Stodders Posted February 15, 2012 Share Posted February 15, 2012 Whilst carrying out the rebuild of my Vitesse I noticed that a tandem brake master cylinder was fitted to some variants of the GT6 and also the 1500 spitfire. It would be good to fit one of these to a vitesse but has anyone done this before? Firstly, would one actually fit without modifications to the bulkhead? It does look like they are a lot longer than the standard item. Secondly, what are the bore sizes of the available ones. There are a few of the GT6 ones available from the states and spitfire 1500 ones are not a problem but I do not know what effect one of these would have on pedal pressure and travelHas anyone tried this? Link to comment Share on other sites More sharing options...
nang Posted February 15, 2012 Share Posted February 15, 2012 This was fitted as standard to Aussie and New Zealand cars to meet our transport regulations.I guess you could fit to a Vitesse but master cyl is different and you would have to replumb under bonnet connectors to separate front and rear brakes.Cheers Tony. Link to comment Share on other sites More sharing options...
herald948 Posted February 16, 2012 Share Posted February 16, 2012 The dual-circuit brake systems were fitted to all Triumphs sold in the US from 1968 on; for the most part, finding the bits you need shouldn't be a problem. The one exception is the dual master cylinder for GT6 (presumably what one might use for the Vitesse as well) with its "stepped bore." Last I knew, it was no longer available, but some folks seem to "get by" with the dual master cylinder from the Spitfire. Typically, one would need to either give the bulkhead a healthy bash for clearance on the bigger, longer cylinder or cut the "bulge" from an other wise scrap car and graft it into the bulkhead. Adding the additional plumbing is not that difficult; while others might well disagree, it's probably easiest to do that with the PDWA (not absolutely necessary, but....). Link to comment Share on other sites More sharing options...
Nick Moore Posted February 16, 2012 Share Posted February 16, 2012 I've never seen a Herald or Vitesse with a tandem master cylinder. My ex-US GT6 has a tandem cylinder, and I had to move the bulkhead recess when I converted it to RHD. The cylinder is several centimetres longer than a single cylinder version. Link to comment Share on other sites More sharing options...
JohnD Posted February 16, 2012 Share Posted February 16, 2012 I fitted a dual system brake master to Silverback, Without moving the bracket, the rear end of the reservoir needed a hole cut in the bulkhead. To maintain the integrity of the bulkhead, I filled the hole with a 'reverse glovebox' made of alloy sheet.I did this because the other mods to the car could have disturbed the front-back weight ratio and the brake balance (it didn't). From memory, and not documented on the manuals, the connections on the master to the two circuits have different threads, one metric, one UNF. I presume this was to ensure that they were installed the right way round!JohnSee pic: Link to comment Share on other sites More sharing options...
Vitesseman Posted February 16, 2012 Share Posted February 16, 2012 Is the split Front/Rear or LF/RR & RF/FR and in never cars? Link to comment Share on other sites More sharing options...
herald948 Posted February 16, 2012 Share Posted February 16, 2012 Nick, unfortunately, the only picture I have of such a car (one of the Belgian-assembled Herald 13/60s for the Puerto Rican market) doesn't show the bulkhead very well:You can just see the PDWA and the top of the dual master cylinder's reservoir in the picture above.Vitesseman: the split was always front/rear. Link to comment Share on other sites More sharing options...
JohnD Posted February 16, 2012 Share Posted February 16, 2012 Agree, front/rear split.Which was crazy! Loose the fronts, you lock the back - and spin!Loose the back, you lock the fronts - and spin!Not sure that a diagonal split is any better.John Link to comment Share on other sites More sharing options...
Gt6s Posted February 16, 2012 Share Posted February 16, 2012 I was in the process of fitting a balance bar setup to the EFI Gt6 Not saying it cannot be done, HOWEVER the end of the balance bar will foul on the wiper motor and then cylinder mount brackets will need fabricating. Here evilbay raises its head. I have aquired a very cheap Spitfire dual circuit cylinder and feel fitting that will be a lot simpler and I do'nt really need adjustable bias either.Does someone out here know which outlet goes to which pair of brakes? I am presumeing forward outlet goes to fronts rear outlet to rears. Link to comment Share on other sites More sharing options...
Nick Jones Posted February 16, 2012 Share Posted February 16, 2012 Older stuff tends to have front/rear split - which has it's problems as already noted - not least that rear brakes only tend to be pretty ineffective. However, it was presumably felt to be less alarming than a diagonal split - which produces a very violent pull to one side - unless the suspension geometry has been designed with this in mind.Most modern cars have diagonal split dual circuit. They also have large amounts of caster in the front suspension that makes them more inclined to hold a straight line - and makes the steering much heavier. Ever driven a non PAS Micra :oOf course, for a while some manufacturers, Volvo and even BL were making true dual circuit with twin brake lines to each caliper and 4 pot calipers with two pots operating from each line. Complex, expensive, but safe.(in)famous Princess 4 pot calipers have this very arrangement - which makes them a bit of a pain to plumb into a single line system.Nick Link to comment Share on other sites More sharing options...
herald948 Posted February 16, 2012 Share Posted February 16, 2012 Nick_Jones wrote:Older stuff tends to have front/rear split - which has it's problems as already noted - not least that rear brakes only tend to be pretty ineffective. Certainly true compared to front brakes only, but if your brakes are otherwise in good condition, and your ARM is in good condition, you can do some pretty decent stopping with just the handbrake! :)Nick_Jones wrote:Of course, for a while some manufacturers, Volvo and even BL were making true dual circuit with twin brake lines to each caliper and 4 pot calipers with two pots operating from each line. Complex, expensive, but safe.I don't know if it was true in all markets, but Volvos that came to the States had "dual triangular" systems, each of the two circuits controlled both front brakes plus one rear brake. Took FOREVER to bleed, but safe as you note! Link to comment Share on other sites More sharing options...
Nick Jones Posted February 16, 2012 Share Posted February 16, 2012 Ah, triangular..... I wondered what they did about the rear.I suppose it should be noted that some (hydraulic) brakes will almost always be better than no brakes. The thought of trying to stop from speed on a hill using only a Triumph handbrake...... :o :oA further observation - when my A6 (with diagonal split dual circuit) suffered a large hydraulic leak from a rear circuit, it had NO brakes apart from the (very effective) handbrake. Not sure quite why that was, but I was glad I discovered it on the driveway!Nick Link to comment Share on other sites More sharing options...
Nick Moore Posted February 17, 2012 Share Posted February 17, 2012 JohnD wrote:Loose the fronts, you lock the back - and spin!Loose the back, you lock the fronts - and spin!JohnHmmm. I know that too much rear brake bias causes spins, but too much front? I though many cars had a very large front brake bias, and that the rears only help keep the car pointing straight under braking. Does a lack of rear braking also lead to spinning? Link to comment Share on other sites More sharing options...
JohnD Posted February 17, 2012 Share Posted February 17, 2012 Nick M,Try going into a corner, fast , with the brakes still on.The back is lifting under brakes, so little braking force.............and you spin.John Link to comment Share on other sites More sharing options...
rlubikey Posted February 17, 2012 Share Posted February 17, 2012 I don't think the Herald/Vitesse has the bracing brackets/gussets similar to Spit/GT6, does it? These are different - lower - on late UK Spits with tandem M/C so the brake pipes (which exit sideways) *juuuust* clear over the top of the off-side bracket. Possibly not necessary if you put a very tight bend in the pipes.Richard Link to comment Share on other sites More sharing options...
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