Nick Green Posted March 19, 2002 Share Posted March 19, 2002 Is there any ?? This is on a De Dion axled car. I know the front bearings can be adjust to take up wear. It seems very reasonable to me that the rears can also be adjusted. Trying to get to the bottom of an occasional long brake pedal problem. I am aware that air in the system is a possible cause of this, but I'm also pretty sure that is not the case on my car. Ta very much. Link to comment Share on other sites More sharing options...
oilyhands Posted March 19, 2002 Share Posted March 19, 2002 I sincerely hope not, the hub nuts are done up to 250ft/lb, if that sort of torque were brought to bear on the bearing races they would sieze solid. The rear bearings are not adjustable unless you plan to strip the hub and use some shims/ file off some metal. oily Link to comment Share on other sites More sharing options...
Nick Green Posted March 19, 2002 Author Share Posted March 19, 2002 Ok, cheers Oily. I stand corrected smile.gif Any idea could be causing the long brake pedal ? Possible numpty statement number 2: With the handbrake on, the pedal is rock solid. This kind of implied something to do with the rear brakes, as being the cause of the softness... Link to comment Share on other sites More sharing options...
EFA Posted March 19, 2002 Share Posted March 19, 2002 Nick, Torque on the nuts should actually be 200lb/ft There are some bearning carriers which are in circulation whihc exhibit some end float as they are marginal on the machining. Unless you have changed these or the driveshafts , your hubs should be the smae now as always. (The 200ft/lb nut does not tighten the bearing beyond the machines flange. Its also possible you have some out of tolerence bearings. I do not have the dimenaions though so can't help. The most likely problem however is air in the rear calipers. Best to take the calipers off the car, put a piece of wood between the pads and hold the caliper with the bleed nipple as the highest point. This is particularly so of the 2 pot AP rar calipers. Fat Arn This is a Testid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
oilyhands Posted March 19, 2002 Share Posted March 19, 2002 200 or 250ft/lb the effect would be the same. If the rear calipers are the Ford Sierra single pot type then the self adjusting mechanism is known to give problems, the clue is in the handbrake giving a firm pedal, if there were air in the calipers it would compress regardless of the position of the pads. From 10 years experience of these calipers, one thing which stops the self adjusting mech. from working properly is the handbrake cable being over adjusted. One way to get the self adjusters working properly is to slacken the handbrake cable right off until the actuating quadrants on the calipers return all the way, then repeatedly pump the brake pedal up and down, do this for five minutes or so or until your leg siezes up. I have found this method very effective. Following this you can re-adjust the handbrake. If you want to test the bearings for slack, jack up the rear and grasp the wheel firmly, try to see if the wheel will 'rock' bottom in, top out, any apreciable play here indicates play in the bearings. Another way to spot play in either bearing or carrier is to watch the carrier and hub with the rear wheel off as the brakes are applied by a friend, make sure the disk is properly located onto the hub using a couple of wheel nuts. Any excessive movement of carrier or disk/hub should be easily spotted. Oily Link to comment Share on other sites More sharing options...
felix.klauser Posted March 19, 2002 Share Posted March 19, 2002 I had an occasional problem with long pedal travel. I never fully understood what the source of the problem was but the rear pads were getting quite low and replacing them solved the pedal travel problem. Oilyhands' solution might well have done it for me. Link to comment Share on other sites More sharing options...
Rob Walker Posted March 19, 2002 Share Posted March 19, 2002 Nick, I have looked into this problem, and would endorse all that Oily has posted but would add that it is very important that the position/orientation of the four cut outs in the piston face are aligned with the protusion on the back of the pads. The protrusion on the pad must be able to locate within the cutout/orifice on the face of the piston. If its out of alignment the pad will be presented to the disc face at an angle. This will cause the whole caliper to move on its slides and cause excess peddle travel and excellerated uneven pad wear. The piston can easily be turned to align with the pad by using a pair of sniped nosed plyers or the proper tool is available from Halfrauds. Link to comment Share on other sites More sharing options...
mic Posted March 19, 2002 Share Posted March 19, 2002 The causes already mentioned would be noticable almost every time you braked. If you get a long pedal only now and then, I would consider changing the master cylinder. Link to comment Share on other sites More sharing options...
mic Posted March 19, 2002 Share Posted March 19, 2002 The causes already mentioned would be noticable almost every time you braked. If you get a long pedal only now and then, I would consider changing the master cylinder. Link to comment Share on other sites More sharing options...
Nick Green Posted March 20, 2002 Author Share Posted March 20, 2002 Cheers all, for responses so far. A few things for me to check out then. To add a little more info, the "occasional" bit should really read "when on track, when braking for a corner following a long sweeper". This can be after a long straight, so I don't think brake fade is an issue, as it is on first press of the pedal. I thought it was only following long lefts, but the other day, it was after a long-ish right. I was suspecting knock off for a while, but if all the bearings are wobble-free, that doesn't seem likely. This never happens on the road. Well, not yet at least. Link to comment Share on other sites More sharing options...
Blatman Posted March 20, 2002 Share Posted March 20, 2002 I'd have said it was knock off. I was involved with racing a saloon car some years ago, and even on a car with new discs and pads, we'd get knock off. If you have a habit of monstering the kerbs, then it's almost certainly knock off. Link to comment Share on other sites More sharing options...
felix.klauser Posted March 21, 2002 Share Posted March 21, 2002 Those are the same circumstances under which I had the problem. How worn are your current pads? Link to comment Share on other sites More sharing options...
Nick Green Posted March 21, 2002 Author Share Posted March 21, 2002 Felix, I was checking the pads through the gaps in the calipers last night. They looked ok, but I'm going to whip them out anyway for a proper look. I have some new ones in the bits box, so I can make an immediate comparison. I first noticed the effect with the car less than 6 months old. It's still on it's original pads. Blat, so it might be the case that despite the bearings being properly adjusted, cornering forces can move things around enough to cause knock off then ? I have tended to dismiss this as I am by no means the fastest driver I know, and I haven't seen anyone else querying this before. Link to comment Share on other sites More sharing options...
Blatman Posted March 21, 2002 Share Posted March 21, 2002 Nick Yeah, pad knock off is almost expected, even for shall we say, the less enthusiastic driver.......bear in mind that even though you may consider yourself (as I do) only moderately quick, you are still driving *much* harder than you do on the road. The stresses passing through the various moving parts are much higher, and I also would consider that a hot set of pads/discs, after cooling at the end of a straight, would have a larger gap between them than "normal" hence the first push of the pedal is longer than you might expect. If you watch touring cars closely, you'll see them prodding the brake pedal along some straights/before they get to the corners. This is taking up of the slack that they're expecting to find........ Link to comment Share on other sites More sharing options...
oilyhands Posted March 21, 2002 Share Posted March 21, 2002 Beware the sliding pins on that type of caliper, if they are shafted then the calipers can move around a fair bit causing quite bad knock-off. Dave Link to comment Share on other sites More sharing options...
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