"Bouncing" volt meter

RonKMiller

New member

• Nov 6, 2010

• #1

The OEM volt meter mounted in my factory mounted 1979 R80/7 S fairing "bounces" sometimes - fluctuating around 13 volts.

Then, mysteriously, it remains perfectly calm and indicates just over 13 volts.

I don't think it is due to mechanical issues since it does it just tooling around town on rough roads - as well as at an indicated 80mph on smooth pavement.

The only electrical mods I've done is to install the Thunderchild diode board, hotter coils, new OEM plug wires, new plugs and a new battery. Everything else is OEM.

I don't know if these mods had any effect since the bike was not running before I did them. Other than this everything is copasetic and it starts and runs like a champ.

Time to start looking for a short - but where to begin? I'm kinda thinkin' somewhere inside the headlight bucket...

Thanks in advance!

 

Anyname

Active member

• Nov 6, 2010

• #2

I wouldn't leave out all the places that wires are held by cable ties and are routed over sharp edges. It could also be a loose or corroded connector. Time to start wiggling wires...

 

bmweuro

New member

• Nov 7, 2010

• #3

It's the inner working of the volt meter. The later ones are dampened so you don't have this issue.

 

B

bikerfish1100

New member

• Nov 7, 2010

• #4

when i had that (or similar) issues with my VDO voltmeter decades ago, i was told the best way to repair it was to use black electrical tape. a heavy coating applied liberally to the face of the gauge would resolve the issue- there's a much greater likelihood that the gauge is wrong than the charging system is at fault.
(turned out to be bad ground tab on the back of the gauge, iirc.)

 

R

robsryder

Motorcycleton

• Nov 7, 2010

• #5

On my 77 R100RS (a /7) the OEM voltmeter gave erratic readings despite my cleaning of the contacts and connectors for the wiring system. And the OEM clock did not keep time. I got rid of the OEM equipment and replaced the units with VDO marine units.

The VDO volt meter reads a consistent voltage (13 to 14 volts with the bike running) and the clock keeps time. No second hand on the clock, but that was a good trade for accurate time keeping.

Here is the OEM equipment

Here is the replacement VDO meter

 

RonKMiller

New member

• Nov 7, 2010

• #6

Thanks all! I think I'll do a little "sphritzing" with my Nutrol contact spray cleaner/lube and maybe pull out some dielectric grease. I'm thinking corrosion may be the culprit.

It's such a strange little gremlin since it is PERFECT for miles - then starts wiggling.

Nice replacement with the marine VDO's! - luckily my clock has taken a lickin' but keeps on tickin'. Keeps perfect time.

 

brownie

Member

• Nov 7, 2010

• #7

Nice improvement!!

Looks great!!!

 

RonKMiller

New member

• Jan 26, 2011

• #8

This is truly bizarre - but the volt meter has somehow fixed itself.

Steady as a rock.

 

rapiddog

Barback King

• Jan 26, 2011

• #9

robsmoto

can you 'splain how you went about hooking up the new gauges as far as connectors and light bukbs or where they just plug and play? PN#'s?
My clock is good, but the VM is just whack!

 

R

robsryder

Motorcycleton

• Jan 26, 2011

• #10

I purchased my VDO VM and clock from Lauderdale Marine some years back. In another thread someone cited Summit Racing as a source for VDO meters. I've looked at the Summit Racing website and their clock and VM look identical to mine. Links to the SR website for these meters are below -

http://www.summitracing.com/parts/VDO-332103/
http://www.summitracing.com/parts/VDO-370155/

I used spade connectors (available from Radio Shack or other electrical / electronic suppliers) to hook the VDO units to my existing wiring. As I recall, I made a "Y" connector to provide power to the lights for each meter. I made certain that the existing wiring connectors were free of corrosion and I used di-electric grease on each connection. Di-electric grease can be purchased at any auto parts store. One could also use vaseline in place of the di-electric grease. The idea is to limit the amount of corrosion to electrical connections.

Here is a link to the user manual for the VDO marine VM -
http://www.vdo.com/generator/www/co...lc_installation_instructions_voltmeter_uv.pdf

 

rapiddog

Barback King

• Jan 26, 2011

• #11

Wow, I lik that idea of the lighting they have:

sing fiber optic technology, these gauges feature VDO's Trioptic through-dial lighting technology for superb nighttime illumination.

Click to expand...

So no bulbs to deal with?
Then you made the Y from the existing lightbulb wire?

 

R

robsryder

Motorcycleton

• Jan 26, 2011

• #12

My VDO units used standard light bulbs (similar to those used in the speedo / tach unit). I think that there was some light pipe-type material that helps move photons about the instrument for more uniform illumination.

I used regular copper stranded (22 or 24 gauge) wire with regular 1/4-inch Radio Shack spade connectors.

 

lmo1131

New member

• Jan 26, 2011

• #13

Thread Jack ON:

For a while, back in the 80s, VDO offered 52mm (2-1/16") water-proof handlebar mounting "cups" that were spun aluminum (with black crinkle-finish); they included a handlebar clamp and rubber isolators, and came with their black-face " Biker" series instruments. I thought it would be relatively easy to find a couple, but it isn't proving to be the case.

Has anyone seen these new VDO cups in person, or better yet have them on their bike? They don't look to be waterproof, and no specs are mentioned.

Unlike the new version, the mount was at the top of the instrument so that the mass of the instrument hung below the bar.

Thread Jack OFF:

 

rapiddog

Barback King

• Jan 26, 2011

• #14

I ordered up the C & VM fro Summit to have a look see.
Will report back on this and thanks foor the tip. If this works I'll have a perfectly good extra OEM clock...