Variomatic query 1986 Mk3

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baron_matt
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Joined: 30 Oct 2012 01:53 pm

Variomatic query 1986 Mk3

Post by baron_matt » 14 Jan 2013 06:09 pm

Hi
The light has stopped working on the low range (gradient) button is there an easy way to get to the back of this switch?

baron_matt
Posts: 85
Joined: 30 Oct 2012 01:53 pm

Re: Variomatic query 1986 Mk3

Post by baron_matt » 14 Jan 2013 06:31 pm

Also is there a test you can do with the car on the drive to tell if the ratio hold system is working? It will energise one side of the 4 way won't it?

I took the car out this lunch time and clicked the switch as I was descending a snowy hill. The switch didn't light up and when I switched back to normal I couldn't tell if the overdrive was working (stuck in town traffic). Anyone got any advice?

volvomania
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Re: Variomatic query 1986 Mk3

Post by volvomania » 15 Jan 2013 09:50 am

Have you read the "CVT diagnistic manual" yet in the engine section?
This will pretty much cover it all.
It sounds to me that the inners of the EMV (4-way valve) or the tachorelay are gone, if so try contacting Mac or Macplaxton as they hold a stock of overhaul kits for these.
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Middxmike
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Re: Variomatic query 1986 Mk3

Post by Middxmike » 15 Jan 2013 04:26 pm

If you can't tell whether the low-ratio switch is making any difference, my suspicion would be that you're stuck in low ratio. Even at urban speeds engaging and disengaging the switch makes an almost instant change on my vario.

If the problem is with the changeover relay earth line, the fault is more likely to be with either the kick down switch on the accelerator cable or the high pressure brake switch on the master cylinder. All three switches (ie low ratio hold switch, the kick-down switch and the high pressure brake switch) do exactly the same thing - they break the earth connection to the changeover relay which causes the relay to change contacts, de-energising the overdrive solenoid and energising the braking solenoid instead, which in turn opens the primary pulley inner chambers to vacuum and so lowers the ratio.

The bulb in the low ratio switch earths through the kickdown switch, so the fact that it doesn't work could mean that the kick down switch is stuck open or has a poor earth - a pretty common problem.

My vario had an annoying habit of intermittently getting stuck in low gear. I eventually traced the problem to the high pressure brake switch which would stick open after heaving braking - an easy temporary fix, I just bridged the two terminals with some wire but at some point I ought to replace the switch (anyone got a spare one?).

Anyway, given the lack of light from the switch, if it's clear that you're stuck in low ratio I would start with the kickdown switch - but Duvel's guide to the CVT in the V3M How To section will tell you everything you need to know...

baron_matt
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Re: Variomatic query 1986 Mk3

Post by baron_matt » 15 Jan 2013 04:48 pm

Great thanks for that.

Now, lol where is the kickdown switch located? Is this the connection that is on the carb by the throttle stop or is it located near the pedal end? A photo would help as I can't tell from the guide what this item looks like.

Middxmike
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Re: Variomatic query 1986 Mk3

Post by Middxmike » 15 Jan 2013 05:03 pm

It's on the bulkhead (on the inside near the top of the pedal) - haven't got a photo but hope the attached diagram helps.
Attachments
image.jpg

baron_matt
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Re: Variomatic query 1986 Mk3

Post by baron_matt » 15 Jan 2013 06:27 pm

I've found an old post on this site that suggests issues with Kickdown switches.

Is there way of repairing these? Or is there a way to get a new one if its broken?

baron_matt
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Joined: 30 Oct 2012 01:53 pm

Re: Variomatic query 1986 Mk3

Post by baron_matt » 15 Jan 2013 06:30 pm

Middxmike wrote:It's on the bulkhead (on the inside near the top of the pedal) - haven't got a photo but hope the attached diagram helps.
So when they fail, ie the white plastic switch fails to remake contact with the bulkhead plate, what causes that? How can you fix it?

baron_matt
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Re: Variomatic query 1986 Mk3

Post by baron_matt » 17 Jan 2013 12:09 pm

Just to give an update on my low ratio hold issue.

I gave the contacts on the brake pressure switch a wiggle and gave the low ratio hold light on the switch flickered. I then gave the throttle kick down switch a wiggle also and bing the light came on. I think I had flash corrosion on both switches due to all that rain we had. Will apply cleantronic to get it all clean.

Thanks Mac for advice. Just got to adjust the fast idle cam now and track down that fuel leak off the tank (when full) and we are back in business.

volvomania
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Re: Variomatic query 1986 Mk3

Post by volvomania » 17 Jan 2013 02:14 pm

That truly is good news.
Perhaps a decent clean of the contacts wiith a fine piece of sandpaper or wirewool will keep the problems away for good.
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Chris_C
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Re: Variomatic query 1986 Mk3

Post by Chris_C » 17 Jan 2013 02:16 pm

volvomania wrote:Perhaps a decent clean of the contacts wiith a fine piece of sandpaper or wirewool will keep the problems away for good.
Nothing more aggressive that a scotchbrite, the terminals are plated. Contact cleaner and a rag is always the best start though
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