cmc-gauge help needed

i just purchased a cmc on 1971 vw pan. the gagues are marked vintage-reproduction
i am having the following problems.
1. speedometer reads 8 to 10 mililes to slow. i purhased a new cable for a 71 vw but does not fit. tires are 165r15, can the speedometer just be bad? cable is turnung, and it is through the wheel dust cap.
2. tach does not go over 1500 rpm. have a mallory unilite distributor. will the tach adaptor correct this?
3.oil temp gauge, not hooked up at sending unit. i have ordered a new sending unit. But when i turn the "dimmer" switch up for the dash lights the gauge needle goes up pass the 300 degree mark. i have disconnect the red/yellow wire and it stops? the other wires have no affected.
any information would be helpful
thanks.......

Ed - My kit came with the Vintage gauges and they had an instruction booklet. I sold off the gauges and the instructions years ago. I'm sure someone still had the instructions. Do the instruction in the build manual (check library) help any? Not sure that a generic (VDO) sender will work as they expect specific OHMs on senders. Make sure each gauge has ground wire. On temp it sounds like you have light wire to the gauge wire. Does the tach have a 4/6/8 cyl switch on the back? Sounds like it could be set wron. Hopefully someone will provide you the instructions that came with them. There was a guy comeing from Scotland that had set of the CMC gauges he'd bring on visit to PA ($100 asking)- hopefully that included the senders. Might be worth having a second set - in case. Welcome to DC area!

Hey Edward,,
I have a similar issue with my cmc/vdo speedo. Up here,, we ride in kilometers kph,, but of course my speedo is in mph. Also,, I changed the front tires to a higher aspect touring treads, which handle much better,, but contribute further error to the speedo. So what I did,, was just took my gps, and calculated the error/correction factor to what my speedo's dial face shows. It turned out to be .7,, and that is consistant no matter what the speed traveled. First I made up little stick on labels and stuck those on the guage face glass,,, but that looked kind of tacky. Then I made up a little conversion chart,,, but that was a pain to locate and use. Then I just got good again at my 7 times tables. That works best for me,, as there are only a handful of speed limit values that I need to consider anyway. ie: if I am in a 100kph zone,, then I want to see 70mph on my speedo. Heck,, I spend more time looking at my tach anyway !!
Alan

I'm sure Alan knows that there are several instrument houses that will re-label your existing gauge face to whatever you want it to read. Since he has done the math, it's only a matter of disassembly and modification. Not much money if you do the labor.

I mention only because others may have the same issue.

Well, some of this is an easy fix, and others not so easy:

1. speedometer reads 8 to 10 miles to slow. i purhased a new cable for a 71 vw but does not fit. tires are 165r15, can the speedometer just be bad? cable is turnung, and it is through the wheel dust cap.

Yes, unfortunately the Speedo is bad. If it were reading high, then going to a 16" wheel would have brought it in about right, but with a 15" wheel and it reading slow, then it's plain bad and has to be rebuilt or replaced. (see other comments on North Holywood speedo).

2. tach does not go over 1500 rpm. have a mallory unilite distributor. will the tach adaptor correct this?

Beats the hell out of me - I've never used a "tach adaptor", but it sounds like you have a tach set up for an 8-cylinder engine (1/4'th of 6500 is about 1500, OK?) so that'll have to be "adjusted" (see North Holywood yadda, yadda) or replaced.

3.oil temp gauge, not hooked up at sending unit. i have ordered a new sending unit. How did you know what to order?? But when i turn the "dimmer" switch up for the dash lights the gauge needle goes up pass the 300 degree mark. You have the wires connected to the Combi-gauge incorrectly. i have disconnect the red/yellow wire and it stops? the other wires have no affected. God only knows what that red/yel wire goes to, but it looks like the wire coming from the headlight switch to the other gauge running lights is/was somehow connected to the "+" tab on the rear of the combi gauge. I'm pretty sure that there is a decent wiring guide for the gauges in the late CMC manual in the "library" section of this site - THAT should tell you what goes where, and then you'll have to use a tester to tell you which of the wires up under the dash goes to each expected sender. Good luck.....gn

Expounding on Gordon's #2 point. It may be possible that the small switch located in the back of most tach's is not set to the 4 cyl position. Most tachs has switches that allow you to select 4cyl, 6cyl, or 8 cyl applications.

I agree that it would seem that the red/yellow wire comes from the dimmer (adjusts the brightness of the dash guages) portion of the headlight switch and it has been incorrectly attached to either the sender tab or the power tab on the guage. I would check it with a voltmeter and if the power changes as you rotate your light switch I would hook it up to your guage light.

That of course begs the question: What is the guage light currently attached to? The sender wire maybe?

By the time you fuss with the Vintage CMC gauges you could have glassed the dash and replaced with quality VDO Porsche 914 gauges. Benfit is that big tach centered in dash where it should be and an accurate Speedo with trip.

I recall reason I got rid of my Vintage CMC gauges was new out of box the tach read 2500 RPMs and the oil pressure 40#. Unfortunately this was after I had cut the holes in the dash.

I would not waste $ shipping them to HW Speedo. If you can't find NOS replacement - sell ones you have and go with 914 gauges. You can get ~$80 for old with senders and get 914 ones for about same cost (will need senders though for gas and oil temp if you mod combo gauge for oil temp).

Should you opt for the 914 gauges (RECOMMENDED ! ! ! ), the 914 fuel level sender can be expensive mostly due to the "Porsche" name attached, but also because it has a low fuel level sensor and electric output for the gauge warning light.

If you can live without the idiot light and want to save some cash, grab up a Karmann Ghia sender. Same "tube" configuration, works with the gauge, fits the Beetle tank, and totally cheap on TheSamba.

T

I thought about using the 914 sender but never could find out if it actually fit.

Even if the bolt holes matched I thought it might be the wrong length.

Nope....Fits like the proverbial glove.

That's what I run, too.