Dave C Posted August 19, 2016 Report Share Posted August 19, 2016 Earlier this year my GT6 needed new rear brake shoes and new rear shock absorbers in order to pass its MOT. The work was done by a local garage/alleged classic car specialist. Since then, I've noticed that the brake pedal pulses when braking. My first thought was that the most likely cause was the old drums being no longer round and needing replacing. I was wondering if there are any other likely causes to consider before I investigate? I realise it could be the front discs but the problem coincided with the rear brakes and suspension being done. (By the way the car will never be returning to that particular garage, but that's another story) Link to comment Share on other sites More sharing options...
spitty76 Posted August 19, 2016 Report Share Posted August 19, 2016 Hi Dave, It'll be worth knocking the drum off and checking the inside for a ridge caused by the metal edge of the old pad as it wore down. The new pad will be forcing its way over the 'ridge' in the drum and potentially causing the pulsing feeling. Its worth a look. Thomas Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 19, 2016 Report Share Posted August 19, 2016 Rear drums can get a build up especially if left long with brakes on out in the wet a coarse sandpaper cleans it up most pedal pulsing is disc runout , this can be due to damaged faces even hub face runout To decide front or rears give the hand brake a pull at low speed does it stop see saw fashion front will generally give some steering wheel wobble /sensation as parts have been replaces it there you need to look first , especially if it was ok before . pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 19, 2016 Report Share Posted August 19, 2016 Meant to add depends a bit on what wheels are fitted but if the drum retaining screw is proud ,and fouling the wheel centre the drum will be distorted when you tighten the wheel nuts which is a nice cheap problem to fix and quite common pete Link to comment Share on other sites More sharing options...
JohnD Posted August 19, 2016 Report Share Posted August 19, 2016 Also, if the garage not as classic friendly as they said, that the shoes are fitted the right way around. With only one slave cylinder, there is a leading shoe the first after the cylinder as the wheel rotates,and a trailing shoe. The brake material should be nearer to the slave on the lead shoe than the trail. Modernswifh drums tend to be dual slave and two leading shoes. And that the various springs have been correctly reassembled. Consult your workshop manual! John Link to comment Share on other sites More sharing options...
Dave C Posted August 19, 2016 Author Report Share Posted August 19, 2016 Thanks everyone, I'll have a look over the weekend weather permitting. Link to comment Share on other sites More sharing options...
Nick Jones Posted August 20, 2016 Report Share Posted August 20, 2016 One more for you list of checks, especially if the problem didn't appear right away. I fitted some new rear shoes to my Vitesse 2L a few weeks before doing the Club Triumph 10 Countries. Initially all was fine but within a few hundred miles we started to get brake judder and a pulsing pedal. This got worse the further we went to the extent that hard braking actually made the steering shake. This rather slowed us down in the mountains. I was convinced the problem was at the front but couldn't work out why as I'd not messed with the front and pads and discs were well proven over a number of previous events but not badly worn. When we got home I checked everything over carefully at the front and could find nothing. Then I removed the drums too be greeted with the most monstrous amount of dust. I knocked/brushed this all out and the problem was immediately solved. It recurs every couple of thousand miles though. The shoes material is clearly not right. Where did your shoes come from? Nick Link to comment Share on other sites More sharing options...
Dave C Posted August 20, 2016 Author Report Share Posted August 20, 2016 Thanks Nick, I'm not sure where the shoes came from to be honest. Probably Rimmers. The car was in for MOT and they needed changing so they were done by the garage at the same time. Hopefully I'm going to have a look tomorrow. The weather forecast is a little better and I was doing a few other little GT6 jobs today. Link to comment Share on other sites More sharing options...
Dave C Posted August 21, 2016 Author Report Share Posted August 21, 2016 I managed to get out and take the drums off this afternoon. They are both worn, the offside seemed noticeably more worn and scored than the nearside. The offside was also worn more unevenly. There was a narrow channel evident which might show up on the photos.... Offside Nearside Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 22, 2016 Report Share Posted August 22, 2016 Have in mind that Club shop do brake drums Pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted August 22, 2016 Report Share Posted August 22, 2016 Is this a late mk3? they have wider drums than earlier models. Link to comment Share on other sites More sharing options...
Dave C Posted August 22, 2016 Author Report Share Posted August 22, 2016 Yes, late MK3. I also had my first encounter with the auto-adjustment mechanism...... Link to comment Share on other sites More sharing options...
dougbgt6 Posted August 22, 2016 Report Share Posted August 22, 2016 You mean the so called "auto-adjustment mechanism" ! Mine are hopeless, I have to take the drums off to adjust the brakes! I don't no if the club shop stock the late drum, best ask Gareth. Canleys stock a "late mk3 drum", don't know if it's the right one. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 22, 2016 Report Share Posted August 22, 2016 club shop BDM0090 late GT6 Link to comment Share on other sites More sharing options...
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