Community Forums

poppatello · 09-06-2010, 02:42 PM

I was under the Winnie today to look @ how to remove my gas tank and saw this. It looks like something that is for the braking system but I have two of them. One for the front and one for the back? They have hydraulic lines come from them...

GOLDWINGER2 · 09-06-2010, 06:44 PM

Why the warning for CWB.com?
J

stangdoc · 02-01-2011, 01:48 PM

It looks like you got no answers on your question. I have something like that under the stairs on my 83 Holiday Rambler 33. It looks like it is a second vacuum booster and small round master cylinder with a bolt-on cap for the tag axle drum brakes. You will know for sure if there is a hose that goes from it to the engine's intake manifold (to pull vacuum from). Your pic shows a regulator and it seems to be a one way check valve to keep a vacuum on the booster. Does yours have a tag axle? Mine has the VacuBoost system which you will have to google as it is kind of odd in the way it works. This strange system was developed for diesel engines (due to low engine vacuum) to provide steady vacuum for secondary braking, and P/S assist.

QuietWater · 02-01-2011, 09:58 PM

We would need a little more info. If you have a 23 ft Indian you don't have a tag axle so you wouldn't have a separate brake system. It could go to the steps. Argosy motorhomes had something similar on their steps. Or it could be something completely unique to your era. Out of curiosity, does your motorhome have the shower and toilet right behind the driver seat?

poppatello · 02-02-2011, 07:16 AM

No, I am running a Dodge 440 drive tran and the shower and bathroom is behind the dinning area on the driver side. Not sure what you guys mean by steps. But I have to manually pull the steps out from under the door. I haven't done anything else to this thing since I reinstalled the fuel tank. I can't for the life of me keep my power steering belt on...

QuietWater · 02-02-2011, 08:03 AM

I guess it looks like the one in this brochure.
http://www.winnebagoind.com/products/previous-models/1973/pdfs/73-Indian-bro.pdf

I looked all over my motorhome for something similar, but, except for the tag axle brake system, couldn't find anything like it. I'm not familiar with the Dodge chassis or motor. Is the alternator and the power steering on the same belt? Either something isn't lined up properly, or there is a big drag on the belt.

myron sowry · 02-02-2011, 09:45 AM

this is the unit that provides power brakes on or coach. they are used on thrucks and cabchassis's because the automotive units were too small. myron

TQ60 · 02-02-2011, 12:31 PM

Due to the number (2) and the size limitations of your chassis, there is no room for the vacuum booster at the firewall for your power brakes.

Pop the hood on most vehicles and you see something like these.

Instead, at your brake pedal you have a normal non-boost type of master, then it feeds the 2 remote masters under your MH, there is room here for the vacuum boosters, and 2 are used, one each for front and rear.

Since this is a new discovery I suggest a flushing of the brake fluid and good brake bleeding, the fluid in there is old and may not be very good anymore.

Check the vacuum lines as well, they are cheap to replace, buy in bulk from Napa or any other supply house.

LVJ58 · 02-02-2011, 12:33 PM

vacuum brake booster??

TQ60 · 02-03-2011, 10:48 AM

Ok, let me try to explain...

Your engine has a vacuum inside the manifold while running, and this is equal to about 5 1o 14 pounds per square inch of pressure.

The surface area of the diaphram inside the booster is say 100 square inches, this equals 500 to 1400 pounds of force available, my math could be off, but follow for the theroy.

There is a valve inside the booster that when the brake is activated it allows air to flow thus using the pressure difference between surounding air and the vacuum to add force to your action.

So light pressure is amplified to great pressure with the help of the vacuum that exists in the intake manifold.

A poorly running engine or leaky hose reduces the braking effect, and a bad hose at the booster leans out the engine.

If you need to have a heavy foot on your brakes it could be a capped hose instead of a repaired leak.

The old models back in the 60's had poor valves compared to today's models and the result was very touchy and fast acting brakes, poor feedback meant excess braking with minor pressure.

Late models now use the power steering system for the boost so the booster may not be present on all cars, ABS also complicates things.

73DodgeTitan · 04-26-2011, 10:58 AM

great descriptions here guys. I have a '73 with the 440 and same setup discussed here. We're in the process of troubleshooting the boosters/brake issues on my '73. We had it running last weekend for about 30 minutes.. and no problems. YAY! So, we moved onto the brakes. We added brake fluid to master cylinder under the drivers side and a few minutes later white smoke was ROLLING out the exhaust. Come to realize that the vacuum line from the booster up to the manifold is pulling the brake fluid and it was making its way through and out the exhaust pipe.

We're thinking at least one of the boosters are bad - but stopped messing with it and need to explore it further.

Scooter Ride · 05-04-2011, 03:28 PM

This is a "Hydrovac" power brake unit. These were popular add ons in the early years of power assisted braking systems and where additional braking was required (such as tag axles.