Repair and reconstruction of the Harley-Davidson brakes

In this article we will perform a purely practical operation, consisting of the repair and reconstruction of the rear brake system.
Although in this specific case we have chosen the brake of a Harley-Davidson Softail model, the truth is that most brake pumps and bombs are very similar, and similar procedures, so you can apply the methods used for other models of Moto, yes, using common sense and within your possibilities, since we talk about a very important element for our security.

The problem
The braking system repair is generally done when the motorcycle accumulates quite a few kilometers, and we begin to notice an excessive friction of the pills against the brake disc when we release the handle or the pedal (the pills do not return correctly to their rest location ), which in extreme cases can generate excessive heat due to rubbing and a brake block. If this happens and we continue rolling with the motorcycle we will reach a total block and a deformation of the disc, leaving it unusable.

The solution
The system repair consists in the installation of a repair kit for the brake pump, a repair kit for the clamp and a new disc if there is deformation of it.

In the mimo mode we will need brake fluid (DOT 4 or DOT 5, depending on the year and model if it is an HD). It is important to use the right fluid, since they are generally not compatible and in case of error we will fail the brake when we need it most. We can find this information the pump tapas or in the service manual.

We start with the wheel
We will start uninstalling the vehicle wheel to extract the brake disc.

What we will do next will be to verify the deformation of the same, this will be done with a straight rule and a game of gauges, if the maximum slack specified in the workshop book is exceeded, the disc must be replaced.

In the next step we will install the new brake disc, it is advisable to also replace the assembly screws, the any case will use a droplet of Fijatornillos "Strong" in each bolt and we will tighten with a Dinamometric key, at the same time specified by the manufacturer.

Normally we will use a star tightening sequence.

After the installation we will re -assemble the wheel following the procedures and squeezes of the manual (I am insistent with this topic, but it is essential to get a good job).

We continue with the clamp

To work with the brake clamp, the most comfortable thing is to release it from the motorcycle, in this way we can take it to the work table. We will extract the piston using compressed air or a specific tool.

With the piston it was and we can replace the toric joint of the square section, which is responsible for the piston and the pills to be retracted when we release the brake. To not damage the joint we will manipulate it with some plastic or wood object.

Now we can replace the gums with those of the reconstruction kit, there is a key topic in the success of repairing a braking system: cleaning. We must be very careful so that dust or foreign bodies are not deposited inside the components, and we will clean everything with alcohol.
Once everything will lubricate the Board with a Specific product or brake fluid and we will install the piston again.

After this we install the brake clamp and the pills in its motorcycle location.

Finally the brake pump
Ya sólo nos queda trabajar con la bomba de freno, tras desmontarla de la moto aflojaremos la tuerca de montaje principal, permitiéndonos así extraer el émbolo y su mecanismo interno.

We will use the same cleaning and assembly procedures as for the brake clamp and replace the components supplied in the kit.

We install the brake pump again and we only have to fill it with the appropriate brake fluid and “bleed” the system, that is, extract all the air bubbles from it so that inside the components and hose has only liquid.
There are many different systems to perform this operation (in another article we will talk about it and compare them), this time we have used a manual vacuum pump MITYVAC, tool specified in the indications of the HD manual.

Final checks
As always we will review everything to verify that the operations have been carried out conveniently and we will test the motorcycle on the road, progressively until we ensure that everything works correctly. Ride Hard, Brake Hard!

Frank Burguera

#mecanicaharley