Chilewillie Posted February 18, 2020 Report Share Posted February 18, 2020 Hi I am new to the blog and have recently restored a 1975 TR6 in Chile. The car works great however I have an issue with the rear brakes, they lock easily and makes it difficult to handle sometimes. Do you think I should install a proportioning valve to get more control on back brakes and it so where can I get such a valve. Many thanks Willie Quote Link to post Share on other sites
JochemsTR Posted February 18, 2020 Report Share Posted February 18, 2020 Hello Willie, do they lock before the front brakes? which rear brake cylinder is installed? 0.7", 0,75" or even 0.875" ?? Jochem Quote Link to post Share on other sites
Waldi Posted February 18, 2020 Report Share Posted February 18, 2020 Hi Willie, Welcome to the forum. How is the overall braking performance? If the front brakes are poor, the rears will lock quicker. Not the likely cause but worth checking. I would not fit a pressure regulator, but fix the issue. Waldi Quote Link to post Share on other sites
Z320 Posted February 18, 2020 Report Share Posted February 18, 2020 (edited) issue: brakes, no special model Hi Willie, a good point from Jockem, if not I have another idea. Drum brakes tend very much to lock when the shoes are based "fix" on a pivot point. You perhaps know that from motorbikes. To avoid this the brake shoes on all cars I know are based on sliding points, so they hardly never lock. Make shure your brake shoes can move on the adjustor and are not fixed like on on pivot points for any reason (modification). Ciao, Marco Edited February 18, 2020 by Z320 Quote Link to post Share on other sites
BlueTR3A-5EKT Posted February 18, 2020 Report Share Posted February 18, 2020 PDWA shuttle is not centred. PDWA is pressure differential activation valve. If one brake circuit front or rear leaks the shuttle valve is forced to block the leaking circuit, so you still have half the car’s brakes. .The valve Is a brass H shape under the bonnet with 4 brake pipes attached and one electric wire. The shuttle needs re centring inside it if it is that causing the problem. Cheers Peter W Quote Link to post Share on other sites
Keith Warren Posted February 18, 2020 Report Share Posted February 18, 2020 Hi Willie Has the master cylinder Been connected the wrong way round the front should be 7/16 and the rear 3/8 uni this could be pushing greater fluid pressure to the rear. Keith Quote Link to post Share on other sites
stuart Posted February 18, 2020 Report Share Posted February 18, 2020 3 hours ago, BlueTR3A-5EKT said: PDWA shuttle is not centred. PDWA is pressure differential activation valve. If one brake circuit front or rear leaks the shuttle valve is forced to block the leaking circuit, so you still have half the car’s brakes. .The valve Is a brass H shape under the bonnet with 4 brake pipes attached and one electric wire. The shuttle needs re centring inside it if it is that causing the problem. Cheers Peter W Sounds like this is his problem.easy to dislodge if bleeding too hard too. Stuart. Quote Link to post Share on other sites
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