Speedo gear chewed

bear108 · Oct 1, 2006

Was working on my car over this weekend and at one point I removed the speedo cable and gear. The tranny is only a few years old with about 14,000 miles on it. When I had new gears put in, I replaced the speedo gear on the cable with the white one. It was the closest to the correct speed. Problem is, when I removed the cable and the gear, about 2/3 of the depth of the gear has been chewed off or worn down. It does still work fine, but it has me a little concerned. Is this a normal thing to happen with not that many miles on it? Should I just leave it be or replace it and hope for the best?

jrichker · Oct 1, 2006

The white gears tend to self destruct for some guys. Others run them and have no problems. It's a crap shoot: roll the dice and see what happens.

Check to see if there is a speedometer shop in your area. If there is, ask about the Stewart-Warner speedometer gearbox. I believe it is either a 777 Series Drive Joint Kits and Parts or 666 Series Drive Joint Kits and Parts. It is a small gear box that fits between the speedo pickup gear on the transmission and the speedometer. It has quick change gears that allow you to choose almost any tire size and rear end gear ratio you want. This will allow you to get the accuracy with within 1%-3%. The drawback is that it isn't cheap.
Please excuse the typo (their's, not mine) in the following picture - it should read Custom ratio adapters, not Custom radio adapters.

See http://www.gaugeguys.com/ratioadapt.htm for more info.

Roland69 · Oct 1, 2006

replace it for the $7 they cost from a ford dealler

2000xp8 · Oct 1, 2006

Only the stock speedo gear has perfect matching teeth. Any change of gears, tooth count won't line up correctly causing it to slowly eat itself.
It can be fixed by replacing the gear inside the trans, but that's usually more trouble than it's worth.

Roland69 · Oct 1, 2006

even if you need to change the speedo gear once every year or 2 it's only a 5 minute job.

TRWXXA · Oct 2, 2006

The 23-tooth gears get chewed up very easily. The teeth on them are much thinner than the ones on the other gears. Expect them to last anywhere from 6 months to 2 years depending on how much you drive. They can get quite chewed up before you'll see the telltale, bouncing speedo needle that warns you that it's time for a new gear.

dls322 · Nov 6, 2006

Roland69 said:
even if you need to change the speedo gear once every year or 2 it's only a 5 minute job.

I need to change my speedo gear out after my 4.10 gear swap. Is there a write up out there how to do this? I don't have to open up the tranny do I?

millhouse · Nov 6, 2006

The reason the white gears get chewed up is because they have the wrong pitch. They are not a ford gear…but I believe a DCX one instead. They do seem to work for most…but you should consider them a consumable. Plan on replacing them every year or two….or whenever you start to notice your speedo acting flaky.

Chuckman · Nov 6, 2006

dls322 said:
I need to change my speedo gear out after my 4.10 gear swap. Is there a write up out there how to do this? I don't have to open up the tranny do I?

its very easy, just follow the speedo cable to the tranny, undo the one bolt, wiggle the cable out, pry the clip off, take the old gear off, put the new one on, replace the clipe, reinstall the cable and bolt it down. just make sure the new gear sits all the way on the cable, i bought a tci piece from summit and had to get an xacto knife to clean out the flash on the inside of the gear to make it seat right, dont know if a genuine ford part would have this problem or not.

dls322 · Nov 6, 2006

Chuckman said:
its very easy, just follow the speedo cable to the tranny, undo the one bolt, wiggle the cable out, pry the clip off, take the old gear off, put the new one on, replace the clipe, reinstall the cable and bolt it down. just make sure the new gear sits all the way on the cable, i bought a tci piece from summit and had to get an xacto knife to clean out the flash on the inside of the gear to make it seat right, dont know if a genuine ford part would have this problem or not.

Thanks
I see the speedo gears on ebay all the time. My speedo is jumpy when your doing around 10-15 mph, then goes up smooth, it's about 20mph off I assume. Is there a way to know if the speedo cable needs to be replaced too?

2000xp8 · Nov 6, 2006

dls322 said:
Thanks
I see the speedo gears on ebay all the time. My speedo is jumpy when your doing around 10-15 mph, then goes up smooth, it's about 20mph off I assume. Is there a way to know if the speedo cable needs to be replaced too?

The cable is not that expensive, if you think it may need replacing, just eliminate it as a possible problem and just change it.
Only use a REAL ford cabe, the rest are crap.

Blk91stang · Nov 6, 2006

I have a white one for my 3:55's and it is all chewed up also. I just leave it since it still works, a little jumpy, but still works and whats the point in replacing it if it's just gonna get chewed up again.

If it still works at higher speeds, forget about it

$uperstang · Nov 7, 2006

just leave it 4:10's here and the same problem all though mine is about 12 years old

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