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Electric brake vacuum pump


v8bobber
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Hi all,

The trialler build is continuing apace, however to sort a complicated problem out, or rather to make a complicated problem simpler, I am looking for an electric vacuum pump to work on the brake servo, as opposed to using the vacuum normally generated from the engine.

I've searched fleabay but to no avail, i'm beginning to think that such a thing does not exist.

I have contemplated about fitting some kind pulley driven pump on to the 3.9 (rover v8), but this seems over complicated. I appreciate however that something of that nature may fit nicely where the aircon pump would normally go?

Anyway, I am open to solutions and ideas. However it works, i need some kind of additional vacuum to operate a brake servo.

Hope someone can assist

Dave

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Cheers for the advice,

There's nothing wrong with the vacuum pickup off the plenum chamber but this will be used to power the original brake servo for the footbrake.

I didn't go into too much detail originally as it's a bit of wierd set up. I'll try and explain

The vehicle is an 80" trialler which I want to have fiddle brakes. As you probably know fiddle brakes are things that quite often don't work properly. With regular levers (such as Milner) you either use drum brakes on the rear axle to give the required bite or discs. Problem with drums is that once they get wet they're not brilliant until they dry out and are never as efficient as they could be.

Disc brakes themselves are brilliant however they were never designed to work without servo's, especially relatively modern ones. So in order to try and get them to work you have to heave on them quite often will only work in the mud. Other surfaces are just beyond them..

The solution is going to be, of course, twin servos, one for each side. However, i'm a bit loath to run vacuum pipe from the front of the vehicle where there's a possiblity that they'll get ripped off, which will give unmetered air to the engine and knacker the brakes.

I'd prefer to keep the fiddle brakes and the main brakes separate if possible. Electric pump would be ideal as I could site it in the back with the servos. Second choice would be an aux pump from the engine which would mean unfortunately that I would have to run pipes dpwn the length of the vehicle but would not leave the whole vehilce u/s if the pipes get ripped off.

In addition to this, i'm not entirely sure that the engine vacuum would be enough to operate 3 servo's, although I am aware that the three of them wouldn't be operating at the same time.

Whadya think?

Dave

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If damage to pipes is an issue then run them inside the body as rally cars do.

Running all three from the engine should not be an issue because as you said they will not all be working together. In addition there is actually very little air movement in a servo. If there were then you would hear it release every time you took your foot off the brake in the same way as you hear lorry brakes.

Steve

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Also, a lot of vehicles e.g. Daihatsu Fourtrack 2.8 have a vacuum pump built in to the alternator.

Don't quite understand the problem with having a tube running the length of the vehicle. Ordinary Nylon pneumatic hose works well under vacuum and is no more difficult to deal with than cable?

Si

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How about adding a non-return valve at the engine end of the vacuum system? In the event of a leak the valve would shut - would save your engine, but you would loose servo assistance. I would have thought the vacuum generated by a V8 should be plenty enough to run 3 servos.

Or use an electric air compressor? Put a fitting on the inlet side - should generate a nice vacuum, especially if you use a small reservoir as well.

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How about adding a non-return valve at the engine end of the vacuum system? In the event of a leak the valve would shut - would save your engine, but you would loose servo assistance. I would have thought the vacuum generated by a V8 should be plenty enough to run 3 servos......

Sorry, wrong way round. The engine is pulling air towards it so a non-return valve would prevent the brakes working.

Steve

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Also, a lot of vehicles e.g. Daihatsu Fourtrack 2.8 have a vacuum pump built in to the alternator.

Don't quite understand the problem with having a tube running the length of the vehicle. Ordinary Nylon pneumatic hose works well under vacuum and is no more difficult to deal with than cable?

Si

yeah, you're probably right. just the way i fancied doing it. I think what i'll do is run and extra hose and split it the rear end and hope for the best. If that doesn't work then i'll go for gold with an alternative method.

Where's the best place to get some hose as where I live we seem to be bereft of car spares shops

Dave

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