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A silly question
- Thread starter curtis
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Bruce Bowker
Obi Wan
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Side it is pulling towards. Pulls to the left - left brake is bad. You can check after a drive if that wheel is hotter than the other side. If so brake is binding.
If not then it is possible there is an alignment problem or unequal tire pressure.
Bruce
If not then it is possible there is an alignment problem or unequal tire pressure.
Bruce
Hello Curtis,
sorry to confuse you, it could equally be the other side. If one brake is not functioning, e.g. a stuck piston, the car will pull to side of the brake that is working. In other words it will pull to the good brake. A stuck piston, by the way if neglected can end up shearing a disc due to unequal pressure on it.
Alec
sorry to confuse you, it could equally be the other side. If one brake is not functioning, e.g. a stuck piston, the car will pull to side of the brake that is working. In other words it will pull to the good brake. A stuck piston, by the way if neglected can end up shearing a disc due to unequal pressure on it.
Alec
Curtis, It reality, it probably doesn't matter, because both the right and left side probably need attention. If for example, you have a stuck piston on the right side. It is likely stuck because it is pitted and rusted. You would want to rebuild both the right and left calipers as more than likely the left one would not be in much better shape. And spend the few extra bucks and get the stainless pistons. While your at it, replace those 40 year old brake hoses, too. They make look fine on the outside, but they deteriorate and collapse on the inside.
OP
curtis
Jedi Trainee
Online
Thanks for the thoughts.You are right it could be either side.In fact the brakes were apart about 10 months ago and all seemed fine then.Will check out everything and report back if anything interesting.This will have to wait as I have just come back from an Historic rallye in the Alpes,in my Wolseley 1500 and the rear shocker mountings have broken.That will keep me quiet for a while!
PS,the Healey has drum brakes.
PS,the Healey has drum brakes.
Bruce Bowker
Obi Wan
Offline
Just curious. Are you talking about pulling when just driving the car or only when the brakes are used?
Bruce
Bruce
OP
curtis
Jedi Trainee
Online
Only when the brakes are used. It's a very small amount but a bit disconcerting on competitive rallyes!
I'm getting closer to checking them out,as I have nearly finished the current job. Today I did a test fitting of the Wolseley rear suspension and now once the paint is dry I can re fit it. The two year test is due this month so it's a good job I found that beforehand.
Curtis
I'm getting closer to checking them out,as I have nearly finished the current job. Today I did a test fitting of the Wolseley rear suspension and now once the paint is dry I can re fit it. The two year test is due this month so it's a good job I found that beforehand.
Curtis
Banjo
Yoda
Offline
Front wheel drums are VERY sensetive to adjustment. If they are not adjusted equally you will get a pull under braking (even if there are no other problems).It dosen't take much of a difference in side to side adjustment to cause a pull that will drag you off the road. If you're sure they are in good working order,Try to get them equal by adjusting until you can feel about the same amount of drag on each side, then back them off the same number of notches so there is no drag. This should get them real close.
From there its trial and error. Take a drive. If it pulls left under braking then back the left adjuster off a notch or two (or add a notch to the right if the pedal feels a little low) then drive again. And so on. If this is the problem you should be able to cure it within a few Adjustment-drive cycles
This might help. Good luck Guv'na
From there its trial and error. Take a drive. If it pulls left under braking then back the left adjuster off a notch or two (or add a notch to the right if the pedal feels a little low) then drive again. And so on. If this is the problem you should be able to cure it within a few Adjustment-drive cycles
This might help. Good luck Guv'na
Hello Banjo,
I have to disagree that adjustment will cause a pull, there is no real braking effort until all the clearances in the drums are taken up with the initial push of the pedal, then once that is accieved further travel of the pedal produces the pressure to apply the brakes as required. All that poorly adjusted brakes gives is a long pedal.
(This is not the case in pure mechanical systems, e.g. rod or cable brakes used in much older vehicles, where correct balance is required.)
Alec
I have to disagree that adjustment will cause a pull, there is no real braking effort until all the clearances in the drums are taken up with the initial push of the pedal, then once that is accieved further travel of the pedal produces the pressure to apply the brakes as required. All that poorly adjusted brakes gives is a long pedal.
(This is not the case in pure mechanical systems, e.g. rod or cable brakes used in much older vehicles, where correct balance is required.)
Alec
Banjo
Yoda
Offline
OK, I'm not trying to further any argument, so please don't take this wrong.
The hydraulic princaple stated is 100% correct. And that law applies directly to what we are discussing, but, that is not the only factor at work in a drum brake scenario.So I have to re-disagree with the statement that "adjustment cannot cause a pull" (I'm not saying that this is definatly what's wrong with this car by any means either)
Your refrence to that princaple made me rethink and go in search of some answers. I know from personal experience that the adjustment on front drum brakes is critical to even braking, and asking some of my mechanic and racing buddies with experience on front end drums I got the same answer, "they gotta be dead on". But we discussed the possibilities of why, and came up with some thoughts.
1. It's not a purely hydraulic system (like disc brakes) its a hydraulicly operated mechanical leverage system, and this comes into play when applying the hydraulic principle.
2. If one side is adjusted so it drags then it will tend to be at a higher temprature, thus changing the friction rate and possibly causing a pull.
3. the way shoes are designed and actuated they can cause a drag as soon as they come in contact with the drum with minimal hydraulic force, and cause a pull.
Of course these are just theories made up by a couple of old-time mechanics trying to justify why they have always had to make sure the front drums were adjusted properly to prevent pulls.
Then I found My old Textbook from Trade school and it explained what we were grasping at. It said this:
With the vehicle moving in either the forward or reverse direction with the brakes on, the applies force of the brake shoe,pressing agenst the brake drum, increasingly multiplies itself. This is because the brake's anchor pin acts as a brake shoe stop and prohibits the brake shoe from its tendancy to follow the movement of the rotating drum. The result is a wedging action between the brake shoe and the brake drum. The wedging action combined with the applied brake force creates a self-multiplied brake force"
Excerp from "Automotive Technology, a systems approach"
Like some of the other good advice you got, make sure you don't have a leak (soaks the pads and makes them grab) or a sticky wheel cylinder (one side won't actuate or it may hang up) or a restircted brake hose (same problem as the sticky cylinder) any of these can upset the balance.And they all fall within the hydraulic principal
Again, please don't take this as an attack on any part, I'm just clarifying where I was coming from on my suggestions. One thing I've learned in the automotive world is to never say that "somthing" could never cause "somthing else" to occour. More times than I care to tell "with countless hours spent in the wrong direction" I've been proven wrong.
My hats off to the Intelligance of this forum's members. Whenever I see any ideas contested on this site they are backed to the hilt with very solid information. Noone ever comes back with somthing that dosen't require some real solid answers.
What say you, Sir Piman /ubbthreads/images/graemlins/grin.gif
The hydraulic princaple stated is 100% correct. And that law applies directly to what we are discussing, but, that is not the only factor at work in a drum brake scenario.So I have to re-disagree with the statement that "adjustment cannot cause a pull" (I'm not saying that this is definatly what's wrong with this car by any means either)
Your refrence to that princaple made me rethink and go in search of some answers. I know from personal experience that the adjustment on front drum brakes is critical to even braking, and asking some of my mechanic and racing buddies with experience on front end drums I got the same answer, "they gotta be dead on". But we discussed the possibilities of why, and came up with some thoughts.
1. It's not a purely hydraulic system (like disc brakes) its a hydraulicly operated mechanical leverage system, and this comes into play when applying the hydraulic principle.
2. If one side is adjusted so it drags then it will tend to be at a higher temprature, thus changing the friction rate and possibly causing a pull.
3. the way shoes are designed and actuated they can cause a drag as soon as they come in contact with the drum with minimal hydraulic force, and cause a pull.
Of course these are just theories made up by a couple of old-time mechanics trying to justify why they have always had to make sure the front drums were adjusted properly to prevent pulls.
Then I found My old Textbook from Trade school and it explained what we were grasping at. It said this:
With the vehicle moving in either the forward or reverse direction with the brakes on, the applies force of the brake shoe,pressing agenst the brake drum, increasingly multiplies itself. This is because the brake's anchor pin acts as a brake shoe stop and prohibits the brake shoe from its tendancy to follow the movement of the rotating drum. The result is a wedging action between the brake shoe and the brake drum. The wedging action combined with the applied brake force creates a self-multiplied brake force"
Excerp from "Automotive Technology, a systems approach"
Like some of the other good advice you got, make sure you don't have a leak (soaks the pads and makes them grab) or a sticky wheel cylinder (one side won't actuate or it may hang up) or a restircted brake hose (same problem as the sticky cylinder) any of these can upset the balance.And they all fall within the hydraulic principal
Again, please don't take this as an attack on any part, I'm just clarifying where I was coming from on my suggestions. One thing I've learned in the automotive world is to never say that "somthing" could never cause "somthing else" to occour. More times than I care to tell "with countless hours spent in the wrong direction" I've been proven wrong.
My hats off to the Intelligance of this forum's members. Whenever I see any ideas contested on this site they are backed to the hilt with very solid information. Noone ever comes back with somthing that dosen't require some real solid answers.
What say you, Sir Piman /ubbthreads/images/graemlins/grin.gif
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BJ,
I mostly agree. Most front drum brakes are "self energizing". They do have a mechanical wedging action to increase the shoe pressure which is a way of reducing pedal effort. This type brake is more sensitive to friction coefficient of the shoes & mechanical adjustment, or one side will self apply more than the other side. Any contamination or mis-adjustment will make the car pull to one side.
I disagree with the fixed anchor pin part though. The anchor has to effectively force the shoe to slide (wedge) out as the drum rotates. It's a sliding ramp anchor or in the case of the Bendix, a linked anchor.
The Bendix design used linked shoe anchors with a single wheel cylinder (Duoservo). Old Healeys used sliding (wedging) shoe anchors & dual wheel cylinders similar to old Chryslers "center plane" brakes which used a similar self energizing method. They were really a pain in the tail to get working & keep working. Of course disc brakes are not self energizing, which is why they require more pedal pressure when not servo equipped. At least they don't have the problems of the old self energizing drums.
D
I mostly agree. Most front drum brakes are "self energizing". They do have a mechanical wedging action to increase the shoe pressure which is a way of reducing pedal effort. This type brake is more sensitive to friction coefficient of the shoes & mechanical adjustment, or one side will self apply more than the other side. Any contamination or mis-adjustment will make the car pull to one side.
I disagree with the fixed anchor pin part though. The anchor has to effectively force the shoe to slide (wedge) out as the drum rotates. It's a sliding ramp anchor or in the case of the Bendix, a linked anchor.
The Bendix design used linked shoe anchors with a single wheel cylinder (Duoservo). Old Healeys used sliding (wedging) shoe anchors & dual wheel cylinders similar to old Chryslers "center plane" brakes which used a similar self energizing method. They were really a pain in the tail to get working & keep working. Of course disc brakes are not self energizing, which is why they require more pedal pressure when not servo equipped. At least they don't have the problems of the old self energizing drums.
D
Hello all,
I generally believe that 'absolute statements' are not correct for every eventuality, but in the majority of cases there are answers that are more likely to be true rather than a rare or obscure proposal. Most faults are due to basic and common failures and mal-adjustments.
Alec
I generally believe that 'absolute statements' are not correct for every eventuality, but in the majority of cases there are answers that are more likely to be true rather than a rare or obscure proposal. Most faults are due to basic and common failures and mal-adjustments.
Alec
martx-5
Yoda
Offline
From How Stuff Works...Drum Brakes There is some neat animation on the wedging effect of the brake shoes /ubbthreads/images/graemlins/cheers.gif