 80 series also came out as 3.7 diff ratio in certain countries/models so I'm...

forum.ih8mud.com

Many of the gears seem to be NLA, but some are still available overseas.



You can get up to about 20% correction with various OEM transfer/speedo gear sets. Which is WAY more than anyone would need. If you're off by more than 10% you really need to re-gear..

Very interested, please provide examples of the transfer/speedo gears that correct 10% or more.

Thanks.

 

[TurboDennis]

Very interested, please provide examples of the transfer/speedo gears that correct 10% or more.

Thanks.

All the possible gear ratios are in that thread. 31:14 combination (for example) will provide 17% correction

 

[DSRTRDR]

I can actually calculate it in my head

 

[amgraham]

I just installed my yellow box the other day after running my ultragauge for a couple years to display correct speed.. Got the plug and play harness. It took forever to get (like, over a month). I just plugged it in and ran the cable temporarily through the back door. Played with it a couple days until I was happy and then bagged and taped it and zip tied it up over the fuel tank. I didn't really see and good place to run it up into the cab but I won't need it again unless I change tire size or gearing. If I had to do it over again I wouldn't have gotten the plug and play harness since apparently you can tap it into a harness behind the glove box.

Good news is it did help my shift points and will now kick down into passing gear without having to drop the shifter manually.

 

[logicbyondreaso]

@amgraham - do you have more info on the tapping behind the glove box? I saw this for the 100 series but not the 80. That would be best option if it’s possible. Any details greatly appreciated.

 

[amgraham]

@amgraham - do you have more info on the tapping behind the glove box? I saw this for the 100 series but not the 80. That would be best option if it’s possible. Any details greatly appreciated.

Search around. I think it was @LandCruiserPhil who was talking about it.

 

[thatcabledude]

@amgraham - do you have more info on the tapping behind the glove box? I saw this for the 100 series but not the 80. That would be best option if it’s possible. Any details greatly appreciated.

Search around. I think it was @LandCruiserPhil who was talking about it.

I also tapped in behind the glovebox. Doing any of that under the truck is just silly.

I can tell you from memory it's a red wire w/ green stripe located at pin 1 on the IH1 connector near the ECU behind the glovebox.
*on 93-94 year models*

Not sure on OBD2 trucks.

 

[midfat]

Reviving this thread. Have had a Marks4WD in the drawer for several years, but just got around to installing it yesterday. I’m running 37s with 4:88 gears on my ‘97. “Program 1” (OEM tire size) is set to 275/70r16. “Program 2” is set to 37x17. My speedo is way off on Program 2, but seems pretty close on Program 1, which makes no sense as that’s supposedly factory wheel setting. What am I missing on the set up? Should I convert the Program 2 to metric tire size (330/75r17)? And by off, I mean like 10-12mph.

 

[SpenserAK]

Did you take your gearing into account? If they put you back near stock ratio with 37s, your findings make sense to me. Does the tool have an adjustment for gears? I’m not familiar with that one, using yellr box myself

 

[midfat]

Did you take your gearing into account? If they put you back near stock ratio with 37s, your findings make sense to me. Does the tool have an adjustment for gears? I’m not familiar with that one, using yellr box myself

Tool doesn’t have an adjustment for gears, but I’m guessing you’re correct. The speedo sensor is on the transfer case front drive flange, so axle speed is relevant to the diff gear ratio. I think the plan is to program the second set of wheels at OEM size, then trim the percentage to get it exact.