:confused:I was just on a long road trip and about 2/3 way through the trip my speedometer started jumping around eratically i replaced the tone ring sensor but that didnt work if anyone has an idea my truck is a 93 f250 4x4 with a 7.5l and sterling rear 10.25 auto tranny

I have no idea if this even applies to the new rigs, but in the old days when we'd have a speedo start getting bump like that we'd pull the cable and spray some graphite down it. Cure it right up.

I have no idea if this even applies to the new rigs, but in the old days when we'd have a speedo start getting bump like that we'd pull the cable and spray some graphite down it. Cure it right up.

It's hard to spray graphite down a set of wires, but you are welcome to try. :flipoff2:

Did you try cleaning/replacing the sensor on the diff? Thats where I would have started.

ya replaced the sensor but nothin happened

It's hard to spray graphite down a set of wires, but you are welcome to try. :flipoff2:

Yea, I figured the new stuff was all wires and sensors but I did qualify my response with I don't work on the new stuff :D

Still, a little lube is always a good solution to pretty much any problem:homer:

The 460 should have a trans mounted speed sensor too.

where would that be located at on the trans?

Still, a little lube is always a good solution to pretty much any problem:homer:

A-men Brother.

The 460 should have a trans mounted speed sensor too.

I've never seen one. even behind the 460, the only speed sensors I've seen were later on the newer 4R100 tranny

To the origonal poster, does the speedo jump at high speed, low speed, both? Is the ABS light on? has the cover been off the diff lately? (possibly damaged tone ring itself)

Still, a little lube is always a good solution to pretty much any problem:homer:

It never hurts...

A-men Brother.

To the origonal poster, does the speedo jump at high speed, low speed, both? Is the ABS light on? has the cover been off the diff lately? (possibly damaged tone ring itself)

It starts jumping around 35-40mph all the way up to 80. ya the cover was off about 3 weeks ago for a service. abs light is not on

is the check engine light on???abs light on???does the cruise control work???does the trans shift the same as before???was there any debris on the rabs sensor indicating an internal axle problem???the sensor in the rear axle is the input to all those thing i listed as well as the speedo

You said you replaced the sensor, & the ABS light is not on, so I wouls suspect the tone ring itself, or the speedo head, take the diff cover off & look for any damaged teeth on the tone ring, if you do not want to pull the conver you could remove the sensor & peer in the hole with a flash light, but I would pull the cover, (easier to see damage) if all looks good I would lean towards the speedo head,

okay ya no lights are on cruise works but it acts up cause of the needle bouncing there was no debri on the sensor but there were some shavings in my diff when i pulled the cover last time ill check the ring and see where i end up thanks for your input