Steve R Posted August 2, 2014 Report Share Posted August 2, 2014 The title says it all, all the brakes locked on, it doesn't have a restrictor fitted, both front disks were locked , before i replace the master cylinder has anyone else had this? i can imagine the master cylinder seals letting fluid past but that would have the opposite effect wouldn't it? as soon as i undid the brake line going into the union with the switch attached the brakes released. All seems a bit odd. Steve Quote Link to post Share on other sites
Richardtr3a Posted August 2, 2014 Report Share Posted August 2, 2014 Do not buy a new master cylinder. The repro items have significant shortcomings. Get your unit sleeved in stainless steel and fit new rubbers. There is a pressure release jet in the m/c which is not allowing your fluid to return into the cylinder. There has been a lot of info on the forum and that includes pictures of the repro parts from our forum team in USA. Good luck. Richard Quote Link to post Share on other sites
Steve R Posted August 2, 2014 Author Report Share Posted August 2, 2014 My misake, it does have a restictor fitted, didn't realise what they looked like, that'll be my first suspect, my master cyliner looks to be new'ish ( more than 15, less that 20 years old). Onwards and upwards! Quote Link to post Share on other sites
ianc Posted August 2, 2014 Report Share Posted August 2, 2014 My disc-braked TR2 suffered this in the early 1960s. Dismantle the pressure valve, discard its innards, re-assemble and re-fit. Ian Cornish Quote Link to post Share on other sites
Steve R Posted August 2, 2014 Author Report Share Posted August 2, 2014 Hi Ian Yes, thanks i've just done that, i had in my mind the sort of balancer valve that my mini cooper had, once i had a look at the parts book it all became clear. I'll refill and bleed tomorrow. Steve Quote Link to post Share on other sites
Rodbr Posted August 2, 2014 Report Share Posted August 2, 2014 (edited) Hi Steve, I had the same situation I could drive and the brakes would lock and nothing I could do until cooled down. I had adjusted the pedal to master cylinder too much trying to get pedal height, which did not allow the fluid to return. I suggest that you back off the adjuster and see it that helps before thinking of changing MC. perhaps slight wear over the time. Edited August 2, 2014 by Rodbr Quote Link to post Share on other sites
Fireman049 Posted August 2, 2014 Report Share Posted August 2, 2014 I think that Rod's on the ball here. That's the first thing I thought of. Give it a try. Tom. Quote Link to post Share on other sites
vivdownunder Posted August 2, 2014 Report Share Posted August 2, 2014 When a restrictor valve fails, pedal pressure still forces fluid past, but there's insufficient return pressure to release the brakes. Steve, suggest checking the front brake hoses too. Best replaced every 10 years (also the rear hose to the diff). Loss of internal diameter sneaks up on you and eventually one front brake locks on, usually at an inconvenient time. Check for adjuster clearance at the clutch master cylinder too, or the same thing happens. Clutch stays unengaged and no forward progress until the pressure is released at the slave cylinder. Not good if it happens at a busy intersection Rgds, Viv Quote Link to post Share on other sites
Steve R Posted August 3, 2014 Author Report Share Posted August 3, 2014 All sorted now, i removed the guts from the restrictor and binned them. I thought there was something amiss before they locked on fully, the pedal felt "dead" no feel to it, i just didn't recognise the symptoms, and once i realised that i did have a restrictor fitted it was the main suspect. Thanks for your suggestions, much appreciated. Steve Quote Link to post Share on other sites
lynchpin Posted August 4, 2014 Report Share Posted August 4, 2014 Had the same problem with my 4 earlier this year, took the restrictor apart cleaned it all out and reassembled been fine ever since, I believe it was fitted to keep the pads near the discs when the pedal is released so you don"t get a long pedal on the next use of the brakes. It must have been fitted for a reason and triumph did get it right sometimes.. PHIL. Quote Link to post Share on other sites
vivdownunder Posted August 4, 2014 Report Share Posted August 4, 2014 During hard cornering such as in competition work the stub axles flexed. This axle flexing caused the pads to move away from the rotors, leaving an alarmingly low pedal. The factory's response to this problem was a restrictor valve designed to always keep the pads close to the rotors. It doesn't do much in normal driving and was eventually deleted during TR4 production. Viv Quote Link to post Share on other sites
Steve R Posted August 4, 2014 Author Report Share Posted August 4, 2014 Thanks for the explanation Viv, if i ever manage to corner hard i suppose it'll be a toss up whether the brakes or my 48 spoke wires give up first! Quote Link to post Share on other sites
McMuttley Posted August 4, 2014 Report Share Posted August 4, 2014 I find that talent and kahuna's give way long before mechanical bits. Quote Link to post Share on other sites
Guest Posted August 5, 2014 Report Share Posted August 5, 2014 I never knew why there 's a restrictor installed. Nice piece of info Viv. Menno Quote Link to post Share on other sites
vivdownunder Posted August 6, 2014 Report Share Posted August 6, 2014 Interestingly, an American vintage racer Jack Drews (better known as Uncle Jack), went about fixing the axle flexing problem in a different way. He developed a strengthening sleeve that slipped over the stub axle between the two tapered bearings. Uncle Jack also developed a shim kit that accurately set front bearing clearance. All in all a much better engineered solution to the axle flexing problem and a simple upgrade for road cars. To this day Uncle Jack's Spacer Kits are still available in the USA through Uncle Jack Racing Services, or TRF. Viv Quote Link to post Share on other sites
ianc Posted August 6, 2014 Report Share Posted August 6, 2014 Kits similar to Uncle Jack's are available in the UK from a number of suppliers, including RevingtonTR, TR Enterprises and Racetorations, I believe. Ian Cornish Quote Link to post Share on other sites
2long Posted August 6, 2014 Report Share Posted August 6, 2014 Fwiw, a kahuna is a sort of Hawaiian priest. Cojones is probaby what you are going for. Funny how language evolves. Dan Quote Link to post Share on other sites
McMuttley Posted August 7, 2014 Report Share Posted August 7, 2014 ....and there was me thinking kahuna was a coffee based licker - just shows how fick I is. http://i1295.photobucket.com/albums/b640/mcmuttley/IMG_0019_zps7af3bc52.jpg Quote Link to post Share on other sites
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