Speedometer stripping out dust sheilds

[bruscreen]

As spring approaches, I'm realizing I need to get the speedometer working in #5316.

When I bought the car, it had no dust shield and a seized angle drive. I bought a new angle drive and dust shield from delorean.com, and that lasted a couple of years. Then the speedometer became intermittent, low-speed only, then nothing. I lubricated the cables. The lambda counter is still hooked up with the cable, with the wire disconnected by a previous owner. I've pulled it out and tested it, but it doesn't appear to be slipping. With everything hooked back up, I pulled the dust cap and tested the cable with fingers (turns freely) and a drill (reads highway speeds, easy). I suspected the dust cap was spinning against the wheel, but gluing it on with lock-tite didn't help (I got about half a mile out of that). So I pried it off, bought a new dust cap, and that fixed it for a couple of months before the problem came back.

I suspect that the square hole in the dust cap that accepts the speedometer cable is rounding out, and the only thing I can think to do for it is to fill it with JB Weld and try to mold it to the cable without effectively gluing it on. Before I go to those extremes, what else should I try? Is there a better dust cap on the market? Am I missing some other component to test?

[SS Spoiler]

Head on down to ace hardware and look for a square brass
tube that fits over the angle drive. Fit it into the dust cap and
enjoy a working speedo. I did this 23 years ago, no problems......

[David T]

Head on down to ace hardware and look for a square brass
tube that fits over the angle drive. Fit it into the dust cap and
enjoy a working speedo. I did this 23 years ago, no problems......

One car I worked on was "eating" angle drives and dust caps. I pulled the speedo head out and opened it up. One of the plastic posts had broken off and still had the steel clip on it. It was moving around inside until the magnet in the speedo mechanism attracted it and jammed the works. All that resistance was the problem. If you are having similar problems you may have the same cause. Might be time to pull that head and examine it's innards.

[sdg3205]

The lambda counter is going to add resistance no matter what, but not so much as to kill a dust shield.

I solved this problem by completely cleaning all the 35 year old grease out of the lambda counter, regreasing the mechanisms and installing tin shims in the dust cap itself. This was Toby's idea and it's practically free. You cut thin tin strips from a can to fit the 4 walls of the dust cap. This provides a tighter fit and does the trick.

[PJ Grady Inc.]

FWIW I'd like to let the group know we have made up this part using a stronger urethane resin because many people have experienced fit issues and/or failures of the commonly available replacement.
Rob

[bruscreen]

Thanks for all the advice guys, I knew I'd find some experts here! This should keep me busy experimenting for a weekend, and if it doesn't work out I'll turn to the upgraded dust cap.

[David T]

Thanks for all the advice guys, I knew I'd find some experts here! This should keep me busy experimenting for a weekend, and if it doesn't work out I'll turn to the upgraded dust cap.

That dust cap is like a mechanical "fusible link". It breaks before other, more expensive and harder to replace parts break, like the angle drive. Making the dust cap more robust may not be the thing you want to do.

[PJ Grady Inc.]

That dust cap is like a mechanical "fusible link". It breaks before other, more expensive and harder to replace parts break, like the angle drive. Making the dust cap more robust may not be the thing you want to do.

We made the dustcap as strong as the original because many people had repeated failures with the currently available replacement. It's like using a 10 Amp fuse when the current draw is 20! They also are often too big to fit in the hub and need modification to fit. We made these adaptor cups only because we felt a need for a more durable part. David if you prefer to replace your dustcap every few times you drive your car I can understand your desire to preserve your angle drive at all costs but it's unnecessary. We also have a one piece cable that eliminates the extra drag of the lambda counter. As for angle drives I prefer reconditioned Smiths Instrument units as opposed to the inaccurate Chinese/Indian units currently available. We offer a kit with all three of the above for those who want to fix their speedo woes once and for all.
Rob

[David T]

We made the dustcap as strong as the original because many people had repeated failures with the currently available replacement. It's like using a 10 Amp fuse when the current draw is 20! They also are often too big to fit in the hub and need modification to fit. We made these adaptor cups only because we felt a need for a more durable part. David if you prefer to replace your dustcap every few times you drive your car I can understand your desire to preserve your angle drive at all costs but it's unnecessary. We also have a one piece cable that eliminates the extra drag of the lambda counter. As for angle drives I prefer reconditioned Smiths Instrument units as opposed to the inaccurate Chinese/Indian units currently available. We offer a kit with all three of the above for those who want to fix their speedo woes once and for all.
Rob

My car has the original dust cap, angle drive, speedo cables, Lambda counter, and head. I lube everything once a year and it all works fine. The original parts can be reliable if everything is working as it should and you keep it all lubricated.

[PJ Grady Inc.]

My car has the original dust cap, angle drive, speedo cables, Lambda counter, and head. I lube everything once a year and it all works fine. The original parts can be reliable if everything is working as it should and you keep it all lubricated.

You also only drive your car about once a year! Ok a few times a year. Btw the original adaptor cup was fine. I'm referring to the current repro's unless they were recently improved?
Rob