Jumping speedo

[littlebro294]

I have a 94' ford explorer sport with a 4.0, 2 wheel drive, my speedo when it gets to 55+ mph the needle starts to jump or "bounce" around across the gauge. I dont have 4 wheel drive so it cant be the gear in the transfer case. Is there a gear in the tranny? or would it be the speedo spring? if so how does this get replaced? ive had this problem for awhile now but havent paid much attention to it but it gets annoying at times so i figured if i can figure out what exactly the problem is i will just fix it if it is an easy and semi cheap fix.

 

[Maniak]

You still have a driven gear (end of the speed cable) and a drive gear. In your case the drive gear is in the tail of the transmission instead of the transfer case.

The driven gear is easy to change.. The Drive gear, I don't now on the 2wd.. The Drive gears wear so they are concave (center is lower than the edges) which can make things bounce and can even cause the driven gear to wear out quickly.

~Mark

 

[littlebro294]

ok, so should i pull the driven gear and check it? i've never been the biggest on transmissions so i dont know much about them. They and expensive part?

 

[FR-425]

Ford speedometer "driven" gears are generic. (fits almost any ford)

The different colors represent the number of teeth on the gear.

Any auto parts store will have these for about $10.

The "driven" gear usually fails way before the "drive" gear.

You may also need to pull the speedo cable out and lube it.

Once you disconnect from the speedo, (top end) a quick shot of WD-40 will do.

 

[FR-425]

Oh, it's right here in the tail housing.

One bolt and a horse-shoe clip, and pull it out.

No need to disconnect the cable, just pull it out with the cable still on.

 

[Maniak]

Also, The Manual transmission driven gear is the same as the 4x4 driven gear.

The Automatic 2wd trans driven gear is the odd-ball.

From looking at that pic above, IF the drive gear needs to be pulled it looks like pulling the tail shaft housing off makes it easy to get to.. You just pull it off the shaft by pulling it towards the back of the vehicle..

You can "feel" the drive gear (and even see it) once you pull the driven gear out of the trans. It should be flat across the length of it.. if the center is worn (lower) then the drive gear is bad.

~Mark

 

[FR-425]

Duh, I'm not sure why I assumed it was auto?

 

[littlebro294]

it is a 5 speed, and thanks guy i will take a look at it when i can hop down there

 

[Jason94sport]

Any auto parts store will have these for about $10.

Not in my area...dealer was my only option.
I recall someone had this problem & said it was the gears inside the trans that were worn. I had this problem on a 94 5 speed as well. Nothing i did fixed it. I sold it with it still bouncing. Tried a new cable, new cluster, & new speedo gear.