J

jambo123

New Member
Hi All,
Wondering if anyone can point me in the right direction to a braking problem I have.
I have a 1970 S2A 2.25 petrol that's been totally rebuilt from the ground up , when braking heavy I feel a very pronounced pulsing feeling through the brake pedal. I don't feel it with light braking.
The brakes are standard single master cylinder , non-servo , all drums (10 inch) with all new parts (new MC , pipes , fluid , drums , shoes , springs , adjusters , wheel cylinders , hoses). I've had to chamfer the shoes to get them past the drums , plus the drums have been checked and machined square. I've checked that everything is tight and spins true and round , I can't seem to find out what's causing this pulsing? Any ideas?
Thanks!
 
My thought too , I had all 4 (brand new Britpart) drums checked and machined true. I was thinking of trying to troubleshoot the problem by removing the shoes on corner and then taking it for a drive to see if the problem went away? Do that 4 times and hopefully find the problem?
 
You can not just remove the shoes,the pistons would pop out. If you clamp off the two front flexable pipes and the rear one in turn this could give you an idea where the problem is.
 
If you are confident the drums are true, I would be looking at the shoes themselves. Are they fitted properly and square to the backplate? Also, is the brake fluid reasonably new? I had a similar problem on a mk1 escort in the 1970's and it turned out that there was so much moisture contamination in the brake fluid it was trying to boil under heavy braking.

Col
 
Drums seem the most likely particularly if it's worse under heavy braking.
Are the shoes making contact all around and are not contaminated?
If you play with the adjusters, can you make the symptoms better or worse?
Less likely, check for fluid loss anywhere and look in the reservoir as someone stands on the brake to see if the master cylinder is loosing pressure.

Just a thought,but you don't suffer from st.vitus dance or Parkinson's disease, do you?
 
Haha love the Parkinson's reference , it would certainly make lots of sense!
Just to answer a few questions , the fluid is brand new , the shoes are not making contact evenly on the drums , they are only really touching at the top and bottom of the shoe , the middle seems untouched. I tried to adjust out the problem but it really didn't make a lot of difference. When I first assembled the brakes I couldn't fit the drum over the shoes (common problem i'm told) so I chamfered the top edge of the shoe until the drum fits. I'm also thinking that the shoes are now at fault. They all appear to be sitting correctly. The pulsing happens with the adjusters on and off so I doubt they are the problem. I've bought a new set of shoes and will be fitting them tomorrow , hopefully i'll see a difference. Going back to the point where I want to troubleshoot each wheel separately , I don't want to clamp the hoses as they are braided and I've been told not to clamp them. If I removed the shoes and cabled tied the pistons , would that be ok just for testing purposes (running up and down the garden)?
 
jambo123 said:
Haha love the Parkinson's reference , it would certainly make lots of sense!
Just to answer a few questions , the fluid is brand new , the shoes are not making contact evenly on the drums , they are only really touching at the top and bottom of the shoe , the middle seems untouched. I tried to adjust out the problem but it really didn't make a lot of difference. When I first assembled the brakes I couldn't fit the drum over the shoes (common problem i'm told) so I chamfered the top edge of the shoe until the drum fits. I'm also thinking that the shoes are now at fault. They all appear to be sitting correctly. The pulsing happens with the adjusters on and off so I doubt they are the problem. I've bought a new set of shoes and will be fitting them tomorrow , hopefully i'll see a difference. Going back to the point where I want to troubleshoot each wheel separately , I don't want to clamp the hoses as they are braided and I've been told not to clamp them. If I removed the shoes and cabled tied the pistons , would that be ok just for testing purposes (running up and down the garden)?
Click to expand...

The idea of cable tying the cylinders is ridiculous. Why did you have new drums machined? Drums should go over shoes easily with adjusters backed off. Only way you can get pulsing of the pedal is if something is pushing back on the cylinder pistons. That suggests a oval drum. It cannot be anything else.
 
I had the drums checked due to this pulsing brake pedal. All 4 drums were out of round and needed to be machined. They were brand new britpart drums and were all out by the same amount.
 
have you still got old drums if so try changing one at at a time with old drums to see if it makes any diferance I had a series 2a doing same thing this turned out to be off side rear as you cant clip off brake hoses you could jack up one back wheel and put in gear run press pedel hard if no pulse do same on other side if both ok you could leave on back wheel jacked up put landy in 4 wheel drive and do the same with front wheels do brake drums fit reasinbly over hub how much had to be skimed off did you fit set screws in drum they might help keep drum in right position if they are a bit slack on hub I had one on a series 2 the only way I could stop it pulsing was to do up wheel nuts lightly then tap drum to point where there was least drag then tighten wheel nuts the drum was quite slack on hub must have been run with loose wheel nuts
 
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If the shoes are only touching at their ends something is well wrong. Hope the new shoes you have bought are of a good make like Mintex.
 
+1 on Mintex. I tried three different sets of shoes on the front of my 109 station wagon before I was happy with the brakes. The third and final set was Mintex. I don't know what make the others were, I got them from my local Europarts place.

Col
 
If your drums are good. If you've got new shoes that are correctly adjusted (!) and this still happens => wheel bearings? Universal joints in the half shafts.

As said above the braking system itself is most likely to be the cause but if you're absolutely sure it is in tip top condition you have to start looking elsewhere.
 
well done you stuck to it and beat it thanks for telling us what you found very interesting
 
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Mintex have been getting a terrible reputation recently for the adjuster pins falling off , couple of years ago I sent a set back as the linings where braking up.
 
fancy that I used to use them on hgv they were the only ones that would not break up mad driver Leyland bison headless wonder
 
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