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MG MGB Technical - Cap & Switch Assembly - Float for Master CylinderC

Hi,
I have seen the discussions before where the late MGBs have a dual circuit braking system which is monitored by the horrible plastic switch AAU2454 underneath the fluid reservoir / parallel to the MC which is a pig to get to work properly. I would also like to fit a Cap & Switch float assembly which has been suggested before in an earlier thread which i can't find! I appreciate this will only monitor the rear chamber that supplies the front disc brakes, but that to me is the important one.In that earlier thread someone i think suggested using a C & S float assembly from a Mini / other BMC/Bl/Austin Rover. Can anyone advise which one will have the same size diameter & thread cap as a 1980 Roadster if at all?
I have seen pictures on line of a Metro / Mini part SJL10001EVA & MG Rover CDU3161EVA , but not sure if these would be suitable.
Cheers
Charles


Charles9

Hi Charles, If you have a plastic master cylinder reservoir you could fit
one of these kits from Bob Owen, who has produced a kit for low brake fluid
warning. I have fitted one a few years ago now and it works very well.

http://www.teelectronics.co.uk/automotive_products.htm


Or if you just want to fit a warning light, you could fit one of these.


http://www.minispares.com/product/Classic/GRK6009.aspx


Andy
Andy Robinson

Hi Andy,
Thanks for your speedy response. I think I'm going to go down the mini spares route as I can do a simple wire modification under the bonnet without having to introduce any changes within the cockpit!
Cheers,
Charles
Charles9

Hi Andy,
The mini spares product with that model number comes with a cap that is far too big for my filler neck which has an outside diameter of 1".
I have spoken to Bob Owen who can make me one with a cap to fit & am waiting for a quote which will be somewhat more expensive & radical.
Are you,or is anyone else aware of a float cap similar to GRK6009 that would fit the neck of my reservoir?
Cheers, Charles
Charles9

Hi Charles, I have the larger brake fluid reservoir cap so have not had your problem. Have a look at the Car Builder Solutions website below. They seem to have a good selection of reservoir float switches.

https://www.carbuildersolutions.com/uk/brake-clutch-system-parts-reservoirs

It may be worth giving them a call to see if they have one that will fit your master cylinder.

I know that Bob Owen can make his kit for the smaller reservoir cap, but I don't know whether he can make you just a float switch.

Andy
Andy Robinson

I made my own with a polypropylene float switch fitted to the standard cap for the smaller metal masters.

paulh4

Hi Andy,
Thanks for your reply. I will check these alternatives out.
Cheers, Charles
Charles9

Hi Andy & Paul,

Thanks for your responses this morning. I spoke to Carbuildersolutions who don't stock a float cap kit that has a small cap to fit the neck of my original AP reservoir. They have a float switch similar to Paul's solution (whose response crossed with my previous post,but didn't show until i visited this site later on in the morning). The float switch they have could be possibly modified using my current cap,but needs a depth of 54mm so would not fit in my reservoir of which the side is only approx 38mm (1&1/2" in old money). I will have another chat with Bob Owen when i get his quote!

Cheers

Charles
Charles9

Charles - what master is this for? Mine have a depth of 56mm, and there were 44mm and 72mm float switches available, both will fit depending on how you mount them to the cap. Initially I went for the shorter one as it seemed it would be easier to mount to the cap, but in the end I used the longer one.

Full story here http://www.mgb-stuff.org.uk/bflevel.htm
paulh4

Hi Paul,

I have attached a photo of my brake reservoir tank (as fitted by the factory on the car that i have had from new). I am aware that a cap mounted float will only monitor the level in the rear chamber that serves the front brakes! I appreciate that i can add on an element of the neck to arrive at the total depth available.

I am having problems accessing your referral link at the moment which may be due to the very slow internet speed here which hopefully is going to be upgraded fibre wise in the next month or so (only 18 months behind schedule). I think the pages you are referring to are what i found on the internet a few hours ago which covered making a float to fit an older square type reservoir tank,but thanks anyway.

Cheers

Charles


Charles9

Right I was forgetting you had already said it was the later dual system. I used the longer float which goes up through the middle of the cap, secured in the space between the cap proper and the removable 'lid'. That allowed a 77mm switch to work in a 56mm space (by trimming the bottom of the switch shaft slightly) i.e. 'saving' 11mm. The difference between the 44mm switch and your 36mm clearance is 12mm i.e. almost exactly the same.

Incidentally the link I posted doesn't work for me either, for some reason it displays as https rather than http as this second try does. Try http://www.mgb-stuff.org.uk/bflevel.htm, and if that doesn't work delete what is before the 'www'.
paulh4

Thanks Paul for your further observations. I have viewed the very detailed exercise you carried out to come up with a solution much of which was beyond my electrical knowledge!
I'm going to wait to hear back from B Owen before making a decission & proceeding further.
Cheers
Charles
Charles9

Checked my M/C reservoir and cap. There is no wiring and/or float monitor attached at all. Perhaps your monitoring cap and switch assembly is for your market.

Cheers

Gary
79 MGB
gary hansen

Hi Gary,
Thanks for your post.This type of float cap,to my knowledge, was never fitted.I just want to have an additional method of monitoring the brake fluid level albeit just on the brake reservoir that serves the front brakes.
Cheers,
Charles
Charles9

"... the link I posted doesn't work for me either, for some reason it displays as https rather than http "

I've noticed that a few times, when posting links.

It seems that it adds the 's' when posting a link, but if you then edit the post, the 's' disappears.
Dave O'Neill 2

Damn computers thinking they know best ...
paulh4

There's a comma accidentally added in the hyperlink at the very end.

I didn't notice first time but second time I went to edit the address in the wotsit box I noticed. As with the cars knowing very little and nothing technical I start with and can only deal with the basics.

Try this. -
http://www.mgb-stuff.org.uk/bflevel.htm

I'd love to be a paid tester for Micros**t instead of, like all of us, an unpaid tester.
Nigel Atkins

Huh, that comma was me. Usually I make sure there is a space or a new line after a link.
paulh4

If only I could spot my own numerious typos. :)
Nigel Atkins

This thread was discussed between 24/04/2018 and 03/05/2018

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