Mangusta Brake Hoses - April 27 2008

Contrary to popular belief, factory flexible brake hoses are not designed to last 41 years!

According to one brake hose manufacturer, original equipment flexible brake hoses are designed to last 6 years on average, and should be changed in order to eliminate potential failure. 

The original equipment hoses on the Mangusta have a rubber interior and a woven exterior.  When replacing our hoses on the Mangusta International test car, we chose to have custom stainless hoses made as replacements, in order to use the highest quality product currently available.  These hoses are rubber inside and have a braided stainless outer.  The stainless is not only cosmetic in nature, but also serves as exterior support to fight against hose expansion as fluid pressure increases. 

According to a well known aftermarket brake manufacturer, SSBC, flex hoses should be replaced every time the calipers are serviced, since they flex up and down just like a shock absorber and are under high pressure internally.  Flex hoses also have a rubber liner inside which will collapse over time.  When this happens, the liner will act as a check valve and not allow fluid to return to the master cylinder.  It is interesting to note that as a general rule, flex hoses can hold up to 3,000 psi.  Most vehicles develop 1,200 psi, and panic stops generate a surge of up to 1,400 psi.

Regarding brake fluid, when the fluid turns brown in color, this indicates that the fluid has absorbed water and dirt.  (DOT #3 & #4 fluids absorb water).  We have chosen Castrol GTLMA for our replacement fluid.

The following is a general review of the process we used to successfully replace our factory brake hoses.  Please realize that this is only a general guideline, and that best results typically come from a professional shop.  Either way, safety and common sense prevail!

STEP 1

Most braking companies recommend taking your time with this entire process, as the results are much better when doing so. Properly support the underside of the car (Lifting via the very front tube frame structure and not the underbody of the car is preferred with the Mangusta), and remove driver’s side wheel.  Clean the area around the existing brake line connection fittings with a toothbrush to remove debris.  Loosen the factory hard brake line nut from the flexible hose connection.  Once loose, note that the flexible hose is held in place by a jam nut which seats against a steel washer and bracket which is connected to the car’s frame. Loosen the jam nut and remove the steel washer and flex hose from the bracket.

STEP 2 

Loosen the fitting which is threaded into the back side of the front brake caliper. Note that the hose and fitting are one piece (no jam nut).

STEP 3 

Remove the flexible hose from the car.  Reverse this procedure, installing the new flexible hose into the caliper and then into the hard line bracket. Re-check all fitting connections, but do not over tighten.  Repeat for the passenger side of the car.

Open the front trunk lid and remove the cover which is over the three fluid reservoirs.  The reservoir which is closest to the front of the car feeds the front brakes.  The center reservoir feeds the rear brakes, and the last reservoir feeds the clutch cylinder. 

Remove the old fluid from the front brake reservoir using a suction ball available at most hardware stores.  Do not use the wife’s turkey baster, however.  Our old fluid looked more like sewer sludge.

STEP 6 

After the fluid has been removed, unbolt the reservoir support bracket and then carefully remove the bottom feed hose from the reservoir.  Note how the rubber plug and screw-on fitting connects (realize there are no replacement reservoirs on the market!). Remove the reservoir and clean it thoroughly with an evaporating solvent (No water!) dry, and re-install.

STEP 7 

Now that you have a clean reservoir and new front brake hoses, refill the reservoir with new brake fluid (in our case, Castrol GTLMA).  Starting on the driver’s side caliper connect a multi-purpose hand vacuum pump to the caliper bleed screw.  After pumping up the vacuum pressure, loosen the bleed screw until the remaining old fluid, followed by the new, is pulled into the vacuum chamber reservoir.  Continue to hold a vacuum until most of the new clear fluid in the brake reservoir (the one located under the trunk lid) is pulled through the system.  Make sure to re-fill this reservoir during the process so as not to pull any air through the system.

Repeat this process on the passenger side, until all the fluid which is draw into the pump reservoir is clear and new.  Start the car and then check the pedal pressure to make sure the pedal is firm, confirming that no air is in the system.  A soft brake pedal is typically a result of air being trapped in the lines or brake calipers.  When this happens, try re-bleeding the system.

Once confirming that the pedal is firm and the job is complete, repeat for the rear brakes using the same general principle.  Note the factory arrangement of the fittings and washers, and make sure to re-assemble in the proper order.  Again, most braking companies recommend taking your time with this entire process, as the results are much better when doing so. 

That’s it!  Below are images of the project for your reference.

UPDATE July 2008: Replacement Stainless Brake and Clutch Slave Hoses now available through the MI Online Store.