Patrick Taylor Posted December 4, 2021 Report Share Posted December 4, 2021 OK, so the front brake replacement is done -has been for a couple of weeks, but the results aren't perfect. There is no air when I bleed the brakes (using a Gunson Easibleed, i.e. pressurised bleeding), but the pedal travels further than expected when I apply them. They do stop the car, though. If I pump the brakes, the pedal firms up and there is less travel on the pedal. So my question is this: is this a case of needing to bed the brakes in (new calipers pads and discs have been fitted), or do I go back to bleeding the offside rear and work forwards again (I have done so several times in the past fortnight), even though there is no sign of air? I am not keen on using the car on the Queen's Highway in its current state, although if it is just a case of bedding the brakes in, where I can expect to see an improvement, I would do so. I think I should have a solid pedal right from the off, but is this not the case? Link to comment Share on other sites More sharing options...
NonMember Posted December 4, 2021 Report Share Posted December 4, 2021 Just now, Patrick Taylor said: new calipers There have been several reports that new calipers are not machined quite right, so the piston can't "slide through" the seal as it's supposed to, and therefore pulls back away from the disc. This gives the long pedal that you're experiencing. Apparently sometimes improves if you wedge the pedal hard down overnight. Link to comment Share on other sites More sharing options...
johny Posted December 4, 2021 Report Share Posted December 4, 2021 Also Ive found in older vehicles the pads sometimes dont sit exactly parallel with the disc so to start with the pad only contacts in a reduced area giving a spongy pedal. After some miles theres complete contact so the braking will be better and the pedal more solid. You could check the pads to see if this is the case... Link to comment Share on other sites More sharing options...
Chris A Posted December 4, 2021 Report Share Posted December 4, 2021 I have/had this when I replaced mine last year. Not spongy but just a fair bit more travel than before the replacement. I have done the wedge the pedal thing a couple of times, not an immediate improvement. However the last few times I have taken the car out the pedal travel is much reduced and 'solid' feel to it. Maybe they just take a long bedding in period. Link to comment Share on other sites More sharing options...
Patrick Taylor Posted December 4, 2021 Author Report Share Posted December 4, 2021 5 minutes ago, NonMember said: There have been several reports that new calipers are not machined quite right, so the piston can't "slide through" the seal as it's supposed to, and therefore pulls back away from the disc. This gives the long pedal that you're experiencing. Apparently sometimes improves if you wedge the pedal hard down overnight. 3 minutes ago, Chris A said: I have/had this when I replaced mine last year. Not spongy but just a fair bit more travel than before the replacement. I have done the wedge the pedal thing a couple of times, not an immediate improvement. However the last few times I have taken the car out the pedal travel is much reduced and 'solid' feel to it. Maybe they just take a long bedding in period. Perhaps I need to go for a run while the roads are quiet. Trouble is, my last outing in the car was total, foot-to-the-floor brake failure, with the handbrake applied to avoid rear-ending the car in front , so I've lost a bit of confidence in her... Link to comment Share on other sites More sharing options...
Mark B Posted December 4, 2021 Report Share Posted December 4, 2021 In my experience, if the pedal firms up when you pump it, it would usually indicate there is still air in the system. I would bleed them the old fashion way, with the help of an assistant. I use a bleed pipe in a jar of fluid, but lock off the bleed nipple before the assistant lifts off of the floor for the up stroke. I always thought there is a chance air could be sucked in around the thread of the nipple. Link to comment Share on other sites More sharing options...
68vitesse Posted December 4, 2021 Report Share Posted December 4, 2021 21 minutes ago, Mark B said: I always thought there is a chance air could be sucked in around the thread of the nipple. Bit of grease around the threads should seal them, have used this method when solo brake bleeding. Also tend to push pedal down fast and let up slowly. Regards Paul Link to comment Share on other sites More sharing options...
Chris A Posted December 4, 2021 Report Share Posted December 4, 2021 1 hour ago, Patrick Taylor said: Trouble is, my last outing in the car was total, foot-to-the-floor brake failure, I would also say air in the system. The 'new caliper syndrome' gives firm brakes but longer travel, it seems the seals hold the piston to tight and pull it back further from the disc. There was an article about it in the club magazine a while back : Link to comment Share on other sites More sharing options...
Patrick Taylor Posted December 4, 2021 Author Report Share Posted December 4, 2021 1 hour ago, Chris A said: I would also say air in the system. The 'new caliper syndrome' gives firm brakes but longer travel, it seems the seals hold the piston to tight and pull it back further from the disc. There was an article about it in the club magazine a while back An interesting read. I may try a short run to see if things improve, but if the suggested hack is as effective as it sounds it must be worth a try. Link to comment Share on other sites More sharing options...
PeteH Posted December 4, 2021 Report Share Posted December 4, 2021 Because I had a "Brown Trouser" moment some years ago with a 9t Motor-home. which required a full fluid change. Something I do now every 2 years or even less if stood. I have a Air driven Vacuum Brake bleed kit, which allows me to solo bleed. https://www.amazon.co.uk/Sealey-VS020-Pneumatic-Bleeder-Multicoloured/dp/B008632ERA/ref=sr_1_4?adgrpid=114098198150&gclid=CjwKCAiAwKyNBhBfEiwA_mrUMqqZtKhdX9RK2Vn8TZzJHxnZ5iINHFXyZpq_XxFv9QAhRl8oh6_4YRoCLxoQAvD_BwE&hvadid=469071168464&hvdev=c&hvlocphy=1006816&hvnetw=g&hvqmt=e&hvrand=7398883923580443282&hvtargid=kwd-416104248407&hydadcr=1132_1867099&keywords=sealey+vacuum+brake+bleeder&qid=1638626813&sr=8-4 Don`t know if that is of any assistance? Pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 4, 2021 Report Share Posted December 4, 2021 travel can be incorrectly set hand brake cables holding the wheel cyls open always bleed use a catch jar up high above the wheels and new pads take some bedding in attached is the mintex plan , if you make them smoke youve gone a bit to far mintex bedding.pdf Link to comment Share on other sites More sharing options...
Patrick Taylor Posted December 4, 2021 Author Report Share Posted December 4, 2021 27 minutes ago, PeteH said: Because I had a "Brown Trouser" moment some years ago with a 9t Motor-home. which required a full fluid change. Something I do now every 2 years or even less if stood. I have a Air driven Vacuum Brake bleed kit, which allows me to solo bleed. https://www.amazon.co.uk/Sealey-VS020-Pneumatic-Bleeder-Multicoloured/dp/B008632ERA/ref=sr_1_4?adgrpid=114098198150&gclid=CjwKCAiAwKyNBhBfEiwA_mrUMqqZtKhdX9RK2Vn8TZzJHxnZ5iINHFXyZpq_XxFv9QAhRl8oh6_4YRoCLxoQAvD_BwE&hvadid=469071168464&hvdev=c&hvlocphy=1006816&hvnetw=g&hvqmt=e&hvrand=7398883923580443282&hvtargid=kwd-416104248407&hydadcr=1132_1867099&keywords=sealey+vacuum+brake+bleeder&qid=1638626813&sr=8-4 Don`t know if that is of any assistance? Pete Not for my garage: it requires an air line, which I don't have. The Gunson system uses a tyre at 20 psi. Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 4, 2021 Report Share Posted December 4, 2021 most will use a right foot down quick, nip nipple, back slower , open nipple , down quick top up and keep jam jar up high easy to make a bleed pipe valve plug end of tube use sharp blade make a slit in the tube about 3/4" long this acts as a valve allows fluid out and closes on returns simpluze Pete 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted December 4, 2021 Report Share Posted December 4, 2021 52 minutes ago, PeteH said: Don`t know if that is of any assistance? Pete I have one gathering dust somewhere; never could get it to work satisfactorily. Probably just me... Link to comment Share on other sites More sharing options...
dougbgt6 Posted December 4, 2021 Report Share Posted December 4, 2021 2 minutes ago, Colin Lindsay said: I have one gathering dust somewhere; never could get it to work satisfactorily. Probably just me.. You mean the assistant? Doug Link to comment Share on other sites More sharing options...
PeteH Posted December 4, 2021 Report Share Posted December 4, 2021 1 hour ago, Colin Lindsay said: I have one gathering dust somewhere; never could get it to work satisfactorily. Probably just me... Needs 90psi of air. But mine works well enough to have replaced the fluid in what (was basically) A Fire Truck chassis. Pete. Link to comment Share on other sites More sharing options...
Patrick Taylor Posted December 4, 2021 Author Report Share Posted December 4, 2021 Just returned from a run: the brakes work, but are better with a preliminary shove on the pedal. The travel seems less when the handbrake is on; is that because I've just braked, or could it point to the rear brakes being out of adjustment? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted December 4, 2021 Report Share Posted December 4, 2021 2 hours ago, dougbgt6 said: You mean the assistant? Doug The point of those, and I must have tried half a dozen over the years, is to remove the need for an assistant. "I've got this whining noise from the brakes.... shouldn't have asked her to help, then...." 1 Link to comment Share on other sites More sharing options...
PeteH Posted December 4, 2021 Report Share Posted December 4, 2021 1 hour ago, Patrick Taylor said: Just returned from a run: the brakes work, but are better with a preliminary shove on the pedal. The travel seems less when the handbrake is on; is that because I've just braked, or could it point to the rear brakes being out of adjustment? Try backing off the handbrake, adjust the rears. Then the hand brake. And see if it improves? In my view you never adjust the hand brake without ensuring the rears are spot on?. Pete Link to comment Share on other sites More sharing options...
NonMember Posted December 4, 2021 Report Share Posted December 4, 2021 56 minutes ago, PeteH said: never adjust the hand brake without ensuring the rears are spot on Yes, no point trying to set the handbrake if the shoes are out of adjustment. Also, you need the rear axles under road load, not dangling against the chassis, when adjusting the cable. Link to comment Share on other sites More sharing options...
Andrew Posted December 4, 2021 Report Share Posted December 4, 2021 This is how you solve your issue. I had exactly the same issue when I replaced both my front callipers on my 13/60. Do it one side at a time. Remove both pads out of the calliper give the pedal a couple of pumps to get the pistons out of their normal position, and make the piston seal movement. Push both pistons back in replace pads and do the same on the other side. I guarantee that will fix the problem. The piston seals are dragging the piston back into the calliper and not allowing any movement Andrew 1 2 Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 5, 2021 Report Share Posted December 5, 2021 20 hours ago, Pete Lewis said: travel can be incorrectly set hand brake cables holding the wheel cyls open couple of clues the handbrake lever pivot pins can wear a groove in the back plate stops the cyl from sliding properly always raise the axle to a near running height and not hanging (as Rob said ) disconnect the handbrake cable ( just one end) and fully lock up hard the adjusters on both rear brakes now reconnect the cable adjust the fork end and clevis to a nice neat fit no tension /no slack then de adjust the adjuster some 4 clicks or just enough to free the wheel Pete Link to comment Share on other sites More sharing options...
Nick Jones Posted December 5, 2021 Report Share Posted December 5, 2021 On 04/12/2021 at 10:59, NonMember said: There have been several reports that new calipers are not machined quite right, so the piston can't "slide through" the seal as it's supposed to, and therefore pulls back away from the disc. This gives the long pedal that you're experiencing. Apparently sometimes improves if you wedge the pedal hard down overnight. If new (repro) calipers, it will be this. You can prove it by removing the pads one at a time, carefully pumping the piston out a little, then levering it back in just enough to squeeze the pad back in. Repeat for the other three. If you now have a decent pedal, the issue is proven. This will remain for a few miles until the pads wear down as they’ll “adjust” back to where you are now. The best solution IMO is to remove the repro tat and return to supplier for full refund as unfit for purpose. Or you could waste hours of your life (as I did) repeating the above at intervals in the hope that the seals will “get the idea”. They won’t. You could try fitting alternative caliper seals in the hope that’ll resolve the issue. I tried 3 different versions including some used OE ones from an old caliper. That didn’t work either. IMO the shape of the seal groove is wrong. Certainly it’s different from OE. I’ve posted about this on here before https://forum.tssc.org.uk/topic/3884-suspect-repro-girling-type-16-callipers/#comment-42468 Nick Link to comment Share on other sites More sharing options...
johny Posted December 5, 2021 Report Share Posted December 5, 2021 Has this repro problem been found with calipers other than type 16? I believe Patricks Bond might not have these.... Link to comment Share on other sites More sharing options...
Patrick Taylor Posted December 5, 2021 Author Report Share Posted December 5, 2021 @johny is right: the Bond has Type 14s. Although I get the impression the problem may be the same/similar... Link to comment Share on other sites More sharing options...
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