Using FI Hose for Brake Booster

Run it down a long hill with the engine doing the braking. Apply the brakes numerous times to see if the booster goes away. If it does, the hose could be collapsing under maximum vacuum. On mine, the line is hard plastic in the engine compartment. I used FI hose to connect on the conversion - no problems so far (a year about!)

carb manifolds

installed the

outside pressure, as

this application?

It's probably better than fine. If you're worried about it, take a look at it occasionally when the engine is running. It will be flattened if there's a problem. I doubt if there will be a problem with this.

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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I brought a chunk of this hose into the local CarQuest/FLAPS and asked the guys if they had any. They asked what it was for. Brake boost application, I said. They backed away from me as if I had the plague or was itching to commit suicide. Can't use that for power brakes, they said, with fear in their eyes. It'll collapse and you'll kill someone. Need reinforced hose. It's not really for power brakes, I tried to explain, just a bit of vacuum to assist the braking on a VW bus. They wanting nothing to do with it or me.

That *is* power brakes.

And they are basically right.

Jan

My ignorance again. When the power brakes shut off on my parents' old Buick Roadmaster, you had to wedge a hydraulic jack between the seat and the brake pedal to apply enough pressure to slow the thing down. If I remove the vacuum on the Wonderbus, the brakes require a little more force to stop it. But it's not like when the engine is not running.

The hose is gonna collapse and I'll run over someone?

Problem is not necessarily the force required to use the bus brakes, but the moment when the brake booster suddenly does not work as suspected and you have not anticipated this. Driving usually is constant preparing for the future and you tend to adapt your driving to the cars capabilities. If the suddlenly change, you and others are in danger.

Point /very/ well taken.

I'll keep an eye on the hose and if any sign of cancaving will seek more robust replacement (presently attached to intake manifolds fitted with barbed male brass fittings, inside diameter of hose 1/2'' [12.7mm]).

parents' old

between the seat

thing down.

require a little

is not

bus

future

capabilities.

will seek more

fitted with

Considering that the hose from the check valve to the booster is rubber with cloth braid and about an inch in diameter, I bet the copper or steel connecting the manifolds to the check valve might be a bit of overkill.

It would be impossible to disagree with those who point out that a sudden unexpected change in your braking behavior might lead to an accident. OTOH, I think that if you look at the hose that VW originally supplied in that location you'll see that it is no different in construction from any of the other hoses in the engine compartment.

Hoses made for vacuum service have to have stiff jackets so that they can't collapse, so a hose made like a fire hose certainly won't work, but fuel hose is going to be fine, and FI hose is even stiffer than regular fuel hose. Large diameter hose used for vacuum service is sometimes used with a spring steel helical insert to prevent collapse, but that is usually just in much larger diameters.

If you're worried, you can try your VW dealer and see what he wants to sell you for that application. I think it's going to be the regular European single fabric braid over rubber that they sell for everything else. If they have something special, I'd like to hear about it.

BTW, If you lose your vacuum assist, you just go back to having to press on your pedal harder. It's not a good situation, but it is NOT a complete loss of brakes.

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Other than it's originally metal reinforced.. a stiff metal wire is coiled inside, embedded into the rubber... Ask my bleeding fingers how I know. Just messed with the very hose last week.

Jan

Okay, that makes sense. But didn't someone else post that they used a hard plastic tube? Did they use different styles in different years?

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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...ok here is the deal (at least on late model busses) Vw did use a hard plastic tube in the engine compartment as stated. The line up front at the booster is a braided rubber line with inner steel reinforcement. What can be used to replace a section of the front rubber hose is regular cloth wrapped breather hose....what must then be done before installattion is to go to a hardware store and get a screen door spring. Snip the ends off, lube it up and twist it into the rubber hose. You now have a steel reinforced, cloth covered, section of tubing that is impervious to collapse under the vaccuum pressure and is very similar to the stock hose.

...Gareth

I was a little rluctant to get in too deep here cuz I've made so many changes and I can't remember just exactly how far that hard plastic line goes. I think just past the firewall, then it's steel up to the front... Didn't wanna go crawl under - I'm gonna be under there enough the next coupla weeks! Sounds like a good solution, Gary. -BH

metal wire is

bleeding fingers how I

they used a

different years?

did use a

line up

steel

the front

must then

and get a

twist it into

covered,

vaccuum

Dunno. The 2 buses I've recently (within 2 weeks time) removed engines from, both were like this. I think both buses were 76 or thereabouts. My ex Baywindow was a 78 and while it was T4 powered, I seem to remember it had the same type of hose? Plus a one-way valve (plastic).

Can't vouch for any other years than 76.

Jan

DAMN boy!!

Excellent!

I used garden hose and copper tubing in my younger years ;)

Jan

Shoot, son. I gots me a /metal/ one-way valve and some kinda chubby cloth-covered rubber hose going from the engine compartment to points forward.

With metal wire insert embedded in it? That's how they are on the 76

Jan

Well I suppose I need to either cut or X-ray the hose to find out. Next time I'm in the engine room I'll see.