harrytr5 Posted September 29, 2013 Report Share Posted September 29, 2013 Thanks All, I am aware that I have hi jacked this thread and I am sorry for that.I am fitting the RPV on the front tomorrow to see what changes it does and then report on in a new thread. Regards Harry TR5 Nutter New thread. I fitted RPV's from Willwood. 2 lb front and 10 lb rear close to the master cylinder.Took calipers off and machined the alloy support to give me equal clearances both side of the disc,s.Bled the system twice.Reversed out of my garage with a slight hump to pavement and braked,drove forwards and braked,same result as before long brake pedal. What the f$$k is going on!. Looked at buckeye.org for clues.I had all this with standard parts when first fitted up eight years ago.Been changing parts and upgraded with the same result.I will be looking at the rear cylinders as this has not been changed since the rebuild and could be here.I checked the servo push rod and adjusted up too far, I now believe according to buckeye.It should have 35 thou clearance and could be here.The pedal is rock hard with the engine off.I put the old master cylinder back on as the new one did not make any difference.I just can not believe something so simple can cause so much grief.This time I am going to persevere till I solve it,BUT WHAT! Regards Harry TR5 Nutter Quote Link to post Share on other sites
Guest ntc Posted September 29, 2013 Report Share Posted September 29, 2013 Told you that some time ago Harry on here shame you did not reply to pm sent take care Quote Link to post Share on other sites
Tony Millward Posted September 30, 2013 Report Share Posted September 30, 2013 Harry, just a suggestion but as you haven't looked at the back brakes yet try isolating them (using those pipe clamps on both rear rubbers) and see if there is any difference. Cheers Tony Quote Link to post Share on other sites
harrytr5 Posted September 30, 2013 Author Report Share Posted September 30, 2013 Sorry Neil, I keep on forgetting to look at the top for PM,s Is it too late to comply with your wish? Regards Harry Quote Link to post Share on other sites
harrytr5 Posted September 30, 2013 Author Report Share Posted September 30, 2013 Hi Tony, I have braided hoses on all four corners so can not clamp off,but thanks anyway. Hi Neil, Sent you a PM.(just forget to look up there for PM,s in red) Quote Link to post Share on other sites
Guest ntc Posted September 30, 2013 Report Share Posted September 30, 2013 Harry Email sent you are correct you need 35 thou the books are wrong.Try it with the servo drained of air and disconnected Quote Link to post Share on other sites
Stanpartmanpartwolf Posted September 30, 2013 Report Share Posted September 30, 2013 As I mentioned previously, RPVs do NOT work- a waste of time & money. Measure the caliper piston areas & compare the total with the original 2.125" pistons. Any increase leads to a longer pedal. The most problematic brakes I ever encountered were caused by a pair of beautiful 2-pot alloy Girling BR calipers, fitted with lightweight hard anodised alloy pistons. The pedal would vanish at random; we went through every step Harry describes, to no avail, then had a proper think & fitted hard-chromed steel pistons. Perfect ever since. AP have done their sums for the alloy caliper/piston combo, others have not. I would wager you are suffering from excessive piston retraction. Investigate. Good luck.SPMPW Quote Link to post Share on other sites
Tony Millward Posted September 30, 2013 Report Share Posted September 30, 2013 Hi again, I fitted Wilwood vented disks with four pot calipers and have not experienced any of the problems that Stan and Harry have. I have to agree with Stan that it sounds like either excessive piston retraction or the pushrod is adjusted out too much and has already actuated the servo mechanism leading to a long brake pedal travel. Cheers Tony Quote Link to post Share on other sites
mike3739 Posted September 30, 2013 Report Share Posted September 30, 2013 Hi again, I fitted Wilwood vented disks with four pot calipers and have not experienced any of the problems that Stan and Harry have. I have to agree with Stan that it sounds like either excessive piston retraction or the pushrod is adjusted out too much and has already actuated the servo mechanism leading to a long brake pedal travel. Cheers Tony I have had Wilwood four pot calipers with vented disks fitted for four years & have also not had any problems that Stan or Harry have & run silicone fluid. Hiding now!! Cheers Mike. Mike. Quote Link to post Share on other sites
LGFromage Posted September 30, 2013 Report Share Posted September 30, 2013 My suggestion would be to make sure that the rear brake cylinders slide easily back and forth, check that the pistons are not stuck and set the adjusters so that the shoes retract as close as possible to the drums. Tim Quote Link to post Share on other sites
Stanpartmanpartwolf Posted October 1, 2013 Report Share Posted October 1, 2013 (edited) The adjusters make comparatively little difference to the rest position of the shoes, since they're at the opposite end to the cylinder. Excess travel at the piston end will be caused by: Worn or "reground" drums Shoes that have been previously filed or ground at the abutment points (see M20 note below) If you suspect either of these, it is possible to add a dab of weld to the shoe ends & dress it back. Don't try this at home, folks. On the subject of shoes, avoid the uprated exchange M20s like the plague. The company that produces these can no longer grind the linings to the correct radius (Health & "Safety" reasons!), & thereby causes much more danger than it supposedly avoids. NFI here, but PM if you'd like more info. I should add that we've never had any issues with Wilwood calipers, either; cheap & cheerful. SPMPW Edited October 2, 2013 by Stanpartmanpartwolf Quote Link to post Share on other sites
LGFromage Posted October 1, 2013 Report Share Posted October 1, 2013 The adjusters make not a jot of difference to the rest position of the shoes I would not put money on that. Tim Quote Link to post Share on other sites
harrytr5 Posted October 1, 2013 Author Report Share Posted October 1, 2013 Well I did a test that NTC suggested.I adjusted the servo rod yet again to give 35 thou clearance.Was not that far out.I clamped the servo hose and tried reversing out of my driveway with its inherent hump braked and drove forwards and braked.The pedal stayed firm and did not give a long pedal.So it looks like it could be the servo that is the culprit. Moss are out of stock although TR Shop has some.Has the issues of the servo,s gone now regarding the clevis pin to brake pedal being wrong.The thing is when I first put all this together and everything was new and standard I had the same thing.Could it have been the servo all along.I have changed callipers,shoes,brake drums,uprated bigger stub axles with bigger bearings,Willwood RPV 2lb front 10lb rear.Apart from selling her and let someone else deal with it if the servo turns out not to be the case????? I 'm going slightly mad and I am humming it as I write this ! Regards Harry Quote Link to post Share on other sites
mikew Posted October 1, 2013 Report Share Posted October 1, 2013 I've had this issue - it turned out to be the calipers expanding ! - it was ok, firm pedal without engine running, but when the servo had vacuum the extra effort supplied by the servo distorted the caliper bodies. The piston pressure, stopped by the immovable disk and pads, was pushing the caliper body apart - I had about 1.5 mm movement, and its enough to let the pedal fall to the floor. Use a dial guage and see if the caliper body distorts when pedal pressure applied. The calipers that I had the problem with were alloy. New calipers fixed it Quote Link to post Share on other sites
Guest ntc Posted October 2, 2013 Report Share Posted October 2, 2013 Harry Just a thought where are you taking the inlet from to feed the servo? Quote Link to post Share on other sites
Stanpartmanpartwolf Posted October 2, 2013 Report Share Posted October 2, 2013 Point taken, Tim, post modified accordingly. I will also add that the majority of brake modifications belong in the "useless upgrades" category. Who here can honestly say they have ever reached the limits of a properly fitted OEM set-up on UK public roads? The tyres were always the limiting factor in period, though, & I accept that the envelope can now be safely pushed; better a larger diameter solid disc than some of the complicated multipot caliper & vented disc arrangements that contribute very little, except of course on the circuit. That is an entirely different discussion that does not belong here. SPMPW Quote Link to post Share on other sites
Motorsport Mickey Posted October 2, 2013 Report Share Posted October 2, 2013 Jon, Now don't you go telling some of the guys that their bling calipers and vented discs are there purely for show and don't actually add anything to their road driving experience...it will give them the vapours, lol. Mick Richards Quote Link to post Share on other sites
Tony Millward Posted October 2, 2013 Report Share Posted October 2, 2013 Jon, I'm very happy with mine although I'm using a Nissan Skyline servo and my vacuum is generated from a pump on the back of my alternator....I like the security and the feel of modern brakes. The TR6 servo system especially with a long duration cam leaves a lot to be desired when you've tried better. Cheers Tony Quote Link to post Share on other sites
harrytr5 Posted October 5, 2013 Author Report Share Posted October 5, 2013 I have now stripped out the rear cylinders and found the back plate where the pivot pin on the handbrake has worn the metal (backplate)nearly in half of its thickness.I suspect this causes the sliding action of the cylinder to stick in this position when driving back and braking then driving forward and braking.I have the back plates off for welding up and I am out of gas.Drat, will have to wait till I get a bottle (argon shield ) to replace it.At least I have found something positive at last.Not saying it will cure my problem but must help. I am determined to cure this once and for all this time.Watch this space---- Can not post a pic on here at the mo.File too big. Regards Harry Quote Link to post Share on other sites
Tony Millward Posted October 5, 2013 Report Share Posted October 5, 2013 (edited) Hi Harry, Consider fitting disc brakes to the rear. Many have done this (including myself), and they do work. Add a proportioning valve and you can set up the rears how you want them. Others may poopoo this but trust me...they work. if you need info on this, let me know. Cheers Tony Edited October 5, 2013 by Tony Millward Quote Link to post Share on other sites
had17462 Posted October 5, 2013 Report Share Posted October 5, 2013 Harry your more than welcome and use my mig I'm about tomorrow, Nick Quote Link to post Share on other sites
harrytr5 Posted October 5, 2013 Author Report Share Posted October 5, 2013 Many thanks Nick, one of our members local to me has offered his.I will come up and see you sometime and look at your restoration if that is okay with you. Regards Harry. Quote Link to post Share on other sites
had17462 Posted October 6, 2013 Report Share Posted October 6, 2013 Anytime your passing pop in Nick Quote Link to post Share on other sites
harrytr5 Posted October 6, 2013 Author Report Share Posted October 6, 2013 Tony, Sent a PM but it is blocked.Might be full up. Regards Harry Quote Link to post Share on other sites
Tony Millward Posted October 7, 2013 Report Share Posted October 7, 2013 Just checked and not full Harry. Use my email addy. Cheers Tony Quote Link to post Share on other sites
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