Dan Frawley Posted November 19, 2021 Report Share Posted November 19, 2021 I only have brake fluid reaching LF and RR wheels ... none whatsoever reaching RF nor LR wheels???? Any body else ever had such a problem or have any idea as to what might be causing the problem??? Quote Link to post Share on other sites
Z320 Posted November 19, 2021 Report Share Posted November 19, 2021 Who is Dan Frawley asking this? Quote Link to post Share on other sites
John L Posted November 19, 2021 Report Share Posted November 19, 2021 Welcome to the forum, I presume its an American car, and I guess you are there also, nice to know where you are, as also helps with the problem solving. there is a brake limiting valve for safety, if you have a problem with one of the circuits, you still have some brakes. Its a valve that slides across and blocks the brake feed diagonally. Its item 78 here, https://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/brake-system/brake-controls-hydraulics/brake-pipes-tr5-6-1967-76.html There is info in the service manual to center it again, and how to bleed the system without locking this valve in one direction. I'm sure others will help with the proceedure John Quote Link to post Share on other sites
JochemsTR Posted November 19, 2021 Report Share Posted November 19, 2021 John, Dan mentions LF and RR, meaning Left Front and Right Rear, right? This means it cannot be the PDWA. Jochem Quote Link to post Share on other sites
RogerH Posted November 19, 2021 Report Share Posted November 19, 2021 Hi Dan, I know that the brake system on the TR4A is different but I had a similar problem a few moths back. Check all the flexible hoses. You could also crack open various joints to see where the fluid is/isn't. Roger Quote Link to post Share on other sites
michaelfinnis Posted November 19, 2021 Report Share Posted November 19, 2021 Brake circuit is split front/rear. PDWA if fitted is sensitive to any pressure difference between the two circuits. If the brakes not getting fluid are RF and LR that would suggest two faults. I'm not sure but I think that if the PDWA shuttle valve was displaced to one side it would operate the warning switch, but would still let fluid pass. Mike. Quote Link to post Share on other sites
Phil Read Posted November 19, 2021 Report Share Posted November 19, 2021 20 minutes ago, RogerH said: Hi Dan, I know that the brake system on the TR4A is different but I had a similar problem a few moths back. Check all the flexible hoses. You could also crack open various joints to see where the fluid is/isn't. Roger Ditto. I had the same problem, blocked/collapsed flexible pipes Quote Link to post Share on other sites
TRier Posted November 19, 2021 Report Share Posted November 19, 2021 Hi Dan, I haven't had this experience on a TR6 but have had similar on other vehicles, check that the bleed nipples are actually open, its very possible to get corrosion in there and for the same amount of mechanical movement as provided fluid on the other corners you get none on some. Then as some of the other guys check that flexibles are OK. I usually use the old fashioned method of having a beautiful assistant pump the pedal for bleeding, have on particular car found that on bleeding from dry this method didn't work at all well on rears so went to pulling from the rears using a vacuum pump, so air lock even with pedal pumping can sometimes at least still be an issue. That all said, I'd take the bleed nipple out and see if you have fluid then as a first step. Quote Link to post Share on other sites
John L Posted November 19, 2021 Report Share Posted November 19, 2021 Dan mentions LF and RR, meaning Left Front and Right Rear, right? This means it cannot be the PDWA. Wouldn't it depend how the pipes were fitted to the valve? John Quote Link to post Share on other sites
RobH Posted November 19, 2021 Report Share Posted November 19, 2021 (edited) 1 hour ago, John L said: Dan mentions LF and RR, meaning Left Front and Right Rear, right? This means it cannot be the PDWA. Wouldn't it depend how the pipes were fitted to the valve? Agreed John. It is possible that some previous owner has connected the PDWA with a diagonal connection instead of front-rear. It is more sensible and safer arrangement after all. That is how it was done on some mid-'70s Minis I believe, and probably others too before they went to split systems. Edited November 19, 2021 by RobH Quote Link to post Share on other sites
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