Speedometer makes "cassette-like" winding noise

[grizparker]

My speedometer sits at 22 when engine off.  GPS shows I'm going about 45 when speedometer says 75.  I'm noticing a distance winding noise that sounds like a cassette rewinding coming from my speedometer unit.   As I start from a stop, tree is no noise and speedometer slowly and steadily goes up.  As I get to faster speeds...maybe 15 mph...the noise starts and my speedometer starts bouncing a good bit.  Any ideas?

[Ghoste]

40 plus years of grime and build up.  May need to lube cable and clean the head.

[grizparker]

Thanks Ghoste, I'll put that on my 'to do' list.

I took a small video clip of it this morning to add to the thread to help clarify my original description...
http://www.youtube.com/watch?v=kUCJRz-MqkE&feature=youtube_gdata_player

[Dino]

Thanks Ghoste, I'll put that on my 'to do' list.

I took a small video clip I it this morning to add to the thread to help clarify my original description...
http://www.youtube.com/watch?v=kUCJRz-MqkE&feature=youtube_gdata_player

Hey you just passed the 910910 mark.   

The discrepancy in speed with gps vs speedometer may be because the speedometer gear in the trans doesn't match the tire size and rear end gears.  Since I changed my gears my speedometer will read 48 when doing 55 for example.

The bouncing is because of wear and tear.  Personally I would wait until you restore the instrument cluster because you'll have to pull the whole thing and take it apart.  The good news is that the speedometer is very easy to clean and rebuild and if all else fails, they are easy to find.  Speedometer cable can be cleaned but if you find any marks you may just want to get a new one to be safe.

[grizparker]

Hey you just passed the 910910 mark.   

Actually it's 51091.0.  There was a glare on the first digit...   

The discrepancy in speed with gps vs speedometer may be because the speedometer gear in the trans doesn't match the tire size and rear end gears.  Since I changed my gears my speedometer will read 48 when doing 55 for example.

The bouncing is because of wear and tear.  Personally I would wait until you restore the instrument cluster because you'll have to pull the whole thing and take it apart.  The good news is that the speedometer is very easy to clean and rebuild and if all else fails, they are easy to find.  Speedometer cable can be cleaned but if you find any marks you may just want to get a new one to be safe.

That certainly could be the case.  I've found that as I get faster, the difference between the two numbers increases.

For example:
At GPS 0 mph, speedometer says 22...a 22 mph difference.
At GPS 45mph, speedometer says 75...a 30 mph difference.
At GPS 55mph, speedometer says 90...a 35 mph difference.

What you said makes perfect sense that the "speedometer gear in the trans doesn't match the tire size and rear end gears."  I'm running a 3.23 rear end and I bet the speedometer gear in the transmission is for a lower gear.  Thanks for the input!

[grizparker]

What about it starting at 22mph?  Is that something that can be calibrated when cleaning/rebuilding the speedometer?

[Dino]

Hey you just passed the 910910 mark.   

Actually it's 51091.0.  There was a glare on the first digit...   

Ha!  I missed that. 

The discrepancy in speed with gps vs speedometer may be because the speedometer gear in the trans doesn't match the tire size and rear end gears.  Since I changed my gears my speedometer will read 48 when doing 55 for example.

The bouncing is because of wear and tear.  Personally I would wait until you restore the instrument cluster because you'll have to pull the whole thing and take it apart.  The good news is that the speedometer is very easy to clean and rebuild and if all else fails, they are easy to find.  Speedometer cable can be cleaned but if you find any marks you may just want to get a new one to be safe.

That certainly could be the case.  I've found that as I get faster, the difference between the two numbers increases.

For example:
At GPS 0 mph, speedometer says 22...a 22 mph difference.
At GPS 45mph, speedometer says 75...a 30 mph difference.
At GPS 55mph, speedometer says 90...a 35 mph difference.

What you said makes perfect sense that the "speedometer gear in the trans doesn't match the tire size and rear end gears."  I'm running a 3.23 rear end and I bet the speedometer gear in the transmission is for a lower gear.  Thanks for the input!

You're welcome.  If you know the height of your rear tire then you can calculate what type of gear you need to make the speedometer (more) accurate.  Because the difference increases with speed it's clear you need another gear, if it was always 22 mph off then it would be a bit easier.

What about it starting at 22mph?  Is that something that can be calibrated when cleaning/rebuilding the speedometer?

Yep, grab the large circular cup on the back of the speedometer and make sure it is as far counterclock wise as it can be, then grab the needle at the base and twist it counterclockwise to read 0.

If you don't hold the cup the speedometer may get damaged beyond repair, this is almost always true when pulling the needle off so don't skip that step!

When done make sure the cup and needle move freely without any resistance.  When I reassembled mine the odometer worked but the speedometer needle didn't budge so I had to take the whole thing apart again.  Turned out you can push that cup towards the speedometer face to 'lock' it in place.  It still turns but the cable won't move it.  Grab the cup and give it a slight tug away from the speedometer face to unlock.

[grizparker]

Awesome advice from someone who has obviously been there before... 

Thanks again.  I'm ready to tackle it.

[Dino]

Awesome advice from someone who has obviously been there before... 

Thanks again.  I'm ready to tackle it.

You're most welcome.

Here's my adventure with gauges, I hope you can get something out of it to avoid the mistakes I made.

http://www.dodgecharger.com/forum/index.php/topic,86736.0.html

[grizparker]

Here's my adventure with gauges, I hope you can get something out of it to avoid the mistakes I made.
http://www.dodgecharger.com/forum/index.php/topic,86736.0.html

Bookmarked!

[Just 6T9 CHGR]

Definitely a problem with the speedo head itself.....developed same issue with mine....swapped it out for a good one.

PS---love how the gauge face faded around the needle at rest for what looks like a lot of years....

[grizparker]

40 plus years of grime and build up.  May need to lube cable and clean the head.

So, about to lube the cable.  What lube is recommended?  Book says "speedometer cable lubricant such as part number 1243632.". Does WD-40 work just fine?

[Dino]

40 plus years of grime and build up.  May need to lube cable and clean the head.

So, about to lube the cable.  What lube is recommended?  Book says "speedometer cable lubricant such as part number 1243632.". Does WD-40 work just fine?

No get liquid graphite or graphite oil.  Most auto parts stores sell it.  Oh and wear gloves.