Speedo gear for 88 F`150

Hi ,

I got a free truck. It’s in fine shape for it’s price. Old owner was not mechanicaly inclined and did not need the truck. I have fixed the 4 wheel drive, I wonder about the gas gauge, it only is accuratew from 1/8 full to empty on bvoth tanks otherwise it reads over full. The question of the day is what driven gear does the speedo need? This seems to be a question like "What is the secret of the unaverese or somthing. Yhe locaL trans shop told me to drive at 60 and see how long it takes to go between 21 mile posts. Without a gear spreed stays at 0 The ford parts guy asked what color is itr? I don’t know because it’s not there. The truck hasa 5 speed manual 4X4 and 3.55 rear axle. I can’t borrow one from my 80 0r 93 fords because they are auto trans.The druck drives about 12 miles to work across the Wyoming planes 4 days a week and into town maby 2 times a month. Since it’s an old truck I don’t go fast burt I dn’t want th go two slow(10 miles under the speed limet seems correct for an uygly old truck. I am mounting my plow on this truck to getr in and out of my yard.

The speedometer is driven by 2 gears.

The drive gear is inside the transfer case tail housing, # E7TZ-17285-B. As you look into the hole where the cable came out of you should see the tops of all the teeth as being straight accross, if the tops of the teeth are worn to a slight U replace the drive gear too.

The driven gear is on the end of the speedo cable and is yellow 18 tooth # CODD-17271-B.
Since you say it’s not there, you probably need it’s retaining clip #C1DZ-17292-A also.

Your Ford dealer can still order these but test spin the cable first to be sure it’s good.

Once he puts in the gear(s), he can check if they’re right by timing the mile posts. If the tires are non-stock sized, he may need a different gear.

Yes, the OP didn’t say tire size.
These parts numbers are for OE, P235/75R15
Change only the driven gear for 5mph per 1 tooth difference.

Cable and speedo work correctly. Currently running stock tires, Had a set of stock studded snows on anouther truck when I got this truck. May go a little larger at some point. I will look in the holew left by the cable for the drive gear before I order a new driven gear. Do you know a place on the web to see an exploded drawing of the gear and retaining clip?

Once you get the speedo working borrow someone’s gps and that will have a mode which will show the actual speed you are going. If isn’t too far off then you’ll how the speedo reading relates to your actual speed. If it is way off you can try some different gears to get a more accurate speedo indication.

I buy speedo gears from this site for my older trucks. The dealers no longer have many of the speedo gears for the older Ford, Dodge and Chevy transfer cases.