Troubleshooting Speedo/Odometer

Post by **ScottBarnes** » Fri Mar 23, 2018 3:12 pm

My speedo has been doing the dance for a while, and that doesn't really bother me. But now, it stopped all together along with my odometer. I NEED my odometer! Both ends of the cable are attached, so not really sure the best way to troubleshoot. Is there a "90% chance it's [this]"?

Also -- where does the "gear" go -- speedo side or transfer case side? and what tooth count do I need w/33" tires and 4:10 gears?

Post by **cpldavis37** » Fri Mar 23, 2018 3:39 pm

You can purchase the gear from Toms, Wild horses, Bronco Hut probably sells them locally.

There is a retaining clip on the transfer case side of the cable that holds the gear on. Check to see if it is still attached. While it's disconnected from the t case you can spin the gear. I did it with a drill. It could also be the speedometer and in that case it could need lubrication, but I am not sure what type (Lithium? Graphite?)

Post by **ScottBarnes** » Fri Mar 23, 2018 3:46 pm

cpldavis37 wrote:You can purchase the gear from Toms, Wild horses, Bronco Hut probably sells them locally.

There is a retaining clip on the transfer case side of the cable that holds the gear on. Check to see if it is still attached. While it's disconnected from the t case you can spin the gear. I did it with a drill. It could also be the speedometer and in that case it could need lubrication, but I am not sure what type (Lithium? Graphite?)

Thanks -- I'll try the transfer case side first.

Post by **Eck** » Fri Mar 23, 2018 4:09 pm

If you have felt that your speedometer now is pretty close to accurate, I would just look at what color gear and/or count the teeth when you pull it out of the transfer case. Then just order up the same one if you determine the gear is bad. If not, it could be in need of lubricating the speedometer gauge side. Or.... you are screwed and you'll need to remove and have refurbished...

Post by **cpldavis37** » Fri Mar 23, 2018 4:16 pm

Here is a pic of a clip and gear.

Post by **Jesus_man** » Fri Mar 23, 2018 4:24 pm

I would think graphite would be best lube as it doesn't collect dust.

Oddly, just cruising on cb.com and saw this:
https://lmr.com/products/Mustang-Speedo ... Calculator

Edit again - I read further down the thread and now I see why that thread popped up! LOL!

Post by **ScottBarnes** » Fri Mar 23, 2018 4:32 pm

Eck wrote:.. you are screwed and you'll need to remove and have refurbished...

Yeah, that's not happening before Baja so you'll be the official keeper of the mileage traveled! LOL

Post by **Viperwolf1** » Fri Mar 23, 2018 6:12 pm

I can get you fixed up. I have some Speedo gears. Might need to do minor surgery on the tcase.

Post by **ScottBarnes** » Fri Mar 23, 2018 7:05 pm

Viperwolf1 wrote:I can get you fixed up. I have some Speedo gears. Might need to do minor surgery on the tcase.

Thanks -- I'll take a peek in the morning to see if it's something simple. Minor surgery on a tcase is above my pay grade! HAHA...

Post by **Kinder** » Fri Mar 23, 2018 7:21 pm

I have a spare nearly new cable if needed, I may also have a gear or two. Let us know what you find when you pull the cable.

Post by **Viperwolf1** » Fri Mar 23, 2018 7:32 pm

ScottBarnes wrote:
Viperwolf1 wrote:I can get you fixed up. I have some Speedo gears. Might need to do minor surgery on the tcase.

Thanks -- I'll take a peek in the morning to see if it's something simple. Minor surgery on a tcase is above my pay grade! HAHA...

Pull the cable out of the tcase. The driven gear will be on the end of it. Look inside the hole that gear came out of. You'll see the drive gear. That gear should be centered in the hole. If it isn't centered it won't turn the driven gear. Make note of the color of the drive gear too. They are either green or blue. The difference is the tooth count, either 6 or 7.

speedo gear chart.JPG

Post by **ScottBarnes** » Sat Mar 24, 2018 9:20 am

Viperwolf1 wrote:
ScottBarnes wrote:
Viperwolf1 wrote:I can get you fixed up. I have some Speedo gears. Might need to do minor surgery on the tcase.

Thanks -- I'll take a peek in the morning to see if it's something simple. Minor surgery on a tcase is above my pay grade! HAHA...
Pull the cable out of the tcase. The driven gear will be on the end of it. Look inside the hole that gear came out of. You'll see the drive gear. That gear should be centered in the hole. If it isn't centered it won't turn the driven gear. Make note of the color of the drive gear too. They are either green or blue. The difference is the tooth count, either 6 or 7.
speedo gear chart.JPG

its not clocked in a way that I can get a view, but when I stick my finger inside it ΓÇ£feelsΓÇ¥ somewhat centered at the top of the gear. ItΓÇÖs blue. The gear on the speedo cable has some teeth grooved out, which could definitely cause the jumping of the speedo I would think. But itΓÇÖs completely inop now. I pulled the wrong part first and exposed the cable. It spins easily with my fingers - just not sure if thatΓÇÖs spinning all the way to the speedo, but it sounds like it is. Now I canΓÇÖt get that darn clip back on though.

Post by **Eck** » Sat Mar 24, 2018 9:36 am

IΓÇÖve got one that I tried but threw my speed off so practically brand new. IΓÇÖll bring it tomorrow.

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Post by **ScottBarnes** » Sat Mar 24, 2018 9:56 am

Eck wrote:

IΓÇÖve got one that I tried but threw my speed off so practically brand new. IΓÇÖll bring it tomorrow.

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thanks Mike - since IΓÇÖve got it apart, IΓÇÖm going to do a little research and try to get one that matches my tires/gearing because this one was about 10 mph off at 50 mph speed.

Post by **ScottBarnes** » Sat Mar 24, 2018 11:24 am

Also - I did confirm the cable to the speedo is ok because I connected it to the drill and moved the needle. Tip for anyone doing that - it spins to the left (counterclockwise). Took me a couple tries to figure that out.

Post by **Viperwolf1** » Sat Mar 24, 2018 11:33 am

ScottBarnes wrote:Also - I did confirm the cable to the speedo is ok because I connected it to the drill and moved the needle. Tip for anyone doing that - it spins to the left (counterclockwise). Took me a couple tries to figure that out.

How many teeth on the red gear? Looks like you need 17 or 18.

Post by **ScottBarnes** » Sat Mar 24, 2018 11:39 am

I counted 16 now, and it's off for sure. I'm running 33's w/4:11's. Any tips for getting that stupid clip back in that holds the cable into that adapter? Also -- based on the pics, are you thinking a new gear will resolve this issue?

Post by **Viperwolf1** » Sat Mar 24, 2018 11:54 am

ScottBarnes wrote:I counted 16 now, and it's off for sure. I'm running 33's w/4:11's. Any tips for getting that stupid clip back in that holds the cable into that adapter? Also -- based on the pics, are you thinking a new gear will resolve this issue?

Looks like you need to push the black plastic into the aluminium piece some more to expose the slots.

Yes, I think a new gear will do it.

Post by **Viperwolf1** » Sat Mar 24, 2018 12:58 pm

I have an 18 tooth gear. Your speedometer must have been reading fast with the 16?

Post by **ScottBarnes** » Sat Mar 24, 2018 2:20 pm

Viperwolf1 wrote:I have an 18 tooth gear. Your speedometer must have been reading fast with the 16?

Awesome! I'll txt you and figure out a way to get it. Yes, it was reading fast. I mis-stated above - had it backwards.

Post by **ScottBarnes** » Mon Mar 26, 2018 10:23 am

New gear got my odometer rolling again. 18 tooth (thx Phil!) has my speedo reading 50 when actual speed is 40 (based on gps phone app). IΓÇÖm wondering if my terra lows have something to do with this? I honestly donΓÇÖt care much about that, though. My odometer is working and thatΓÇÖs the big deal. Thx for the help.

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Post by **Eck** » Mon Mar 26, 2018 10:31 am

ScottBarnes wrote:New gear got my odometer rolling again. 18 tooth (thx Phil!) has my speedo reading 50 when actual speed is 40 (based on gps phone app). IΓÇÖm wondering if my terra lows have something to do with this? I honestly donΓÇÖt care much about that, though. My odometer is working and thatΓÇÖs the big deal. Thx for the help.

Yah but your odometer will move 10 mph faster meaning you are putting a lot more miles on your odometer than you are actually going (so whether you are using it to track actual distance or to keep track of how many miles are on your Bronco for things like value, etc.) you will be way off...

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Post by **Jesus_man** » Mon Mar 26, 2018 1:45 pm

No, you're tera low shouldn't affect it as I am certain in 2WD or 4Hi, it's still 1:1. You're still 20% off. Corrected by another speedo gear, tire size, or axle gears. In order of expense.

Post by **Viperwolf1** » Mon Mar 26, 2018 4:48 pm

ScottBarnes wrote:New gear got my odometer rolling again. 18 tooth (thx Phil!) has my speedo reading 50 when actual speed is 40 (based on gps phone app). IΓÇÖm wondering if my terra lows have something to do with this? I honestly donΓÇÖt care much about that, though. My odometer is working and thatΓÇÖs the big deal. Thx for the help.

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It's actually 25% fast. That is very unusual. We can swap to a 21 tooth gear but that is probably not even enough teeth. 6% per tooth. You should check the accuracy of the odometer. It is separate from the speedometer and it may be more accurate for the 18 tooth gear. The speedo could have a problem with the magnet.

Post by **ScottBarnes** » Mon Mar 26, 2018 6:58 pm

Viperwolf1 wrote:
ScottBarnes wrote:New gear got my odometer rolling again. 18 tooth (thx Phil!) has my speedo reading 50 when actual speed is 40 (based on gps phone app). IΓÇÖm wondering if my terra lows have something to do with this? I honestly donΓÇÖt care much about that, though. My odometer is working and thatΓÇÖs the big deal. Thx for the help.

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It's actually 25% fast. That is very unusual. We can swap to a 21 tooth gear but that is probably not even enough teeth. 6% per tooth. You should check the accuracy of the odometer. It is separate from the speedometer and it may be more accurate for the 18 tooth gear. The speedo could have a problem with the magnet.

got it - IΓÇÖll test odometer tomorrow - thx

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