This is what happens...
 

when you put the wrong speedo gear in for your 3.73's...
(I needed the red gear, not this one)

not quite as dramatic as a split block...though

I'm confused, I thought any gear would physically work. Just that it would adversly effect the reading on the speedometer. Is this a Ford speedo gear or a cheapy?

Yeah, I did the same thing... Used the white one when I needed the red one.

The speedometer was clearly off for the 2 minutes that the gear survived.

That is what ussually happens, Ford doesn't make a gear to fit perfectly. The gear you got is aftermarket. The best way to avoid the problem is to replace the driven gear in the tranny and use the correct ford speedo gear.

checking...
 

yeah, I'm going to give my red one a shot and check it in a week or so.

that white gear is actually made by Chrysler. Ford doesnt make one that works with the T-5 with 3.73 gears, and the Chrysler one is the closest one that works. I have that one in mine, and its chewed up pretty bad (not as bad as yours) and it still works. Its actually very accurate on the highway too

FMS made my red one...
 

FMS box and everything...
The white one didn't come in a box, but the red one did.
I'll get the part number...

Wait, I have 3.73's and the white speedo gear. When I got my geas installed, they told me that they changed that part out. Did they lie to me? I haven't had any problems with my gear and the teeth.

no, you are okay...
 

red gears are for t-5/3.73 combos through 89'.

I have a T-5 out of a 91, thats why I have the white gear.

Cyberstang, have you taken your gear out to look at it? If not, then I'd suspect that it looks atleast halfway similar to the picture above. Mine sure does, but it is still working fine.

I actually talked to a guy at Kenny Brown's shop about this because they do alot of gear installs, and he's the one that told me it gets chewed up because its a Chrsyler gear. He says to change it once a year because of that. I've actally had mine in there for about 1.5 years now and the speedo is still working just fine. Guess I'm luckier than Hozer ;)

Same here, 3:73 and the white gear in my 91. Mine's survived almost 3 years, the accuracy seems ok but it looks worse than that one.:eek:

Yes, I have pulled my gear out when I swapped to my TKO and the gear is white. I've had my 3.73's for almost 2 years now. The gear looks like it is new. There isn't any missing teeth or chips in it. I'm thinking because my TKO has different gear ratios then my T5, that is why my speedo is off by 10 mph. My speedo ran right on when I had my T5.