Amazon: Brake trouble - one or both rear brakes lock up

[samaron]

Hello everyone,

Hopefully someone here has some experience that can point me in the right direction on where to troubleshoot.

Ever since I bought my Amazon, I have had a strange problem where one or both rear brakes lock up when braking. I believe it is the rear left that lock up, but hard to tell. My car isn't fitted with a brake servo, just a regular single circuit brake system.

Normally this occur after the car has been sitting overnight. Just a light push on the pedal and a very brutal stop ensue. Luckily this tend to happen at walking speeds, but I have experienced this at higher speeds too. Braking afterwards performs as normal.

A year ago I had the car at a shop as I don't have an appropriate brake puller. None I bought fit the bolt pattern, and a claw type puller took out a piece of the drum rather than pull it off. The shop replaced the brake shoe linings, springs, performed some cleaning and lubrication. They did say one of the brake cylinders were leaking, and the provided overhaul sets did not fit, but they managed to fix it regardless.

Some other things to mention are that all brake lines and hoses have been replaced the past year. The handbrake is, as far as I understand, properly adjusted. 4-5 notches before it is fully engaged. Brake fluid is replaced and stays at the same level without discoloration.

Since I'm driving the car a lot more now, I probably should get this looked at again. Have taken some measurements and will attempt at getting a brake puller made. Meanwhile I could order up some brake parts. Is there anything I should order up and have ready? When I do get a brake puller made, are there any prime suspects among the brake parts that I should focus on?

[blueosprey90]

I'm not sure I can help with your problem but ...

1) do you set your handbrake when you leave the car overnight? Perhaps your brake cable needs lubrication or replacement - or is somehow getting jammed in the drum because of all that jury rigged work. If I recall, the handbrake cable fits a specific way in the drum.

2) normally I would suggest that when this happens, release the bleeder at the rear slave cylinders. If you get a shot of fluid and the brakes release, then the problem is either your rear slave cylinders or the rear brake hoses collapsing internally and preventing brake fluid from returning to the master cylinder.

3) could be a problem with the master cylinder. Is it overfilled? When you release the brake pedal, fluid has to flow back past the relief valve. The valve may be partially blocked.

In the States, I easily purchased a drum puller from VP Autoparts. Not cheap, but available.

[samaron]

Thanks for your reply!

I do not leave the parking brake on overnight normally. This is just a habit I learned when taking my drivers license. Leave it in gear unless you're on a hill.

When I replaced my support arms in the rear a month ago, I had to disconnect the brake lines. As far as I recall, there were no signs of built up pressure when I loosened the fittings. The rear axle hose were replaced maybe 2-3 months ago, in an attempt to cure the issue.

The master cylinder isn't overfilled I think, but I don't remember seeing any min/max indicators either. It isn't the original type, but I see it is being sold as a compatible replacement on VP Autoparts. Part number 662186. The level is probably just below the bottom of the cap.

I see VP Autoparts in Sweden sell the drum puller you mentioned, but it will cost me at least $230, most likely more. International shipping, fees and taxes makes it very expensive. Might as well try to modify one of the universal pullers I have bought.

Thinking about that the repair kits for the rear brake cylinders didn't fit. This makes me question which brake cylinders are fitted. I don't believe they are leaking, as I cannot see any wet spots behind the wheels. Regardless, probably a good idea to at least order a new set that is correct.

[Clan]

Originally Posted by samaron

Hello everyone,

Hopefully someone here has some experience that can point me in the right direction on where to troubleshoot.

Ever since I bought my Amazon, I have had a strange problem where one or both rear brakes lock up when braking. I believe it is the rear left that lock up, but hard to tell. My car isn't fitted with a brake servo, just a regular single circuit brake system.

Normally this occur after the car has been sitting overnight. Just a light push on the pedal and a very brutal stop ensue. Luckily this tend to happen at walking speeds, but I have experienced this at higher speeds too. Braking afterwards performs as normal.

A year ago I had the car at a shop as I don't have an appropriate brake puller. None I bought fit the bolt pattern, and a claw type puller took out a piece of the drum rather than pull it off. The shop replaced the brake shoe linings, springs, performed some cleaning and lubrication. They did say one of the brake cylinders were leaking, and the provided overhaul sets did not fit, but they managed to fix it regardless.

Some other things to mention are that all brake lines and hoses have been replaced the past year. The handbrake is, as far as I understand, properly adjusted. 4-5 notches before it is fully engaged. Brake fluid is replaced and stays at the same level without discoloration.

Since I'm driving the car a lot more now, I probably should get this looked at again. Have taken some measurements and will attempt at getting a brake puller made. Meanwhile I could order up some brake parts. Is there anything I should order up and have ready? When I do get a brake puller made, are there any prime suspects among the brake parts that I should focus on?

This could be a problem with the front brakes not working, or someone has fitted too large a rear Brake cylinder or two, or shoes which have the wrong linings ( Too high a grip )

[samaron]

The linings should be the correct type. Double checked my order and verified I at least ordered the right set.

The rear brake cylinders should have a 7/8" bore size. Looking at VP Autoparts and in some specifications I found, there are other types with slightly larger sizes available.

Digging a bit deeper on the brake subject, I do see I have a completely different brake setup than most Amazons. This certainly could cause confusion when ordering parts.

Maybe I should spend some money on getting a proper brake function test done once the system is repaired to the best of my abilities.

[Derek UK]

You can use CVI in Sweden for parts. They have the puller.
https://www.cvi-automotive.se/en/art...s-rear-girling
They also have all of the parts to overhaul your brakes.

VP are also in Sweden where they originated. You can also use them.
https://vp-autoparts.se/en/artiklar/...r-2/index.html
Prices may vary a little.

It's possible your brake cables, the parts that go in the drum, need lubrication.

[samaron]

Eventhough Sweden is a neighboring country, it is still international shipping.

A few years ago the tax collection was changed to include the shipping cost as well, making it even more expensive to import items. Not to mention the new money laundering laws that make money transfers abroad a huge ordeal. Just paying for my carburetor rebuild took two weeks of filling out multiple forms in order to transfer the money.

I'd like to try to modify a generic puller before going through that process again. Hopefully I can make a template and drill out new holes, worst case I need to find someone with a welder.

Back to the brake cables... Should the wire itself be lubricated with a dry lube, or just the parts internal to the brake brum? Inside the brake drum I assume it should be sufficient with ceramic grease?

[142 Guy]

Just an observation. Rear lock up during heavy braking is not unusual on non ABS cars. Weight transfer during heavy braking unloads the rear wheels leading to rear lock up. During weight transfer the rear end rises and the pan hard operation causes a differential unloading between the left and rear wheels meaning that one rear wheel generally always locks up first. On my 142 I think it is the left rear. If your problem occurs during normal braking, then the above comments are not material.

I can't remember whether it was on this forum or on the Swedespeed forum; but, 2-3 years ago there was a thread by an Amazon owner discussing rear brake issues. The fact that there are differences or perhaps a design change in the rear brakes during the production run was revealed so it would probably be wise to confirm your actual brake system.

If the repair shop fixed the leaking rear brake cylinder by fitting a new cylinder with a different bore size, this will alter the brake balance. If the new slave cylinders have a larger bore than the original cylinders,

force = pressure x piston area

means that the same brake pressure will be generating more force on the rear shoes. Conversely, the larger piston area means that it takes more fluid to move the pistons with the knock on effect that pressure rise is slower as you apply the pedal and the front brakes are slower to generate stopping force. However, it is not obvious to me why this problem would only materialize first thing and then disappear with subsequent use.

[Volvo_133]

All good comments. While you have the rear drums removed ensure the leading edge of the shoes are in there correct position.
Choose a side, using forwards motion to choose the direction of rotation.
Anti clockwise rotation, the front shoe should have some of its friction lining missing at the top, the rear shoe some of its lining missing at the bottom.
Clockwise rotation, the front shoe some missing at the top, the rear shoe some missing at the bottom.
When located incorrectly they do tend to snatch
Many mechanics today rarely work on drum brakes and may have fitted the new shoes by simply copying.(Fine if they were correct when found).To adjust the rear brakes, initially disconnect the central handbrake rod. Adjust the shoe adjusters till tight, then back off until the drum rotates with minor binding. Reinstate the handbrake rod and adjust if required ensuring the drums only have minor binding. Your HB should now hold good on 4 to 5 ratchet notches
PS This principal is also correct for front drum brake shoes.

[samaron]

I'll get the drum puller prioritized and once the drums are off I need to verify what I have. I assume it is the original system, as I do not have any adjusters (or holes for them) on the back of the back plate. My instruction booklet has it as a main selling point that Amazon comes with self adjusting brakes as standard. I see now that later models have manual adjusters.

Will report back once I have gotten to the point where the drums are off the car.