Intermittent Speedo, Syncro

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rollercoaster
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Intermittent Speedo, Syncro

Post by rollercoaster »

Time to sort this, before I get a speeding ticket.
Also is it possible to recalibrate while I am fixing it,
as I have bigger wheels its a bit off.
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Re: Intermittent Speedo, Syncro

Post by Aidan »

Depends what the cause is, it could be poor connection at the dash, could be the speedo itself, could be the cable, could be the speedo drive in the front diff; if the last it's possible to change that but it depends which speedo drive is fitted
which van ?
If the Tristar then it should have a B or a C code drive in; with a C code running 215/75/15 it should be pretty accurate speed but under read on odo; but it may have something else entirely given the history. The speedo code originally fitted is often stamped under the front diff code which is on the bottom of the diff at the front and relatively easy to see but it doesn't guarantee that is what is inside it now of course
You could also swap to the SyncroSport dash and run an electrical speed pickup and calibrate that in software talk to SyncroAndy about that

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Re: Intermittent Speedo, Syncro

Post by rollercoaster »

I love your attention to detail and thoroughness in the answer,
thought I would also message the previous owner who recommended a tap on the top of the dash,
this worked!

So using that to help diagnose the fault, what do we think? Speedo?

I thought about one of Andy's dash pods.. would like one, still thinking.
It is the Tristar, and it now has Andy's engine loom for the 1.8, so it might be sensible to go that way.
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Re: Intermittent Speedo, Syncro

Post by Aidan »

Does sound like it is maybe the speedo itself
is it a 1600 one - number in middle of speedo ? if so then correct for vehicle but rocking horse pooh mph syncro speedo

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Re: Intermittent Speedo, Syncro

Post by rollercoaster »

So its been working nearly all the time,
and a tap on the top usually gets it going if not.
Any help with a diagnosis?
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Re: Intermittent Speedo, Syncro

Post by rollercoaster »

Would it not be possible to fix whatever is wrong with the speedo if thats the problem?
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Re: Intermittent Speedo, Syncro

Post by Oldiebut goodie »

If you can find a man that can! A mate of mine's dad was a clock /watch repairer who also fixed and calibrated speedos, sadly now dead - there must be some other like minded guys/gals offering that sort of service even in this throw away society that we have now.
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Re: Intermittent Speedo, Syncro

Post by Aidan »

Speedo unit is a pretty simple thing there's a mechanical element that drives the odometer and a magnetic impeller for the speedo needle, without looking at it it's pretty hard to accurately guess what the problem is - most dashes have cracked and broken housings so it may be a disconnect due to the physical installation or it could be dust or dirt or debris in the unit that is impeding the drive which is displaced when you bang it but it then settles back and causes the failure, you are going to have to take it out and take a look, often the plastic housing breaks especially on the trip if fitted as the mechanical pushing in of the reset pin by heavy handed person can do damage to old brittle plastics and on the worm drive for the odometer any original lube will now likely be hard and possibly contaminated by dust

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Re: Intermittent Speedo, Syncro

Post by rollercoaster »

thanks,
I may take it out to have a look then,
its been behaving itself lately,
might do more harm opening it up.
Keep you posted!
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Re: Intermittent Speedo, Syncro

Post by tyredandcranky »

The part that determines the accuracy of the needle is actually a coil that unwinds as you increase in speed. It then returns smoothly upon slow down.

I had a really terrible dashboard in my T25, so I managed to source an early German diesel model (100,000km odometer max, whereas mine was 999,999m max), and I transplanted my clocks onto it.

I had an intermittent speedo reading, and it would make helluva noise too. What I find was that the square part of the end of the speedo cable had snapped inside the back of the original, so any new cables wouldn't be inserted far enough to allow it to rotate the cable.

What I did was cut a few mm off the plastic/nylon end of a new cable to allow it to sit further into the female part of the speedometer, behind the dash.

All in all it was about two hours work, and my speedo reads accurately, the PCB board is in mind condition, all lights work and all screw holes are in tact, no cracked plastic surround!

Worth doing.
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