Rear Brakes Overheat

I had this, after fitting new shoes and drums. Are  your handbrake cables backed right off?

I was amazed at the difference it has made to the brakes and handbrake in terms of performance.

Did you replace wheel cylinders?

I thought all G's had rivted on brake linings, though I suppose it is easier for a company to bond them on.

Can you as a temporary measure clamp off the back hose to see if the front brakes will hold pressure? Any obvious fluid loss?

Hello Ayman,

Thank you for the photos. I notice some faults.

As I expect, I am not to be getting answers to questions I pose, so I will try to cover the topic as best as I can.

To eliminate the brake master cylinder to be faulty, clamp all the brake rubber hoses. Depress the brake pedal this should be firm if the master cylinder is good. I do not have the full picture of how the master cylinder has failed but if the brake pedal is not firm, some bleeding at the master cylinder will be required. I am going to assume you or mechanic knows how to do this if not pose the question back to me.

From your photos, I notice that the brake adjusters are overly extended; the adjuster- screw head must be fully wound in at both ends. Comparing the photos 0155 and 0156, notice the return springs at the top. The left spring seems to be extended, i.e. stretched; my suggestion would be to renew these return springs, there not expensive. The stretched spring could be preventing a quick return or release of the shoe from the drum surface after brake application. Finally, there seems to be some wire at the left shoe retaining spring, this should not be there.

With broad pan head (flat) screw driver; placing the screw driver head at the tip of the wheel cylinder pin and push it inwards checking to see if the pistons are free. The pin, when pushed in will displace an equal amount out the piston out from the opposite end. Repeat this test from the opposite end and the result being the same, you have ensured the wheel cylinder to be free. If not, it could be the cause of your binding.

Unwind the handbrake lever's cable adjuster nuts and release the handbrake lever.

Having wound in the adjuster screws on the shoe adjuster, offer the drum on the axle shaft's flange but no need to fasten the taper screw just yet. From the back plate, notice there is only one window to the adjuster. From this window adjust one notch at a time and make mental note of how many notches it took to get the drum binding with the shoe. No need to achieve lock up at this stage.

Remove the drum, wind in the adjustment just made. Now unwind the blanked (other) side by the same number of notches. Fit the drum back on and this time fit the tapper screw to secure the drum on to the axle shaft's flange.

Slightly slacken the shoe adjuster mounting nut found next to the adjuster window. Take a light hammer and gently tap the nut head of the blanked side towards the drum, which I think is forwards of the vehicle.

This action will lock up the drum as the shoe adjuster moves the shoe towards the drum through this tapping action. To complete the shoe adjustment, very gently tap the adjuster nut rearwards, i.e. away from the drum. Do this, so the shoe just releases from the drum allowing free drum rotation but with a hint of the shoe just kissing the drum surface, you should hear this contact when the drum is rotated. Torque the mounting nut to 40Nm.

Now adjust the other shoe from the adjuster window, locking up the drum and unwinding a notch at a time to achieve the same contact as described for the earlier for the blanked side. Repeat this whole procedure for the other side, drum. Put on the wheel on both sides, this is to give you adequate torque for the handbrake adjustment. Test your brake pedal, if it is soft you will need to bleed the brake starting from the; for a RHD, left-rear wheel, right-rear wheel, front-left wheel and lastly front-right wheel. For a LHD, right-rear, left-rear, front-right and lastly font-left.

If you still have a soft pedal, come back to me.

Have an assistant to apply normal pedal force holding the pressure on, check the rubber hoses to see if these bulge, if it does, replace that rubber hose. Check at each wheel for free wheel rotation just after the brake pedal is applied. If a wheel binds after pedal release, you will need to investigate if it is brake cylinder (rear) or brake caliper (front) or it could be the rubber hose, hence, I have asked to check for hose bulging.

Pull the hand brake lever to its first notch. Adjust each cable up so you achieve a slight binding at each wheel. Release the hand brake lever and take up a further two turns. If your hand brake lever has a notched window stamped out the top back corner showing the ratchet finger through the notch; in that case turn up four turns. Tighten any lock nuts if fitted to the cable and torque your wheel when the vehicle is back on ground.

If I find you email, I will send you an article which I had written for the forum. The diagrams may be of help to you.

Good luck

Hello Ayman,

Thank you firstly for coming back and providing closure to your problem. Yes, the over machining of drum lining does not provide for heat dissipation hence the overheating. Drums are not general expensive, I suppose it would be in Kenya. 

In times of parts shortages in England, during World War 2, owners' took to relining their worn drums some fabricated material which I expect would have been a close fit like a starter ring gear and machined down to the correct tolerances. I do not advocate this practice; for your and others road safety, please stick to properly produced parts. 

Ps, there is a minimum thickness stamped on the lip of the drum which must not be exceeded.

T1 Van drums are certainly what you need.

Part Number A601 423 50 01 is cast into the outside of the Drum

These are for the 3t varients 307D/308D/309D/310/310D

Not the 2t varients (A601 423 51 01) 207D/208D/210/210D (Too small)

Or the 4t varients (A611 356 09 02) 407D/408D/409D/410/410D (Drum / Hub combined)

All Sprinter varients have been on Rear Discs with in built Brake Drum from day one so are no good either.

Gav