Case Studies

Brakes built on a Workhorse W42 chassis

Brakes built on a Workhorse W42 chassis

LAS have noticed that on some Winnebago motorhomes on the Workhorse chassis, there is a brake fault which can occur. This fault applies to all Winnebago motorhomes on the Workhorse W42 chassis built between 2006 and 2008. Winnebago, along with many other manufacturers, use this W42 chassis because the steering turning circle was decreased through the use of Brembo brake callipers.

The brake callipers and rotors are a significant amount smaller than the Bendix callipers, used from 1999 to 2005, allowing the road wheels to turn in more, giving a better turning circle. Both the Bendix and the Brembo brakes are fitted with phenolic resin pistons.

The Bendix brake callipers began to give problems when the chassis was between 8 and 10 years old, but the problems on the Brembo brakes have become apparent much sooner, in some cases when the chassis was only 2 years old. The problems have been caused by the phenolic brake calliper pistons.

The use of the phenolic pistons over the good old steel pistons was due to a reduction in heat transfer from the brake piston to the brake fluid. When you drive your Winnebago down a steep hill holding it on the brakes and the pedal reaches the floor, this is not called “help” but brake fade. Brake fade is what occurs when brake fluid boils.

The manufacturers have now found that phenolic resin absorbs moisture and swells up when hot. This is why some Winnebago and other manufacturers’ motorhomes brakes can start to bind when they overheat, and in some cases catch fire, but cool down and appear perfectly normal. The Bendix callipers are now available with steel pistons, but the Brembo callipers are not, meaning you are replacing the callipers only to get the same problems again later on.

Winnebago Windscreens

It has become apparent to LAS motorhomes that there is a problem with some windscreens fitted by Winnebago. This problem occurs with the bonded screens. This type of windscreen can be found on the Winnebago Brave from around 1999 through to the present Winnebago Sightseer. The problem can be traced back to the metal frame which the windscreen is bonded to.

Winnebago use a frame made from a mild steel box section. Onto this box section they apply a bead of screen bond and then push the windscreen onto the screen bond. With earlier Winnebago’s they used a rubber seal which the windscreen was fitted into, and then they inserted a key rubber into the centre of the seal in order to spread the seal out, holding the windscreen in place whilst also allowing the body to flex without breaking the windscreen.

But these bonded windscreens do not have sufficient rust protection on the box section aperture for our wet climate, so LAS find that the box section corrodes under the windscreen bond, which in turn lifts the bond away from the frame causing the windscreen to break.

Winnebago use a decorative strip around the windscreen to finish it off. One of the ways to slow this corrosive process is to seal the decorative rubber to the windscreen, keeping the moisture away from the steel box section.

If you have any problems with your Winnebago or any other manufacturers American motorhome, please give LAS motorhomes a call on 01604 861999