Too much pedal travel after bleeding brakes
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From: Peter Spikings on 31 Mar 2010 06:41 Hi, 2000 Fiesta.....Did a complete flush of the brake fluid and now the brake pedal travels a bit too much before the brakes bite properly. The brakes effectiveness is fine once the pedal is pushed down fully and I can lock the front wheels up but the travel to do that is significantly greater than before. It's had new discs and pads on the front a few months ago, the rear shoes are borderline - have got new ones ready to fit when I get a chance. Could air in the rear brake lines have been masking a problem with the rear brakes before hand? Thanks, Peter.
From: Conor on 31 Mar 2010 08:01 On 31/03/2010 11:41, Peter Spikings wrote: > Hi, > > 2000 Fiesta.....Did a complete flush of the brake fluid and now the > brake pedal travels a bit too much before the brakes bite properly. > The brakes effectiveness is fine once the pedal is pushed down fully > and I can lock the front wheels up but the travel to do that is > significantly greater than before. > > It's had new discs and pads on the front a few months ago, the rear > shoes are borderline - have got new ones ready to fit when I get a > chance. > > Could air in the rear brake lines have been masking a problem with the > rear brakes before hand? Try it with the handbrake on. If the pedal is higher, the rear adjusters are FUBAR. If you pump the pedal and it comes up, there's air in the system. If you do all of the above and its still on the floor, the master cylinder may be knackered. Unfortunately on one with several years use, a ridge can build up in the bore. This isn't usually a problem as you use the same amount of travel however when bleeding brakes the manual way as opposed to sucking it through with a machine, the piston travels further, over the ridge and it can sometimes fold back the rubber or split it. -- Conor I'm not prejudiced. I hate everyone equally.
From: Peter Spikings on 31 Mar 2010 09:22 On 31 Mar, 13:01, Conor <co...(a)gmx.co.uk> wrote: > On 31/03/2010 11:41, Peter Spikings wrote: > > > Hi, > > > 2000 Fiesta.....Did a complete flush of the brake fluid and now the > > brake pedal travels a bit too much before the brakes bite properly. > > The brakes effectiveness is fine once the pedal is pushed down fully > > and I can lock the front wheels up but the travel to do that is > > significantly greater than before. > > > It's had new discs and pads on the front a few months ago, the rear > > shoes are borderline - have got new ones ready to fit when I get a > > chance. > > > Could air in the rear brake lines have been masking a problem with the > > rear brakes before hand? > > Try it with the handbrake on. If the pedal is higher, the rear adjusters > are FUBAR. > > If you pump the pedal and it comes up, there's air in the system. That might be it then.... though I don't know how that happened if it is that. To be sure we're not talking a cross-purposes the pedal always returns to it's normal position when not being depressed, it never stays down. When you push it, you get immediate light braking but to brake hard it needs to be pushed far further back than normal. > If you do all of the above and its still on the floor, the master > cylinder may be knackered. Unfortunately on one with several years use, > a ridge can build up in the bore. This isn't usually a problem as you > use the same amount of travel however when bleeding brakes the manual > way as opposed to sucking it through with a machine, the piston travels > further, over the ridge and it can sometimes fold back the rubber or > split it. I did neither, I've got one of those pressure kits which keeps the reservoir topped up and pressurized using a tyre at 15psi, no pedal pressing needed :) Also I'd have thought no real risk of air getting back in through the bleed nipples so I'm confused. The car is almost 10 years old though and all the major bits are original so I'm willing to believe things are end of life if the symptoms suggest it. Thanks for your help, Peter.
From: Mrcheerful on 31 Mar 2010 11:59 Peter Spikings wrote: > Hi, > > 2000 Fiesta.....Did a complete flush of the brake fluid and now the > brake pedal travels a bit too much before the brakes bite properly. > The brakes effectiveness is fine once the pedal is pushed down fully > and I can lock the front wheels up but the travel to do that is > significantly greater than before. > > It's had new discs and pads on the front a few months ago, the rear > shoes are borderline - have got new ones ready to fit when I get a > chance. > > Could air in the rear brake lines have been masking a problem with the > rear brakes before hand? > > Thanks, > > Peter. to establish which wheel or wheels have the problem clamp the flexible brake pipes and see whether and when the pedal travel improves. Almost certainly there is air in the system.
From: Arty Effem on 31 Mar 2010 14:14
> I've got one of those pressure kits which keeps the > reservoir topped up and pressurized using a tyre at 15psi, no pedal > pressing needed :) Also I'd have thought no real risk of air getting > back in through the bleed nipples so I'm confused. When using one of those, it's important to ensure that the fluid doesn't become aerated. Shaking the can before pouring out the fluid is a common mistake, however when the fluid is poured into the pressure bottle, it's difficult to avoid air being introduced in the form of tiny bubbles that rise very slowly. Having filled the pressure bottle and connected it to the master cylinder, I wait about 30 minutes before bleeding the system. |