Why does my speedometer cable keep breaking ?

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Richard Sjolund
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Why does my speedometer cable keep breaking ?

#1 Post by Richard Sjolund » Wed Nov 07, 2018 12:13 am

On my way from Iowa to Scottsdale, Arizona my speedometer cable broke in Grants, New Mexico. The replacement will be my 4th cable in 2 years.

I have a world-class 356 restoration and repair shop in Iowa - - and another one in Tempe, Arizona.

Both of them have replaced broken speedometer cables recently - and now I need another new cable.

I hate to return to the truly great service area and tell them that the cable they replaced has broken ---- What should they be looking at or for ???
Richard Sjolund
Solon, (Iowa City), Iowa
"Ruby" 1964 (September, 1963) 356 C Karmann Coupe (Ruby Red, color:6402)
On the 356 Registry cover- November, 2005; July, 2018
Ford F150 4X4 (Winter Snow Plow)
2015 Audi A4 Quattro (Wife's car)

Martin Benade
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Re: Why does my speedometer cable keep breaking ?

#2 Post by Martin Benade » Wed Nov 07, 2018 12:19 am

I suspect your speedometer is seizing up internally and breaking the cables. The part the cable goes in should spin quite easily.

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Richard Sjolund
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Re: Why does my speedometer cable keep breaking ?

#3 Post by Richard Sjolund » Wed Nov 07, 2018 10:04 am

Martin Benade wrote:I suspect your speedometer is seizing up internally and breaking the cables. The part the cable goes in should spin quite easily.

I had it rebuilt at Palo Alto Speedometer a few years ago. Would it work OK for thousands of miles and then just jam up?
Richard Sjolund
Solon, (Iowa City), Iowa
"Ruby" 1964 (September, 1963) 356 C Karmann Coupe (Ruby Red, color:6402)
On the 356 Registry cover- November, 2005; July, 2018
Ford F150 4X4 (Winter Snow Plow)
2015 Audi A4 Quattro (Wife's car)

Dick Weiss
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Re: Why does my speedometer cable keep breaking ?

#4 Post by Dick Weiss » Wed Nov 07, 2018 10:17 am

Richard,

I assume the cable/insert is inserted into the sheath correctly--from the front end: Not the rear due to the little thrust bearing on the end of the tach's entry.
Where is the cable breaking & does the cable have a light grease-wipe when inserting it?

Dick

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Re: Why does my speedometer cable keep breaking ?

#5 Post by Martin Benade » Wed Nov 07, 2018 10:28 am

Dick, it was speedo, not tach. Maybe still the same advice applies?

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Jim Karaba
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Re: Why does my speedometer cable keep breaking ?

#6 Post by Jim Karaba » Wed Nov 07, 2018 10:39 am

Is the cable run properly so as not to be in a bind during steering motions and suspension travel?

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Richard Sjolund
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Re: Why does my speedometer cable keep breaking ?

#7 Post by Richard Sjolund » Wed Nov 07, 2018 10:42 am

Martin Benade wrote:Dick, it was speedo, not tach. Maybe still the same advice applies?
The cable comes from Stoddard - pre assembled and lubricated.
Richard Sjolund
Solon, (Iowa City), Iowa
"Ruby" 1964 (September, 1963) 356 C Karmann Coupe (Ruby Red, color:6402)
On the 356 Registry cover- November, 2005; July, 2018
Ford F150 4X4 (Winter Snow Plow)
2015 Audi A4 Quattro (Wife's car)

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David Jones
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Re: Why does my speedometer cable keep breaking ?

#8 Post by David Jones » Wed Nov 07, 2018 10:57 am

Richard, you need to do an autopsy on the cable to figure out why it broke. Is it fatigue, wrong installation/orientation or a run of bad cables? A close examination of the cable should give clues as Dick suggested. Did they all break in the same place, were they all the same make? What is the common factor? I suspect that the cables were all run in the same place as the one they replaced which may have been incorrectly positioned and contributed to the failure mode. Pictures of the installation can help but as mentioned there should be no sharp bends in the cable and no chafing anywhere. In all my years of ownership since 1963 of VW's and Porsches with speedo cables driven off the left front wheel I have only had one failure, probably due to age so I suspect wrong cable orientation or bad cables.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

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Richard Sjolund
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Re: Why does my speedometer cable keep breaking ?

#9 Post by Richard Sjolund » Wed Nov 07, 2018 11:32 am

David Jones wrote:Richard, you need to do an autopsy on the cable to figure out why it broke. Is it fatigue, wrong installation/orientation or a run of bad cables? A close examination of the cable should give clues as Dick suggested. Did they all break in the same place, were they all the same make? What is the common factor? I suspect that the cables were all run in the same place as the one they replaced which may have been incorrectly positioned and contributed to the failure mode. Pictures of the installation can help but as mentioned there should be no sharp bends in the cable and no chafing anywhere. In all my years of ownership since 1963 of VW's and Porsches with speedo cables driven off the left front wheel I have only had one failure, probably due to age so I suspect wrong cable orientation or bad cables.
Ruby is in storage in Scottsdale, Arizona - waiting for me to arrive back there as a snowbird on New Year's Eve. One of my first projects is to take her to Stuttgart Southwest in Tempe - I trust them. Jack Doverspike is just plain wonderful to work with. He did install one of my cables - it broke on the way back to Iowa. The current broken cable was installed by Lee at Stalltek in Wellman, Iowa. They restored my car - and many other award-winning 356s. Both Jack and Lee are top-notch - Maybe it is a bunch of bad cables from Stoddard ? I'd expect to get some responses if that were the case.

In January I look forward to being there as Jack removes the bad cable - and we examine the path for kinks or bends - and look at where the cable broke. Multiple broken cables installed by 2 superior shops .... sounds impossible, but that's where I am.

It's a mystery ..... an ongoing mystery.

The only good part of the story is that long ago I installed a 6 volt to 12 volt converter - under the passenger-side floor board. I wired it to the lighter socket - and I have a small Garmin GPS that attaches to the windshield with a suction cup. The Garmin Speedometer is more accurate than the dash unit - But, being a scientist, I miss being able to record the mileage for every gas fill and for arrivals at hotels and motels. I miss my odometer more thanI miss my speedometer .... In 4th gear I can multiple my RPM by 2 and get my speed .... 4000 RPM = 80 MPH +/-

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David Jones
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Re: Why does my speedometer cable keep breaking ?

#10 Post by David Jones » Wed Nov 07, 2018 12:01 pm

Richard, like you I have 6 to 12 volt converters in all my 356's wired to dual output lighter style sockets hanging under the dash so I can run the GPS and charge my phone or anything else that does not consume more than a total of 6 amps. My Garmin has the facility to record mileage just like the odometer trip meter does though I do prefer to use the speedometer trip. Of course if you use the Garmin on multiple vehicles the gas mileage calc will not work. I buy my GPS units used or refurbished from Amazon so cheaper than getting the speedo rebuilt.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

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Wes Bender
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Re: Why does my speedometer cable keep breaking ?

#11 Post by Wes Bender » Wed Nov 07, 2018 12:44 pm

My Garmin seems to run OK on my 6 volt system. Not at idle when the voltage drops a bit, but as soon as I get the engine up to speed it's fine. You might try it. I got rid of my 6 - 12 converter quite a while ago.

I'm with Jim on the cable routing being the cause. Your autopsy will show what it is though.
Some days it just isn’t worth the hassle of chewing through the restraints......

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Re: Why does my speedometer cable keep breaking ?

#12 Post by Martin Benade » Thu Nov 08, 2018 12:24 am

There are not many ways to route the cable, especially for an expert. I am running a VW cable in my T6 that I think is a little short but even so has been working fine for years.

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Re: Why does my speedometer cable keep breaking ?

#13 Post by Dick Weiss » Thu Nov 08, 2018 10:41 am

Richard & all;

Sorry; I missed the word 'Speedometer', but the breakage can be due to a sticking input shaft of the instrument,
but an incorrect curvature of the secured cable and the retainment of the cable's end next to the axle most likely
could be the cause during right & left turns.

Dick

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Re: Why does my speedometer cable keep breaking ?

#14 Post by neilbardsley » Thu Nov 08, 2018 12:22 pm

"I hate to return to the truly great service area and tell them that the cable they replaced has broken ---- What should they be looking at or for ???"

Sorry I can't any technical input but great mechanics generally stand by their work and would probably be distressed to learn their cable replacement has failed. I would take it back to them. If you are worried that they are going to spend ages investigating, and bill you, so you want to replace yourself this time then ignore me.

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Richard Sjolund
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Re: Why does my speedometer cable keep breaking ?

#15 Post by Richard Sjolund » Thu Nov 08, 2018 12:43 pm

neilbardsley wrote:"I hate to return to the truly great service area and tell them that the cable they replaced has broken ---- What should they be looking at or for ???"

Sorry I can't any technical input but great mechanics generally stand by their work and would probably be distressed to learn their cable replacement has failed. I would take it back to them. If you are worried that they are going to spend ages investigating, and bill you, so you want to replace yourself this time then ignore me.
The new cable will be # 4 - over a 3 year period. I trust and love the people who work on my car - and the only "problem" is that I will be in Arizona - with a broken cable that was installed in Iowa. Months ago I was in Iowa - with a broken cable that was installed in Arizona .... They never get to see a problem that they may have created ....

Replacing it myself is impossible when I am in my Snowbird phase - no tools, no jack, no floor stands ---

I look forward to an "Ah-Ha" moment of discovery.
Richard Sjolund
Solon, (Iowa City), Iowa
"Ruby" 1964 (September, 1963) 356 C Karmann Coupe (Ruby Red, color:6402)
On the 356 Registry cover- November, 2005; July, 2018
Ford F150 4X4 (Winter Snow Plow)
2015 Audi A4 Quattro (Wife's car)

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