Technical Hard Brake Pedal - Brake Booster Vacuum?

[bugsymike]

Hi,
I am currently trying to take off the rear drum but is stuck. According to the Haynes manual "if the drum is binding on the brake shoes screw two M10 bolts into the locating stud threaded holes in the drum, and progressively tighten them against the hub flange to push the drum from the hub"

I've tried to do this without any luck but I guess it depends on the position of the hub as there are different parts of the rear brake that you could be pushing on. I have tried the 'ten to four' and the 'quarter to three' positions...any trips greatly appreciated !

Thanks again

I have seen people rip the threads out of the drum doing that so be careful.
What I tend to do is spray a little oil around the hub to drum flange area, then I use a large copper mallet "gently" to break it free from the hub against the area the wheel contacts , it tends to spring off then. A normal steel hammer is more likely to cause damage.
The time I have found the bolts and thread method of use is where the brake drum is badly worn and the brake shoes are catching on the wear ridge in the drum and it can help with "see sawing" the drum off. Though I thought it was M8s with a 13mm spanner or socket to extract via the wheel locating studs.
Re the brake servo working when pedal drops on starting the engine, it does sound like it is doing something, though how much is the critical factor. Usually if servo good you can go back to the car 30 minutes or more later and still feel the servo is working holding the vacuum before starting the engine, that would indicate no leaks.
When drums off, if no leaks visible and shoes in good order, I often use two screwdrivers to move the brake shoes forward and back as a guide to any seized brake cylinders, as that can give a firm brake pedal with poor stopping ability. I also flip the dust covers back to see any early signs of brake cylinders starting to leak.
Front brake calipers can seize also, although you are more likely to have noticed pulling to one side if that was the case.

 

[Guerciotti]

I have seen people rip the threads out of the drum doing that so be careful.
What I tend to do is spray a little oil around the hub to drum flange area, then I use a large copper mallet "gently" to break it free from the hub against the area the wheel contacts , it tends to spring off then. A normal steel hammer is more likely to cause damage.
The time I have found the bolts and thread method of use is where the brake drum is badly worn and the brake shoes are catching on the wear ridge in the drum and it can help with "see sawing" the drum off. Though I thought it was M8s with a 13mm spanner or socket to extract via the wheel locating studs.
Re the brake servo working when pedal drops on starting the engine, it does sound like it is doing something, though how much is the critical factor. Usually if servo good you can go back to the car 30 minutes or more later and still feel the servo is working holding the vacuum before starting the engine, that would indicate no leaks.
When drums off, if no leaks visible and shoes in good order, I often use two screwdrivers to move the brake shoes forward and back as a guide to any seized brake cylinders, as that can give a firm brake pedal with poor stopping ability. I also flip the dust covers back to see any early signs of brake cylinders starting to leak.
Front brake calipers can seize also, although you are more likely to have noticed pulling to one side if that was the case.

Thank you. Yes I found that for my car it is M8 with a 13 mm spanner and I am using the two wheel locating studs.

I've got a new problem though - just started the car to move it to free up the driveway and all of the brake warning lights have come on (ABS, tyre pressure warning etc) so I think I've damaged something...

 

[bugsymike]

Thank you. Yes I found that for my car it is M8 with a 13 mm spanner and I am using the two wheel locating studs.

I've got a new problem though - just started the car to move it to free up the driveway and all of the brake warning lights have come on (ABS, tyre pressure warning etc) so I think I've damaged something...

It could be something else but I have had ABS light come on if I have spun one wheel independent of the rest as the ABS computer thinks there is a fault, no guarantees but hopefully if that it will reset it's self after a short drive.

 

[Guerciotti]

I have seen people rip the threads out of the drum doing that so be careful.
What I tend to do is spray a little oil around the hub to drum flange area, then I use a large copper mallet "gently" to break it free from the hub against the area the wheel contacts , it tends to spring off then. A normal steel hammer is more likely to cause damage.
The time I have found the bolts and thread method of use is where the brake drum is badly worn and the brake shoes are catching on the wear ridge in the drum and it can help with "see sawing" the drum off. Though I thought it was M8s with a 13mm spanner or socket to extract via the wheel locating studs.
Re the brake servo working when pedal drops on starting the engine, it does sound like it is doing something, though how much is the critical factor. Usually if servo good you can go back to the car 30 minutes or more later and still feel the servo is working holding the vacuum before starting the engine, that would indicate no leaks.
When drums off, if no leaks visible and shoes in good order, I often use two screwdrivers to move the brake shoes forward and back as a guide to any seized brake cylinders, as that can give a firm brake pedal with poor stopping ability. I also flip the dust covers back to see any early signs of brake cylinders starting to leak.
Front brake calipers can seize also, although you are more likely to have noticed pulling to one side if that was the case.

Hi, I've tried the mallet method but the drum remains absolutely stuck on ! Appreciate any other tips to try and release it as I'm out of ideas ! Thanks again.

 

[John202020]

I had this issue, make sure the bolts press against the shoes inside, however I ended up destroying the fixings that hold the shoes in place so new shoes and fixings it was and a new wheel cylinder as I pulled the plunger out brute force it ended up being though I was replacing the drums anyway

 

[bugsymike]

Hi, I've tried the mallet method but the drum remains absolutely stuck on ! Appreciate any other tips to try and release it as I'm out of ideas ! Thanks again.

Assuming you have oiled around the flange area, I can honestly say I have never had a brake drum that could resist a No 4 Thor copper mallet weighing 2.83Kgs. As you can see this one has had many years of use and never damaged/broken anything . In the 1970s it was the only way of removing Wartburg brake drums, just careful to miss the wheel studs. I also used them on finned alloy brake drums on 1200 Ladas (Fiat 124 under license) without damage as they also wouldn't come off using the bolt extraction method similar to your 500.
Usually one or two at the most blows on the flat flange area where the wheel studs screw in is enough.
I am assuming it has not moved at all i.e. still stuck to the flange and not wobbling, if you have some movement as in holding on the brake shoes or some such issue if that is the case then see sawing with a couple of tyre levers may be the answer, though that often drags the shoes etc. with it.

 

[John202020]

The issue is the lip that forms on the inside edge of the drum, and no ability to wind back the auto adjusters so you're trying to pull the hub away from "on" brakes in effect.
Think I put the wheel bolts in to help pull the drum round whilst pulling outwards

 

[z rider]

I have to adjust the rear brakes on wifes Ypsilon for MOT, because one side doesn't adjust properly. I do it through a bolt hole. You will need a little torch light, technical understanding and a whole lot of patience.

 

[bugsymike]

I think we need some clarification from the OP.
Is the drum stuck on the flange with no movement, in which case if the extraction bolt method isn't working then the large copper mallet is often the answer.
However if the drum is moving away from the flange and then jamming on the brakes shoes due to a wear ridge inside the brake drum, then the two tyre lever method rocking the drum at roughly 12 Oclock and six Oclock (where the brake cylinder and brake shoe anchor points are) along with the wheel bolts used to turn the drum as @John202020 suggests may be the answer, but due to the wear ridge some brake damage may occur.
I usually find if done 9 and 3 Oclock (where shoes sit ) more likely to cause damage as it tends to tip the shoes more.

 

[z rider]

Absolutly right. Till now I allways was able to wriggle the drums off, no matter how deep the ridge was.

 

[jackwhoo]

Is the car safely jacked? On stands not just jack? Front wheels chocked? Hand brake off?
I think the original poster should consider going to someone with practical experience, there is some much that could go wrong.
No disrespect intended at all.
Combined Brake problems (servo and rear drums not coming off) maybe not good start for beginner.

 

[Guerciotti]

I had this issue, make sure the bolts press against the shoes inside, however I ended up destroying the fixings that hold the shoes in place so new shoes and fixings it was and a new wheel cylinder as I pulled the plunger out brute force it ended up being though I was replacing the drums anyway

Thanks. Sorry can you explain how you used 'brute force'

Assuming you have oiled around the flange area, I can honestly say I have never had a brake drum that could resist a No 4 Thor copper mallet weighing 2.83Kgs. As you can see this one has had many years of use and never damaged/broken anything . In the 1970s it was the only way of removing Wartburg brake drums, just careful to miss the wheel studs. I also used them on finned alloy brake drums on 1200 Ladas (Fiat 124 under license) without damage as they also wouldn't come off using the bolt extraction method similar to your 500.
Usually one or two at the most blows on the flat flange area where the wheel studs screw in is enough.
I am assuming it has not moved at all i.e. still stuck to the flange and not wobbling, if you have some movement as in holding on the brake shoes or some such issue if that is the case then see sawing with a couple of tyre levers may be the answer, though that often drags the shoes etc. with it.

Hi. Apologies for the delay in responding and thanks for all of your help and advice.

Following the feedback from bugsymike above I thought I might need a heavier hammer with a bigger contact area. They only had 1kg and 5kg in the shop so I went with the latter. After 3 separate sprays of penetrating oil over the past 24 hours the drum started to move after a bit of 'persuasion' from the bigger hammer and then I was able to get it off fully.

Upon inspecting the drum after a clean it didn't seem unduly worn and had no obvious lips. Similarly the brake shoes looked good and had 4mm left all the way round. Everything else inside looks good.

I then got the Mrs to press the brakes whilst I had a look. During the first go the action looked a bit uneven and then some fluid came out of the wheel cylinder during applications two and three so it looks as if the wheel cylinder is the problem.

I will replace both wheel cylinders and all brake pads (might as well as I will need to take them off anyway) and do a complete fluid flush (last changed three years ago). Is there anything else you recommend that I change while I have everything apart?

Thanks again.

 

[jackwhoo]

Hi,
It is a bad idea to press the brake pedal without the drum on ....doing so will most likely push a wheel cylinder piston out of the wheel cylinder further than in normal use causing brake fluid to leak out.
The drum ensures both shoes are applied. There will always be one shoe tjat moves slightly more freely than tje other.when the free moving shoe contacts the drum the slightly less free moving shoe moves until in contact with drum.

With drum on and shoes correctly adjusted each shoe moves less than 1mm before contacting the drum.

 

[jackwhoo]

With drum removed, check pistons in wheel cylinder are free to move by pushing them IN to the wheel cylinder using a screw driver. You only need move them a couple of millimetres to feel piston moves freely.

 

[bugsymike]

As Jack says re wheel cylinders and as I mentioned earlier to rock the brake shoes using two screwdrivers to check pistons are free, also for peace of mind when servicing I always lifted the rubber dust covers to check for early signs of brake cylinder leaks.
It is very easy with drum off to push pistons out too far by pressing the brake pedal.

 

[Guerciotti]

Thank you for your comments. It sounds as if I may have damaged the wheel cylinder with my 'test' so I will install new ones. Anything else I should replace as a wear item while I have everything open?

 

[jackwhoo]

Post a photo of your rear brake shoes/self adjuster/ wheel cylinder.
How many kilometres has car travelled?

 

[John202020]

If you can open the bleed valve on the side that leaked, push the piston back in place, re fit the brake shoes, clean any lip from the drum edge however small, pop drum back on then bleed the wheel cylinders if it's just popped out there's no need to replace it.
Ideally suck out the old fluid from under the bonnet and fill with new, have a helper to assist and keep an eye on the level you don't want it to fall too low.

 

[Guerciotti]

Post a photo of your rear brake shoes/self adjuster/ wheel cylinder.
How many kilometres has car travelled?

Hi. Please see attached.

The car has done 91,000 km.

Thanks

 

[bugsymike]

Maybe also clean any rust etc. around the hub where the drum sits, I also put a very thin smear of copperslip or similar on that contact area to help next time drum comes off, though wipe off any excess as you don't want it to get on the brake shoes, though others may advise differently.