67 Barracuda rallye speedometer issue

[67fish383S]

So this is technically not an Electrical and Ignition issue, but I didn't see another category that was any more appropriate. I got some good feedback in this section on another gauge-related issue, so here goes. I also recognize by the way that this request for help may be premature, as I will not be able to pull the cluster again for a while, but I'm hoping perhaps someone may have had a similar issue and can offer advice just based on a description of the problem.

So a week or so back, I removed the Rallye instrument cluster from my Fastback to replace the vacuum gauge with an aftermarket tach and upgrade the lighting to LEDs. Since re-installing the cluster I have had an avalanche of problems (related thread concerning faulty OE gauges and the tach). I was careful about re-connecting the speedo cable (thread on connector), and everything seemed fine at first. I did happen to notice after driving it a bit that the needle on the speedo would occasionally modulate a bit at a constant speed, which was something I've not seen before. It was minimal and I thought no big deal.

When pulling into the parking lot at work yesterday, I heard a god-awful clunking noise and had no idea what it was at the time. On the way home, I noticed almost immediately that the 120MPH speedo was acting weird and making a clicking sound. It would read no lower than 10MPH at a stop and no higher than 30-40MPH when moving. I pulled over at the earliest opportunity to check the cable connection. Cable was solidly mated to the rear of the gauge and the odometer was and is still spinning freely. I could also spin the speedo in both directions by hand with the cable disconnected, and got almost no response from the needle. It seemed to turn freely without binding and not make any noise.

Sounds to me like the speedo has or is coming apart internally. As I mentioned, it will be a while before I'm able to pull the cluster again and have a look, and I do need to drive it at least one more time in a couple of days. Should I disconnect the cable just in case? Don't want to mess with odometer accuracy, but also don't want to risk damaging the speedo further if it can be saved. No idea if these can be rebuilt, or if I should just start looking for a replacement. I'm sure they are cheap and readily available lol.

Any advice or tips from someone who may have had a similar issue would be most appreciated. Thanks!

 

[krazykuda]

The strand for the speedo cable is ground square at the ends and needs to be properly aligned when insterted into the speedometer.... Check to make sure that the strand for the cable is properly inserted into the speedo housing...

 

[67fish383S]

The strand for the speedo cable is ground square at the ends and needs to be properly aligned when insterted into the speedometer.... Check to make sure that the strand for the cable is properly inserted into the speedo housing...

So I guess I wondered about that, and I probably should have checked into it further before re-connecting. I guess I just figured that as long as the cable was inserted as far as it would go into the gauge and the nut tightened properly, all would be well, but maybe not. It's not like it's any easy thing to see in there, so I was going by 'feel'. Thanks for the tip.

I guess I also assumed that since the odometer seemed to be turning normally that the cable connection was good. I wish these things were not so damn difficult to get in and out. Why couldn't the 1967 engineers have thought of plug-and-play lol.

 

[Mike69cuda]

Replacing the cable with a new one is relatively easy compared to removing the dash and is probably a good start. Those 50 year old cables don’t like being moved around.

Oops, just reread your post. If the needle is sticking, it is not the cable. Too early in the morning....

 

[66fs]

Your speedo can be repaired but is expensive. Maybe Redfish will chime in.

 

[krazykuda]

So I guess I wondered about that, and I probably should have checked into it further before re-connecting. I guess I just figured that as long as the cable was inserted as far as it would go into the gauge and the nut tightened properly, all would be well, but maybe not. It's not like it's any easy thing to see in there, so I was going by 'feel'. Thanks for the tip.

I guess I also assumed that since the odometer seemed to be turning normally that the cable connection was good. I wish these things were not so damn difficult to get in and out. Why couldn't the 1967 engineers have thought of plug-and-play lol.

Try lubing the speedo cable with some lithium grease when you go back in there again...

 

[Mattax]

If the odometer isn't moving, then it might be cable related.
If the needle is not returning, seems most likely its the internals.
The needle is supported on a shaft that is not directly attached to the drive mechanism.
It's movement is due to magnetic force between the spindle and the drum.

Redfish explains the details here.
Speedometer evaluation?

 

[RedFish]

The part that people miss is the hardened grease/crud build up inside that square drive port. The cable is supposed to slip fit and not put any pressure on the instrument in any direction. The collector nut that your model has never did provide enough cable support and alignment so that nut was changed to a plastic sleeve about 1.5 inches long in 68 and later. All you can do is clean the input port, route the cable in straight as possible, snug that nut and cross your fingers. If your disturbing this worn fitment amplified and showed you the wear that was already in the instrument, you could pay about 200 for restore, or buy a good used 68 or later speedometer without the trip clock and buy a new cable for that 68 and later model. I wont detail the additional problems that the trip clock causes. I will add a tip...
When we see a picture of a speedometer for sale, it is resting or propped on its input/spindle. If that pressure lifts the needle farther than 7 mph, let them keep it, shop for one that shows less wear. Wear in the bore lets the magnet shift off center, that lifts the needle. When they were new, bias pressure on the spindle didn't lift the needle at all.

 

[67fish383S]

The part that people miss is the hardened grease/crud build up inside that square drive port. The cable is supposed to slip fit and not put any pressure on the instrument in any direction. The collector nut that your model has never did provide enough cable support and alignment so that nut was changed to a plastic sleeve about 1.5 inches long in 68 and later. All you can do is clean the input port, route the cable in straight as possible, snug that nut and cross your fingers. If your disturbing this worn fitment amplified and showed you the wear that was already in the instrument, you could pay about 200 for restore, or buy a good used 68 or later speedometer without the trip clock and buy a new cable for that 68 and later model. I wont detail the additional problems that the trip clock causes. I will add a tip...
When we see a picture of a speedometer for sale, it is resting or propped on its input/spindle. If that pressure lifts the needle farther than 7 mph, let them keep it, shop for one that shows less wear. Wear in the bore lets the magnet shift off center, that lifts the needle. When they were new, bias pressure on the spindle didn't lift the needle at all.

Wow that is all great information. Thanks to you and everyone else for the replies!

 

[4spdragtop]

We had a similar issue with our 67. Ifni recall correctly there is a small brass washer between the speedo and the cable? I think it is there as a "spacer"?

 

[67fish383S]

We had a similar issue with our 67. Ifni recall correctly there is a small brass washer between the speedo and the cable? I think it is there as a "spacer"?

Nothing fell out when I originally disconnected it. If it does have one, hopefully it is still in there.

 

[Murray]

You may have multiple problems. Do also R&R cable to see if its bad.

 

[RedFish]

We had a similar issue with our 67. Ifni recall correctly there is a small brass washer between the speedo and the cable? I think it is there as a "spacer"?

Nope. There is a brass collar about 3/16 long pressed onto the end of the spindle. a thrust washer underneath it. The cable has a stop collar on this end of it also ( about 1 inch behind the end). Nothing that should fall out though.

 

[Tylan]

What if the cable is brand new and it still bounces and clicks? Is it more likely that the manufacturers didn't put enough lube on the cable or that the speedo itself is failing?
(Asking for 74 duster, auto trans)

 

[Mike69cuda]

What if the cable is brand new and it still bounces and clicks? Is it more likely that the manufacturers didn't put enough lube on the cable or that the speedo itself is failing?
(Asking for 74 duster, auto trans)

Sometimes it hard to tell. You can unhook the cable from the speedometer & drive it & see if it still clicks.

I have used a drill to test speedometers & cables in the past. It may give you an idea. Easier to troubleshoot noises if the car isn’t moving and the engine is off.

 

[JAndrea]

Mine bounced and clicked. The Speedo needle would rise, then fall back to zero with each click. I tore mine apart recently and found that the initial, rotating part that spins with the square end of the Speedo cable was fine, as well as the nylon gear that runs perpendicular. But beyond that, everything seems seized. The clicking was the nylon gear teeth slipping over the seized gear teeth of the brass gear that leads to the rest of the odometer gears etc. Hence, the nylon teeth seem warn down. No solution yet... just found this out tonight, and I have to see how much of the Speedo head can be taken further apart.

View attachment 1715644006

 

[67fish383S]

Since I originally posted this thread, I removed the original speedo and found the spindle was bent and not spinning freely around the drum (refer to @Mattax 's photo above). The spindle was contacting the housing causing the clicking and erratic needle movement. I attempted to re-shape it and it got better, but was still not right.





I replaced it in the car with a spare speedo I had on the shelf and unfortunately had a similar, but less severe issue, which is probably more like what @JAndrea posted above.

Trying to repair this mechanism myself was more than I wanted to take on. Props to you if you can fix it yourself, but it sounds like worn parts will need replacing and they do not all show the exact same failure mode (different parts could be the issue in any given case). Some combination of magnet shaft / upper jewel / speedcup / bushings were mentioned when I contacted several repair services.

The consensus from those communications was that these mechanisms were not a robust design and frequently wear out. I found a few places that sounded like they were experienced with restoring them. I ultimately sent both units to a place called "Mr Heaterbox" in Canada because they custom manufacture new bushings for these and offer full restoration, including the dial face and needles if you want those rehabbed. The prices were comparable to other places, but they were all in the range of $150-$250 per unit for service and calibration. Shipping to Canada was a pain and I am still waiting for the results, but I hope to have two restored units back in my hands soon. Thanks to everyone who replied with all of the valuable information and pictures.

 

[my68barracuda]

Since I originally posted this thread, I removed the original speedo and found the spindle was bent and not spinning freely around the drum (refer to @Mattax 's photo above). The spindle was contacting the housing causing the clicking and erratic needle movement. I attempted to re-shape it and it got better, but was still not right.





I replaced it in the car with a spare speedo I had on the shelf and unfortunately had a similar, but less severe issue, which is probably more like what @JAndrea posted above.

Trying to repair this mechanism myself was more than I wanted to take on. Props to you if you can fix it yourself, but it sounds like worn parts will need replacing and they do not all show the exact same failure mode (different parts could be the issue in any given case). Some combination of magnet shaft / upper jewel / speedcup / bushings were mentioned when I contacted several repair services.

The consensus from those communications was that these mechanisms were not a robust design and frequently wear out. I found a few places that sounded like they were experienced with restoring them. I ultimately sent both units to a place called "Mr Heaterbox" in Canada because they custom manufacture new bushings for these and offer full restoration, including the dial face and needles if you want those rehabbed. The prices were comparable to other places, but they were all in the range of $150-$250 per unit for service and calibration. Shipping to Canada was a pain and I am still waiting for the results, but I hope to have two restored units back in my hands soon. Thanks to everyone who replied with all of the valuable information and pictures.

Sounds like the OP has found a good speedometers repair shop, I will add one more.
I have had two speedometer heads repaired and cleaned by Deluxe Speedometer in Denver CO. I found their turn around time and pricing to be very acceptable. I am not at all affiliated with that business, passing this on as they did good work for me.