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MG MGB Technical - Brake Servo (72) diameter....?

Hi,

I am thinking of getting a new (recon) brake servo for my '72 BGT. In the Moss catalogue it says "until 1974 servo wasn't standard...one of two different diameter units may be found..."

How do you know which one was fitted??

Thanks in advance, Barry
B Mahon

Your 1972 B/GT was NOT fitted with power assisted brakes from the factory.

You can add this option...but will need to use a 1976 or later brake pedal box, master cylinder assembly, etc.

If your B/GT is left hand drive, the servo can interfere with the stock air filter assembly, requiring the use of an aftermarket air filter such as a pancake.
rick ingram

Barry,

is your car an USA spec LHD modell with the master cyl. pointing to the front of the car or is it a separate servo mounted in some distance to the master cylinder?

Ralph
Ralph

I have a servo fitted - I never even thought it might have been an aftermarket..... it looks so 'original' - so I don't have any problem with the fitting.... I have a RHD car, originally sold in the UK.

I was just wondering what is the differnce between the diameters - marked as 5/8"" or 7/8" in the Moss catalogue, page 58 - to what do these diameters refer??

Bye, Barry
B Mahon

The servo WAS a factory-fit option on earlier models.

Dave
D O'Neill

Sorry if I was mis-informed. I do NOT believe that this was an option on the North American spec models and will stand by that.

rick ingram

I think there were a number of differences between the different markets, i.e. UK cars didn't get dual-circuit brakes until about '77 and they also had overdrive as standard from late '76, which I believe the US did not.

Dave
D O'Neill

The servo 'may' have been an option on US cars prior to dual-circuit brakes, as it was remote from the master cylinder.

Fitting dual-circuit brakes did complicate matters and they presumably decided to do away with it, as it obviously wasn't a neccessity - being optional.

When dual-circuit brakes were fitted in the UK, they had changed the master cylinder to the integrated servo type.

I know that US-spec MGC's had two servos crammed in under the bonnet, one for each circuit.

Dave
D O'Neill

All very interesting, I have overdrive in the '72.....

Anybody any idea about the diameter??

Bye, Barry
B Mahon

Barry

Acoording to Clausager...

"...when a Lockheed type 6 brake servo became available as an optional extra in February 1970, it was only fitted on cars with single-line braking systems and was therefore not available at all in North America. An improved servo with a bigger bore was fitted from May 1970."

Presumably, you would have the larger one.

As mentioned previously, overdrive was standardised in late '76 (UK models) so was only available as an option before that.

On my '67 even the headlamp flash was optional at a cost of
D O'Neill

Hey Rick

I wasn't 'having a go' in the earlier response, so I hope you haven't taken offence.

There are many differences in the specs between different markets - as we keep discovering. The reason that I mentioned the overdrive is that I was previously under the misapprehension that it had been globally standardised in '76, but it was pointed out to me that that wasn't the case in the US.

We live and learn.

Dave
D O'Neill

D..

Heavens no...once again, I've learned something from this BBS!

I was aware of the diference of servoes on the MGCs (I have two NA-spec models...1968 and 1969). My 74-1/2 GT (twin SUs and rubber bumpers) was not power assisted whereas my 1978 tourer is assisted.

Interesting that most MGBs here in the States do NOT have O/D...opposed to the home market. I cannot figure that one out, either...unless is was simply to keep the price down against the competition.

Regards...

rick
rick ingram

Rick, The omission of overdrive in the States was indeed to keep the price down. Initally, the MGB was competeting with the Austin Healey for market sales and it was feared that if they were priced too closley the MGB would leave Healeys on the showroom floor unsold. All Austin Healeys came standard with overdrive. Ray
RAY

But...the MGB was marketed in the States until 1980...long after the Healy met its untimely demise...I would think that the O/D would have been a welcome addition as standard equipment...of course, then MG was in sales competition with the Triumph, wasn't it?!

;-)
rick ingram

What percentage of Triumphs in the US were supplied with overdrive?...anyone?

This seems to have become an overdrive thread. Oooops!

Dave
D O'Neill

This thread was discussed between 28/03/2007 and 29/03/2007

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