rickster1971 Posted March 24, 2014 Report Share Posted March 24, 2014 Hello All, I need a bit of technical assistance which I'm hoping someone can help me with. I've recently replaced the front wheel cylinders on a Swallow Doretti and I've bled the system. I'm 100% sure that there is no air in the brake lines but I can't get a firm brake pedal. If I pump the brakes, the pedal firms up but if I release the pedal pressure and put my foot on it again, the pedal will go to the floor. I think the problem is due to the fact that I have had to adjust the front brakes all the way out, and the rears were pretty much the same. The brake linings have plenty of meat left on them, but the drums (which look quite aged) don't have a lip around the outside (which I would expect), that makes me think they've been skimmed fairly recently. I can't see any leaks around the master cylinder (single Girling type) but I can't say for sure whether I have a master cylinder problem or if I should replace the drums and fix the adjustment first. Any thoughts? Does anyone have the wear limit for the drums so I can measure them? Thanks in advance. Quote Link to post Share on other sites
Steves_TR6 Posted March 24, 2014 Report Share Posted March 24, 2014 Perhaps try clamping off each rubber brake line in turn to isolate a wheel, to isolate the problem ?? Quote Link to post Share on other sites
Graze Posted March 24, 2014 Report Share Posted March 24, 2014 Steve Just re did the brakes on the TR6 and couldn't get the bleed right till we bled the master cylinder - seems tere was air in the top of the lines which we couldn't get thru Might be worth a try if you haven't already Graze Quote Link to post Share on other sites
doretti Posted March 24, 2014 Report Share Posted March 24, 2014 Braking system very similar to TR2 - try posting in TR2/3/3A/3B Forum for more help. Quote Link to post Share on other sites
stuart Posted March 24, 2014 Report Share Posted March 24, 2014 Adjust all the brakes up rock solid and then try a re-bleed, re -adjust to normal after. You could try the old trick of pumping the pedal up hard and then jam it down with a bit of wood back to the seat and leave overnight. If you are using sillycon fluid then you will need to bleed very very slowly. Stuart. Quote Link to post Share on other sites
Don H. Posted March 24, 2014 Report Share Posted March 24, 2014 This sounds more like a hydraulic pressure control problem than a drum adjustment/wear issue. A few of ideas in order of priority... Start with the brake master cylinder and consider a rebuild. Then check the brake hoses -- which if they're aged 10-20 years can easily have swelled, especially with non-Girling fluids, my 50-years-of-experience TR friends report. As a final step, consider wheel cylinder rebuilds. Quote Link to post Share on other sites
littlejim Posted March 25, 2014 Report Share Posted March 25, 2014 .Agree with Don, worth replacing the rubber bits in the master cylinder, mightn't be holding the pressure. Quote Link to post Share on other sites
rickster1971 Posted April 1, 2014 Author Report Share Posted April 1, 2014 (edited) Hi All, Thanks for your replies. I clamped off the rear brake hose (there's only one flexible hose that feeds both rear wheel cylinders) and got a nice firm brake pedal. I've ordered a new set of drums and brake linings for the rear because I have no adjustment left at all on the rear. I'll let you know how I get on. Thanks again. Edited April 1, 2014 by rickster1971 Quote Link to post Share on other sites
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