Notices
1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

speedometer drive gear/seal

Thread Tools
 
Search this Thread
 
Old Feb 4, 2014 | 04:14 PM
  #1  
abyars111's Avatar
abyars111
Thread Starter
|
Elder User
Joined: Jan 2012
Posts: 896
Likes: 0
From: AL
speedometer drive gear/seal

I'm working on my 1970 F250 Crew Cab, 2wd, 390 with a C6. My speedometer cable broke so I ordered a new one to replace it. I ordered the standard screw on speedo end and push in O-ring seal on the tranny end. Here is a link: Speedometer Cable and Housing | Dennis Carpenter Ford Restoration Parts . I've also had a leak at the point that the speedometer cable connects to the tail shaft. Upon removing the cable from the tail shaft I find my drive speedo drive gear assembly is different from anything I've ever seen. It has a screw connector on both ends. This is a C6, I even had it recently rebuilt. The shop said it had a "heavy duty tail shaft with bearings". I didn't think much of it until now. I called NPD and discussed it with them and they sent me the correct cable, it has a screw on connection on both ends.

Can anyone identify this tail shaft and speedo drive gear assembly? and how do I seal it, it leaks where the adaptor screws into the tail shaft.

Below is a pic of the speedo drive gear installed and the second pic is the cable adapter that screws into the tail shaft. This speedo drive gear shaft goes through the adapter. The speedo drive gear is steel.
 
Attached Images   
Reply
Old Feb 4, 2014 | 09:36 PM
  #2  
orich's Avatar
orich
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
Clean it then Put some thread sealer on the threads before installing it into the tranny. IF the cable coupler is leaking.
You might try this. I used a thin o-ring inside the threaded collar that butted up to the thread adapter boss face. Worked for my cable
orich
 
Reply
Old Feb 4, 2014 | 11:40 PM
  #3  
abyars111's Avatar
abyars111
Thread Starter
|
Elder User
Joined: Jan 2012
Posts: 896
Likes: 0
From: AL
Thanks. So this isn't some unsual type of tail shaft/speedo drive? I've just never seen one that accepted a threaded cable coupler.
 
Reply
Old Feb 5, 2014 | 09:00 AM
  #4  
orich's Avatar
orich
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
Originally Posted by abyars111
Thanks. So this isn't some unsual type of tail shaft/speedo drive? I've just never seen one that accepted a threaded cable coupler.
I don't know about the S/Drive but my model 24 trans case was some what like that.
Ford used 3 different types from what, I understand.
Some had the steel gears & plastic ones. Maybe differ then a car C6 tho:

orich
 
Reply
Old Feb 5, 2014 | 09:22 AM
  #5  
abyars111's Avatar
abyars111
Thread Starter
|
Elder User
Joined: Jan 2012
Posts: 896
Likes: 0
From: AL
Thanks for the tip. I'll get under there this weekend and apply some thread sealant and install an O ring.
 
Reply
Old Feb 6, 2014 | 05:11 PM
  #6  
NumberDummy's Avatar
NumberDummy
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
Club FTE Gold Member
1968/72 F100/350 360/390 C6: Two different types of speedo cables. One type is 75.42" long, the other is 70.80" long.

There are also two different types of C6 speedometer DRIVEN gears (end of cable), one is nylon, the other is iron.
 
Reply
Old Feb 24, 2014 | 10:01 AM
  #7  
abyars111's Avatar
abyars111
Thread Starter
|
Elder User
Joined: Jan 2012
Posts: 896
Likes: 0
From: AL
I still haven't tried thread sealant on the drive gear. Been busy so I just add a pint of fluid every other week. The weather is warming up so I'll get on this one soon.
 
Reply
Old Oct 4, 2025 | 09:43 AM
  #8  
Ragin James's Avatar
Ragin James
1st Gear
Joined: Oct 2025
Posts: 1
Likes: 0
Originally Posted by abyars111
I'm working on my 1970 F250 Crew Cab, 2wd, 390 with a C6. My speedometer cable broke so I ordered a new one to replace it. I ordered the standard screw on speedo end and push in O-ring seal on the tranny end. Here is a link: Speedometer Cable and Housing | Dennis Carpenter Ford Restoration Parts . I've also had a leak at the point that the speedometer cable connects to the tail shaft. Upon removing the cable from the tail shaft I find my drive speedo drive gear assembly is different from anything I've ever seen. It has a screw connector on both ends. This is a C6, I even had it recently rebuilt. The shop said it had a "heavy duty tail shaft with bearings". I didn't think much of it until now. I called NPD and discussed it with them and they sent me the correct cable, it has a screw on connection on both ends.

Can anyone identify this tail shaft and speedo drive gear assembly? and how do I seal it, it leaks where the adaptor screws into the tail shaft.

Below is a pic of the speedo drive gear installed and the second pic is the cable adapter that screws into the tail shaft. This speedo drive gear shaft goes through the adapter. The speedo drive gear is steel.
How did you end up sealing this? I have this unicorn also and it’s dumping trans fluid
 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

 Verdad Gallardo
story-1

Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

 Joe Kucinski
story-2

2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

 Brett Foote
story-3

Top 10 Ford Truck Tragedies

 Joe Kucinski
story-4

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

 Brett Foote
story-5

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

 Michael S. Palmer
story-6

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

 Verdad Gallardo
story-7

10 Best Ford Truck Engines We Miss the Most!

 Joe Kucinski
story-8

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

 Brett Foote
story-9

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

 Michael S. Palmer
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Shiveron
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
2
Sep 30, 2014 06:44 AM
Tonygravel
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
33
Aug 17, 2012 11:00 AM
wment
Clutch, Transmission, Differential, Axle & Transfer Case
2
Feb 11, 2006 09:39 PM
bigbadford78
Clutch, Transmission, Differential, Axle & Transfer Case
3
May 5, 2005 08:59 PM
truckmano5-2
Clutch, Transmission, Differential, Axle & Transfer Case
6
Apr 30, 2004 10:36 PM




All times are GMT -5. The time now is 10:03 PM.

story-0
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-05-30 18:33:59


VIEW MORE
story-1
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-2
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-3
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE
story-4
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-5
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-6
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-7
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-8
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE
story-9
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Slideshow: Everything You Need to Know about the 2027 Super Duty Carhartt Package!

By Michael S. Palmer | 2026-05-07 17:51:06


VIEW MORE