front disc brake shuddering
Orig. Posting Date | User Name | Edit Date |
Apr 3, 2017 07:15PM | malsal | |
Apr 3, 2017 05:23PM | h_lankford | |
Mar 30, 2017 12:01PM | CooperTune | |
Mar 30, 2017 02:45AM | oldminimover49 | |
Mar 30, 2017 02:25AM | h_lankford | |
Mar 29, 2017 07:11PM | Alex | |
Mar 29, 2017 02:53PM | h_lankford | Edited: Mar 29, 2017 02:54PM |
Mar 29, 2017 02:52PM | h_lankford | |
Mar 29, 2017 07:11AM | Dan Moffet | |
Mar 29, 2017 07:10AM | nkerr | Edited: Mar 29, 2017 07:11AM |
Mar 28, 2017 04:50PM | h_lankford | |
Mar 28, 2017 03:02PM | DRMINI | |
Mar 25, 2017 02:39PM | h_lankford | Edited: Mar 25, 2017 02:46PM |
Mar 25, 2017 11:28AM | minimans | |
Mar 25, 2017 11:05AM | h_lankford | |
Mar 25, 2017 09:54AM | Alex | |
Mar 25, 2017 04:53AM | dklawson | |
Mar 25, 2017 04:41AM | nkerr | |
Mar 25, 2017 04:31AM | h_lankford | Edited: Mar 25, 2017 04:32AM |
Mar 25, 2017 02:41AM | Alex |
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If in doubt, flat out. Colin Mc Rae MBE 1968-2007.
Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.
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(A) the rotors are getting more warped, or
(B) a loose suspension part is getting looser - either an old part or one of the newer pieces installed preventatively 2 years ago.
I doubt that. Steering back or forth is tight, same for bumps. No noticeable play in system. I even jacked it up and checked again for worn front roller bearings and ball joints with shaking the tires up/down/sideways/diagonal/in/out. Besides, it "feel" like rotors/flanges. Statistically, that is what it is.
A set of higher grade rotors and set of flanges just ordered. Want to be done with this. Get back to everyone in a few weeks. Harvey
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Fully informative, no hype just telling it as it is to help others
Big AL
Niagara Ontario Canada
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I have never felt flat tires from radial tires sitting long, only in past with bias ply years ago. For what it is worth, I will rotate my tires front to back and see what happens but I really do not think this is the issue. This car never sat more than 3 months. Thanks
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My MG ZT-T 260 is a bugger for it, and the owners group recommend leaving the car for a while to cool down and then rotate the wheels half a turn when you get back after a spirited drive. I can certainly attest to brake judder and an uncanny feeling of wheels being out of balance due to flat spots on the tyres (they are a heavy car) after being parked up for a few months.
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Stainless steel caliper pistons . Moved easily when I replaced the pads one week ago as an experiment.
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key information late in the thread: was fine for a long time, but had been sitting a lot and on its own it developed this pulsing, which occurs only under braking, and rotors confirmed not warped. Plus it has been sitting.
My money is on rust causing the issue. Normally, on a regularly used car the rust is continuously removed by pads dragging while driving. A car which sits develops rust on the exposed rotor but the portion under the pads does not = uneven braking, and pulsing.
Either drive it enough so the rust is completely worn off, or have them turned to clean up the faces.
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.
"Hang on a minute lads....I've got a great idea."
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key information late in the thread: was fine for a long time, but had been sitting a lot and on its own it developed this pulsing, which occurs only under braking, and rotors confirmed not warped. Plus it has been sitting.
My money is on rust causing the issue. Normally, on a regularly used car the rust is continuously removed by pads dragging while driving. A car which sits develops rust on the exposed rotor but the portion under the pads does not = uneven braking, and pulsing.
Either drive it enough so the rust is completely worn off, or have them turned to clean up the faces.
N
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More than 1/2 a thou variation, machine rotors or replace.
the problem was NOT there after installation 2 years ago. Smooth as silk then. Surely if it were a factory defect (that thickness variation suggests) then the shuddering would have been there all along.
No, the symptoms have developed after 2 years, and with the car sitting a lot, and no wheel/tire changes or lug nut overtightening. To me, that sounds like warped rotors/rotor runout, although why it developed is what does not make sense considering the light duty the car has had.
When I get all the parts and time, we can measure all that as suggested.
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More than 1/2 a thou variation, machine rotors or replace.
Kevin G
1360 power- Morris 1300 auto block, S crank & rods, Russell Engineering RE282 sprint cam, over 125HP at crank, 86.6HP at the wheels @7000+.
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nkerr - I tried some long hard stops (with the EBC green pads before I replaced them). This just made the shuddering worse. While doing this, the car pulled to the left, but oddly the R rotor was 500F and the L rotor was 360F. Stump the stars.
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Mini's are like buses they come along in a bunch
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The shudder or pulsating feels just like other cars with warped rotors coming down a long mountain grade except mine is not in the mts, but hard stops around town from 60 mph, but not at slower speeds. No wobbly feel like a bent rim or imbalanced tire, I know about those from personal experience. No slop in steering and steering wheel does not shake on brake application, only brake pedal and front of car. . With car jacked up and jerking the tire up down left right diagonal there is nothing to suggest bad suspension parts. Steering rack ends, etc are tight. Wheel bearings rotate freely without suggestion of rough needle or race, and there is no play. Castle nut is tight. I changed the barely worn EBC green pads to black just to do a cheap experiment. I had read about the deposits -on-the-rotor discussion. Rotors look clean and pretty. New pads no different. Package insert said medium braking for break-in, not red hot. I sort of did in between.
The game plan now is to replace the rotors and drive flanges. I am sure that all of you have run out if tests and patience and at some point reached and impasse and decided to just start replacing parts, beginning with those most likely to be the culprit. Stay tuned, it will be a few weeks before I get the parts and work. Harvey
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figured that the inside surface surely must be parallel to the outside surface as it is a solid rotor.
maybe I should put the old rotors back on - there was nothing wrong with them other than some normal rotational grooves. They were neither noisy nor pulsatile. So this might all be a result of modern crap metal going bad just sitting on the garage?
We fitted a new set of hubs, balljoints, discs, pads, CVs etc to Tigger before the IJ in 2011 and he warped the generic budget discs in a week. The much dearer Unipart discs are still on the car and have now done two trips to Italy and back with no problems.
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I offer a different suggestion unrelated to the new disks and pads. Take a close look at the condition of the ball joints and the wheel bearings. Remember one ball joint has the internal spring and may seem OK at first but have play in it that shows when loads are high (like high-speed braking).
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Googling on this I found a lot of brake manufacturers have posted guidelines on how to initially bed them in to avoid uneven braking.
The issue is non-asbestus pads work by depositing a layer of material onto the rotor, and the layer on the rotor interacts with the material in the pad to create braking as intended. If the bedding was done a certain way that layer can be uneven, resulting in bad pulsing.
Either have the new rotors turned (to clean off that layer) and try again, or there are ways to "re-bed" existing rotors on the car (which is what I did, and in my case it was not 100% perfect but it helped a lot).
Note that re-bedding will result in a LOT of brake dust.
Summary of how to re-bed: get the rotors very, very hot (by several very hard brakings from speed), then drive until they have completely cooled. Once the heating procedure is begun do NOT stop and during the cooling use no hard application of the brakes, and no stopping, until the rotors have cooled. So, find a long, straight, deserted road to do it in.
Above is just a summary,
N
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Odd, that's usually what it is - remember they can warp in the blink of an eye especially when new if they are not OE discs...
figured that the inside surface surely must be parallel to the outside surface as it is a solid rotor.
maybe I should put the old rotors back on - there was nothing wrong with them other than some normal rotational grooves. They were neither noisy nor pulsatile. So this might all be a result of modern crap metal going bad just sitting on the garage?
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Pull the front wheels and check for a pad shaped lump of corrosion and use a DTI to check for runout.
So you've checked the inside and the outside of both discs in 3-4 places across the wear surface all the way round for warping and bulges ?
Odd, that's usually what it is - remember they can warp in the blink of an eye especially when new if they are not OE discs...
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