1969 Coronet Speedometer

[markbob]

hey guys
Just had a different speedometer drive gear installed in my 904 3 speed
The speedometer still indicated fast, but worked
Today I took it out and below 30 mph, it worked as before but at higher speeds the speedometer jumped up to 100-120
Now that's all it does.....either zoro when stopped or 120 when going....with wild swings of the needle
Any ideas?

 

[Mopars & Missiles]

The speedometer is the problem, not the gear in the transmission. One other possibility (low probability) is the speedo cable is binding inside the sheath. My bet is the speedometer needs rebuilt.

 

[markbob]

thx for input
I figured it had to do with the speedo gear in the tranny, since the speedometer has never had issues, and I had this recently worked on
Could the cable need lubrication?

 

[Mopars & Missiles]

thx for input
I figured it had to do with the speedo gear in the tranny, since the speedometer has never had issues, and I had this recently worked on
Could the cable need lubrication?

The speedometer can be fine one day and the next day it starts jumping all over the place. Mine did that in my Challenger awhile back and was bouncing so bad it broke the needle off before I got home with it.

Yes, the cable might need to be lubed, that is what I meant by it binding. Also, did you index the cable adapter properly when you installed the new gear in the 904? I don't have a 904, but am guessing that they are similar to the 727's in this respect.

 

[markbob]

i didn't do the work....a Tranz shop did it
What do u mean by indexing?
Will check this all out tomorrow

 

[Mopars & Missiles]

i didn't do the work....a Tranz shop did it
What do u mean by indexing?
Will check this all out tomorrow

Depending on how many teeth are on the gear, you index the transmission adapter to correspond to that gear so that it engages properly inside the transmission.

See section 21, page 58 in the FSM

 

[markbob]

Thx again for the additional info
Here is a video of the speedo action
When my son parked the car, the speedo showed 40 mph
I tapped the cable under the dash and it dropped to zero

Thx for looking

 

[markbob]

Well it won't upload

 

[markbob]

Update

I checked the cable with a power drill....
Cable turns smoothly
I reseated the cable on the back of the speedometer....
That seemed to fix it.....test drive showed it working properly

Thx for all the help