red-dragon Posted March 3, 2016 Share Posted March 3, 2016 Hi all, my 90 has rear drums and disc fronts. On applying full brakes, I'm finding that the rear drums lock up first. It has almost entirely new braking system all round. Is this likely a bias valve issue - any ideas on what route to take to fix this? Quote Link to comment Share on other sites More sharing options...
red-dragon Posted March 28, 2016 Author Share Posted March 28, 2016 Could the new shoes in the rear drums be biting early due to some kind of calibration not being quite right? Any drum brake experts out there, your advice appreciated!! Cheers Quote Link to comment Share on other sites More sharing options...
mickeyw Posted March 29, 2016 Share Posted March 29, 2016 My old 90 originally had rear drums, and also was fitted with a G-valve down below the footwells. This is basically an inertia compensating device. The harder you brake, the less bias you want to the rear. If it's faulty (seized) perhaps that could be causing the bias issues you have. It might be worth re-bleeding all the brake lines, just in case... Quote Link to comment Share on other sites More sharing options...
red-dragon Posted March 30, 2016 Author Share Posted March 30, 2016 Hi Mickey I did also suspect the g-valve.... although it is such a simple device I was sceptical of my own suspicion of it! Will investigate. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 31, 2016 Share Posted March 31, 2016 Also possible the rear shoes have the springs in the wrong place -very easily done if you don't take a photo first! Quote Link to comment Share on other sites More sharing options...
red-dragon Posted April 3, 2016 Author Share Posted April 3, 2016 How do you mean springs in the wrong place? I rebuilt the drums up from scratch a while ago, and it was some time before that when the old kit was removed (no photos were taken sadly!) What should it look like - I can always take the casing off and inspect Are you suggesting that the drums are pulling tight sooner than they are meant to, hence causing over-braking on the rear before the fronts get a chance to bite? Quote Link to comment Share on other sites More sharing options...
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