1957 - 1960 F100 & Larger F-Series TrucksDiscuss the Box Style Ford Trucks
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Well, speedometer quit working on one of the F600s (1960) Started checking things and the cable was OK. When I disconnected the cable I noticed the output housing on the transmission (a T98A) was loose and rotated a bit. All bolts holding it on were less than finger tight. Dropped driveshaft, removed parking brake assembly, and removed output housing. The speedometer driven gear was stripped. But the drive gear looks very good.
If you have a T98A four speed transmission with a transmission mounted parking brake, you might want to check that your output housing bolts are not loose. It looks like as the housing rotates that little bit to take up the bolt to bolt hole clearance it is enough to let the speedometer driven gear disengage enough to lose mesh and start stripping.
Reassembled everything, and all I need now is a new speedometer driven gear. Old one is a 20 tooth, part number 01T 17271C, but going by the parts book, with the axle ratio and tires I have I should be using the 21 tooth 01T 17271D. I have done some looking, but have not found one yet. Anyone have any ideas on where to look?
I checked several places, and no one had the 21 tooth, but I found a 20 tooth at Antique Auto Supply. I eally wanted to find the proper combination of drive and driven gears to get a good speedometer reading, but no one that I called had what I am looking for. But at least the 20 tooth will give me a working speedometer.
I just wish I had found the loose bolts before the gear stripped.
Very common problem on many trucks with the transmission mounted parking brake. My belief is that's caused by not coming to a complete stop before you reef on the parking brake. When you do stop doing that, you will notice the torsional twist in the driveline causes the truck to rock fore and aft a couple times and all that movement is going right to those mounting bolts.
Well, all the parts came in and I put everything back together. Speedometer worked great for about a half mile, then started jumping wildly, then quit. Now to start taking things apart again to see what is going on. Going to start at the speedometer and work my way back. (by the way, everything was lubed, and no sharp bends in the new cable)
Well, had only a little time over the weekend to get into this. Removed new seedometer cable - it was seized solid, core would not turn or move. Put the old speedometer cable back on (it still turned ok) and speedometer did not work. Now to tear everything apart again.
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