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MG MGB Technical - Brake servo

We have an early (1963) LHD B in the workshop which we are restoring at present, and are adding a brake servo which wasn't there before. Not being a common (very rare in fact) version here, I'd like to check before mounting:
Which way does it mount? Is the slave outlet still pointing right (as if RHD moved directly across), is it a mirror image of RHD or is it something else again.
Haven't found any reassuring images on Google....
Paul Walbran

Interesting question, and odd there don't seem to be any pictures as there is no mention in Clausager that it was on RHD only.

Fitted the same way but on the other side the outlet would be pointing at the inner wing aperture, the servo hose route would be convoluted, and the 'drum' would probably be close to the pipes that come through the bulkhead.

But fitted the other way round the inlet and air-valve assembly would be on the back.

There is also less clearance to the heater that side.

How about at 90 degrees similar to the integral unit, i.e. with the outlet facing forwards?

After-market fitting instructions (I've only see RHD) show the air-valve at the bottom (and the outlet cylinder angled upwards) so orientation doesn't seem to be an issue.

I'd just go for whatever fits best for those and any other factors.

But then, is it even worth it? Because the single-line servo was optional (to begin with at least) it only offers very light assistance. I've driven a non-servo without knowing about it and didn't realise, and one with a disabled servo and it was barely noticeable even though I was specifically looking for any difference.
paulh4

Don't know if this helps but lhd MGCs had them pointing straight forward-
The brake lines are wrong in this pic.,that top one goes more in an arc ,not up near the hinge like that
Probably doesn't help really as the rhd Cs were pointing the same, but it does fit in there quite well

William Revit

Paul Kiwi,
Orientation of the unit, whether pointing left, right or forward doesn't matter.
Valve lower i.e. 4 o'clock or 8 is generally accepted as presenting fewer bleeding problems. As is nose up!
Just do it to best suit the hose and the brake lines.
As Paul GB said the low assistance from the original 1 : 1.65 is hardly noticeable. A 1 : 1.9 virtually halves the effort.
Beware there are some rubbish items about. Powerstop seems the worst. A better bet is to get an original Lockheed and re-build it, even getting it sleeved if the slave cylinder is suspect.
Allan Reeling

I've found a US brochure for a '62 MGB

https://mgb1967.com/the-all-new-mgb-1962-brochure/

which doesn't show a servo in the engine bay, nor is it listed under 'optional equipment'.
Dave O'Neill 2

Clausager says the single-line servo was only available from 1970, so North American spec would never have had one as they had dual circuit by that time.
paulh4

Thanks for the comments, which generally echo what's been rattling around in my head on this. But the owner has specified a servo in the rebuild so we have to do it.
Yes, well aware of how the mounting angles affect bleeding having struggled to bleed a wrong one!
BTW the car is European spec rather than US.
Paul Walbran

Can't you persuade the owner to change his mind? Like Paul H I have driven MGBs with and without servos and like him I reckon the remote servo makes almost no difference. The unservoed car pulls up strongly without undue pedal pressure. Unnecessary complication in my opinion, and also not a proper item for that early a car. Try telling him that the remote servo can fail by sucking up all the brake fluid. The first the driver knows is when the pedal goes to the floor and several owners have experienced that heart stopping moment. You don't need to tell him that such failures are pretty rare!
Mike Howlett

“Try telling him that the remote servo can fail by sucking up all the brake fluid.”

One of the factors that convinced me that I could do without it.
Dave O'Neill 2

Found this, looks like about a 70 model with that bonnet stay but-------don't give up there will be a pic of a Mk1 somewhere

William Revit

As said earlier according to Clausager the servo wasn't available as an option until 1970 anyway, so if one had been fitted to a Mk1 it would have been by a PO and so not representative of the factory way of doing it - assuming they did fit them to non-North American LHD.

What that picture does show is that facing forwards probably is the best option - regardless of who fitted it, giving good access to all the connections and the air-valve.
paulh4

I always advise customers not to expect better braking from a servo, just reduced pedal effort. For many, that is the issue - it is well different from other cars they drive, to the extent of being disconcerting. In the end, it is the customer's choice.
As for sucking all the fluid out, yes it does happen with a servo needing an overhaul, but it is relatively rare - I have seen lots of cars with servos, the mayority do here at least, and seen this happen only a couple of times. And each time picked up via normal servicing and lower than expected fluid level and bothering to check why - it doesn't all get sucked away suddenly, just a gradual leak like any other brake fluid leak including getting worse if not attended.

I've certainly seen loss of brakes from fluid loss at the rear wheel cylinders, again because nobody wondered why the fluid was low.

With this install, we've now eyeballed the options and room dictates that the only one which fits is the fore/aft orientation, not only that the bracket holes all lined up too.

Paul Walbran

Not that I've had it, but my understanding is that it CAN vanish very quickly once it starts. If the diaphragm push-rod seal fails manifold vacuum is going to suck fluid out of the cylinder from behind the piston i.e. the fluid inlet side. Yes if the failure is gradual it may only consume fluid slowly, but if you get a sudden failure of the seal it will be rapid. Mind you, I would expect clouds of smoke while that was happening, and fortunately it seems to be very rare given the age of our servos. But I've fitted fluid level monitors to both mine - and check that they work periodically!
paulh4

Never ever had a hydraulic problem with a remote booster, the only issue I've had with one was a 2nd hand one that i fitted to one of my V8 conversions for a try, It had been lying around for a while and the moisture got in through the breather port and the pushrod had rusted up a bit--It was interesting to drive , you could jump on the brakes and on letting off the brakes would stay on for a couple of seconds---not good in the traffic-a rebuild fixed it and as far as I know it's still going ok --over 40 years ago now
William Revit

Sticking-on is occasionally mentioned, but tends to be the air-valve. Hence changing the orientation so that it is pointing down instead of up, but some have found the piston and bore need relieving slightly. It happens in the roadster but only in hot weather and slow traffic, and tapping the pedal usually releases it. A pal's V8 got it so bad when we were on a tour we had to disconnect the servo hose and plug it with a spare spark plug. That was the one I tried knowing it had been disabled.
paulh4

Anything is possible, but none of the servos I've seen with fluid in the vacuum chamber had a rapid leak. But like any hydraulic leak, if left long enough it could no doubt get worse. Well after any prudent owner or workshop would have noticed abnormal fluid loss.
Paul Walbran

I have no experience of a failure on a car with a remote servo, but on the MGCC V8 REgister site there have been several instances of sudden and unexpected loss of brakes. See these articles.

https://www.v8register.net/subpages/servofailurecaution.htm

https://www.v8register.net/subpages/V8NOTE395.htm
Mike Howlett

Paul only wanted to know where best to fit the booster--which I'd imagine is done and dusted by now

All these sudden brake losses due to booster failure are only sudden when they run out of fluid--If the owners had checked their fluid level occasionally they would have noticed the gradual fluid useage earlier and had the issue resolved well before 'sudden brake loss'
William Revit

This thread was discussed between 10/12/2019 and 14/12/2019

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