Angle Drive Diagnostics

[TTait]

My speedo just stopped working. The cable was tight into the back of the speedo.

I have the single long cable setup, no service counter.

I unhooked the cable from the angle drive and spun it with a drill, the speedo worked.

I took off the wheel and observed that the dust cap was not spinning (yay - cheap fix!)

I removed the dust cap and it had no obvious wear.

I then used a drill to spin the input spindle on the angle drive, and the speedo worked - I assumed the dust cap was just loose.

I cleaned and inspected the dust cap and reinstalled it with a bit of silicon adhesive around the perimeter and let it set up. I spun the wheel and I could hear ticking, no speedo movement. Took the wheel off again and the spindle was now snapping inside the dust cap, but the dust cap was now spinning with the wheel.

I removed the dust cap tried to turn the spindle by hand - no dice, either way - way too tight to turn by hand.

I unhooked the speedo cable - it turns by hand with about 50% of the possible effort my fingers could exert.

I then tried to spin the angle drive, with the cable not attached I could turn it but it took about 80% of the force my fingers could exert, and the output turns.

What do we think - replace the angle drive, the dust cap, or the speedo cable?

I'm assuming the angle drive... Advice appreciated - I'd like to get this fixed quickly.

Tom

[stevedmc]

Are you sure the metal shaft is fully seated in the dust cap? The rod on my DMCH unit was actually too short to go all the way in the dust cap. It basically wasn't making a connection and couldn't spin because of this.

I replaced my DMCH angle drive with one from Hervey (his has a longer shaft that goes into the dust cap) and things have been great ever since then.

[Jonathan]

This sounds about like my speedo this weekend. Mine died yesterday. When I got to our club event, a friend and I took off the wheel for a look. The angle drive cable was very difficult to turn with your fingers but fairly easy to turn with some pliers. No signs of damage or slippage on the dust cap. With the lower speedo cable disconnected from the angle drive, the angle drive turned somewhat easy and the lower cable spun fairly easy too (and you could see the speedo needle move).

The problem seems to be similar to yours when you plug the two together. Like you said, it takes most of your finger strength to turn it. So time was running out and we tried our best to secure the cable from bouncing around (I don't have the bracket so we zip tied to the brake line). The speedo worked for about 50 feet.

Fast forward to today when I was back home with my tools and garage. I lubes the angle drive after taking things apart and the angle drive alone REALLY spun easy now. Ok so we're getting somewhere. I connect things again and the system doesn't spin quite as easy as when apart. I go for about a 15 mile drive and it was working but died on the 14th mile.

So a couple ideas. Lube the lower speedo cable somehow or also lube the lambda counter (I need to reset it anyway after doing my O2 sensor). Not sure what else to do if lubing the cable portion doesn't work??

[TTait]

I no longer have the upper and lower speedo cables with the service counter in the middle, I have a long 1 piece cable that goes from the angle drive to the speedo directly.

I'll lube that a bit, but I think the drive is dying...

Steve, I'm pretty sure the spindle is into the cup far enough, but I may try Mr. Hervey's angle drive too - does he sell dust caps?

Can the angle drive be over lubed?

[TTait]

also - John seems very proud that his angle drives have a replaceable flex shaft on them - why would the flex shaft go bad - I thought it was always the gearing inside?

[WelmoedJ]

Sometimes the flex shaft of the AD eats the square centre of the dust cap.

Happened to mine.
A new dust cap made the speedo works as intended.

A stuck or not smooth turning flax shaft will also round the square in the center of the dust cap.
Happened to mine too.

[content22207]

Despite what some British owners say, there are several problems with angle drive gears:

1) Being helical, only the center of the gear teeth actually intermesh with each other. A small amount of wear in the axle gear's brass bushing will allow it to fall away from the speedometer gear and no longer intermesh.
2) Gear teeth are not deep to begin with -- perhaps 1/32"
3) The gear teeth turn into each other, which naturally leads to binding (both gears are angle cut). You can feel the difference turning a brand new angle drive in your hand -- turning it backwards (clockwise) is easier and freer than turning it in the normal direction of wheel rotation

Bill Robertson
#5939

[stevedmc]

I no longer have the upper and lower speedo cables with the service counter in the middle, I have a long 1 piece cable that goes from the angle drive to the speedo directly.

I'll lube that a bit, but I think the drive is dying...

Steve, I'm pretty sure the spindle is into the cup far enough, but I may try Mr. Hervey's angle drive too - does he sell dust caps?

Can the angle drive be over lubed?

Hervey's angle drive is sealed and you cannot lube it. I don't believe he sells dust caps. My advice would be to order a dust cap from DMCMW (I love those guys) and an angle drive from Hervey.

If your old angle drive is from DMCH please put it side by side with your Hervey unit before installation. I really want to know if all of the Houston units have shorter shafts than Herveys or if I might have been sent a defective DMCH part.

[TTait]

I'd be willing to give John's a try, but I need it fast and I couldn't get him on the phone to confirm he could ship today, so I have a drive and dustcap coming up from DMCCA overnight.

I need to get the car back on the road as we are planning on having lunch with the original owner friday. He hasn't seen the car in 18 years.

[content22207]

Keep a laminated RPM xRef (formatted for easy reading at a glance, sized to fit over the speedo) taped to your glovebox lid with double sided tape. If your angle drive ever breaks, you don't even need to stop the car -- just reach over, pop the glovebox, stick the chart to your instrument cluster lens, and keep on driving.
SpeedoxRefInGlovebox.jpg

I've done it many times myself.

Bill Robertson
#5939