herbiemercman Posted July 8, 2015 Share Posted July 8, 2015 Hi Guys, Do the 1993 to 1998 mk4 supras have the dual braking systems.? I ask this as i have a e-300 td merc estate and i blew a brake pipe coming down snaefell mountain at the iom tt races, had five friends on board but fortunately only the rear wheel braking failed, the fronts were ok so not a disaster. I read a sticky thread on here where a member had a close shave with a brake pipe failing due to corrosion, so this suggests that may be the supras do not have dual safety braking systems.? or may be this was only the case with the earlier models.? herbiemercman. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 8, 2015 Share Posted July 8, 2015 I'm pretty sure they don't have dual braking systems. When bleeding and checking brakes, there's only 1 brake fluid reservoir to deal with, which should rule out a dual system. Quote Link to comment Share on other sites More sharing options...
SupraP-Z Posted July 8, 2015 Share Posted July 8, 2015 Hey bud, these cars definately dont have dual braking systems. Something had managed to chew through my stainless steel braided line at the rear and compromised the whole system - pedal went to the floor. Lucky it happened just as i got home, was doing a few high speed motorway runs with hard braking beforehand! Had the casting of the bleed nipple crack off when it was undone (j spec brakes) same thing, pedal went to the floor and barely any brakes at all Quote Link to comment Share on other sites More sharing options...
garethr Posted July 9, 2015 Share Posted July 9, 2015 (edited) All cars have had dual-circuit brakes for decades. EDIT: Apparently, the USA has required dual-circuit brakes since 1967. Edited July 9, 2015 by garethr (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris88 Posted July 9, 2015 Share Posted July 9, 2015 I'm pretty sure they don't have dual braking systems. When bleeding and checking brakes, there's only 1 brake fluid reservoir to deal with, which should rule out a dual system. Only one reservoir but there are two pistons (one behind the other) so unless the reservoir itself is empty there is a redundant system. Of course if you have a pipe failure you can empty the reservoir pretty quickly. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 9, 2015 Share Posted July 9, 2015 All cars have had dual-circuit brakes for decades. EDIT: Apparently, the USA has required dual-circuit brakes since 1967. Yep, you won't find a production car going back years and years without a split system. Concentrate on making an N/A T run properly before worrying if you can stop it Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted July 9, 2015 Author Share Posted July 9, 2015 Hi Guys, Just been in my local pub amongst older petrol heads, they say from 1973 all cars by law had to have dual brakes, or as some refer to them split brakes, one guy said it may be jap imports did not comply ? i don't think so. to cover chris's point, i have commissioned someone to fit and guarantee the fourth coming na/t kit, but i have to make sure i have back up on my braking system, i am still not sure what the import cars have.? because why have we a few members who have experienced total brake failure.? unless they have a fault in the dual brake system.? herbiemercman. Quote Link to comment Share on other sites More sharing options...
garethr Posted July 9, 2015 Share Posted July 9, 2015 In the exploded diagram from the EPC, you can see that the reservoir has two outlets, and there are two separate pistons in the master cylinder. Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted July 10, 2015 Author Share Posted July 10, 2015 so it looks like the mk4 supra does have a dual braking system, which is what you would expect, the members who lost all there braking therefore must have had a fault in the system which got around it somehow.? be good if someone could put forward what it might be.? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 10, 2015 Share Posted July 10, 2015 so it looks like the mk4 supra does have a dual braking system, which is what you would expect, the members who lost all there braking therefore must have had a fault in the system which got around it somehow.? be good if someone could put forward what it might be.? Have you got a link to a thread, or a specific user? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 10, 2015 Share Posted July 10, 2015 There's a spring between the two pistons (front circuit piston and rear circuit piston). Normally the volume between the two pistons is solid with fluid and incompressible. If one circuit fails and it's fed by the piston furthest from the servo push rod, the spring collapses before the first piston physically pushes the second piston and which then compresses the fluid in the good circuit. In some cases the pedal will go a long way down before any hydraulic pressure is produced. In extreme cases the pedal may need a pump or two. Believe me, the pumping is a natural reaction to being propelled at speed towards a solid object and needs no practice The MKIV has a fairly crude system in that one can end up with just rear brakes, which is akin to pulling he handbrake on, with unpredictable results. The likes of Volvo and others use diagonal split systems where a more balanced retardation is maintained. More costly and more complex, but a lot safer. Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted July 10, 2015 Author Share Posted July 10, 2015 hi chris, good technical reply, you are an asset to this club. nice to know now that at least there is some braking if one system fails. hi gareth, thanks for exp. diag. the brake failure waring was a sticky, can't remember where the other one was. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 10, 2015 Share Posted July 10, 2015 http://www.winbrake.com/training_autofundamentalsbrakes.html Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted July 10, 2015 Author Share Posted July 10, 2015 thanks for info, very interesting stuff. Quote Link to comment Share on other sites More sharing options...
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