+2 brake master cylinder fluid level sensor (aka Sovy)

[k00pa]

Hi,

The brake fail light on the dashboard of my '71 +2S is illuminating intermittently. The brake fluid level in the master cylinder reservoir is fine so I'm guessing that the Sovy float mechanism has failed.

I see that the subject of repairing or replacing the cap and float assembly has been discussed on these forums several times (e.g. here, here & here).

The most well-documented solution seems to involve cannibalising a generic cap and float assembly from Car Builder Solutions (this one) and installing it into an Girling alloy cap (like this one).

However, I see that Car Builder Solutions are now offering this generic float assembly designed to be installed into any cap. I'm wondering if this might be a better solution as it appears that it can be installed without any cannibalisation.

Any insights would be gratefully received.

Regards,

Simon

[pharriso]

You want it to look original? NO use the Car Builder Solution bits... YES... cannibalize & have fun doing it.

Don't overthink it...

p.s. Welcome!!

[k00pa]

You want it to look original? NO use the Car Builder Solution bits... YES... cannibalize & have fun doing it.

Don't overthink it...

p.s. Welcome!!

Thanks pharriso!

I'm not too concerned about originality. My question is really about which Car Builder Solutions part to use: the cap and float assembly that other people have used to cannibalise or the new float assembly that can be used in any cap (with a 10mm hole) without cannibalisation.

Simon

[steve.thomas]

Simon,
On my 72 Plus 2, the brake warning light is also activated by the handbrake, therefore it could be the switch failing on the handbrake lever rather than the master cylinder.
Regards
Steve

[k00pa]

Simon,
On my 72 Plus 2, the brake warning light is also activated by the handbrake, therefore it could be the switch failing on the handbrake lever rather than the master cylinder.
Regards
Steve

Hi Steve,

Thanks for your response.

I'm pretty certain it's the master cylinder reservoir sender that's at fault. I can make the light go out by pulling up the pin in the centre of the cap (see pic below)

Simon

[rgh0]

Sounds like the switch is working but that the float has lost it float. The float is just a cork. Easy enough to replace with a carefully selected wine cork. You need to drink a few bottles and collect enough samples before you select the cork you need

cheers
Rohan

[k00pa]

Sounds like the switch is working but that the float has lost it float. The float is just a cork. Easy enough to replace with a carefully selected wine cork. You need to drink a few bottles and collect enough samples before you select the cork you need

cheers
Rohan

Thanks Rohan. Is there a particular grape, region or vintage you'd recommend? :^)

I had considered attempting that but I'm not sure I could dismantle the float and switch assembly without destroying it. Not much to lose, I guess.

Simon

[Robbie693]

The float unit comes apart pretty easily, bear in mind that you will probably need an unused, i.e. not corkscrewed cork...

I've been meaning to do mine for ages but still haven't got around to it

Robbie

[k00pa]

The float unit comes apart pretty easily, bear in mind that you will probably need an unused, i.e. not corkscrewed cork...

I've been meaning to do mine for ages but still haven't got around to it

Robbie

Thanks Robbie - good to know.

I have ordered a new alloy cap (just in case) and will attempt a repair once that arrives.

Simon

[k00pa]

I'm pleased to report a resounding success in the repair of my existing float and switch assembly.

A few notes for posterity:-

• I was able to get the top off by gently levering until enough of the threaded rivet heads were exposed to allow them to be gripped with pliers. They could then be twisted out.
• Although the original cork float was totally intact, 45 years of immersion in brake fluid had turned it into a sponge with no buoyancy.
• The trickiest part was attaching the new cork to the central pin. The cork is held on by a washer which is prevented from coming off the pin by a crimp at the end. So I had to cut off the crimp, remove the washer and old cork and then put the new cork on followed by the washer and then a new crimp to the end of the pin. As a result the pin is now slightly shorter and the replacement cork had to be correspondingly shorter than the old one. Doesn't seem to matter though.
• The cork I used was an artificial one that had been corkscrewed. It didn't seem to matter though. The corkscrew hole was even slightly off-centre, which also didn't seem to matter.

All in all, a very satisfying result.

I now have a barely used (2 hours!) alloy master cylinder cap and washer going spare if anyone is in the market for one.

[Greg Foster]

You may consider the fact that the original was CORK not fake cork. Don't know how this material will be affected by brake fluid???
Greg