problems with brakes...again

[MMamdouh]

since i have done my 1.6 brake upgrade on my woo and i am having problems

the left wheel got a ton of issues... it locks prematurely and the car pulls to left when brakes applied... specially in the very first couple of kilometers of driving

since i have encountered those issues i have:

1- replaced OEM 20mm master cyl. with 22mm master cylinder (pedal travel reduced significantly but same problems occur)
2- replaced used, wrapped GM rotors with brand new SK rotors (same problem occurs)
3- bleeding the system
4- replaced shitty pads with new set (same issues)
5- replaced tires (same issue)
6- replaced all caliper pins that goes into the brackets (same issue)
7- replaced left caliper bracket (same issue)
8- bleeding the system
9- unified brake hoses between left and right as i was using a longer line on the left side so i:

a- used both OEM lanos lines (nothing happened)
b- using both nubira - longer - lines (premature locking seems to be better but not cured)

10- bleeding the master cylinder
11- replaced right wheel piston (same issue occurs)
12- bleeding the sytem
13- replaced pads again (same issue)
14- bleeding the system

the only things that were not replaced here are:

left wheel piston
right caliper bracket

i am fed up with this problem and i am running out of ideas... i am thinking of replacing both wheel pistons with their brackets and call it a day but i am not sure if this will cure the problem

can you guys tell me if their are any causes for such problems that i have missed out??

i am expecting a set of slotted and dimpled EBC rotors and i already have my EBC green stuff pads and i don't want to put this setup on the car till i get this problem sorted out so please please help

MMamdouh

[Daniel]

Hi MM,

Not cool this issue.

1st idea: Do you still have rear drums? I have had a similar issue of blocking one front wheel due to a opposite (diagonal) defective rear cylinder. One of it's pistons didn't return to rest position and the relative lining was too close of the drum. The pressure build up was then faster on this branch of the X braking system.

2nd idea: One of your proportional valve is not functionning correctly. Try to swap them.

Hope you'll have no need of emergengy braking till it's fixed .

Daniel

[GsiTurbo]

There is another possibilty. One or more of the front suspension components may be worn (old, very flexible by now bushings etc, or weak upper strut mount)...so you apply brakes...the force from braking makes the weak component(s) starting to flex and causing one wheel all the suddent to go out of alignment. As a result it has less friction between the tire and the surface than the other one and locks up????

[MMamdouh]

Hi MM,

Not cool this issue.

1st idea: Do you still have rear drums? I have had a similar issue of blocking one front wheel due to a opposite (diagonal) defective rear cylinder. One of it's pistons didn't return to rest position and the relative lining was too close of the drum. The pressure build up was then faster on this branch of the X braking system.

2nd idea: One of your proportional valve is not functionning correctly. Try to swap them.

Hope you'll have no need of emergengy braking till it's fixed .

Daniel

i still have rear drums indeed and you reminded me of something... every time i recalibrate the rear shoes i get knocking noise from the rear right tire for some time so i am suspecting some problems from the rear end... and i also have worn rear rotors and a replacement (including pads and bearings) will cost as much as the projected rear disk upgrade i am planning to do soon

anyways the point here is i might be having issues with the rear brakes indeed but it doesn't explain why this happened after the swap??... actually i got that noise right before the swap and it was the reason i rushed into the swap as i thought the problem was the front brakes

will try to check the P valves and see if they are blocked or look bad... i will have to mod them anyways for the rear disks swap (no idea what exactly to do about them really)

MMamdouh

[MMamdouh]

There is another possibilty. One or more of the front suspension components may be worn (old, very flexible by now bushings etc, or weak upper strut mount)...so you apply brakes...the force from braking makes the weak component(s) starting to flex and causing one wheel all the suddent to go out of alignment. As a result it has less friction between the tire and the surface than the other one and locks up????

i am suspecting that too and i am already planning for 4 new Monroe shocks as the current shocks are weak as hell (currently feel like driving a boat) and during the replacement we will tear down the front suspension and will be able to check every bit of the suspension and make sure it is fine

i have found something in the alignment sheet though... i got 2.30 caster in the front left and only 2.15 in the right... can this be a factor affecting the car balance under braking and cause what i have described??

MMamdouh

[wolfhound]

I had similar problem on my classic Mini - turns out the rear flexible hoses were persished on the inside - changed them and the brakes are now perfect.

Sean

[GsiTurbo]

I am curious...any developments on this?

[MMamdouh]

so far no

i am currently raising up funds for the monroe gas shocks and once i got the money i will tear down the whole front suspension for replacement and checkup

my mechanic said it might be something related to improper wheel bearing installation so i will take this into account as well

can the caster measurements have an effect regarding what i am suffering from?

MMamdouh

[MMamdouh]

here is the update... and i always give the bad news first... i still got premature wheel lockup... but now it is in the front right wheel

i honestly don't remember when the hell did this issue switch to the other wheel but anyways lets keep diagnosing together...

since the last report i did the following:

1- replaced all 4 shock absorbers with Monroe shocks, strut mounts and spring seats
2- the above replacement was accompanied with rotors and pads replacement
3- some 5k kms later i swapped rear drum brakes with rear disks
4- some 3k kms later i replaced front pads with EBC green stuff

during this period i didn't notice the lockup issue or the switch from left to right at all... i only noticed that after i have painted the calipers in red and went for a test drive and was doing like 160 KPH and then braked hard for a U turn... car was going some 30 degrees to the right and the front right locked

this only occurs when the brakes are applied hard... easy or "usual" brake usage doesn't induce such problem

i was fed up with the problem so i went to my mechanic yesterday and replaced both front brake calipers.... i got a couple of 1.6 lanos calipers and i did pop both pistons and cleaned the hell out of it as well as the piston housing from all dirt and deposits and also removed the nubira brake hoses (too long) and reverted back to the OEM hoses (short)>>> and as you guessed... problem is still their

i am frankly fed up with this issue and i am running out of ideas... i highly suspect that this is a brakes issue... i mean i have already came across a shit load of parts that didn't cure the problem and those are:

2 master cylinders (20 and 22mm)
3 sets of rotors (used OEM, SK and Technotrade)
2 sets of rims (14" steel and 15" sport)
3 sets of tires (GT radial & Nankang NS-1 185/60/14 and Kumho ecsta MX 195/50/15)
2 sets of calipers (Nubira and lanos)
5 sets of pads (Turkish pads, 2 sets of gold, Japanese pads and EBC)
2 sets of brake lines (Nubira and lanos)

and despite all that i have managed to switch the problem from left to right and i have no idea when and why did this happen... i am beginning to suspect that the issue is suspension related rather than brakes but again i got new shocks, spring seats and upper strut mounts... the only old component is the control arm bushing set ( i have swapped my springs with 1.6 spec springs down the line)

i also want to add that i have some 2 cms extra on the ride height of the front right wheel, car pulls to right under acceleration (could be torque steer) and 15' discrepancy in caster angle of the front and this car feels a bit more fluid that my dad's woo that is 2 years older and have 20k kms more on the odometer... now given all that... can it be a suspension problem??? probably worn control arm bushings or so??

edit: i have to say that i might be wrong when i say the problem occurred after the brakes upgrade... it might have been their prior to that and it only showed after the upgrade simply because i didn't have enough braking power to induce the problem... sounds logical???

MMamdouh