Athomas Posted August 23, 2008 Report Share Posted August 23, 2008 (edited) Just had the dreaded news form the MOT tester that handbrake effort is too low, and failure certificate was duly issued. The rear brakes are fully refuilt:- New cables Backplates Cyliners Shoes Adjusters Return springs Etc The only items not new are the drums themselves, but they are in sound order. The new shoes should be bedded in OK, adjusters are set correctly. The only thought I have is to make up a shim to fit between the hand brake actuation lever and the shoe, to slightly change the geometry and hopefully increase the level of force applied. This used to be a tweak for Ford Escorts in the 80s. Any words of wisdom out there? Many thanks AT Edited August 23, 2008 by Athomas Quote Link to post Share on other sites
foster461 Posted August 23, 2008 Report Share Posted August 23, 2008 (edited) Just had the dreaded news form the MOT tester that handbrake effort is too low, and failure certificate was duly issued. The rear brakes are fully refuilt:- New cables Backplates Cyliners Shoes Adjusters Return springs Etc The only items not new are the drums themselves, but they are in sound order. The new shoes should be bedded in OK, adjusters are set correctly. The only thought I have is to make up a shim to fit between the hand brake actuation lever and the shoe, to slightly change the geometry and hopefully increase the level of force applied. This used to be a tweak for Ford Escorts in the 80s. Any words of wisdom out there? Many thanks AT Well its not like the hand brake worked all that great from the factory but if adjusted correctly it should lock up both wheels after three or four clicks and another click or two hold the car on an incline. If everything else is known to be good having one wheel lock up before the other will make the brake look weak. Jack up the rear end, raise the lever one click at a time and verify that both wheels lock up at the same point and adjust if necessary. One of Roger W's books described an extension to the lever on the slave cylinder to increase the effort but that really should not be necessary. Maybe all you need is an MOT tester that has a clue. Stan Edited August 23, 2008 by foster461 Quote Link to post Share on other sites
Richard Crawley Posted August 23, 2008 Report Share Posted August 23, 2008 I would not Advise you modify the linkage or increase the leverage; in spite of what Roger W says in his books! If all the parts are new, something has gone amiss with the reassembly, adjustment & setting up. Applying the H/brake should easily lock both rear wheels at 8 MPH & usually much higher. I always test test my handbrakes pre-MOT in this way & the only car I’ve ever had continuous problems with was my Daughters 98 Escort; no matter what I did, the only way I could ever get that bugger through the MOT every year was to fit new shoes! Have you checked the internal diameter of the drums, perhaps they have been skimmed! Quote Link to post Share on other sites
RogerH Posted August 23, 2008 Report Share Posted August 23, 2008 Hi AT, you say you have new shoes. If they have not beded in well then that may be the problem. Were the brakes OK before renewal - if so I would suggest go for a long drive and use the hand brake to slow down - don't over do it though in case you heat the slave cylinders. Roger Quote Link to post Share on other sites
Athomas Posted August 23, 2008 Author Report Share Posted August 23, 2008 Hi AT, you say you have new shoes. If they have not beded in well then that may be the problem. Were the brakes OK before renewal - if so I would suggest go for a long drive and use the hand brake to slow down - don't over do it though in case you heat the slave cylinders. Roger Thanks for the ideas folks. The shoes have done 250-300 miles since fitting, so I would expect bedding to be OK. I will check the drum ID just in case they have been machined oversize. The strage thing is that there is no feel or bite when the hand barke are applied. I doubt that applying the brake at 8mph as suggested would even slow the car let alone lock up the wheels. Had enough rear brakes for one day, time for a glass of red to drown my sorrows. will continue the inspection in the morning. Cheers AT Quote Link to post Share on other sites
Richard Crawley Posted August 23, 2008 Report Share Posted August 23, 2008 I will check the drum ID just in case they have been machined oversize. They should be well bedded in by now & that won’t unduly affect slow speed h/brake performance in any case; I’ve fitted new shoes many times immediately before an MOT with no problems &, as I said earlier, it was the only way I could get the h/brake to pass on my daughters’ Escort. Have you measured the internal drum diameter? As little as possible should be removed & the maximum diameter should be no greater than 1% of the original drum diameter (228mm) so maximum diameter should not exceed 230.28mm; if the internal dia. significantly exceeds this, it could well be the cause of your problems! Quote Link to post Share on other sites
88V8 Posted August 23, 2008 Report Share Posted August 23, 2008 My handbrake is OK but still requires a good pull. The shoes were replaced about 1,200 ago and are still not fully bedded all over. Also, I changed the drums about 500 ago for an old finned pair, and I think the shoes still haven't fully rebedded. It takes a while - have a look and see. Did you check the backplates were smooth where the wheel cylinders slide? Are they actually sliding freely? If not, only one shoe will engage. When you fitted the new cables, did you oil them through fully before fitting? That took about two hours and a lot of engine oil, and made the difference between MOT pass & fail for me. Ivor Quote Link to post Share on other sites
wheeler Posted August 23, 2008 Report Share Posted August 23, 2008 Hi AT Looks like you have tried everything! Have a look here http://www.buckeyetriumphs.org/technical/B...e/Handbrake.htm may be something you have missed, information regarding rear brakes also on this site. Good luck Cheers Bill Quote Link to post Share on other sites
Geoff Davies Posted August 23, 2008 Report Share Posted August 23, 2008 I have seen problems where there is a lip at the edge of the drum where the shoes have worn the drum. This gives a false impression as you fit the drum over the shoes they appear tight but infact are some way off when fully in place. Remove the edge around the drum with some emery cloth and then adjust the shoes up as tight as they will go. Check the linings havent glazed through too much heat as well. Geoff Quote Link to post Share on other sites
Bald Rick Posted August 24, 2008 Report Share Posted August 24, 2008 My handbrake was useless. It wouldn't hold the car on the slight slope of my drive. I had to use a brick under the wheel to the amusment of my neighbours. It scraped through the MOT by a whisker. This year as part of my pre-MOT check I stripped cleaned and greased the threads on the adjusters. Then set up the handbrake and cable EXACTLY as described in the Triumph workshop manual. My handbrake now works and it passed this years MOT with flying colours. Might be worth trying. Tony Quote Link to post Share on other sites
littlejim Posted August 24, 2008 Report Share Posted August 24, 2008 Don't know about over there, but the machines used for the test in Canberra used to be rather crude. Eg. one of the pilots I knew who had to train in the UK brought back a car with Maxaret brake units on. They kept failing it because it wouldn't lock the back wheels. At the time he probably had the best brakes in Australia. Can you do a retest with a bit of pipe in the brake handle or with one of your weightlifting friends in the driver's seat? The speed and distance of the handle yank is the other variable, it is not only the bits at the back wheel. Quote Link to post Share on other sites
TR6 Poor Posted August 24, 2008 Report Share Posted August 24, 2008 After CF50000, there were handbrake extensions used, at least in the US. Part numbers are, UKC7195 LH side, UKC7194 RH side. These were used to lessen the effort required to put sufficent pressure on the brake shoes to hold the car. They are shown in the TRF blue parts book, page 257. Now, the hard part is finding them. I would suggest breakers as you call them, or wrecking yards as we call them. I believe this was a US only part, not sure however. Quote Link to post Share on other sites
foster461 Posted August 25, 2008 Report Share Posted August 25, 2008 After CF50000, there were handbrake extensions used, at least in the US. Part numbers are, UKC7195 LH side, UKC7194 RH side. These were used to lessen the effort required to put sufficent pressure on the brake shoes to hold the car. They are shown in the TRF blue parts book, page 257. Now, the hard part is finding them. I would suggest breakers as you call them, or wrecking yards as we call them. I believe this was a US only part, not sure however. Interesting, I never knew that. Here's the picture from the TRF blue book http://www.zeni.net/trf/TR6bluebook/125.php These parts are NLS of course Stan Quote Link to post Share on other sites
john.r.davies Posted August 25, 2008 Report Share Posted August 25, 2008 Check that they are doing the calculation correctly: "Class III and IV Vehicles [Class IV is passenger vehicles up to 3000kgs] Determine the weight of the vehicle from the current Brake Data Chart (the data includes an element of 140kg or 300lbs for the weight of the driver, fuel, tools, etc) Calculate the service brake percentage efficiency by dividing the total brake effort achieved when the service brake is applied by the vehicle weight and then multiplying the result by 100,ie Total brake effort x 100 = % Efficiency Vehicle Weight Calculate the parking brake percentage efficiency by dividing the total brake effort achieved when the parking brake is applied by the vehicle weight and then multiplying the result by 100, as above." (From UKMOT.com) Over on the CT MsB, someone has been failed because their Herald was listed as weighing 1300kgs, when it really weighs 800 odd. TR6 should be about 1285kgs (Book 1145+140kgs). Ask to see the chart. John Quote Link to post Share on other sites
Athomas Posted August 25, 2008 Author Report Share Posted August 25, 2008 (edited) This is the latest on the handbrake front. Drums are within spec. Cables are adjusted correct length Shoes adjusters are correctly set. Cylinders are free to slide, plenty of copper slip everywhere. After complete disassembly /reassembly two or three times over the past few days, the only thing I can find marginally out is the pivot pin in the handbrake lever on the wheel cylinder, which is showing some slight wear. Being undersize I can understand some excess movement in the lever, which may reduce efficiency. From the responses I have received on the forum and some of the info I have found on the web, I can’t help thinking that parking brake efficiency was never brilliant on the 6, which is bourn out by the factory modifications to the US cars and the lever extenders illustrated in the Roger Williams book. I will make up some lever extenders this week and head for an MOT retest next weekend. Many thanks for all the suggestions and interesting info provided. Regards AT Edited August 25, 2008 by Athomas Quote Link to post Share on other sites
Stoker Posted August 25, 2008 Report Share Posted August 25, 2008 Copper slip is the wrong thing to use. It's not a lubricant, but a clay based anti seize compound and in time will dry out. I used a water proof grease on mine and the handbrake works like a dream. Best of luck John Quote Link to post Share on other sites
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