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MG Midget and Sprite Technical - Brake servo

hey there

i have search and search but couldnt find any info

i am wondering if the is a more uptodate car which i can use its brake servo on my 1979 mg midget?

Thanks again guy
AJ Farrell

Here you go:
Graham P

Unfortunately that will not work because the 79 Midget is dual line brakes.

Not sure what would fit that was remote but I will investigate.
Bob Turbo Midget England

is there a special reason that you need a servo, I only wonder as it wont make the car stop quicker it just means you don't have to press so hard on the pedal

Midgets are quite light cars so normally you're not pressing that hard on the brake pedal

you also have more 'feel' of the brakes via the pedal without a servo

with a heavier and much more powerful and fast car then it would be more useful but a standard Midget doesn't need a servo
Nigel Atkins

Anthony, for any spridget info on improving/modifying there is this must have book:
(for road, fastroad, rally and/or racecars)

It has everything you need to know about brake servo's incl. installation drawings.

Arie de Best

Firstly, I would never take trade away from the MGBhive and would strongly suggest that you give them a call - you might as well make your contact with them now, as you're bound to use them ALOT! They are great people, and will answer all your questions with knowledge and good humour :)

Plug over!

Secondly, Nigel is right in his comment - and you might want to consider the options.

If you're wanting better stopping power, then, a better upgrade is to Goodridge brake lines and making sure you've got decent pads and there is no rust/dust/mud on your discs - and you could even consider gooved discs if you plan on alot of faster work.

Then - there's miles of information regarding what other things you can do - it's up to you how much you want to spend really.

Again, before doing ANY mods to the car - whether for speed and safety, or just safety, then, have a good think "What do I want to do with it?", the answer to this will not only give you direction, but will also save you money and alot of time!!!!

blimey rach we're agreeing :)

(although I'm not convinced by grooved discs)

another item for braking is the tyres, regardless of tread left if they're old and hard they wont be best at doing all the stuff tyres do including braking
Nigel Atkins


You will notice that I said he could consider them - NOT to go out and buy them, as I don't think they are necessarily needed on normal road going cars, and vented ones never get warm enough outside of track use to make the money worth it.

Yeah - Black Circle are doing an offer on Toyos at the moment :)!!!!!

"and vented ones never get warm enough outside of track use to make the money worth it."

Except when you are descending in the Austrian Alps, on a very very steep road that avoids using the somewhat expensive at the time motorway pass, and the discs are glowing red. Then they might seem worthwhile. :)
Lawrence Slater

Speaking of vented discs, shouldn't that have been a song by spinal tap? :)

Oooops. Wrong thread. :P
Lawrence Slater

If you consider buying servo's or groved disks you should go to an historic MG race meeting.
Then ask for a look under the bonet and look behind the wheels.
Then decide what you need to brake properly.....

Good MC
Fresh braided lines
Good quality disks

If you switch from a modern a lot or are not as strong fit a servo.
But do remember it does not increase braking effeciency it only reduces pedal effort
Onno K

I agree with Onno on this, I'm not running a Servo on my K-midget - just shoving hard. The first junction after driving the Servoed V8 and the overservoed g/f's starlet is always exciting, but once you get used to it the feel is so much better.

I've got greenstuff pads and braided lines, (would get mintex next time as greenstuff are a bit poor when cold) and I can still lock the front wheels in the dry if I want to (175 avons) Fade's not an issue on the road, and I don't hang about.

You can fit harder pads in with a servo, so that can get you more braking power for less pedal effort. But I'll be keeping mine 'standard'.

And get the book :);)
Rob Armstrong

Switching between cars is a really valid thing to consider. I had an exteme case once - we were looking after my brother's company Falcon (Aussie Ford) which was of a variant which had very over boosted brakes. A fly on the pedal would put you through the windscreen. I eventually adjusted to it. But then after his holiday finished and he got the car back I jumped back into my B, headed down our road and nearly ended up in the creek the other side of the Tee junction.

Reason? Didn't adjust to the heavier pedal effort! Heavier than a normal B because of twin master cylinder brakes together with cold DS11's. I was usually quite used to it, but the change of car caught me out.
Paul Walbran

I beg to differ slightly. :)

Adding a servo (assisted braking), whilst not increasing the overall braking efficiency of the brake system, can increase the effective braking efficiency, under the proviso, that the driver either can't or doesn't want to exert full pressure on the brake pedal.

Or more simply put, a servo makes it far easier to get the maximum braking efficiency out the brakes that they are capable of.

Take drum brakes.

Some drum brakes were assisted brakes by being self-actuating. When the pedal is pressed, and the brake shoes contact the drum, there's a sort of wedging action, which causes the shoes to be pushed against the drums with more force. That extra braking force provided by the wedging action, lets you press less hard on the pedal, and allows drum brakes to use a smaller piston than disc brakes.

With disc brakes you need more force. So adding a servo, for someone with a weak ankle or calf muscle for example, does increase braking efficiency.

So if you want a servo Anthony, it won't be a waste of money. IMHO of course. :)

The only real reasons I don't have one, are because 1), I am too lazy to have fitted one, 2), I already used the available space under the nearside front wing to keep my tool box, 3), I just got used to it without, which is an extension of 1 really. :)
Lawrence Slater

What do you beg to differ?

All I said was that it will not increase braking effeciency.
But if you want one for reasons stated above fit one.

Just don't use it to "fix" bad brakes because they wont.

And do not underestimate the fact that you are bringing something extra in to the system that can fail.
And if they fail they do dramaticly because the vacum sucks in all the brake fluid!
Had it recently in the GT and it made for some exiting moments
Onno K

I beg to differ (slightly as I stated) with, ---

The generally implied consensus, that Spridgets don't benefit from the addition of a servo. ---

- In that, it can indeed improve braking efficiency, for those drivers who are either unwilling and or unable, to apply the force neccessary on the brake pedal, to extract the maximum braking capability, that their particular spridget is capable of. And in that sense, it can improve braking efficiency. :)

As regards the pro's and con's of a servo being unreliable, and sucking in brake fluid if they fail,--make sure you get a good one. :)
Lawrence Slater

I have a servo fitted to my Midget. The reson for fitting it was because with green stuff pads fitted in normal road driving conditions you have to exert so much pressure. They are fine when hot / smoking but I found it tiring in normal driving conditions, perhaps this is a function of being old and wearing out!

Because the car is supercharged it also has a sevo boost pump fitted to maintain induction pressure when the servo is activated. I am really impressed with the system, it does not grab and is still progressive unlike our horse lorry where the slightest touch induces significant breaking.

Eddie Brown

I have a servo for the reasons Paul mentions !

Not over servoed, very progressive and loses no feel at all.

If you want more true stopping power the best way in my opinion is definetely bigger discs (says he with 12inch dinner plates on the Modern !)

Onno - most of the trouble with servo's is people never replace / overhaul them when they do the rest of the braking systems - I know of servo's on B's that are coming up to 40 years old i.e 1972 - how old was yours ?


richard boobier

It was a "74 but the servo had been replaced in the 90's

More stopping power can only be obtained through better tyre's!

Every midget with good serviced brakes can lock it's front wheels.
Then all braking is lost.

So for better stopping you need better tyre's

But this is only based on street use not track or rally where you brake hard far more often.
Then you need brakes that can better deal with the repeated heat input (that is what brakes do turning kinetic energy in to heat)
There are several options to deal with this.

Bigger diameter
more thicknes
with a matching caliper

Though most go for bigger I think vented is a better option.
As you effectifly double the disk surface.
Onno K

Exactly right Onno!

I coax my customers out of spending needless money with exactly the same arguement, noting that I've retained the original brakes with uprated friction material on my rally B without a problem in the stopping department - though admittedly quite a lot of smoke at the end of a very fast special stage.

(I have to confess that I'm considering changing to discs on the rear as it's set-up has more weight on the back than the front and on gravel surfaces you don't get as much weight transfer ... so the shoes, though still working well, wear rapidly as a result, have to be adjusted after each special stage and replaced at the end of each day if a multi day event.)

Back to topic - My concluding comment on this "un-sell" is that if you are going to out-drive the standard brakes on most public roads then you are unlikely to retain your licence for long!

There are exceptions of course - mountain passes as Lawrence mentions require good brakes if you are going to have an enjoyable blat on the downhill side - that's another to add to Onno's list of when you need better brakes.

I would also add to Onnos' upgrade list uprated linings, always a cost-effective improvement and usually enough to deal with mountain passes. The most important "upgrade" for the passes is to make sure you have fresh brake fluid in the system. No use having flash brakes if the old fluid boils!
Paul Walbran

I have a servo fitted and would never remove it it is so much better.

The suggestion that servo brakes have less feel is senseless.

Imagine for a moment a pin in a tight hole. You need to drift(hammer) the pin into the hole by 2 inches.

Which is better to get an accurate position (more feel)

Is it better to need a BFH to drive the pin into the really tight hole?

Or is it better to have a small hammer and a few small taps to get the pin to the desired position?

Obvious isn't it!!
Robert (Bob) Midget Turbo

My point is as Bob has noted its down to progressive feel - we all understand the relationship with tyres/locking etc - been driving the things since 1970 as only car and now play thigs.

If I have to floor the peddle it will lock - so I want as much progression as possible prior to this.

I find the Midget brakes (as opposed to the B's I've owned and still maintain for others - which I find is quite a good set up) has a rather poor rear brake set up and needs regular adjustment to be at its best.

I have not tried a car with rear discs, but if this reduces the need to keep adjusting the rears I would seriously think about it.

richard boobier

But robert as an engineer you must know that with the BFH you have a very big chance of bending the pin before it goes in the hole!

Or have you never worked with your hands

No need for several pushes here!
If it is needed it is an indication something is wrong!

There are endless other reasons to upgrade ranging from looks to ultimate weight saving.

And even the adjusting issue has crossed my mind several times..
Onno K

On a race Midget, I have found that the standard rear wheel cylinders wear the shoes out in no time. 1500 Midgets had a smaller bore wheel cylinder, which works better, although Cooper S - smaller still - is best.

As for Bob's hammer analogy, it is easier to use a big hammer lightly than a small hammer heavily.
Dave O'Neill2

Forgot to mention... still fairly easy to lock the front wheels when using Yoko 048Rs without a servo!
Dave O'Neill2

you'll note I put 'feel' not feel - as this is subjective

I know the racing guys and gals wear slippers (and romper siuts, what you'll do to get your kicks :shakeshead:) but most road users will be wearing shoes with thickish souls and socks so feel is muted

it's not like you've got your hands around the brake calipers

you get used to the feel of any brakes if you're driving the car often enough

as for swapping from modern to classic - what I've done since I had a classic withgradual braking and a modern with oversharp breaking and swapping between the two - and it's a good habit anyway especially in a vehicle you've never driven before -

as soon as possible after pulling off, at low speed, test the 'feel' of the brakes, and it also checks that they are working at a low speed when you don't really need them rather than the first time you really do
Nigel Atkins

ha ha.

As with sooooooo- many issues, this is another example of --

"would you prefer tea or coffee with your cake or bicuits sir/madam?" :)
Lawrence Slater

Nice one Lawrence! Just for the record, I have no servo, but I do have Goodridge flexis, grooved discs and Greenstuff pads. Rears are standard. I was up on Holme Moss having a good blurt and my wife said "what's that burning smell?" It was the brakes, but they didn't fade at all and that is some road for heavey braking on the way down if you're really trying.

b higginson

if this was the case you should have reduced the car's load - made your wife get out and pick her up later when the brakes had cooled down

it would be for her own safety

and your further enjoyment :)
Nigel Atkins

Nigel. I'd rather have the smell of burning brakes than the pain of having my ears chewed off. LOL
b higginson

did you come to a conclusion of your own (?)

I understand, the significant others tend to have little mechanical sympathy :)
Nigel Atkins

This thread was discussed between 23/11/2011 and 27/11/2011

MG Midget and Sprite Technical index

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