Pull to left under heavy braking

[slybunda]

hey all, iv had this problem for 2 or more years now where the car pulls to the left under very heavy braking. more apparent when driving on motorway at 70mph. reason iv not investigated it further is due to my driving style im always light footed on the brakes and car is usually used in town driving so the problem is never seen unless an emergency hard stop is needed. but these days im using it more for highway driving so its starting to bug me.
car passes the UK MOT fine with sufficient brake force and within the acceptable tolerance limits for balance between left and right.
the car in question is the toyota celica year 2000.
the brake calipers were second hand and came off a scrapyard toyota avensis which are larger than the original celica ones. as such these were fitted along with brand new larger brake pads and discs for the avensis too. this was done in feb 2014.
the car has passed the UK MOT 4 times (4 years in a row, MOT is in May every year) since fitting the brakes.
now my memory doesnt serve me that well but im sure its pulled under hard braking from day one but again too long ago to remember
since then i have replaced the brake hoses for HEL braided ones (in jan/feb 2016), and few months ago i replaced the slider pins and pad guides which still make no difference to the pull.
fingers are being pointed to the calipers now but they dont stay stuck and retract back.
under low braking effort it brakes in a straight line, but when you push down harder on the pedal it starts pulling to the left.

what could cause this to happen?
tyre pressure is even.
im thinking before i spend some money i should swap the pads and discs from left to right wheel to see if pull changes direction?
wondering if this is a hydraulic issue or mechanical and where i should start looking?

 

[CharBaby]

A mechanic friend told me this and it is my understanding with vehicles that pull one way or the other while braking(light or heavy braking) is that:

Whichever way the vehicle pulls, it is the other side brake causing this issue.

In other words, if your car is pulling "LEFT", then it's an issue with the "RIGHT" side brake components, be it the brake line(restricted) or pad sticking(slider pins) or brake caliper not functioning properly.

I'm not sure how I feel about this as it's to opposite of my thinking!

 

[dlundblad]

Rotors and collapsed brake hoses can cause pulling too.

I like the idea of upgrading to the larger brakes.

 

[Billbert]

you also need to check the front suspension bushings for any wear. under heavy braking, a worn bushing(s) can change alignment angles and cause a pull

 

[slybunda]

Originally Posted By: dlundblad
Rotors and collapsed brake hoses can cause pulling too.

I like the idea of upgrading to the larger brakes.


How can a brake rotor cause pulling?

 

[mk378]

If the friction surface of the rotor has a ring of rust on it, the pad doesn't work on that area and braking effect is reduced.

 

[slybunda]

i just went and checked this and you are correct, the outside surface of the right hand side disc which can be seen through the wheel is fine but the inside part facing the hub has a ring of rust on it. the left side disc doesnt have any rust.
dunno how i missed this when changing the caliper sliders although i was only looking from the outside face of the disc.
the ring is 1cm thick in diameter, dunno if this can affect the brake force by much. i will wait for weather to get better then swap discs and pads from one side to the other and see if the pull goes in the other direction.

what would cause this to happen? discs and pads are about 10k miles old at most. and plenty of pad life left.

 

[slybunda]

can tyres cause this issue? just checked and the left tyre is down to 2.2mm tred across the tyre width. the right side tyre has nearly 4mm tred remaining. dunno if the brake pull has caused the left tyre to wear more than the right tyre. alignment is fine.

 

[mk378]

You have found the problem, quit fooling around. Replace that rusty rotor. And new pads.

I assume you've also checked the rear brakes?

 

[mk378]

Originally Posted By: Char Baby
A mechanic friend told me this and it is my understanding with vehicles that pull one way or the other while braking(light or heavy braking) is that:

Whichever way the vehicle pulls, it is the other side brake causing this issue.

In other words, if your car is pulling "LEFT", then it's an issue with the "RIGHT" side brake components, be it the brake line(restricted) or pad sticking(slider pins) or brake caliper not functioning properly.

I'm not sure how I feel about this as it's to opposite of my thinking!

When you're in a curve to the left, the left side of the car is moving slower than the right one.

So when someone like the OP is going in a straight line and put on the brakes, the right brake is bad but the left brake works normally to slow down the left side of the car, the car is going to want to curve to the left.

 

[slybunda]

Originally Posted By: mk378
You have found the problem, quit fooling around. Replace that rusty rotor. And new pads.

I assume you've also checked the rear brakes?


iv just checked the rears now and they are fine. looks like i will sort out the front discs and pads

 

[SilverFusion2010]

Regrease the caliper pins and make sure they are moving freely. You can try sanding off the rust ring and see if that resolves the problem. If it does not, then new pads and rotors for the axle

And make a hard stop once or twice a week, get the brakes hot. Don't go crazy, just get them hot

 

[Warstud]

Originally Posted By: slybunda
I have replaced the brake hoses.... I replaced the slider pins and pad guides which still make no difference to the pull. Fingers are being pointed to the calipers now but they dont stay stuck and retract back.


I think your right caliper isn't engaging as fast as the left caliper. You could try exercising the caliper piston in and out to free it up.

 

[slybunda]

Originally Posted By: Warstud
Originally Posted By: slybunda
I have replaced the brake hoses.... I replaced the slider pins and pad guides which still make no difference to the pull. Fingers are being pointed to the calipers now but they dont stay stuck and retract back.


I think your right caliper isn't engaging as fast as the left caliper. You could try exercising the caliper piston in and out to free it up.



yes it does feel like the caliper is slower to engage.

slider pins have been replaced for brand new ones and greased up with ceratec grease

 

[slybunda]

so an update, today i swapped the discs and pads from left to right. the pull is the same. still pulls to the left. done some very heavy braking sessions today and when i got out i noticed the side it pulls to which is the left that side is hotter than the right side.
so i guess that rules out the discs and pads.
both discs had the inside part suffering from a rust ring.
photos attached

oddly the side of the discs thats visible from the wheel spokes doesnt have a rust ring but there is a discoloration of the outer edge part.

any ideas what would have caused this? pads were free moving and not stuck and the sliders are moving perfectly fine too.

 

[slybunda]

full size pics:
http://picpaste.com/pics/rotor1-d2B06GH7.1502016230.jpg
and
http://picpaste.com/pics/disc1.1502016182.jpg

 

[KrisZ]

Could be a collapsed hose. It works fine under normal braking, but under heavy braking, when more fluid is displaced, it restricts the flow.
Also, looking at the pictures, the inside pads are not properly contacting the discs, so there is a problem there as well.

 

[slybunda]

Hoses are HEL stainless braided teflon ones. They dont fail like rubber hoses. If a teflon hose fails it instantly ruptures from inside and suffers total loss of braking. If i had known this before i would have never bought them. Too bad i disposed of my old rubber hoses.

Not sure why the inside pads are not in contact. Everything is free and greased up.
Im wondering if dodgey caliper pistons can cause this sort of issue?

 

[Warstud]

I would remove the calipers and hang them upside down and put 2 brake pads or? at the end of the caliper so the piston doesn't come out. Apply the brakes and check the travel of the pistons. Exercise those pistons in and out about five times until it free's it up. If that doesn't work you may need to rebuild your calipers.

 

[slybunda]

hmm if the piston pops out can i just be put back in or will there be issues. it looks fairly rusty on the outside but dont know its condition on the inside. i tried to push the pistons back in with my hands but they were not budging, normally i would need a clamp tool to do that though.