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Car Forum / MINI / February 2004clutch "scrape"
Hello again everyone I've been having a few problems with my clutch. (I'm a novice mechanic and trying to pick up as much expertise as possible along the way, but out of my depth here...) The story is this: a few days ago there was a slight scraping noise from the right hand side of the engine bay (from the driver's pov). This got worse the next time I took her out and the clutch suddenly changed its feel to only biting right next to the floor. It was previously much higher. This really scared me so I took it to my not-so-local mini mechanic (1.5 hrs drive) which was a gamble but it was all motorway and hardly any gear changing. I took a half day and got to the garage at about 3pm friday. The mechanic said the pedal problem sounded hydraulics-related, and recommended changing the slave cylinder (I understand this wouldn't hurt even if I end up with a new clutch). I somehow persuaded him to drop what he was doing and fix it there and then as I work full time and it's a massive hassle to get to. The fluid level was low and the old slave unit was leaking, so a job well done (-£83). The car then drove great for about 100 miles. The the next day (this morning) it started to scrape again. Then it stopped. I'm now fearing it'll come back. Does anyone know what this might be? A mate mentioned the release bearing- could this be bust? I can't tackle this on my own I'm afraid, so I'm kind of resigned to paying someone to look into it. The trouble is I don't want to drive to the specialist again as I've no time. My main option is the local "Mr Clutch" (Highgate). They've quoted me £150 for new clutch/ labour/ vat/ guarantee. They don't sound like somewhere I'd relish leaving my pride and joy, but if they can fit a new clutch for this fixed fee does this seem worth it? Would they automatically change the release bearing while the thing's apart? The entire cost is pretty much labour, so should I be attempting this myself? The fact that it's audibly scraping leaves me thinking there's damage in there, so how much might I have to change? Thanks for reading this far.. Any opinions/ advice very much appreciated. Will  SignatureUsing M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ hiya Sounds like the clutch thrust bearing is on its way out or the friction plate is down to the rivets, you will need to remove the engine casing where the slave cylinder is, Not a bad job but very tight to get the rear bolts. unbolting the engine mount and slightly jacking up that side of the engine helps. Either way if you are going to the trouble of replacing the bearing you might as well do the whole clutch for what they cost, and it saves having to remove the engine casing again to do the bits you didnt replace. Its false economy to just do the bearing or just the friction plate. ?83 for a cylinder and fluid sounds a lot to me. did he replace the whole cylinder or did he just replace the seals in the old one ? If just the seals they cost about ?5. fragged > Hello again everyone > [quoted text clipped - 39 lines] > -- > Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ when release bearings go they make a squealing noise when you put any pressure on the pedal, I have known them squeal for hundreds of miles with no ill effects other than annoying passers by. its is a fiddly job, but not hard, and does not in any way indicate that you need a new clutch plate or spring. its the sort of job that any competant mechanic or garage should be able to do in less than an hour - even i would only allow a bit over an hour, and i am SLOW.... old age and too high a value on fingers.. I can only assume that the new slave has cured all the "feel" and function of the clutch and that the only issue now is the noise? Jim > Hello again everyone > [quoted text clipped - 39 lines] > -- > Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ > when release bearings go they make a squealing noise when you put any > pressure on the pedal, I have known them squeal for hundreds of miles [quoted text clipped - 13 lines] > function > of the clutch and that the only issue now is the noise? No and yes. The noise is constant (when the car is moving and clutch engaged (foot off pedal)), not when pushing the pedal. It seems proportional (in terms of frequency) to the speed of the car. But yes, it feels fine from the driver's point of view (if a little embarrassing when carrying passengers!). Thanks for your time Jimbo, Will >> Hello again everyone >> [quoted text clipped - 55 lines] >> -- >> Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ SignatureUsing M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ > No and yes. The noise is constant (when the car is moving and clutch > engaged (foot off pedal)), not when pushing the pedal. Does pushing the pedal change the noise? > It seems proportional (in terms of frequency) to the speed of the car. Rather than the engine? It's not the clutch release bearing. It's probably a wheel bearing, a CV joint or a diff bearing, in that order. > > No and yes. The noise is constant (when the car is moving and clutch > > engaged (foot off pedal)), not when pushing the pedal. [quoted text clipped - 7 lines] > It's not the clutch release bearing. It's probably a wheel bearing, a CV > joint or a diff bearing, in that order. That's interesting. The reason I thought of the clutch is that the scraping started just before the pedal went, and went away for one whole day the day I got the slave cylinder replaced... but it's back now, and thinking about it it's possibly a coincidence. I'm new to cars (but very keen to learn), so if it's not too much trouble can you give me some pointers as to how to diagnose this further? If I jack up the front right, is there likely to be play in the wheel if I wiggle it and the bearing's gone? Would I have to replace both sides at once? I don't really know what a CV joint does, so I'll check Hynes when I get home, but I'm assuming that the order of things that might be wrong are also the order of difficulty to fix?! Thanks Graham Will > > > No and yes. The noise is constant (when the car is moving and clutch > > > engaged (foot off pedal)), not when pushing the pedal. > > Does pushing the pedal change the noise? > > > It seems proportional (in terms of frequency) to the speed of the > > > car. > > Rather than the engine? > > It's not the clutch release bearing. It's probably a wheel bearing, > > a CV joint or a diff bearing, in that order. > That's interesting. The reason I thought of the clutch is that the > scraping started just before the pedal went, and went away for one [quoted text clipped - 4 lines] > trouble can you give me some pointers as to how to diagnose this > further? OK, you report that the noise "seems proportional (in terms of frequency) to the speed of the car." So it doesn't happen at all when you're standing still, and it gets "faster" as the car goes faster. Therefore it has to be something which moves when the car moves and doesn't when the car doesn't move. Think about the power train. The motor changes speed with the throttle and load. When you change gear, the engine speed changes, so any noise which comes from the engine turning must do the same. After engine, power passes through the clutch. A noisy clutch problem will make a noise which rises with engine speed, not road speed. Because the clutch release bearing is simply what applies the release force to the clutch, it makes most noise when the pedal is pushed down. So a sick release bearing makes noise which rises with the engine speed, not road speed and which gets quieter or goes away when you release the clutch pedal. Power then passes through the gearbox. Gearbox noises go away when the car is stationary (with the clutch depressed) since nothing in the gearbox is moving. After the gearbox (inside the gearbox in a Mini) is the diff. The diff, driveshafts, CVs and wheel bearings are all fixed to the wheels. When the car moves, they turn, even if the motor is off. And when the car is stopped, they don't turn, even if the motor is revved wildly. Since your noise is related to roadspeed, not engine speed, it's got to be after (or in) the gearbox. Driveshafts are pretty simple, there's not much can go wrong with a steel rod with splined ends. CV joints join the drive shafts to the diff and to the hubs. CV joints wear if the boots are damaged (grit gets inside) and then they click, but they rarely grind. Dead diffs are relatively unusual, whereas dead wheel bearings are fairly common. > If I jack up the front right, is there likely to be play in > the wheel if I wiggle it and the bearing's gone? It could be the front left... Or does it sound like it's coming from front right? > Would I have to replace both sides at once? No, but if one side has failed, you should consider why it has failed and perhaps have a look at the opposite side... > I don't really know what a CV joint does, It's a way of joining two shafts together so that as one rotates, the other does too, AND the angle between them can vary. Think of the problem of a drive shaft driving a front wheel which moves up and down and which steers left and right. Something has to bend and transmit drive. Ordinary universal joints can do this for small angles, but for large angles such as when steering a front drive car, the output side doesn't turn at a constant speed - it's speed varies through one complete revolution of the shaft. A CV joint does not have this "lumpiness". > so I'll check Hynes when I get home, but I'm assuming that the order > of things that might be wrong are also the order of difficulty to > fix?! Curiously, yes it is. It is not always so. When deciding what to check from a list of possibilities you typically balance probability and ease of checking and check the simplest, most likely faults first. When the most likely cause is also spectacularly difficult to check, it is alway wise to check all the bizarre and unlikely possiblities before pulling out the motor and box and dismantling them... That's really helpful. Many thanks for all this Graham. I shall have to experiment further to get to the bottom of it. At the moment I'm stationary as the brakes need urgent attention (master cylinder I think-pedal travels right to the floor, bleeding them hasn't helped, rear drums look ok on inspection (no leaks), handbrake ok, calipers on front changed for MOT <1000 miles ago, can't "pump it up"; so I'm tied up with that for the next couple of days). As soon as I'm moving again I'll double check the symptoms (clutch in/ clutch out, etc.). Like I say I've limited experience, but logically one of the plates in the clutch must be revolving at the same rpm as the wheels? This is how I justified the symptoms being part of the clutch to myslef, given that I had the clutch m/c problem at the same time, although I appreciate that it's incresingly unlikely. It's definately from the right hand side of the engine bay, but I'll be investigating! Cheers, Will >> > > No and yes. The noise is constant (when the car is moving and clutch >> > > engaged (foot off pedal)), not when pushing the pedal. [quoted text clipped - 97 lines] > is alway wise to check all the bizarre and unlikely possiblities before > pulling out the motor and box and dismantling them... SignatureUsing M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ Could it be a stone caught in the brake calliper or the shoes down to the studs? The Muffin Man > That's really helpful. Many thanks for all this Graham. I shall have to > experiment further to get to the bottom of it. [quoted text clipped - 119 lines] > -- > Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ > Could it be a stone caught in the brake calliper or the shoes down to > the studs? Neither of those would cause this: > > At the moment I'm stationary as the brakes need urgent attention > > (master cylinder I think-pedal travels right to the floor, bleeding > > them hasn't helped, rear drums look ok on inspection (no leaks), > > handbrake ok, calipers on front changed for MOT <1000 miles ago, > > can't "pump it up"; so I'm tied up with that for the next couple of > > days). As soon as I'm moving again Pretty clearly it's a major wheel bearing failure. I do apologise, only half paying attention and looking for the simple and easy to check rather than the complicated. The Muffin Man > > Could it be a stone caught in the brake calliper or the shoes down to > > the studs? [quoted text clipped - 9 lines] > > Pretty clearly it's a major wheel bearing failure. > I do apologise, only half paying attention and looking for the simple > and easy to check rather than the complicated. 8-) I think we covered this earlier when I wrote: "When the most likely cause is also spectacularly difficult to check, it is alway wise to check all the bizarre and unlikely possiblities before pulling out the motor and box and dismantling them..." > That's really helpful. Many thanks for all this Graham. I shall have to > experiment further to get to the bottom of it. > > At the moment I'm stationary as the brakes need urgent attention You have disk brakes don't you? Stuffed wheel bearing. The brake problem is caused by the slop on the bearing - the disk knocks the pads back. > Like I say I've limited experience, but logically one of the plates in > the clutch must be revolving at the same rpm as the wheels? No. The flywheel and pressure plate turn with the engine. The clutch driven plate turns at the speed of the input side of the gearbox. If you put your foot on the clutch (to disconnect the engine) as you roll down a hill, the driven plate speed is determined by road speed and by which gear you're in. If the car is in neutral, then the driven plate doesn't turn. If you put the car in 1st as you roll down a steep hill at 60mph, you can easily sping the driven plate far faster than it can withstand, bursting it with centrifugal forces. This failure is sometimes seen in 4WDs when the driver loses control in lowrang first or second climbing a hill and rolls back with his foot on the clutch. The gearing on a 4WD can be so low that quite moderate speeds will overspeed the clutch. > > That's really helpful. Many thanks for all this Graham. I shall have to > > experiment further to get to the bottom of it. [quoted text clipped - 5 lines] > The brake problem is caused by the slop on the bearing - the disk knocks > the pads back. Eureaka! That would certainly explain everything going at once... Would this broken bearing be likely to cause further damage to other parts of the car? (I'm thinking of the cv joints which you say are in close proximity) I can't thank you enough for your ideas and feedback; can you let me know how easy/ hard this is going to be to fix? My original plan was to fix the brakes and then drive it to a friend's place (1 hr away) and look into the rest. It's parked outside my London flat- I have only as many tools as would fit in the boot- i.e. a range of spanners, pliers, screw drivers and jack (no axel stands, torque wrench, which I assume are necessary?). And I'd love to avoid sending her to the dodgy mechanics in the North London area! > > Like I say I've limited experience, but logically one of the plates in > > the clutch must be revolving at the same rpm as the wheels? [quoted text clipped - 4 lines] > The clutch driven plate turns at the speed of the input side of the > gearbox. Ah, that makes sense. I thought the clutch came between the gear box and the wheels (can you imagine changing gear if I had designed your car?!! *crunch*) > If you put your foot on the clutch (to disconnect the engine) as you > roll down a hill, the driven plate speed is determined by road speed and [quoted text clipped - 8 lines] > hill and rolls back with his foot on the clutch. The gearing on a 4WD > can be so low that quite moderate speeds will overspeed the clutch. Many thanks, Will Don't get too excited Will.... If it was a wobbly disc from a bad wheel bearing you would be able to pump up the brakes when stationary. A bad wheel bearing usually is accompanied by a rumbling sound that is fairly constant and just gets worse. Most likely you have lost the seals in your master cylinder. Any brake fluid dripping on your foot? That's a sure sign while it is also possible to lose a seal that will cause the fluid to bypass the piston inside the master. Good luck, Kelley >> > That's really helpful. Many thanks for all this Graham. I shall have to >> > experiment further to get to the bottom of it. [quoted text clipped - 19 lines] > >Many thanks, Will > Most likely you have lost the seals in your master cylinder. Any brake > fluid dripping on your foot? That's a sure sign while it is also > possible to lose a seal that will cause the fluid to bypass the piston > inside the master. Yeah, I've no fluid leaking to my knowledge- the level in the m/cyl hasn't changed other than when I bled the brakes. I'm coming back to the idea that it's the inner seal- I've odered a refurb kit. I was looking at changing the entire unit, but it's so hard to work out which one I've got! It's a mini 25, which was the first standard car to have discs (other than coopers and GTs). I'm fairly sure it has two pipes leaving the m/cyl, and only one going to the back wheels (front to back brakes?) but the suppliers recommend a "nov '85 onwards" kit which has metric unions, which I'm sure won't fit my car without extra hassle. So I'm going to try and repair what I've got. I guess I have to drain the cylinder from one of the front bleed nipples, take it off, then rebleed the whole system again. I'm *hoping* it will be fairly straight forward to renew the inner seal, but if anyone out there knows any pitfalls I'd be grateful. As for the noise- back to the drawing board I think. I've jacked up the front right, spun the wheel without any play or noises. I've grabbed hold of the axel (/driveshaft?) and felt for play (the cv joints test?) and nothing noticable there either... Once the brakes are (hopefully) fixed on Saturday I'll be able to road test her again and take it from there. Cheers, Will. The Lockheed catalog shows two tandem masters used in the UK. The later unit used from 10/78 to 88 has stepped bores of 19mm and 18mm. The tube nuts are also different sizes the top is 10mm and the bottom is 12mm. This is the easiest way to identify which master cylinder you have. The rebuild kit is LK11408, the earlier unit used LK11237. It sounds like the suppliers might be right for your Mini. Sometimes you just have to take a chance :^) Cheers, Kelley >> Most likely you have lost the seals in your master cylinder. Any brake >> fluid dripping on your foot? That's a sure sign while it is also [quoted text clipped - 24 lines] > >Cheers, Will. > The Lockheed catalog shows two tandem masters used in the UK. The > later unit used from 10/78 to 88 has stepped bores of 19mm and 18mm. [quoted text clipped - 3 lines] > > It sounds like the suppliers might be right for your Mini. Yeah, having come home from work I've seen the tell-tale yellow tag which identifies it as the one supposedly for 1985 onwards cars. As my car is '84 I've ordered the previous repair kit, which I'll have to send back and have the correct one organised... I'll do that first thing tomorrow morning (I desperately want her fixed this weekend!), but just in case anyone reads this within the next twelve hours and has experience of reconditioning master cylinders, am I better to just replace the whole unit (at 3x the cost, £100ish) or is the risk of it not coming apart(and/or me breaking it) relatively low? > Sometimes you just have to take a chance :^) err, I bought a mini, didn't I?! Cheers for your time Kelley Will Having had some problems in this area myself - i have found that rebuilding and replacing the seals on a twenty year old part that is pretty worn to be a false economy - personally i would bite the bulet and fit a new one, especially if you are going to have to remove the whole master cylinder anyway,it will last longer and will give you peace of mind. Btw £100 for a clutch master cylinder sounds VERY steep to me mate.... Good luck Ed hiya I was just saying that i would replace the lot to save having any trouble in the same area again, for the cost its silly not to. fragged > Hello again everyone > [quoted text clipped - 39 lines] > -- > Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ > hiya > I was just saying that i would replace the lot to save having any trouble > in the same area again, for the cost its silly not to. > > fragged Thanks Fragged, I'm thinking of sending it in to Mr Clutch, where labour will be a large part of the cost and so like you say, I'll have all three pieces changed at once. Just wish I had premises/ tools/ balls to tackle it myself! Cheers, Will. >> Hello again everyone >> [quoted text clipped - 55 lines] >> -- >> Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ SignatureUsing M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ |
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