Technical Rear brake wheel cylinder change problem

[dorlv]

hello all,

I have a Fiat 500 F 1968 and my left rear brake wheel cylinder was not working anymore. Therefore, I ordered 2 new rear cylinders and a breaking shoes to replace the old ones. I started with the defect rear wheel and canged the cylinder and the shoes exactly like told in the manual. When I tried to put back the break drum it did not fit well so I had to apply a bit of force. When I put the wheel back the break then was completely blocked.
The cylinder size i ordered is 19,05 mm. Is there a chance that this size is wrong or did I do something during the process which was wrong?

Many thanks for your help in advance !

 

[the hobbler]

If you have fitted new brake shoes you will need to alter the adjustment of the handbrake. At the rear of the rear brakes you will see the cable that operated the hand-brake. Follow that along for a few inches and you will come the the adjuster---2 X 17mm nuts, 1 either side ofa little vertical plate. Loosen the 17mm nuts and alter the length of the handbrake cable 'outer-sheath' so that the hand-brake (and therefore the brake shoes) adjustment is loosened. This will enable you to refit the brake drum much more easily. Although the handbrake cable (for BOTH sides) is a single cable that runs round a roller at the hand-brake lever, it is wise to free off the hand-brake cable at both sides. If for no other reason, this allows you to check that the adjustment nuts CAN be loosened off and adjusted on both sides. Give the unused threads a good clean and light covering with grease to protect the exposed section of thread. At the end of the day, with your new wheel cylinders and brake shoes fitted, you require 3 clicks when you pull the hand-brake on, and it is holding.

 

[dorlv]

If you have fitted new brake shoes you will need to alter the adjustment of the handbrake. At the rear of the rear brakes you will see the cable that operated the hand-brake. Follow that along for a few inches and you will come the the adjuster---2 X 17mm nuts, 1 either side ofa little vertical plate. Loosen the 17mm nuts and alter the length of the handbrake cable 'outer-sheath' so that the hand-brake (and therefore the brake shoes) adjustment is loosened. This will enable you to refit the brake drum much more easily. Although the handbrake cable (for BOTH sides) is a single cable that runs round a roller at the hand-brake lever, it is wise to free off the hand-brake cable at both sides. If for no other reason, this allows you to check that the adjustment nuts CAN be loosened off and adjusted on both sides. Give the unused threads a good clean and light covering with grease to protect the exposed section of thread. At the end of the day, with your new wheel cylinders and brake shoes fitted, you require 3 clicks when you pull the hand-brake on, and it is holding.

Hey the hobbler thanks so much for the reply!
I tried to release the handbrake and the drum enters more easily but still the wheel does not turn.
I am thinking of trying to buy the 15.72MM cylinder instead of the 19.05MM do you think it will help?
Thanks!

 

[the hobbler]

All the wheel cylinders are of the same EXTERNAL size---it is the internal bore that changes. If you can get the drum on easily, but the wheel still doesn't turn, check that the wheel bolts are not extending into the brake-shoe area and catching on the brake shoes. If the drum turns easily, the wheel bolted to it should also turn easily. Have you backed off the hand-brake fully on both sides? You will be surprised just how much you may need to back it off.

 

[dorlv]

All the wheel cylinders are of the same EXTERNAL size---it is the internal bore that changes. If you can get the drum on easily, but the wheel still doesn't turn, check that the wheel bolts are not extending into the brake-shoe area and catching on the brake shoes. If the drum turns easily, the wheel bolted to it should also turn easily. Have you backed off the hand-brake fully on both sides? You will be surprised just how much you may need to back it off.

Yes yes I realized the external size is the same.
I add a picture of the cylinders.
The first cylinder is malfunction so I do not know if the edges should be outside like the new cylinder or not.
I opened the handbrake cable until it did not press on the brake shoes at all.
Could it be that the internal bore is too big in the new cylinder and that's why the brake hits the drum??

Pic number 1: https://imgur.com/yLGGJXC
Pic number 2:https://imgur.com/uHj4smh

Thanks again for the help!