Guide to brake refurbishment

How does the braking system on the Volvo C303 work?

At Tatanka Parts, you will find brake components for both refurbishing the existing braking system and completely replacing worn parts. We have also developed several newly manufactured parts for the Volvo C3 series to simplify the refurbishment process.

The Volvo C3 series features two separate hydraulic brake circuits, each with its own brake fluid reservoir.

Viewed in the direction of travel, the circuits are distributed as follows:

Left brake fluid reservoir

• Rear wheel cylinders on both front wheels
• Left rear wheel

Right brake fluid reservoir

• Front wheel cylinders on both front wheels
• Right rear wheel

The system also includes a pressure differential/warning valve. During a major overhaul, or if the system has been completely drained of brake fluid, it is important to bleed the system thoroughly.

Overhauling the brake system step by step

If you are overhauling the brake system on a Volvo C303 or TGB, it is advisable to go through the system in the following order:

1. Check the brake lines – Look for rust, damage, and previous repairs.
2. Check the brake hoses – Rubber ages even when the vehicle is not being driven. Therefore, inspect the hoses carefully; the rubber often deteriorates internally, creating a check-valve effect that prevents the fluid from returning.
3. Check the wheel cylinders – Inspect for leaks and rust, and ensure the pistons move correctly.
4. Check the brake servo – Inspect the servo and connections before filling and bleeding the system.
5. Fill with brake fluid and bleed the system – Start at the brake servo and then proceed to the wheel cylinders, following the correct bleeding sequence.
6. Check the entire system after bleeding – The pedal should feel firm, and the brake system must be completely leak-free before the vehicle is put into service.

Bleeding the brakes

The brake servo is a component often overlooked during bleeding. To address this, we have developed a custom banjo bolt with a bleed nipple, making it easier to bleed the brake servo.

Replace the old banjo bolt with the custom bolt, using new copper washers.

Always begin bleeding at the brake servo, then proceed according to the correct bleeding sequence for the brake circuits.

The warning light is on in the Volvo C303 – what should I do?

If the brake warning light is on in your Volvo C303/TGB, you first need to determine why it has come on. The braking system features two separate brake circuits and a warning function that triggers if there is a pressure difference between the circuits.

It is common for the light to come on after the brake system has been bled or repaired. In such cases, the switch at the brake pedal may have shifted from its normal position and requires manual resetting. There is also a separate switch on the chassis underneath that must be removed before bleeding the system.

Start by checking the following:

1. Check the brake fluid. Ensure there is sufficient brake fluid in both reservoirs. If the level is low, do not simply top it up—investigate why the brake fluid has been lost.
2. Check the brake system for leaks. Inspect the brake lines, brake hoses, wheel cylinders, connections, and the brake servo.
3. Have you just bled the brakes? If the light came on after bleeding, the warning valve may have tripped due to a pressure difference between the brake circuits.
4. Check the warning switches. The C303 has a switch linked to the pressure difference between the brake circuits, as well as a switch at the brake pedal that can activate if the pedal travels too far down.