Air vs Air Over Hydraulic Brakes?

[jcbett]

I thought I had reg Air Brakes..but went to have a M&G brake system installed on tow vehicle and come to find out they are Air over Hydraulic.

What is the difference...which is better?

[wolfe10]

Not sure it is "one is better" vs they are different and require different maintenance.

Couple of variations:

Air drum (Our 1993 Foretravel had this type)

Air disk

Hydraulic over hydraulic floating caliper disk brakes (Our 1998 Safari had this type)

Hydraulic over hydraulic fixed caliper/4 piston caliper disk brakes with ABS (Our current 2003 Alpine 38FDDS has this type along with engine compression brake-- EXCELLENT).

Air over hydraulic.

Are you certain yours is air over hydraulic vs hydraulic over hydraulic as were earlier Safaris? You do not mention what year your Safari is--

[jcbett]

2003 is the year...the spec sheet list air over hydraulic...it has an air system...I just did not know it was incorporated with a hydraulic system... I thought it was just air.

Not seeing behind the wheels...do not know if drum or disc?

Coach is at shop having Radiator, CAC, belts, hoses, regulators....fluids, move oil breather tube...Air brake line for the M&G brake system (this is when I found out it was Air over Hydraulic)

Could I have disc brakes?

[wolfe10]

Yes, you certainly could have disk brakes-- either floating caliper or (better) fixed/4 piston calipers.

With hydraulic brakes it is important change the BRAKE FLUID every two years! And, if floating calipers, the caliper slides also need to be cleaned and lubed.

Also, with the 2003 Cheetah, be sure to verify that you have the new-design rear trailing arms-- THIS IS AN IMPORTANT SAFETY ISSUE:

http://community.fmca.com/topic/569-important-safety-issue-monaco-hr-safari-chassis/

[jcbett]

I did read here about the trailing arm issue (here on this forum) and did verify the installation of the up dated system...it is there, in fact looks brand new with bags and shocks. Having new tires (using the Michelin FMCA Program, New alum wheels and alignment).

Did not know about brake maintenance...Will add to the list at the shop tomorrow...that list just keeps getting longer.

[rsbilledwards]

Brett, I would add here that the it is probably not necessary to make a total change of the brake fluid but a through breeding of the caliper chambers, particularly the fronts as this is where most of the heat is generated. The full flush of the system could probably go out five or six years. Faithfulness of this exercise would extend the full change interval.

I checked the fluid on the just purchased 99 Safari Panther with almost 12K on the odo and I found the front master cylinder chamber was very viscous and clean, fluid dripped quickly. It appears to have had recent service, but the rear pot however, was stringy and slow to drip...darker in color too. It needs a full flushing and new fluid even though it has been sitting for the most of the last 17 years. Brake fluid is HYDROSCOPIC meaning it will draw moisture just sitting.

Bill

[wolfe10]

Bill,

Would agree on longer change intervals in dry climates. But in the east and NW, humidity suggests more frequent complete changes.

Brake fluid is cheap. Master cylinders and calipers are not. And, as the brake fluid absorbs moisture (to protect the iron components of the brake system) its BOILING POINT LOWERS-- dramatically. So, a panic stop can have temperatures in the calipers exceeding the boiling point of the hydrated fluid.... no brakes. Just not worth the risk.

[rsbilledwards]

Brett,

I concede the locale, I had not considered that kind of environment, EAST as have never lived there.

Thanks

Bill