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MG MGA - Brakes
|I drove my MGA for the first time today. The brakes work, but they don't seem to stop well. This is the first time I've driven an MG, so I don't know if this is normal. I got silicon break fluid on the front disks, could this be the problem? If so, what should I do about it?|
|By the way, the brakes were just worked on.|
|The silicon is NOT your problem as long as your pedal holds pressure. If the pedal drops you have air in the system. You can put your car up in the air and check to see that the brakes are working correctly by having someone putting pressure on the brake pedal and then you try to turn the wheel. If it turns you have a bad caliper, or a bad wheel cyliner or a bad hose. Your brake may also need to "seat" to be a prefect match.|
|If you spilled brake fluid on your rotors, it will burn off with use, but be careful until it gets better.|
|If you have just worked on your brakes I assume you have new pads & linings - these take quite a few applications to bed in and reach their full braking force. Might just need a few miles to sort them out - if that doesn't work you could have a sticking piston (even new ones can play up!!)- cheers Cam|
|If you are used to driving modern cars with power brakes then the MGA seems to need a lot of pedal pressure to stop. That's just the way cars were before power boosters were common. Also, as Cam mentioned, if your brake shoes are new, they will take some time to wear to the exact diameter of your rear drums and achieve full contact. I suspect that silicon fluid on the front pads isn't helping the situation any. I don't know what you can use to clean them, but there should be something you can clean them with.|
|Hi Darian. Fluid on the brake pads can be burned off with a propane torch, once they have been romoved from the calipers. Cheers, Glenn|
|Okay, so I'll drive them for a while and see what happens. Good to hear that it's likely they're not too messed up.|
|I live in a city with lots of stop signs and when I drive around I find my brakes tend to fade and require extra pressure to stop. Is this just heat build up or should I be looking at some other problem? Gordon|
|Gordon, unless the stop signs are every few feet and you are gong real fast, the problem is the brakes. The heating you are talking about occurs comming down a mountain hill riding the brakes to slow down. The the brakes overheat and fading will occure. Check your pads or shoes for oil.|
|The proper way to deal with brake fluid spilled on rotors is to remove it chemically (Brakleen spray), not hope it 'wears off'. Depending on how much you got on the pads it may be some time before they are as good as new. Hopefully it wasn't much.|
Others will disagree, but in my experience silicone fluid rarely gives as good a pedal as regular fluid (he said, ducking)
|Gordon;; I know your area well and there are no hills within 50 miles that would cause fading not even Mt Royal. I suspect the you either have oil,grease or brake fluid on your linings or pads. Also when you did your rebuild was there a chance you got paint overspray on the inside of the drums, That too will create your problem. Is it just a soft pedal or hard without braking action. If the pedal goes down part way before you have a hard resistance try pulling up your handbrake part way and see if it makes a difference. If so then you have a lining problem with the rear brakes. either too much clearance or the shoe arc does not match the drum. Sometimes you have to have the shoes re-arced to fit the drums.|
|Hi Bill. I have been using silicome fluid for many years, and have not noticed any difference in pedal feel or firmness between silicone and regular brake fluids if the system has be bled properly. I do admit that silicone fluid is a bit more difficult to bleed than regular fluid, and it is easier for air bubbles to become trapped in silicone fluid. When I replace hydraulic parts and bleeding becomes necessary, I generally bleed my silicone filled brake system twice, over a two day period. The first bleeding gets most of the air bubbles out, and gives a more than adequate pedal for driving. After the first bleeding, I can usually feel that the pedal is still a little spongy, but the sponginess disappears if the pedal is repeatedly pumped. This indicates that there is still air in the system. After letting the car sit overnight, so that the air bubbles can "congregate" I re bleed the brake system. The second bleeding gets rid of any air bubbles that were trapped during the first bleeding. If done correctly, you should have a rock hard pedal with no sponginess. If you find that your brake pedal is still spongy , then I would be carefully checking all hydraulic components for seepage. Old, worn seals, or a bit of dirt in the hydraulic system can cause a very minor seep that will allow air back into the brake system. I know that many people seem to have problems with silicone fluid, but I will use nothing else! Cheers, Glenn|
Since you are a little "Looney" from Canada, I will have to shoot you!!!. I can't tell the difference from a looney or a "Duck".
As you say, no hills. The brakes start off solid but fade as I use them. If I take it out on the highway the cool air seems to reduce the effect. The pedal starts off hard but then goes half way to the floor. I will check everything, as you mention this weekend. BTW how do you adjust the emergency brake. It has a new cable ,new spring mechanism and the brake system is completely new IE: cylinders/brake hoses/silcone fluid/new MC.
thanks for the help. Gordon
|Are they getting hot and fading? If they are in that type of driving they might be adjusted too tight and getting too hot from dragging (drum type) or if disc the calipers or master cyl may be sticking.|
|R J Brown|
|Well, if anyone is interested, my breaks work much better now. I towed the car about five miles and the brake pads rub against the disks when I do that; the disks were a little hot when I finished. Anyway, I guess this cleaned off the fluid/broke in the pads. Is it normal for the pads to be rubbing a little in the beginning?|
|Gordon;; The handbrake is adjusted by the brass nut on the end of the cable by the handle . There is the adjusting cams on each rear wheel brake shoe. Adjust these first and then the handbrake last. If you have shoes on the front they too need adjusting. Did you have the shoes cam ground to fit the drums? Pull the drums and look at the contact area on each shoe. You might have to scuff them up with sandpaper and then drive a little and then re-check the contact area once more. Many times the drums have been cut and this leads to an oversize arc on the drum. This may not match the arc of the shoes.Then what you get is slight contack of the shoes and following further pressure the shoe tries to conform to the drum. |
The next time you have a low pedal try pulling the handbrajke just a little and note the difference in pedal height.If this is so then pull shoes and either give to a brake shop to cam grind the shoes or you can do the same with coarse sandpaper. Be certain to use a good mask as that powder can be detrimental to your future health.
Loonies are a BUCK. Bucks got hair and ducks got feathers.
Sorry. I just could not resist.
Our bucks are still worth more than a looney.!!!!!
I disagree with the idea of grinding shoes to fit non-standard drums. If the drums are not to spec, they are cheap enough to be replaced. Skimping on brake parts is not a good idea - is your life really worth the risk of the few dollars it costs to do the job right.
Brake pads doo rub, all the time. They should not, however, be rubbing hard - the wheel should turn freely by hand if the car is jacked up (this should be true of all wheels). If there is more than a little resistance, you have at least one calliper piston that is sticking. This will cause the brake pads (and disks) to wear out more rapidly than normal. If they don't free up over a few hundred miles, then the callipers need to be rebuilt.
If your pads are rubbing on the front discs enough to make them hot, the first thing you should do is check the brake pushrod clearance at the master cylinder.
This is described in the Workshop Manual, but just check that you have some clearance, any clearance.
Adjust the pushrod as required.
|When calipers are in good condition the pads do not rub the disc when brakes are released. They run free with a small air space between pad and disc. If you jack it up and spin the wheel once you should thereafter be able to turn the road wheel with one finger. If the pads rub when brakes are not applied there is something wrong that needs to be fixed.|
If the disk brake drags, open the bleed nipple. If after releaving the hydraulic pressure it still drags, rebuild the caliper. If relieving the pressure stops the dragging, then check for a clogged hose (old hoses) or a master cylinder pushrod with no freeplay.
|I think I found the problem. The rear brake cylinder...where it attaches to the backing plate...are not moving in their groove as I think they are supposed to. When the brakes were applied the cylinder rose up and is stuck in this position. If I am correct I will remove the cylinders ...re-clean the backing plate...apply a little grease and see what happens. This might also be the cause of why I think my E-brake needs adjustment. YES...NO???? Thanks Gordon|
|Thanks for the advice.|
This thread was discussed between 02/04/2007 and 07/04/2007
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