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Thu Oct 30, 2008 2:12 am

I was thinking of mounting an MGB brake servo on my Beetle. The advantage is that it's mounted between the brake lines and not attached to the brake pedal. So you can fit it anywhere in the car.
I wondered if I should mount it in the rear (close to the engine) or in the front (close to the master cylinder).

* Close to the master cylinder: I keep the original brake line, just interrupt the one that goes to the front brakes. But I need a very long vacuum hose, all the way to the engine.

* Close to the engine: I need a relative short vacuum hose, but very long brake lines -> from the master cylinder to the rear of the car (brake servo) and to the front brakes again.

Has anybody ever done this and what's the best option?

Thu Oct 30, 2008 4:04 pm

id think its a lot cheaper and easier to run longer vac lines then lots of unnecessary brake lines. but its your build, you'll have to decide.

Thu Oct 30, 2008 4:22 pm

Heh, and here I though I was the only one with this idea! :)

Are you talking about this servo?

I have one, but it'll be going in my Mini, of course.

My vote is use a long vacuum line, and mount it up front near the master. If I'm not mistaken, this is what the late Busses did.

Sun Feb 01, 2009 7:02 am

Sorry for the late reply.
The one you show is for the Mini Cooper S Mk1 and 2

The one I mean is for an MGB, which is the same as the Mini Cooper S Mk3 (and Clubman 1275 GT, if I'm not mistaken). This one is bigger and works a little bit better, but it's the same principle.

Sun Feb 01, 2009 1:59 pm

rainierdeklark wrote: I was thinking of mounting an MGB brake servo on my Beetle.
What problem are you trying to solve?

Sun Feb 01, 2009 2:12 pm

Bruce wrote:
What problem are you trying to solve?

Pussyfooting it...

Sun Feb 01, 2009 4:12 pm

Bruce wrote: rainierdeklark wrote: I was thinking of mounting an MGB brake servo on my Beetle.
What problem are you trying to solve?

Not really trying to solve a problem, just to add some assistance with the braking, like the Cooper S had back in 1963 and today all modern cars have.

Sun Feb 01, 2009 4:32 pm

Personally, I think disks on a Beetle have all the power you should ever need. Heck, I still have drums on the turbo and it stops just fine with moderate pedal effort. Fade, now that's another issue!

Besides, I thought you said you'll only have a 100 HP engine. Why look for better brakes if you don't really have the need?

Sun Feb 01, 2009 4:39 pm

First of all, I already have the servo.
Second of all, the brakes on your car can never be TOO good.

Sun Feb 01, 2009 5:55 pm

I am very interested in your idea.
If you place the servo in the front lines, you will only have powered brakes at front, won't you?

The beetle has poor braking for today's standards. As you said, brakes are never too good, but specially in a beetle.

Sun Feb 01, 2009 6:09 pm

A booster assists the master not a single circuit. How would you plumb vacuum to it? I would assume you would need a reservoir.

Sun Feb 01, 2009 6:18 pm

fxnprsh wrote: A booster assists the master not a single circuit.

On some models of Mini Cooper, only the front circuit is assisted. Rear remains unassisted. I believe you're thinking of masters where the booster is part of the hydraulic assembley- the one we're talking about is remotely mounted, and not directly coupled to the master.

Sun Feb 01, 2009 6:27 pm

miniman82 wrote: fxnprsh wrote: A booster assists the master not a single circuit.

On some models of Mini Cooper, only the front circuit is assisted. Rear remains unassisted. I believe you're thinking of masters where the booster is part of the hydraulic assembley- the one we're talking about is remotely mounted, and not directly coupled to the master.

So, if we want to boost both circuits we could mount two servos ¿?
What about the vacuum? Is the vacuum of a single throat (dual carb setup) enough?

Sun Feb 01, 2009 6:31 pm

Luftgekült wrote: miniman82 wrote: fxnprsh wrote: A booster assists the master not a single circuit.

On some models of Mini Cooper, only the front circuit is assisted. Rear remains unassisted. I believe you're thinking of masters where the booster is part of the hydraulic assembley- the one we're talking about is remotely mounted, and not directly coupled to the master.

So, if we want to boost both circuits we could mount two servos?

No, you run a single circuit. I don't think it would be very safe having 2 servos, who's to say they would both act the same exact way every time?

Luftgekült wrote: What about the vacuum? Is the vacuum of a single throat (dual carb setup) enough?

I've heard people say that yes it's enough, but having personal experience with a single barrel on a BWM it felt weak. Best scenario is to tap a common plenum, so you have the strongest signal possible. After all, it kinda defeats the purpose of having a booster if it's not gonna work very well.

Mon Feb 02, 2009 12:41 am

no plenum in a idf setup, so I believe tapping two intakes and T them togheter is the way to go.

rainierdeklark,
please post your work, it would be a great help :wink:

Mon Feb 02, 2009 12:58 am

rainierdeklark wrote:
Second of all, the brakes on your car can never be TOO good.
Adding the servo does NOTHING to increase your car's braking power. For that you need bigger drums, or discs.

The only thing a servo does is reduce pedal effort. The lever ratios of a Beetle's brake pedal, MC bore, wheel cylinder, bore are all designed to provide minimal pedal effort.

I know a girl who weighs only 80 lbs (37kg), and she has no difficulty pushing the brakes of her Beetle. How much of a wimp are you?

Mon Feb 02, 2009 1:18 am

Bruce wrote:
Adding the servo does NOTHING to increase your car's braking power. For that you need bigger drums, or discs.

I know, I'm not trying to get more braking power by adding a servo. I do that by mounting disc brakes (probably on all 4 wheels).

Bruce wrote: The only thing a servo does is reduce pedal effort. The lever ratios of a Beetle's brake pedal, MC bore, wheel cylinder, bore are all designed to provide minimal pedal effort.

Minimal effort? Try a modern car, thát's minimal effort.

Bruce wrote: I know a girl who weighs only 80 lbs (37kg), and she has no difficulty pushing the brakes of her Beetle. How much of a wimp are you?

Well, in that case all people who drive modern cars are wimps (I agree on that, but for other reasons then having a brake servo ;) )

Mon Feb 02, 2009 1:22 am

[quote="Luftgekült"]no plenum in a idf setup, so I believe tapping two intakes and T them togheter is the way to go.
quote]

Exactly, just like the Mini Cooper S with double SU's.
Why do you think the Coopers won the Monte Carlo rally 4 times in the '60s, even leaving the Porsches behind? ;)

Mon Feb 02, 2009 1:29 am

Actually, I hate power brakes. You lose road feel with them. I also don't think that power brakes recover as fast as manual brakes when you are pumping the brake pedal. When you drive on ice and snow covered roads it makes big difference!

I hate power steering even worse.

Neither power brakes or power steering are needed or desirable on a Bug.

Scott Novak

Mon Feb 02, 2009 1:31 am

Scott Novak wrote: Actually, I hate power brakes. You lose road feel with them. I also don't think that power brakes recover as fast as manual brakes when you are pumping the brake pedal. When you drive on ice and snow covered roads it makes big difference!

I hate power steering even worse.

Neither power brakes or power steering are needed or desirable on a Bug.

Scott Novak

Power brakes are fantastic, but I agree; power steering is the worse invention ever. That's for what I call Sissies :D