 | Home > Technical > how does the hand brake work |
 
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264   
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having been patience with the tools I've got I've taken the drum off again only to find the left pad seems to be sticking / staying slightly off 'line' and causing it to drag slightly on the drum and I believe is the final 'issue' I seem to be having.
its the top edge of the left pad that rubbing but I'm not sure how to ensure it returns such that it misses the drum? below see the marks on the pad - presumably where its over heated through friction?  Click image to enlarge |
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11th Jul 2013 5:29pm |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264
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LS
thanks for the reply suggestions however the drum appears to be ok....(to the eye at least). the believe the problem is the left shoe doesn't always like to return home but not sure how to adjust it....it may just be a case of adjusting the tension where it goes into the seat box prior to the hand brake? if so how do you workout the how much to adjust it by? |
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11th Jul 2013 7:41pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16871  
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Which way does the drum rotate? I can't remember offhand but I'm guessing anticlockwise, in which case the self-servo characteristic of the leading shoe in a drum brake may be what's causing this. If so it's probably normal.
Edit - if the drum rotates clockwise it is possible that the adjuster is not centralised correctly and the leading edge of the LH shoe is picking up on the drum. |
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12th Jul 2013 12:06am |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264
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So adjusted and torqued up the pro bolts last night (suspect they hadn't been tightened enough previously)
I started by loosening off the adjuster by 1.5 turns as suggested in the workshop manual and then a further quarter turn.....how much do most of you loosen yours off by as I gather more than 1.5 turns is common.? |
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20th Oct 2014 6:45pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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if you got a binding shoe or shoes , best to file the leading edge down
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20th Oct 2014 7:12pm |
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| martinfiattech Member Since: 13 Nov 2013 Location: leicester Posts: 422
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From the photo everything looks very clean, the shoe looks a bit rusty as if moisture has got in, possibly causing drag.
When I first got mine, about this time last year the hand brake lever travel was excessive 7 or 8 clicks. I removed the prop shaft and drum, cleaned the shoes chamfered the top and bottom edges, cleaned the drum up. made sure the cable was slack (slightly). Re fitted the drum adjusted the brake shoes on the adjuster till the drum would not turn by hand Then backed off 3/4 of a turn, readjusted the cable tension to 4 clicks of lever travel. Re checked for binding all ok, carried out short road test a couple of miles jumped out placed my hand on the drum. Nice and cold, has been fine ever since. It`s normal of the car to move slightly forwards or back depending on angle. Of course the movment will increase as the drive line ware`s. The drum may become oval over time due to the shoes pushing out. The quickest way to check it is with a Dial test indicator and a magnetic stand. Just bolt the drum on backwards using 4 nuts / bolts evenly tightened, now here`s the hard bit, make the magnetic stand attach it`s self to the back plate it`s not easy but it`s doable. Pre load the gauge gently rotate the drum and read off ! As for MOT brake testing I was the testers assistant that day, we put the transfer box in netural and main box in netural. Used the brake tester in manual mode so once 16% of braking force achieved we could stop the tester. (MOT minimum value). We tried again to see if it would lock, and it did at 23% and pulled it`s self out of the rollers. Oh by the way always mark your prop to drum and flange in one place so they all go back together in line, this will stop any unwanted prop shaft vibration. tip ex will do fine. Excuse the spelling I`am better with spanners and wires. |
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21st Oct 2014 10:00pm |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264
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thanks guys. been away so sorry for the slow response.
I'm hopefully getting my hands on another drum to test just in case mine is slightly oval. - will let you know how I get on.....and I need to investigate one of those magnetic things 
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10th Nov 2014 9:57am |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264
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so back to the hand brake.
I replaced my drum (well someone else did) and yes it was rubbing as it was rotated and difficult to remove. new used drum fitted and still rubbing but less often. when I say rubbing not all the way round but like a buckled wheel on a bike would rub on the brakes as it's rotated. so what I can't understand is even if both were oval shaped (and I've been advised the second one was round) why would the drum rub occasionally and not all the time after all the shoes are pretty much round / and cover all most all over the circumference of the drum. I'm either both of the drums were oval shape but to a less degree and / or the output to the transfer box is off centre / bent? and to make matters worse the hand brake doesn't always retract as much as it should? so back to the shoes / hand brake as a whole - is it common for the hand brake lever to feel different from time to time - as if there's more movement in the cable / resistance from application to application is do you all get a consistent feel? I've stripped the drum more than once and it SEEMED to fix the 'problem' short term only for it to go back to it's 'normal' state. each time I've removed the drum the 2 retaining pins seem to be ski wif. as if the holes in the drum don't line up with the holes on the drum back plate. I presume these shoes can be fitted either way (from memory they looked the same)? is there anything else that could perhaps have been fitted wrong that would prevent the shoes from returning fully? I couldn't see anything ? any help / suggestions would be much appreciated. |
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19th Feb 2015 8:22pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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how do you mean don't retract fully ?
don't forget the shoes are sort of semi floating to allow them to self centre 99.9% of shoes will show some sort of rubbing marks |
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19th Feb 2015 9:32pm |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264
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hi munch90. when I say not retracting fully I mean not returning to the 'home' position ie returning towards the centre and not rubbing on the drum.
I assume this to be the case for different reasons. one of the most obvious being when parking and applying the hand brake - sometimes there appears to be some resistance from the moment I start lifting the hand brake lever increasing gradually until the hand brake is fully engaged. other times there appears to be no resistance until the very last moment when the hand brake is fully engaged. I started 'playing' today by very gradually applying the hand brake while slowing to a stop and the 'droning' noise was clearly the same as I get when coasting to a stand still or braking slowly to a standstill at traffic lights for example. - other times things can be PERFECT and the truck runs incredibly smooth in everyway ??? |
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19th Feb 2015 9:45pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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the noise as your slowing down is quite common , seems normal fix is to de-adjust handbrake abit ( normally get the juddering and noise after a longer run )
mine done it from new , just de-adjusted the cable a bit and seemed to fix it wont do it now as I haven't got a handbrake drum , disc conversion fitted the shoes will never centralise themselves they rely on the drum for that , thatS why they normally rub very very slightly , but as there is no pressure (OR THERE SHOULD NOT BE ANY PRESSURE IF ADJUSTED RIGHT ) , they don't tend to bind or get hot how many clicks does your lever come up ? also my advice is don't pull handbrake up while moving , unless its a emergency ! |
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19th Feb 2015 11:04pm |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264
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that's just it. I've adjusted (and even replaced the cable) and it starts off ok then gets worse and had a pro adjust it and replace the drum and it's still a problem....like you say its worse when warm / after a long drive but also does it on a short drive ie commute to work of only 8 miles local roads?
perhaps the only answer is a disc conversion but I can't see why I can't get a simple drum brake to work as it should ? very frustrating - not just because it's rubbing but because I can't understand why the damn shoes won't sit centrally when other do and yet its the same damn set up? ps only been applying the hand brake while moving as a test recently. would normally be completely stationary before applying. |
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19th Feb 2015 11:29pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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How many clicks does lever come up when pulled normally to lock ? ( not pulling hard as you can ! )
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20th Feb 2015 12:07am |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6264
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4 at the moment (that's kinda the minimum number to make it engage sufficiently but I've had it looser to see if that helps previously and it didn't?
you mentioned the shoes kind of float and centre themselves.....its as though the centre they find is off centre if that make s sense. if that is the case is there anyway of changing where the centre point is other that getting a new back plate? |
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20th Feb 2015 8:37am |
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