How to install speedo correction gearbox?

[Demonic92]

I went from 31's to 33's on my 91 FJ80 and now the speedometer is off 1-6mph depending how fast I'm going, meaning I'm also not tracking gas mileage, etc correctly.

I saw that a member here with I think a 70 series had Deluxe Speedometer in Denver build them a custom speedo correction gearbox with good results, so I did the same. I couldn't use the plug-in solution as the speedometer was fully cable-driven for 1991 MY.

Now I just need to install it! But I'm a little confused on how to. The speedo cable goes from the transfer case to the back of the speedo, with the cruise control speed senor in between the transfer case and the speedo cable. So my question is, where do I install the speedo correction gearbox? In between T case and cruise control sensor? Between cruise control sensor and speedo cable?

I also have a sizeable leak coming from where the speedo cable leaves the t case. Do we think this is just the O-ring in there that's easy to replace, or something more involved? How to tell?

I tried figuring it out using the FSM but I may not be smart enough. Thanks in advance.

 

[Marvelicious]

I'm just taking a guess at it, but I would think either would work. The cruse control on the 80 is a fairly low tech "dumb" system. It doesn't much care how fast you're going, it just tries to hold things where you have them set.

 

[GORDA91]

I went from 31's to 33's on my 91 FJ80 and now the speedometer is off 1-6mph depending how fast I'm going, meaning I'm also not tracking gas mileage, etc correctly.

I saw that a member here with I think a 70 series had Deluxe Speedometer in Denver build them a custom speedo correction gearbox with good results, so I did the same. I couldn't use the plug-in solution as the speedometer was fully cable-driven for 1991 MY.

Now I just need to install it! But I'm a little confused on how to. The speedo cable goes from the transfer case to the back of the speedo, with the cruise control speed senor in between the transfer case and the speedo cable. So my question is, where do I install the speedo correction gearbox? In between T case and cruise control sensor? Between cruise control sensor and speedo cable?

I also have a sizeable leak coming from where the speedo cable leaves the t case. Do we think this is just the O-ring in there that's easy to replace, or something more involved? How to tell?

I tried figuring it out using the FSM but I may not be smart enough. Thanks in advance.
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Leak is probably just the o ring. Easy to swap out.

 

[steve578]

I would like to do this for my 1991 on 33’s. Would you mind sharing how much it cost and how long the wait was?

 

[Demonic92]

I would like to do this for my 1991 on 33’s. Would you mind sharing how much it cost and how long the wait was?

Sorry for late response.

The custom correction gearbox was $170 after tax, from Deluxe Speedometer in Denver. Just give them a phone call and you will discuss form factor and all of the other things then. I highly recommend taking some measurements of how far the speedo is off by using a GPS speedo app on your phone and comparing it to actual speedo reading. You can always just tell them "I went from 31x10.5s to 285/75s" but those numbers will help fine-tune the gear ratio. After my phone call and payment, it was on my front porch in maybe 3-5 days. Can't remember.

Should be pretty easy to install. As you can tell, I have not gotten there yet.

 

[Rusty Marlin]

Do it electronically with one of these...https://www.lutzauto.com/product-page/80-series-landcruiser-lx450-speedometer-calibrator
That way if you change, gears or tires in the future you can dial it in to perfect.
I've had one for years now and they work a treat.

 

[Demonic92]

Do it electronically with one of these...https://www.lutzauto.com/product-page/80-series-landcruiser-lx450-speedometer-calibrator
That way if you change, gears or tires in the future you can dial it in to perfect.
I've had one for years now and they work a treat.

Great product, wont work for 1991-92.

 

[steve578]

Installed mine this morning. If you haven’t already figured out the order, the adapter goes in between the speedo gear and cruise control sensor.

I replaced the o ring seal. I wish I had ordered the internal seal as it needs to be replaced too.