I've noticed my speedometer can get quite goofy at times, it's inaccurate then seems dead on for a while then slows down or speeds up while at a steady cruise. Here's how I found this out: Drove the truck to a truck show locally, took a relatively flat turnpike type road to get there and back. I set the cruise control to 70 MPH and settled in for a nice cruise. Noticed it indicated I slowed, but it didn't feel like it. Whenever taking hills, I could tell the cruise would compensate by pulling the throttle and going down hills it let out of the accelerator. It's a Dana speedostat system with speedometer cables going in/out. I recently had it apart, cleaned and greased it all, and sealed the servo to backing plate to prevent leaks. Tested it and it worked well, set it to 80 MPH, hit resume from 50 and it took off like a rocketship right to 80 and stayed there. This speedometer issue cropped up recently. I also noticed it likes to stick high for a spell if I goose it and let out. Just weird.
Anyway, I think the problem lies either in the cable from the speedostat to the speedometer or in the speedometer itself. Question is, is there anything I can do to the speedometer to clean/lubricate it? I searched this and drivetrain forums and came up with little about the speedometer head itself. I'd hate to pull it all out only to find it's a sealed assembly serviceable only by nuclear physicists with PhDs who have underwater basketweaving minors.
1969 F-250 390 Camper Special
Candy Apple Red/Wimbledon White
I think I would try to get a known-working-part and swap it out temporarily. Once you see the results, you can either try to buy the speedometer or get a new cable.
Alternatively, replace the cable and hope for the best.
Bill
68 F100 Ranger
73 F100 Ranger XLT
Believe me, my young friend, there is nothing - absolutely nothing - half so much worth doing as simply messing about in garages. (Apologies to Kenneth Grahame.)
I'll do what you recommended. Start with easy and work my way in. The cable's accessible enough. I'll try some lock-ease graphited oil on the cable and see where that takes me. Thanks.
1969 F-250 390 Camper Special
Candy Apple Red/Wimbledon White
first take your speedometer out. i highly reccomend ballistol as a lubricant in this particular application. kroil or a graphite impregnated lubricant may work as well. place a small drop of lubricant on the back side of the speedometer needle where the shaft of the needle engages the rest of the parts. i like to use a oil can that has the flexible base so that single drops can be applied. see if that helps. do not move the needle by hand to work in the lubricant. let it do the work by itself while running. if that does not work i would replace the speedometer cable first. make sure speedometer cable is well lubricated. if needle is still bouncing get another speedometer. i'm on my 2nd speedometer from a junk yard and my 3rd speedo cable. none of this crap holds up. whether it's aftermarket or oem. just purchase a used speedomoter off of ebay or something if it comes down to it. in the mean time i would start collecting parts for your dream gauge setup like a f600 gauge plate.
i wish some of these talented ford guys would throw up some copies of the gauge plates they have made for sale. theres a couple i would spend some bones for
I have Aerokroil (aerosol Kroil), stuff is amazing. I watched it creep through a fully rusted bolt/stud assembly and spun it off with a ratchet after I failed to disassemble with a breaker bar dry. I thought I was going to have to use the fire wrench, but reached for this first. I'm a disciple now. I heartily recommend it for disassembly of anything mechanical. It will eat through sensitive stuff though, so I'm careful using it near plastic parts. Absolutely powerful stuff for stuck spark plugs, it chews right through carbon build up.
1969 F-250 390 Camper Special
Candy Apple Red/Wimbledon White
I am in need of a speedo cable, I visited several yards and searched everywhere on the web for one. I am in the process of installing new dolphin gauges on my bump and I need a speedometer cable. Perhaps you could chime where to find them.
Believe me, my young friend, there is nothing - absolutely nothing - half so much worth doing as simply messing about in garages. (Apologies to Kenneth Grahame.)
