speedometer gear/cable gurus
Thread Starter
|
Senior User
Joined: May 2010
Posts: 307
Likes: 1
From: McMinnville, TN
speedometer gear/cable gurus
I have an 89 250 4wd with a 5 speed manual. The speedometer doesn't work. I found that the speed sensor gear housing was broken, so I bought a new one. The speedo jumped a time of two and that was it. So now I have a few questions.
The first picture is a few speed sensors and gears.
The left is a sensor and 18 tooth gear from an AOD. This sensor had a little yellow plug where the cable would normally go. Why was it there?
The middle is just a regular cable end with a 18 tooth gear from an AOD.
The right is my replacement sensor with the original 19 tooth gear that was in my truck.
The bottom picture is a comparison between the unworn teeth of a gear and the worn teeth from my truck.
Would this wear cause my speedo to not work?
Why can't the gears between an automatic and a manual be interchanged...other than the number of teeth. The sensor with the 18 tooth AOD gear will physically fit in my truck, but I didn't drive with it in there.
My cable turns freely and so does the gear/sensor assembly. However, when the cable is pushed into the gear and it clicks in there, everything is tight and there is some stiff resistance. What's going on there?
The first picture is a few speed sensors and gears.
The left is a sensor and 18 tooth gear from an AOD. This sensor had a little yellow plug where the cable would normally go. Why was it there?
The middle is just a regular cable end with a 18 tooth gear from an AOD.
The right is my replacement sensor with the original 19 tooth gear that was in my truck.
The bottom picture is a comparison between the unworn teeth of a gear and the worn teeth from my truck.
Would this wear cause my speedo to not work?
Why can't the gears between an automatic and a manual be interchanged...other than the number of teeth. The sensor with the 18 tooth AOD gear will physically fit in my truck, but I didn't drive with it in there.
My cable turns freely and so does the gear/sensor assembly. However, when the cable is pushed into the gear and it clicks in there, everything is tight and there is some stiff resistance. What's going on there?
i ain't rite
Joined: Mar 2005
Posts: 65,579
Likes: 5,611
From: Marlboro Mental Hospital.
the worn teeth on the bottom gear will most likely not spin the speedo, or make it skip. the top gear is different. the alignment dowel is way to long.
i have extra 17,18, and 19 tooth short pin gears. if you want one, let me know the gear count, and i will send it to you for postage price.
i have extra 17,18, and 19 tooth short pin gears. if you want one, let me know the gear count, and i will send it to you for postage price.
Thread Starter
|
Senior User
Joined: May 2010
Posts: 307
Likes: 1
From: McMinnville, TN
the worn teeth on the bottom gear will most likely not spin the speedo, or make it skip. the top gear is different. the alignment dowel is way to long.
i have extra 17,18, and 19 tooth short pin gears. if you want one, let me know the gear count, and i will send it to you for postage price.
i have extra 17,18, and 19 tooth short pin gears. if you want one, let me know the gear count, and i will send it to you for postage price.
The gear with the long alignment dowel will physically fit into my transfer case. I haven't tried to drive it that way, but I may give it a shot for the sake of experimentation.
I did get some info from the Ford service tech today.
Earlier I asked/described the sensor on the left side. It had a factory installed plug over the cable hole. I took it out and everything looked ready for a cable. So how did the speedo work with the hole plugged? This is the scenario...
The middle gear/cable was how speedometers worked. the gear turned the cable that turned the speedo.
Later came the assembly to the right. The gear turned the cable that turned the speedo, while an electrical connector told the computer at what speed the vehicle traveled.
Then a rear differential sensor was added to control ABS.
Then there was a time when the cable was no longer needed sensor/gear assembly got a plug to cover the cable port. The speed sensor alone told the computer the speed traveled AND provided the signal to an electrically operated speedometer.
Finally, the speed sensor/speedo cable assembly was done away with and the rear differential sensor provided all the signal to the computer, speedometer, and ABS system.
i ain't rite
Joined: Mar 2005
Posts: 65,579
Likes: 5,611
From: Marlboro Mental Hospital.
i think you got it rite. once upon a time, we had cable only.
then we got cable and VSS in the tailshaft, then cable in tailshaft and VSS in rear diff, then VSS in place of the cable still in the tailshaft.
finally they went to VSS in rear diff only.
it is SLIGHTLY confusing.
then we got cable and VSS in the tailshaft, then cable in tailshaft and VSS in rear diff, then VSS in place of the cable still in the tailshaft.
finally they went to VSS in rear diff only.
it is SLIGHTLY confusing.
Posting Guru
Joined: Jan 2002
Posts: 1,346
Likes: 8
From: Baltimore
The two speedometer cables with the 2 pin electrical plug are
used for vehicles with cruise control.
used for vehicles with cruise control.
Trending Topics
Thread Starter
|
Senior User
Joined: May 2010
Posts: 307
Likes: 1
From: McMinnville, TN
Hmmm. My truck has cruise control? I'll have to check that out. I've never really paid attention.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Thread Starter
|
Senior User
Joined: May 2010
Posts: 307
Likes: 1
From: McMinnville, TN
Reviving an old thread to update and possibly help someone else.
I finally got my speedo working in my 89. It turns out that over the years the cable "grew" in length and made for a tight fit when all assembled and installed. My speedo gear/speen sensor assembly would turn freely on the bench as would the speedo cable/speedometer. Stick it together and the gear would turn, but there was a lot of resistance. Drive it down the road and the speedo needle would jump and sometimes stop working entirely. I ended up taking a 4.5" angle grinder and grinding away a little from the end of the cable. I kept testing/checking until everything turned smoothly and freely. In all, I guess i removed about .250" from the cable end. My speedometer is smooth and stable now.
I finally got my speedo working in my 89. It turns out that over the years the cable "grew" in length and made for a tight fit when all assembled and installed. My speedo gear/speen sensor assembly would turn freely on the bench as would the speedo cable/speedometer. Stick it together and the gear would turn, but there was a lot of resistance. Drive it down the road and the speedo needle would jump and sometimes stop working entirely. I ended up taking a 4.5" angle grinder and grinding away a little from the end of the cable. I kept testing/checking until everything turned smoothly and freely. In all, I guess i removed about .250" from the cable end. My speedometer is smooth and stable now.
Thread
Thread Starter
Forum
Replies
Last Post
GreatNorthWoods
1948 - 1956 F1, F100 & Larger F-Series Trucks
21
Oct 10, 2012 09:46 AM
jimmyb08SD
EcoBoost (all engine sizes)
11
Apr 25, 2011 10:30 PM
cdrmotorsports
1999 - 2016 Super Duty
22
Sep 3, 2010 12:02 PM
