Speedometer Woes, very slow reading

Well now that I am driving the bronco I see that my speedometer is not working right. I finally remembered the GPS and it looks like 10 on the speedometer is 26 in GPS and 20 on speedo is 45 in GPS. 22 is about 50.

I have an NV3550, 31" tires, a 17 tooth speedo gear, a brand new speedo cable, and the cluster was rebuilt before I put it back in. It didn't work at all before that. The speedometer was a mess, it was in pieces internally when the re-builder took it apart.

Does the new transmission mess up any of this? Time for a new cluster or is there more tweaking that can be done?

Thanks,
Jason

It's not a speedo gear issue. Your tire size and tooth count are about normal. Your speedo is reading 44% what it should be and I assume you didn't put 1.50 gears in the axles. You would need a 7 or 8 tooth driven speedo gear (not available) to correct that error. I'd say the speedo head is not working correctly.

Trans makes no difference.

That's kind of where I was leaning but I am not familiar with the insides of a speedometer. What's inside there? Anything that can be tweaked or is it toast?

Jason

Drive a mile and see how the odometer is.
When it is this far off, it sounds like there is an issue with the speedometer head. Maybe lost a magnet off the eddy current generator?