[spikedog]

I've searched the Hotrodders database and can't find an answer to my problem. I have tried to reach VDO Tech Support, but they don't answer email and they never return a call.

I have a new VDO tachometer that reads erratically all of the time. I have checked and double checked all of the wires, and it is installed correctly. I have a one wire Magnum 80 amp alternator, an Accel 71000 series billetproof distributor, along with an Accel coil made for the breakerless distributor. The engine is a GM 305V8.

Can anyone help?

[bracketeer]

Since VDO tech isn't all that great I guess we should avoid their products.

Some tachs on Gms require filters.

Some aftermarket tachs require tach adapters to change to square wave patterns.

[docvette]

Doc here,

You may need as Bracketeer Said, an Adapter for that Ignition.

Try going to the Accel Website and looking under troubleshooting for Tach, tach adapters for the proper hook up..for the Dizzy and coil..

Usually you just require a wire to the coil points side to get a proper sample but not all operate this way with aftermarket ignitions..so check to be sure..

OR you may just have a Defective Tach itself..Since they opt not to answer Field support..I'd just send it back as "New Inop" and request a FULL refund or exchange (if you want to stay with VDO)

If you have a Cheepie Tach (or go buy one at a flea market) you can "mirror" the hook up at the Car..If it operates decently you can rule out the system and focus on the tach or an adapter..

Doc

[spikedog]

My first thought was that I had a defective tach, so I sent it to a VDO service center ( Nichols Speedometer Service) where is was bench tested and passed. They also checked the dip switches to be sure they were set properly for my application.


I checked with Accel and they wern't much help either. They told me I may need a Accel part#49365 tach adapter, which I purchased but have not installed. The Accel tach adapter directions and wiring diagrams have nothing to do with the distributor and coil that I am using, so I am waiting for a clarification from Accel tech support ( another tech line that takes 7-10 to respond) as to how to install this part with the 71000 series distributor.


The thing that bothers me most is the lack of response and poor product knowledge displayed by both tech support teams at VDO and Accel. Both of these companies are major aftermarket suppliers, and should be able to answer elementary questions regarding their products.

I have also had a fogging problem with the small VDO gauges (fuel, H2O, volt, oil pressure) in the evening when the panel lights are on. Although VDO makes a very nice looking product, next time I think I will use a different company's gauges. ( Unfortunately, I think Auto Meter is owned by VDO/Siemens)

Thanks to you guys that responded.

Conrad Lanoue
Jacksonville, VT

[JohnTN]

I bought a VDO electronic gauge package last year and had a question about calibrating the speedometer. They never answered my e-mail inquiry, but I was able to get the speedo to work on my own. No problem with fogging so far.

John

[docvette]

Doc here,

Didn't think Calibration was possible on those..The one's I have dealt with were calibrated for the transmission when built, and you selected the right pickup for yours..learn something new everyday..!

As far as the condensation, usually it attacks through the illumination hole and seeps into the gauge..(although a bad fitting lenses is not to be ruled out..)

I usually use VERY CAREFULLY a heat gun..with the bulb out. Heat it until the fogging goes away in several steps..

You can use also a hair dryer, better, cuz it has a lower temp...Either way..DO NOT overheat, you will melt internal parts and screw the gauge up..

If he budget allows, next time I'd go Dolphin gauges..much better gauge, AND good support..with a price to match (unfortunately..)

Doc

[swvalcon]

I have a vdo tack in my drag car with the play back feature. It worked fine but play back was erratic. First they gave me some covered wire Lomb that did'nt help. When i told the rep at the race track about it he told me to bring him my old tack and come back in a hour and he would have it figured out. When i returned he handed me a new tack for free and said the wiring in the tack was messed up. the new one has worked perfect sense it was installed. I've never had a company go that far out to service a product to a racer. I've got nothing but good thinks to say about vdo as company or their product.So if you are having problems take it to a company rep at a NHRA national event and i bet he can fix you right up.

[spikedog]

If you need the VDO instructions for programing a VDO electronic speedo, send me your address and I will send you a copy of the instructions. You can reach me at spikedog@together.net.

[spikedog]

I appreciate your input, but I think my fogging problem is because the gauges are NOT ventilated. The gauges fog up when the lights go on which tells me that the heat from the bulbs is creating steam and it cannot escape the gauge. I do not have an extra gauge to look at, so I don't know if there is a built in vent hole. My dash mounting surface is quite thick because it is wood veneer over fiberglass, and I'm wondering if the vent hole is blocked by the dash.

[spikedog]

Your response validates my impression of the VDO tech support people. They tried to fix your tach and failed. Instead of figuring out what was wrong, they just replaced it.


As far as checking with a VDO rep at at National NHRA event, I'll be sure and do that the next time NHRA comes to Jacksonville, Vermont.