The tale of two discs !
Discussion
Here's two pictures of the l/h and r/h discs on my car. As you can see the left disc is not getting much contact from the pad on the outside edge,,
Here's a picture of the pad and caliper up close,, it appears that the pad is not sitting square to the disc,,
The caliper is square to the disc as the protruding lug suggests,, the lugs are even on all four points of the caliper to the disc,, checked with feeler gauges,, hmm,
Pistons sticking or somehow pushing out unevenly,,,I'll take wheel off and check alignment of caliper etc more carefully and remove pads and see what the Pistons are doing,,
Brembo brakes on 324 mm discs but here's the spanner in the works,,, my old brakes showed the same issue but to a far lesser degree.
Brakes feel good and under normal road conditions are effortlessly stopping the car with a very light press of the pedal, joyous it's that good,,, it doesn't pull to the left under braking unless really stopping from very high speed, 125 mph +
I can feel an imbalance but it's not really noticeable at normal braking use, an emergency stop at 40 mph and both brakes stop the car very quick and the steering stays straight,,
But it's obviously not working as good as the right brake,,
Waffle,,, it's clear I need to ascertain why that pad sits wrong?
L/H
R/H
L/H caliper and pad,,, I'll check the pad with feelers ASAP. Hmm
Here's a picture of the pad and caliper up close,, it appears that the pad is not sitting square to the disc,,
The caliper is square to the disc as the protruding lug suggests,, the lugs are even on all four points of the caliper to the disc,, checked with feeler gauges,, hmm,
Pistons sticking or somehow pushing out unevenly,,,I'll take wheel off and check alignment of caliper etc more carefully and remove pads and see what the Pistons are doing,,
Brembo brakes on 324 mm discs but here's the spanner in the works,,, my old brakes showed the same issue but to a far lesser degree.
Brakes feel good and under normal road conditions are effortlessly stopping the car with a very light press of the pedal, joyous it's that good,,, it doesn't pull to the left under braking unless really stopping from very high speed, 125 mph +
I can feel an imbalance but it's not really noticeable at normal braking use, an emergency stop at 40 mph and both brakes stop the car very quick and the steering stays straight,,
But it's obviously not working as good as the right brake,,
Waffle,,, it's clear I need to ascertain why that pad sits wrong?
L/H
R/H
L/H caliper and pad,,, I'll check the pad with feelers ASAP. Hmm
Edited by ClassiChimi on Friday 27th May 19:41
I don't know if this of any relevance Alun, but I had this on my back brake on my bike .. it turned out that I had slightly crossed threaded the sliding pin/bolt so the calliper wasn't square when I pressed the pedal .. when I pressed the pedal I could see the calliper move in rotation slightly rather than square .. on the bike the sliding pin/bolt was bolted into the calliper that slid onto the mounting bracket ... if any of that makes sense .. so what ever is still original on your set up that keeps it square could be out of alignment ..
Sorry, Alun, but that calliper lug doesn't look square to the disc to me.
If the uneven wear is the whole way round then it rules out the hub not being flat.
But if the place that the calliper bolts on isn't square to the disk/hub, that would give you the issue on both old and new disks, and would be more marked on the bigger disks because the callipers are further away from the centre point, so the error will be magnified.
If the uneven wear is the whole way round then it rules out the hub not being flat.
But if the place that the calliper bolts on isn't square to the disk/hub, that would give you the issue on both old and new disks, and would be more marked on the bigger disks because the callipers are further away from the centre point, so the error will be magnified.
Hi Graham, these Brembo calipers are simple and just have two pins retaining the pad in place, 4pot so pads being pushed from either side and no sliders,,
Got what your saying, I had a mate apply the brakes as I looked at the calipers to see if I could see distortion but I couldn't detect anything!
Anthony your point is where I'm also going here, the hub?
If I'd tapped a hole out of alignment it could pull the bracket askew but I was extremely diligent and in fact very easy to re cut the thread as the original hole is actually slightly larger than ideal to tap, used cutting oil etc so I feel sure it's the holes not being perfectly aligned on the original hub,, or it's been knocked somehow,,
I can show you the original discs and there's a similar wear pattern on the left disc which is why I'm sure it's something to do with those holes?
I need to check carefully again my caliper position and go from there. Cheers boys.
Got what your saying, I had a mate apply the brakes as I looked at the calipers to see if I could see distortion but I couldn't detect anything!
Anthony your point is where I'm also going here, the hub?
If I'd tapped a hole out of alignment it could pull the bracket askew but I was extremely diligent and in fact very easy to re cut the thread as the original hole is actually slightly larger than ideal to tap, used cutting oil etc so I feel sure it's the holes not being perfectly aligned on the original hub,, or it's been knocked somehow,,
I can show you the original discs and there's a similar wear pattern on the left disc which is why I'm sure it's something to do with those holes?
I need to check carefully again my caliper position and go from there. Cheers boys.
It looks to me like the l/h calliper is just radially a little closer to the hub than the r/h? if you look at the r/h disc there is an unworn section on the inner edge but on the l/h the disc it is worn right to the inner edge and the pad is overhanging a little. if you pull the pads you might see the section of pad that is overhanging? this piece of pad might even bake off when you pull the pad? likewise the r/h may have material on its outer edge that is overhanging.
I can clearly see that difference,, so the l/h caliper is sitting closer to the hub,,
So that's either the bracket kit is drilled wrong or my caliper hub bolt holes are drilled a mm or so differently causing the same issue on the old standard brakes?
Does that make sense?
Nice observation NZ, hmmm,,, bugger!
I'll drag my old discs out and compare.
So that's either the bracket kit is drilled wrong or my caliper hub bolt holes are drilled a mm or so differently causing the same issue on the old standard brakes?
Does that make sense?
Nice observation NZ, hmmm,,, bugger!
I'll drag my old discs out and compare.
Edited by ClassiChimi on Friday 27th May 21:50
I removed L/H caliper today and replaced top ball joint at the same time,
The two lugs that the caliper bracket fixes to is not quiet square so it's causing the caliper to lean slightly, oddly I have accurate gaps when using Feeler gauge to square caliper to disc,
I re fitted caliper and bled system,
A combination of new top ball joint and bleeding the brakes and running a lot of fluid down the lines has resulted in next to no pulling on the steering when braking hard , the left caliper is now working better and the brakes are awesome.
I think I never quiet got all the air out the outside bleed nipple before although the pedal was hard,
Bled system, pumped brakes then bled system again,
I use a vacuum pump type bleeder that sucks the fluid through so you don't need to pump brakes, one man operation and it's very good, takes only a few minutes to bleed and the pedal is rock hard.
I've been driving about country's lanes tonight and the brakes seem to be working very consistently and evenly,
Did a few big stops and the brakes are better than before, it must have been air in the system.
Well pleased.
The two lugs that the caliper bracket fixes to is not quiet square so it's causing the caliper to lean slightly, oddly I have accurate gaps when using Feeler gauge to square caliper to disc,
I re fitted caliper and bled system,
A combination of new top ball joint and bleeding the brakes and running a lot of fluid down the lines has resulted in next to no pulling on the steering when braking hard , the left caliper is now working better and the brakes are awesome.
I think I never quiet got all the air out the outside bleed nipple before although the pedal was hard,
Bled system, pumped brakes then bled system again,
I use a vacuum pump type bleeder that sucks the fluid through so you don't need to pump brakes, one man operation and it's very good, takes only a few minutes to bleed and the pedal is rock hard.
I've been driving about country's lanes tonight and the brakes seem to be working very consistently and evenly,
Did a few big stops and the brakes are better than before, it must have been air in the system.
Well pleased.
Thanks Anthony,, it's a conundrum because my calipers are actually very square to the disc as I used 0.5 mm shims and feeler gauges,, you would expect the lugs to be tighter on one side but the feeler gauges show that not to be the case.
I'd took so long to get ball joint out that I was under some pressure to re assemble the car yesterday, PITA as I wanted to rub the discs and pads down a tad, I'll be pulling the right side soon enough just to check my joints so I'll do them all then.
I cured terrible brake squeal with liberal use of copper slip and it's been fine for about 2 weeks,,
I've purchased some of his, when I pull both sides off I'll use it and see how effective it is.
I'd took so long to get ball joint out that I was under some pressure to re assemble the car yesterday, PITA as I wanted to rub the discs and pads down a tad, I'll be pulling the right side soon enough just to check my joints so I'll do them all then.
I cured terrible brake squeal with liberal use of copper slip and it's been fine for about 2 weeks,,
I've purchased some of his, when I pull both sides off I'll use it and see how effective it is.
Just a little update on this one,
Pulled O/S wheel off and inspected caliper and suspension,
Checked bolts are tight etc and left calliper alone
I've been experiencing lock up on the right wheel momentarily before the left and a combination of things seem to have cured it,,
I tried setting ride heights with the chassis corner measure technique etc,, found a flat car park and decided the car was still lower on the left side,
So as an experiment I raised the left front ride height until it was slightly higher than the right side,, ( the theory being it would make the left heavier )
Brake test revealed I was now locking the left front before the right,,,, !!!!! It's never done that before,, so went home and dropped left about 3 mm and did brake tests,,,
Eureka, brakes stop the car on a sixpence and both wheels when seriously provoked lock at about the same time,,
I then did similar stuff on undulating country roads with road camber,, the lot,, same thing applies,, brakes are massively stopping the car and the steering wheel and cars balance is now neutral.
So it's clear to me now that as well as a brake issue on the left I had slightly differing ride heights so the front left wheel was sitting light on the road, raising the ride height on the left side has introduced more weight on that corner and essentially levelled up the braking force,,
I just used that old school approach of adjust based on how the car feels and if I corner weighted the car now I'd be confident the weights on the front wheels are pretty close.
To adjust corner weights you should actually raise or lower the opposing rear corner but that gets complicated without the scales,, I just looked carefully at the cars body attitude,,, this is quite easy if you go to a shopping mall car park and park so you can see the car from front to back using a window transom or door frame line from the building behind to get a very accurate level,,
it's a good guide if you have an accurate eye,, so loaded with crap from PC world and my new eye line, went home and adjusted heights,, kin elk it worked,, hahah. I do realise this is not very accurate and the car park might not be particularly level but it just gave me a thought and then the testing proved the theory.
I'd advise getting geo done at Matt Smiths if your a serious person.
Pulled O/S wheel off and inspected caliper and suspension,
Checked bolts are tight etc and left calliper alone
I've been experiencing lock up on the right wheel momentarily before the left and a combination of things seem to have cured it,,
I tried setting ride heights with the chassis corner measure technique etc,, found a flat car park and decided the car was still lower on the left side,
So as an experiment I raised the left front ride height until it was slightly higher than the right side,, ( the theory being it would make the left heavier )
Brake test revealed I was now locking the left front before the right,,,, !!!!! It's never done that before,, so went home and dropped left about 3 mm and did brake tests,,,
Eureka, brakes stop the car on a sixpence and both wheels when seriously provoked lock at about the same time,,
I then did similar stuff on undulating country roads with road camber,, the lot,, same thing applies,, brakes are massively stopping the car and the steering wheel and cars balance is now neutral.
So it's clear to me now that as well as a brake issue on the left I had slightly differing ride heights so the front left wheel was sitting light on the road, raising the ride height on the left side has introduced more weight on that corner and essentially levelled up the braking force,,
I just used that old school approach of adjust based on how the car feels and if I corner weighted the car now I'd be confident the weights on the front wheels are pretty close.
To adjust corner weights you should actually raise or lower the opposing rear corner but that gets complicated without the scales,, I just looked carefully at the cars body attitude,,, this is quite easy if you go to a shopping mall car park and park so you can see the car from front to back using a window transom or door frame line from the building behind to get a very accurate level,,
it's a good guide if you have an accurate eye,, so loaded with crap from PC world and my new eye line, went home and adjusted heights,, kin elk it worked,, hahah. I do realise this is not very accurate and the car park might not be particularly level but it just gave me a thought and then the testing proved the theory. I'd advise getting geo done at Matt Smiths if your a serious person.
Edited by ClassiChimi on Sunday 29th May 23:29
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