Speedometer - What The Heck Happened - 1969 Dart

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3rdLM23P9

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!969 Dart, the needle dropped below "0" at rest, and speeds measure 3 to 5mph slower than actual. Speeds get closer to actual approaching 60 mph. What happened and how do I fix it?

Speedometer_2.jpg
 
The needle is probably sitting on the rest peg. Have you checked the speedometer cable to see if it's starting to unravel?
 
My sad news is....

Your going to have to pull the cluster.

Pull out the front seats.
Pull out the steering column.
Tape up the dash.
And be ready to get your hands cut up

And go easy on the wires and connectors.

Be prepared to replace or repair the cir boards.

After the cluster is out find a reputable repair shop in your area .

My bet is the spring that resists the needle movement is free to move or not adjusted correctly, (should not happen all by itself).

There may also be a 0 stop that may have broken off


I feel your pain.

When I pulled my cluster in late 22 I knew I should send the speedo out to have it repaired. But I did not and now I'll be pulling it this Winter
 
^^^ Listen to what @Dana67Dart says about taking the seat(s) out. It does not take that long and it makes working under the dash SO much easier.
 
My sad news is....

Your going to have to pull the cluster.

Pull out the front seats.
Pull out the steering column.
Tape up the dash.
And be ready to get your hands cut up

And go easy on the wires and connectors.

Be prepared to replace or repair the cir boards.

After the cluster is out find a reputable repair shop in your area .

My bet is the spring that resists the needle movement is free to move or not adjusted correctly, (should not happen all by itself).

There may also be a 0 stop that may have broken off


I feel your pain.

When I pulled my cluster in late 22 I knew I should send the speedo out to have it repaired. But I did not and now I'll be pulling it this Winter

Ugh -thanks for that sad (bad) news! Is the 0 stop a physical "peg" on the cluster that stops the needle at 0 or part of the spring?
 
Ugh -thanks for that sad (bad) news! Is the 0 stop a physical "peg" on the cluster that stops the needle at 0 or part of the spring
This is the speedo head
PXL_20240819_154632762.jpg


Side shot
PXL_20240819_154645135.jpg


Back
PXL_20240819_155122357.jpg



Green is the adjuster to correct the speed and the spring that returns the needle to 0

Red is the 0 stop
PXL_20240819_154700185~2.jpg


Functionality

The part (red arrow) spins with the speedo gear and shaft in the speedo cable.

It causes the part it spins around to move. Since it is attached to the needle the needle moves. The spring resists the movement otherwise it would read 120 when ever the car was moving.
PXL_20240819_154714068~2.jpg
PXL_20240819_154718648.jpg
PXL_20240819_154716663.jpg


Any contact of the outer piece to the inner piece will cause the needle to be dragged farther than it should and when the contact stops the needle rebounds to where it should be till the next contact.

That's one way you get a bouncy needle.

The other is a speedo cable that is sticking so it winds up a bit like a torsion spring then releases causing a speed increase at the needle.
 
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This is the speedo head
View attachment 1716291634

Side shot
View attachment 1716291635

Back
View attachment 1716291641


Green is the adjuster to correct the speed and the spring that returns the needle to 0

Red is the 0 stop
View attachment 1716291639

Functionality

The part (red arrow) spins with the speedo gear and shaft in the speedo cable.

It causes the part it spins around to move. Since it is attached to the needle the needle moves. The spring resists the movement otherwise it would read 120 when ever the car was moving.
View attachment 1716291638View attachment 1716291636View attachment 1716291637

Any contact of the outer piece to the inner piece will cause the needle to be dragged farther than it should and when the co tact stops the needle rebounds to where it should be till the next contact.

That's one way you get a bouncy needle.

The other is a speedo cable that is sticking so it winds up a bit like a torsion spring then releases causing a speed increase at the needle.

Wow, thank you - very helpful. So likely that the 0 stop (red) failed/broke off? Guess I won't know until it gets pulled.
 
That stands to reason. Buy unless it's been hacked in the past unlikely.

It could also be the needle on the shaft has spun a few degrees

As for 3-5 mph off, unless it just started doing that at the same time the needle went south, I would say that's really good?
 
That stands to reason. Buy unless it's been hacked in the past unlikely.

It could also be the needle on the shaft has spun a few degrees

As for 3-5 mph off unless it just started doing that at the same time the needle went south, I would say that's really good?

The 3-5 mph drag started simultaneously with the needle drop.
 
I'm going on a 300 mile trim this weekend, and my speedo has been getting progressively worse (it used to tick and bounce below 50 but recently it was doing it at 65 to 75) so I pulled the cable out and in October (3 more car shows in Aug and Sept) I will pull the cluster. :eek:
 
CHeck your ODO against the mile markers. If that is ok then it may just be a needle adjustment. There are companies that will rebuild this for you, but you may just want to find another one. There is also someone that sell decals to renew the background.
 
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