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MG MGA Rear Brake Locking Up BBS discussion at MG-Cars.net
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MG MGA - Rear Brake Locking Up
| I have discs on the front, drums on the back. In the last week the right rear wheel has started locking up and skidding under moderate braking, usually preceded by a noticable pull to the right. I have just been round all 4 wheels. Had them all off and checked the linings and pads. All look clean, no sign of contamination. Adjusted rear brakes, all to no avail. Drums in good condition, only done about 14,000 miles. The only thing I have not checked for is a seized piston (Can't get the wife to press the pedal for me - got her Christmas Present sitting on the passenger seat under the half tonneau!). Is this the most likely cause (not the present, the piston!)? Steve |
| Steve Gyles |
| Steve I would always expect that if a rear brake locks up then somehow the front brakes have lost their efficiency. From your description it sounds like the left caliper is somehow faulty. |
| Bob (robert) yes I own an MG Dwarf! |
| Thanks Bob. Interestingly the left front pads (MGB calipers and pads) have been squealing a lot recently. I assumed it was just a case of a bit of 'Copper Ease' grease required on the back of the pads, but I will investigate a bit deeper. Steve |
| Steve Gyles |
| Thanks for the tip, I'm off to look for it now, dinner is in the oven. I hope its better than last years! Happy Xmas XXXXX |
| Mrs Gyles |
| Hi Steve.It sounds like you have either brake fluid or rear axle gear oil contaminating the brake shoe linings. I had the same problem a while ago, and found gear oil in the brake shoe linings. Cheers, Glenn |
| Glenn |
| Don't be suprised if its a new distributor! It may be big but it won't be expensive if it's been stored in the MGA with a tatty, leaking tonneau - I speak from experience!!! Kim Bray (always playing second fiddle to rusting pile of metal) |
| K Bray |
| Glenn No leaks in my car. Back axle totally dry (on the outside) and nothing dripping from the pistons. Kim, actually it's a smart leaking tonneau. Steve |
| Steve Gyles |
| Huh - he's got me what looks like a rolling pin! It's a metal lumpy thing, its got PIPER BP285 on the box, I can't see one like it in the Argos catalogue. Maybe I'll hit him with it when he comes home from work, wet again! Even worse, is when we go out in it and it rains, people think were both incontinent, how embarrassing! I remember last year at Le Mans a nice chap with a smart red coupe, what a sensible car, pretty as well. Digruntled Wife |
| Mrs Gyles |
| I was thinking of buying her a supercharger rather than a high spec cam. She is never happier than when I am happy working away on the car. It would have been a great present! Steve |
| Steve Gyles |
| My undersatanding is that anything with Piper Kent or Elgin on it is indeed a rolling pin with eight bits of dried pastry stuck to it. Apparently the position and amount of dried pastry has some significance. My advice is to go for the chap with the nice warm red coupe, alternatively give him my phone number. Mrs Kim Bray |
| Mrs Kim Bray |
| So, you think I have been joking? http://freespace.virgin.net/stephen.gyles/odds_and_sods.htm Steve |
| Steve Gyles |
| A colleague at work agrees with Bob's analysis. He commented that the dual pistons can get sticky and eventually seize because of their limited moment during normal brake applications. He suggested that one way to get sticky pistons moving again is to remove the pads and replace with thinner section metal bar (spanner?), apply brakes, release, push the the pistons back, repeat a few times, then bleed off the fluid in that caliper. Is this a worthwhile procedure or should I, as my gut feeling tells me on safety grounds, dismantle the caliper and give it all a good clean? Steve |
| Steve Gyles |
| Steve, Are you sure the problem is not being caused by the weight of that large box on the passenger seat? Malcolm |
| Malcolm Asquith |
| Malcolm Chicken or the egg? If my brakes were working properly the box would be in the footwell, not on the seat! Steve |
| Steve Gyles |
| Me, a large box! How rude! What about the lump on the drivers seat? What is a supercharger? Maybe some sort of hairdrier? Knowing my other half its probably something for the car, bless him, at least it keeps him off the streets. Happy Xmas Again M G |
| Mrs Gyles |
| Thanks for that Mrs Gyles. I think I will adopt the initials as my normal sign off from now on! What about the serious side to this thread? I need some genuine advice about my brakes. Mr Gyles MG |
| Steve Gyles |
| If this is a "mechanics Democracy" I vote for rebuilding the brake parts. I'm not sure how the diagnosis went from right rear wheel l"locking up and skidding" to front left caliper seizing, but, in any event I've found that problems like this frequently come from corrosion in a brake wheel cylinder (or caliper, in the case of disk brakes), so a clean out and rebuild is the best (safest)way to avoid a lockup in the future. Steve |
| Steve Brandt |
| Steve If the front caliper(s) sieze in the "open" position then they will not provide much braking force and leave the effort of stopping the car to the rear wheels. HTH Larry 58A |
| Larry Hallanger |
| I vote for fluid contamination. Axle seals or brake seals. All of the above and new linings will only be a few hundred, Mrs. Gyles. But necessary to keep you out of the footwell. |
| Tom |
| Tom As I said in earlier posts, there is no contamination and no leaking axle seals etc. I have already inspected the linings and pads. My car does not leak - amazingly! Braking performance was poor when I last tested, accompanied by a pull to the right, followed by a right rear lock-up. I cannot discount the possibility that the left rear was also locking, but it is the right rear that is closest to my ears and focussed my attention. At slow braking speeds the front nearside brake pads squeals horribly, leading me to believe that the front nearside calipers are 'lazy'. The brake fluid (silicon) is brand new, barely 4 months old, following a MC rebuild. The entire system has been silicon from new, some 9 years for many of the parts although the front MGB calipers are about 5 years old. Currently, the car is laid up pending rectification. Steve MG |
| Steve Gyles |
| Steve You haven't got worn out rear drums have you? Remember reading something about this. The shoes then don't fit the larger radius properly??? Assume you have the little central springs holding the shoes to the backplate and you have 'coppereased' where the shoes rub the backplate... Are the drums still round? i.e. Even rubbing as you rotate the drum when adjusting. Are you near to full adjustment on the rear brakes, making the leading edge really bite and lock things up? Have you tried filing a chamfer on the leading edge of the shoes? Personally I don't think it's anything to do with the front discs. Crimbles Pete |
| Pete Tipping |
| Pete The rear drums and linings are 7 years old - from when I converted my 1500 rear axle to wire wheels. Oodles of wear left on the linings. Nowhere near full adjustment on either drum. Car pulls up very square and relatively powerfully on the hand brake. Leading edges chamferred. I am convincing myself (with the help from Bob) that my problem is the front left disc. That is certainly where my further investigation and overhaul will commence. I will do one brake at a time with a road test to confirm which one is the cause. Steve MG |
| Steve Gyles |
| Just checked above again... Re: The noise in the front brake... Have you checked the caliper pistons are correctly orientated? This is clearly shown in the W/manual. Are the front wheels free to turn when footbrake is released? Do the front wheel(s) run very hot? There can be a situation where the master cylinder can leave a low residual pressure in the system. The rear brakes springs will return the shoes OK, but the pad(s) can be held in contact with the disc, building heat and causing squealing. Don't forget the 'copperease' on the back of the pads and the pad guides. I had this one took ages to suss too. Pete |
| Pete Tipping |
| Steve - have you considered road/weather conditions at this time of year? The rear brakes on an 'A' have a tendency to lock ( I've had mine sideways several times before I improved the front brakes) Damp conditions can cause drums to grab, I had a sherpa van many years ago which was leathal in wet/damp coditions. Also there is a lot less grip on cold damp roads ( the traction control on my Golf confirms this ) I don't think you have a front brake problem, scuff the shoe lining with some coarse sanding paper, try swapping the drums left to right, this used to work on Mini's and Marina's back in the good old days (NOT!). Regards Terry P.S. Supercharger's dont go down to well on Xmas morning, you may have it thrown at you, if so, make sure you catch it ! Get her something practical like a 45 DCOE and manifold, maybe a rear disc brake conversion? |
| Terry Drinkwater |
| Terry Some good points. I guess cold tyres and road surface don't make for the best grip. I am in the process of looking at the front nearside discs and pads. Pistons are moving. I will give it a road test later this afternoon and report back. Steve MG |
| Steve Gyles |
| Spot on Terry. Road test after left front caliper clean up made absolutely no difference. Swapped the rear drums round and roughened up the linings as per your instructions. Next thing I knew I was picking wife's Xmas present out of the footwell! Steve MG |
| Steve Gyles |
| As it's Xmas, there is no charge for my useful ( sometimes useless) advice. Happy Xmas Terry |
| Terry Drinkwater |
| Ahhh Merde now I feel completely useless. Never mind I bought a Metro from a young lady once that she was unable to drive. On the way home from purchasing it one "Dank" night I soon found out why. The front brakes were in a terrible state and hardly working so everytime I needed to stop the back wheels just locked up! Very exciting I must say! |
| Bob (robert) yes I own an MG Dwarf! |
| I once was given an old DeSoto that went for the ditch every time you stepped on the brakes. I found a rear wheel cylinder had leaked and saturated the brake linings. After repairing the cylinder, it still pulled to the right so much that it was hard to drive. So, I removed the brake shoes on the other side and soaked them in brake fluid too. After reassembly it stopped straight as an arrow. I would not do that now, but in those days money was tight, and I hated to toss nearly new brake shoes in the trash. I drove that car for several years without any other brake problem. |
| Ed Bell |
| Now there's one I don't think I would have ever come up with! My old mechanic uncle, long gone now, told me to use carbon tetrachloride to clean the shoes. The linings tend to soak up fluids like a sponge, though. New seals and linings, maybe from a mechanic that guarantees his work. Some guys love a challenge, and will persevere until the problem is resolved. These are the mechanics to give your business to. My old van locks up the right rear whenever there's moisture in the air. Only a problem when moving slowly, otherwise the speed dries it out enough immediately at first application. Not a big enough problem to take it apart for a lazy guy like me. See you in heaven (I hope). |
| Tom |
| Bob, Don't feel bad about it. It forced me to check and clean the whole system out which is no bad thing. I have to say that I too had convinced myself it was the front left. The bonus is that I have got rid of the squeal from that brake. Tom's reference to carbon tetrachloride brings back memories of my youth. I remember using it in the early 60s. I recall having to sign a register for it in our local chemist shop, probably because I was only 16 at the time and the chemist was a bit suspicious of my intentions with it. Is it still readily available or what is the recommended brake lining cleaner these days? Wife's present now out of the car and under the tree. I hope she likes the supercharger! Steve MG |
| Steve Gyles |
| One cause for a sticky brake shoe when damp is the leading edge of the shoe digs into the light rust of the drum. This can be remedied by adding a chamfer to the leading edge of each of the brake shoes. Carbon-tet was commonly available here in the states for many years up till..... maybe 1970 or so? It was used for many things such as spot cleaners and fire extinguishers. I really don't know of a readily available substitute today. Chuck |
| Chuck Schaefer |
| Seems like carbon tet was what we used to kill the bugs for our bug collections as kids. I suppose it causes cancer and brain damage. |
| Tom |
| Hi, hope you all had a great Xmas. Tetrachloride was used in brake cleaner up to a few years ago, then they discovered it wasn't very good for you and banned it. Interestingly 'they' also new asbestos brake dust wasn't very good for you either but it took something like 15 years to ban it! Terry |
| Terry Drinkwater |
| Can't spell, for 'new' read KNEW, to much red wine consumed over Xmas! Terry |
| Terry Drinkwater |
| Thanks for the info Terry. What stuff would be used today? - not that I have any contamination at the moment. I know you can't spell! No problem. For 'to much red wine' read 'too much red wine'. Steve MG PS. It wasn't a supercharger. At a bit of a loss of what to do now on the A. |
| Steve Gyles |
| When I had repetitive rear hub seal problems, I sometimes gave oiled up brake shoes a quick wash in lacquer thinner, blow dry, and put them back in service. Never had any problem with this. |
| Barney Gaylord |
| A friend of mine, mow in his mid 80's, has lots of tales of shoe-string motoring in the early post war days. He told me once that they used to "repair" fluid soaked brake shoes by throwing them on the coal fire in the house for a few hours. I add the usual disclaimer, and no, I have never tried it. |
| Malcolm Asquith |
| When they were riveted on, it might just have worked. Today, the linings would probably fall off when the glue burned. I'm kind of curious as to what kind of hi-temp glue they use today. |
| Tom |
| Tom Glue? Still using rivets on mine. Steve |
| Steve Gyles |
| Back when my MGA was only a few years old, my high school shop teacher had me remove the oil-soaked rear shoes and use an oxy-acetylene torch to clean them. I ended up buying new shoes when the linings crumbled. New axle seals and new shoes did cure the brake lockup problem, though. |
| ken morton |
| Steve, Glad to see your brakes are working. Trust your wife liked the pressie. My 1600 road car has done 500,000 miles without disturbing the calipers! Only touch them as a last resort. My brakes work perfectly, you should know, you drove the car!! Cheers, Barry |
| Barry Gannon |
| Hi Barry Great to see you on board. After the miserable Xmas weather over here maybe I will get to drive your car again next Christmas!! Glad we did not come over this year. It would have been too embarrassing suffering your comments about our cricket team's performance! How about a picture of you and the car for the gallery? Have a look at the thread titled 'Foto' Steve |
| Steve Gyles |
| The spray-on brake cleaner I have smells a lot like lacquer thinner. I don't think heat would help, it might burn off some oil from the shoe surface but I would be concerned about delaminating if the shoes have glued-on lining and warping if riveted. |
| Steve |
| Steve, I just read most of your posts. If you have not corrected the problem by now, look to see that the brake pedal return spring is still in place. I had about the same problem with my A and found the spring broken. Good luck, John |
| mgdoc |
| John Yes, all sorted. Swapping the rear drums over cured the problem. Steve |
| Steve Gyles |
This thread was discussed between 17/12/2006 and 06/01/2007
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