Speedometer holds speed when slowing down

[86VickyLX]

Like the title says, as I'm slowing down the speedometer stays at the speed I was travelling for a while before starting to move down. I have verified it is not the vss as it does respond to changes in speed instantly. I'm thinking something with the motor that drives the speedo head. Anything I can do to fix this?
This is in my 92 Grand Marquis.

[sly]

There should be a return spring in that thing, IIRC, and the motor fights it (it's not very strong, either of them)... so you may have a busted spring... or need to lube stuff.

[86VickyLX]

where is the spring? I don't recall it fighting a spring because the needle goes wherever when not powered.

[gadget73]

i think its actually magnetic coupled, no return spring on the electro speedo. Sounds more like lube issues if you ask me.

[VicCrownVic]

where is the spring? I don't recall it fighting a spring because the needle goes wherever when not powered.

Like gadget said, no spring, it is electromagnetically controlled as far as I can tell which is why it behaves as you've seen when not powered.

Could it possibly be the little power board at the bottom right of the cluster not reacting to the change as quickly as expected?
I believe that board is responsible for controlling the speedometer.

[WagonMan]

I believe the board you described is for the gas gauge. WagonMan

[VicCrownVic]

I believe the board you described is for the gas gauge. WagonMan

Looking at it some more...
http://unitedpantherownersassociatio...22176#pid22176

It looks like you are correct, that board may have nothing to do with the speedometer.

[gadget73]

Its the anti-slosh module and the instrument power supply if I'm not mistaken. It powers the gas and temperature gauges. The older ones used a flukey mechanical make/break regulator, newer ones moved from the 1930s to the 1970s in terms of technology for voltage regulation.

[86VickyLX]

Has anyone disassembled one of these? I don't see how it comes apart so I can get at the motor to lube it. I'm afraid to pull the needle off, because of the alignment of it as well. I had a bitch of a time doing it with my 86.

[sly]

you need to pull the needle off, but it's a BITCH to get off. my 93 was a royal PITA to pull off and it required using a pair of needle nose as a pickle fork to do it. Did that when I fixed the damn odo gears the first time. The real bitch of it all was finding zero again. The 93 vic speedo motor can actually be accessed from the back side if you're not removing it by removing the odometer stuff (again... PITA) and using a needle type of lube (or straw type spray) to get the lube where it needs to go. The second time I had to jack with that shit I just put in the digital speedo and said f#$% it!

[86VickyLX]

you need to pull the needle off, but it's a BITCH to get off. my 93 was a royal PITA to pull off and it required using a pair of needle nose as a pickle fork to do it. Did that when I fixed the damn odo gears the first time. The real bitch of it all was finding zero again. The 93 vic speedo motor can actually be accessed from the back side if you're not removing it by removing the odometer stuff (again... PITA) and using a needle type of lube (or straw type spray) to get the lube where it needs to go. The second time I had to jack with that shit I just put in the digital speedo and said f#$% it!

Do you have any pictures of where the lube needs to go? And also what type of lube do you recommend?

[gadget73]

I'd probably be using clock oil for something like that.

[86VickyLX]

I tried lubing it with oil for small motors like model oil. It didn't change. When not energized the needle moves fine. No issues. When energized and I move the needle the magnet promptly pulls the needle back when I let go of it. I'm wondering if the electronics that control the speedo head are to blame?

[sly]

starting to sound like it.

[86VickyLX]

Apparently not. The motor was a little dicked. Spin it by hand and it was making some pretty icky noises. Thain swapped the motor onto the 140 speedo board and we clocked the needle pretty much spot on. It now responds as it should. Thanks Thain!