Notices
928 Forum 1978-1995
Sponsored by:
Sponsored by: 928 Specialists

Speedo/Odo issues

Thread Tools
 
Search this Thread
 
Old Feb 9, 2016 | 12:06 AM
  #1  
bureau13's Avatar
bureau13
Thread Starter
Rennlist Member
10 Year Member
 
Joined: May 2014
Posts: 3,559
Likes: 65
From: South Florida
Default Speedo/Odo issues

I'm pretty sure the odometer is the broken gear I've read all about. My speedometer is weird. It "works," sort of. It acts a bit like a semi-functional peak/hold gauge. It will go up with speed, but if I then slow down, it will usually hold my peak speed. At some point after I come to a stop, it may jump down to zero, or maybe some lesser speed, until I start up again, at which time it will bounce down to zero and then go up again. However this is not 100%, it will be kind of jumpy, but this is its general behavior. Anyone see this?

At some point in the near future I will have the pod off and will do the LED replacement...good time to do these fixes as well, I would think.
Reply
Old Feb 9, 2016 | 12:57 AM
  #2  
GlenL's Avatar
GlenL
Nordschleife Master
20 Year Member
 
Joined: Jul 2003
Posts: 7,742
Likes: 78
From: Minneapolis
Default

That's not the odo gear. Try cleaning grounds and the connector at the right-front of the spare tire well.
Reply
Old Feb 9, 2016 | 10:31 AM
  #3  
bureau13's Avatar
bureau13
Thread Starter
Rennlist Member
10 Year Member
 
Joined: May 2014
Posts: 3,559
Likes: 65
From: South Florida
Default

Well, the odometer doesn't work at all. I neglected to go into details there...I'm pretty sure that is the typical gear issue (or at least I imagine it is?).

I have cleaned those grounds....however there are some other minor, obviously electrical, issues in my instruments...voltage gauge is generally low, but sometimes jumps up or down a bit..so the speedo is not mechanical? I don't know why I was thinking it was, but the behavior does match with an electrical issue...
Reply
Old Feb 9, 2016 | 11:05 AM
  #4  
davek9's Avatar
davek9
Rennlist Member
15 Year Member
 
Joined: Jul 2006
Posts: 5,421
Likes: 627
From: Bloomfield, MI
Default

Sounds to me like poor connections at the Pod, when it's out clean the ribbon connectors, try to use a chemical cleaner and not sand paper or an abrasive as that will only remove the thin coating and they will tarnish even quicker than before
Reply
Old Feb 9, 2016 | 11:06 AM
  #5  
GlenL's Avatar
GlenL
Nordschleife Master
20 Year Member
 
Joined: Jul 2003
Posts: 7,742
Likes: 78
From: Minneapolis
Default

Originally Posted by bureau13
Well, the odometer doesn't work at all. I neglected to go into details there...I'm pretty sure that is the typical gear issue (or at least I imagine it is?).

I have cleaned those grounds....however there are some other minor, obviously electrical, issues in my instruments...voltage gauge is generally low, but sometimes jumps up or down a bit..so the speedo is not mechanical? I don't know why I was thinking it was, but the behavior does match with an electrical issue...
That's the gear, then.

The speedo (and odo) work on very small signals from the pickup on the tranny. Bad connections along the way distort that. It runs through the CE panel, too. an R&R there, or simply working the connectors off/on, will help, too. Then there's the pod foil. Once it's all "new" it'll work.
Reply
Old Feb 9, 2016 | 11:07 AM
  #6  
SeanR's Avatar
SeanR
Rennlist Member
 
Joined: Apr 2006
Posts: 35,695
Likes: 511
Default

Also happens when the rivets on the back of the circuit board start to lose contact for the speedo. I've been able to crimp them down a bit more and that's helped on a few of them that don't want new boards.

If your odo is dead even when the speedo works, you do have a thrashed gear.
Reply
Old Feb 9, 2016 | 11:20 AM
  #7  
bureau13's Avatar
bureau13
Thread Starter
Rennlist Member
10 Year Member
 
Joined: May 2014
Posts: 3,559
Likes: 65
From: South Florida
Default

That all sounds reasonable, thanks. I guess that pod R&R is going to have a lot of potential bang for the buck!
Reply
Old Feb 9, 2016 | 11:37 AM
  #8  
WallyP's Avatar
WallyP

Rennlist Member
Rennlist Site Sponsor

20 Year Member
 
Joined: Jun 2001
Posts: 6,469
Likes: 13
From: Ball Ground, GA
Default

Speedometer behavior sounds more like mechanical stickiness in the needle shaft...
Reply
Old Feb 9, 2016 | 12:49 PM
  #9  
bureau13's Avatar
bureau13
Thread Starter
Rennlist Member
10 Year Member
 
Joined: May 2014
Posts: 3,559
Likes: 65
From: South Florida
Default

Would this be something that requires cleaning and lubrication, or do you think something could be slightly bent?

Originally Posted by WallyP
Speedometer behavior sounds more like mechanical stickiness in the needle shaft...
Reply
Old Feb 9, 2016 | 05:20 PM
  #10  
DeMille's Avatar
DeMille
AutoX
 
Joined: Feb 2004
Posts: 13
Likes: 0
From: West of Boston
Default

You will find that the rivets are a source of poor or intermittent or no connection.
I eliminated the rivets on my speedo pc board by soldering a short wire (about 2 in long) on the back of the board, from the printed circuit trace under the rivet, to the trace around the square pin. You need to do this in four places. Sorry, I forgot to take a picture, but I think you will get what I'm saying by the time you replace the speedo gear. Even if those rivets are holding a good connection now, they may give out in the near future. So you might as well do this fix while you have it apart.




Also happens when the rivets on the back of the circuit board start to lose contact for the speedo. I've been able to crimp them down a bit more and that's helped on a few of them that don't want new boards.

If your odo is dead even when the speedo works, you do have a thrashed gear.
Reply
Old Feb 9, 2016 | 07:28 PM
  #11  
bureau13's Avatar
bureau13
Thread Starter
Rennlist Member
10 Year Member
 
Joined: May 2014
Posts: 3,559
Likes: 65
From: South Florida
Default

OK thanks for the info. It sounds like I definitely need the odo gear, and I'll keep this info handy when I open up the speedo assembly
Reply




All times are GMT -3. The time now is 12:10 AM.