VDO Speedometer

ninexrep · #1 (**permalink**) 11-11-2011, 11:33 AM

Hello out there. This is my first attempt at writing to Club Cobra and I definitely need help. I recently purchased a BDR roadster build # 1054. Brand spanking new. I love the car but the VDO speedometer is giving me a constant problem. I've tried to calibrate it according to the instructions in the BDR manual. The first time I did it the pulse number was 550, it reset but the speedometer never made a "full sweep" and worked for about a day. Then it started to fluctuate all over the dial again. So I went thru the instructions again. This time the pulse number came up 7330 and it reset to the mileage again, but still no full sweep at the end of the calibration process. Worked for a while then quit again. I then tried the setting with a known pulse it worked okay for about an hour then started either not registering at all or wildly fluctuating over the speedometer range. It has been driving me crazy. Can anybody out there tell me what I'm doing wrong? I don't have too much hair to begin with and I'm pulling out what little I do have. PLEASE HELP!

Cashburn · #2 (**permalink**) 11-11-2011, 05:21 PM

Should not reset odometer like that, suspect bad gauge. Dealer can warranty that for you.

ninexrep · #3 (**permalink**) 11-12-2011, 05:21 AM

Thanks a million. I will contact dealer ASAP.

Ron61 · #4 (**permalink**) 11-12-2011, 06:17 AM

I have a VDO electronic one in the Cobra that I had and to reset it all I had to do was push the button until it said automatic, drive 1 mile, stop and push the button again. I put it in back in 1997 and it is still there and working great. I even checked it and the tach with the help of the CHP and their radar at 60,70,80,and 90MPH and it was right on on both of them at all those speeds.

If the new one does the same thing check your sending wire as I had that happen once when it got loose and it would make the needle fluctuate all over. This is all depending on if you have the electronic one like I had.

Ron

ninexrep · #5 (**permalink**) 11-12-2011, 12:22 PM

Thank you Ron;
I'll check it out before I call in for a replacement. Dave

Pmiller176 · #6 (**permalink**) 02-01-2014, 12:06 PM

Folks, I just bought BDR car and speedo not working. I read the posts here and wonder can I just do a reset on my speedo. It's VDO brand gage with analog speed and digital odometer. Anyone know if there is a simple reset protocol?

Cashburn · #7 (**permalink**) 02-01-2014, 12:19 PM

Quote:

Originally Posted by Pmiller176

Folks, I just bought BDR car and speedo not working. I read the posts here and wonder can I just do a reset on my speedo. It's VDO brand gage with analog speed and digital odometer. Anyone know if there is a simple reset protocol?

Most likely your sender in the differential.

Pmiller176 · #8 (**permalink**) 02-01-2014, 01:00 PM

A little more info...just took a ride. After resetting and driving a mile or so speedo was working again. Went over the same rough intersection where it stopped working yesterday and again it stopped working. At first needle bouncing around then nothing. Does that match up with the sender in the differential? Could wire or magnet in pickup be moving around?

6t8stang · #9 (**permalink**) 02-03-2014, 04:19 AM

Agree with Jay - sounds like the sender. Could simply be a loose or dirty connector at the diff. Disconnect, spray with electronics cleaner and plug in again.

Ron61 · #10 (**permalink**) 02-03-2014, 04:58 AM

Jay is right probably. I used a Hall Effect Sending unit and it had 3 wires. Battery, Ground, and the Sending wire to send pulses to the speedometer. Once it got a break in the insulation and it did the same thing yours is doing so I got a little heavier wire and ran 3 new ones and then fixed them so they couldn't rub or be hit by any flying debris from the ground. And as I said above, it is still working perfectly.

Ron

STEVE-O · #11 (**permalink**) 02-06-2014, 07:19 AM

For those tired of speedometer issues, I came across this link on here. Havent tried it but it looks promising, plus no calibration, takes into account different tire sizes, even has 0 - 60 and 1/4 mi timing. Just have to not drive in areas with no GPS!

Cobra Counter Clockwise Speedometers

turbofanman731 · #12 (**permalink**) 02-06-2014, 12:11 PM

I have the GPS speedo and have no issues with it. It also has 0-60 and 1/4 mile timing and speed features. It doesn't work well in tall buildings, canyons, covered parking and such. I don't worry much about the speed when I'm in those places myself. Reasonably priced and gear ratios, tire sizes nor wiring issues don't bother it.

PANAVIA · #13 (**permalink**) 02-09-2014, 02:00 PM

+1 for Speedhut - great stuff. However it would be nice for his VDO unit to work like it is supposed to

- it sounds like there might be a wiring issue , or a damaged gauge.

- if it is a hall effect sensor, I remember from my Jaguar days that they were very sensitive to being the proper distance from each-other ; from the tooth and wheel perspective. also the wires themselves might be suffering from RFI from a fuel pump motor or such...

or there might just be a hinky electrical connection.

--best of luck, let us know what you find

Steve