• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Frustrating Foxbody Speedo

  • Thread starter Thread starter Keith5.0GT
  • Start date Start date Jan 14, 2018
  • Tags Tags
    speedometer speedometercable
Prev
  • 1
  • 2
First Prev 2 of 2

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Jan 16, 2018
#21
  • Jan 16, 2018
  • #21
Keith5.0GT said:
Well the driven gear I bought is white and it’s 17 teeth. I used the calculator on lmr. 3.08 gears in rear end with 245-45-17 tires. The transmission I’m told is a world class t-5 so I think the drive gear is supposed to be 7 teeth.
Click to expand...

Based on that info, you should need a 7 tooth drive gear.

All T-5's in the Mustang from 1985 through 2010 were world class. Ford changed from the 7 tooth to the 8 tooth after 1990. Unsure what gear the aftermarkets had.

You can just tell by color.
Black = 6 tooth
Yellow = 7 tooth
Green = 8 tooth.


Regardless, I think you have all the info you need to diagnose your issue.
 

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 16, 2018
#22
  • Jan 16, 2018
  • #22
Mustang5L5 said:
Based on that info, you should need a 7 tooth drive gear.

All T-5's in the Mustang from 1985 through 2010 were world class. Ford changed from the 7 tooth to the 8 tooth after 1990. Unsure what gear the aftermarkets had.

You can just tell by color.
Black = 6 tooth
Yellow = 7 tooth
Green = 8 tooth.


Regardless, I think you have all the info you need to diagnose your issue.
Click to expand...
Yes thanks for the pictures and kicking around ideas with me. Easy to understand how the gears work now. I appreciate it.
 

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 18, 2018
#23
  • Jan 18, 2018
  • #23
Mustang5L5 said:
Based on that info, you should need a 7 tooth drive gear.

All T-5's in the Mustang from 1985 through 2010 were world class. Ford changed from the 7 tooth to the 8 tooth after 1990. Unsure what gear the aftermarkets had.

You can just tell by color.
Black = 6 tooth
Yellow = 7 tooth
Green = 8 tooth.


Regardless, I think you have all the info you need to diagnose your issue.
Click to expand...
Ok I figured it out. Luckily the drive gear is fine. Although I could get the speedo needle to twitch spinning the cable by hand, when I attached the cable to a dremel,(fit perfectly) it doesn’t work! So do you know of a repair method or do I have to buy a unit off eBay? I don’t see any repair kits or new speedos for sale so far. Thanks
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Jan 18, 2018
#24
  • Jan 18, 2018
  • #24
Are you confident the cable is making a secure connection to the back of the speedo head? Sometimes those aftermarket cables never really fit well, or fall out when you are trying to push the cluster back in.
 

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 18, 2018
#25
  • Jan 18, 2018
  • #25
Mustang5L5 said:
Are you confident the cable is making a secure connection to the back of the speedo head? Sometimes those aftermarket cables never really fit well, or fall out when you are trying to push the cluster back in.
Click to expand...
Well I have 2 good cables now and neither work in the speedo head. I do hear a noise from back of speedo head when I spin cable. So tomorrow I should have time to take it apart again and I’m hoping that the connection has just become slightly rounded or something I can fix myself. I’ve read there are magnets involved with the needle that can get messed up too. But I’ll definitely have a look when I get it apart. I read another guy on here got an eBay replacement and used it for parts to fix his, so that’s an option too. Just hard to find on any forum where anyone has repaired a speedo head. But I’ll look tomorrow eve and post what I find.
 

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 18, 2018
#26
  • Jan 18, 2018
  • #26
Mustang5L5 said:
Are you confident the cable is making a secure connection to the back of the speedo head? Sometimes those aftermarket cables never really fit well, or fall out when you are trying to push the cluster back in.
Click to expand...
Well I have 2 good cables now and neither work in the speedo head. I do hear a noise from back of speedo head when I spin cable. So tomorrow I should have time to take it apart again and I’m hoping that the connection has just become slightly rounded or something I can fix myself. I’ve read there are magnets involved with the needle that can get messed up too. But I’ll definitely have a look when I get it apart. I read another guy on here got an eBay replacement and used it for parts to fix his, so that’s an option too. Just hard to find on any forum where anyone has repaired a speedo head. But I’ll look tomorrow eve and post what I find.
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,916
10,565
203
polk county florida
Jan 18, 2018
#27
  • Jan 18, 2018
  • #27
Pm me you prodution date and I'll check my stash tomorrow.
 
Reactions: Keith5.0GT

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Jan 18, 2018
#28
  • Jan 18, 2018
  • #28
If you spin the speedo head by hand, it doesn't take much to spin it up to 20-40mph or so
 
Reactions: Keith5.0GT

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 19, 2018
#29
  • Jan 19, 2018
  • #29
karthief said:
Pm me you prodution date and I'll check my stash tomorrow.
Click to expand...
Ok thanks. Where would I find the production date? It’s a 1990
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,916
10,565
203
polk county florida
Jan 19, 2018
#30
  • Jan 19, 2018
  • #30
Look on the left side where the door striker is, or when you pull the dash get me the part number from the wire print board.
 

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 19, 2018
#31
  • Jan 19, 2018
  • #31
karthief said:
Look on the left side where the door striker is, or when you pull the dash get me the part number from the wire print board.
Click to expand...
Ok, my car has had door jambs painted in the past so I don’t have stickers there unfortunately but I’ll check the part when I get it off this evening. Thanks
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,916
10,565
203
polk county florida
Jan 19, 2018
#32
  • Jan 19, 2018
  • #32
I would prefer the print board number
 

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 19, 2018
#33
  • Jan 19, 2018
  • #33
Well I got it apart. I double checked the speedo unit and I can get the needle to move. So I have the rear end lifted and I can idle in first and the speedo cable end in the dash isn’t spinning....even though I was able to put in gear with cable and rotate tires to verify that it would spin. So I’m jus baffled. It’s obviously in the trans at the moment but the gears are there and they did work by hand. Something is going on but I don’t know what. Poop
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Jan 19, 2018
#34
  • Jan 19, 2018
  • #34
Smear some lithium grease in the teeth of the speedo drive gear and install it. Turn the rear wheels so the trans nainshagt spins.

Pull the speedo gear out again and see if the grease you packed into the gears is displaced because it's making full contact with the drive gear
 
Reactions: General karthief

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 19, 2018
#35
  • Jan 19, 2018
  • #35
Mustang5L5 said:
Smear some lithium grease in the teeth of the speedo drive gear and install it. Turn the rear wheels so the trans nainshagt spins.

Pull the speedo gear out again and see if the grease you packed into the gears is displaced because it's making full contact with the drive gear
Click to expand...
Ok I may have it figured out! It’s the part that’s not supposed to be the problem, the vss! I spin the driven gear and the cable doesn’t move. Take the gear off and spin the shaft of the vss, nothing. It won’t spin the inserted speedo cable no matter what. So where the cable fits into the vss, something stripped out or broke and that’s it! It’s got less than 2,000 miles on it so I’m buying a motorcraft vss this time. I’ll let ya know if it works but I know that’s it now.
 
Reactions: General karthief and Mustang5L5

Keith5.0GT

Active Member
May 29, 2017
83
17
28
Jan 27, 2018
#36
  • Jan 27, 2018
  • #36
Keith5.0GT said:
Ok I may have it figured out! It’s the part that’s not supposed to be the problem, the vss! I spin the driven gear and the cable doesn’t move. Take the gear off and spin the shaft of the vss, nothing. It won’t spin the inserted speedo cable no matter what. So where the cable fits into the vss, something stripped out or broke and that’s it! It’s got less than 2,000 miles on it so I’m buying a motorcraft vss this time. I’ll let ya know if it works but I know that’s it now.
Click to expand...
UPDATE finally;
Got a motorcraft vss, and yes that fixed the speedo. But the cable was extremely hard to insert. After inserting it, there was more resistance when turning the driven gear, which resulted in a jittery speedo needle. Long story short, my new speed cable was maybe, 1/4” too long, causing the cable to bind and needle to jump. Once I finally shaved enough off the cable where the driven gear had no resistance, I had a smooth speedometer again. Hooray. Onto the next problem
 
Reactions: Mustang5L5 and General karthief

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,916
10,565
203
polk county florida
Jan 27, 2018
#37
  • Jan 27, 2018
  • #37
 
Reactions: Keith5.0GT
Prev
  • 1
  • 2
First Prev 2 of 2
You must log in or register to reply here.

Similar threads

Removing speedo cable from the VSS
  • 91AOD5.0LX
  • Mar 25, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
27
Views
848
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 25, 2026
91AOD5.0LX
C
C4 trans help needed
  • CPH89LX
  • Apr 26, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
6
Views
203
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 28, 2026
CPH89LX
C
C
Drivetrain T-5 transmission issue
  • Ch3No2
  • Jul 11, 2025
  • Fox 5.0 Mustang Tech
Replies
3
Views
373
Fox 5.0 Mustang Tech Jul 18, 2025
2000xp8
S
Drivetrain 8.8 Pinion and 302 rear main seal leaks after replacing. 93 5.0 with t-5
  • Steigy4827
  • Jun 23, 2025
  • Fox 5.0 Mustang Tech
Replies
10
Views
662
Fox 5.0 Mustang Tech Apr 1, 2026
Steigy4827
S
S
5.0 Rebuild
  • smittys7up
  • Nov 29, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
8
Views
562
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Dec 20, 2025
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?