Pulling To The Right Under Light Braking Only

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Mar 10, 2017
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South Wales, UK
Following on from THIS thread, the weird brake pedal is fixed. But now seem to have a new issue.

The symptom is a pull to the right under light braking only. When you brake moderately heavy or anchor on, it pulls straight and true.

This is following work I did to the car on the weekend. This included new ball joints up front, new drop links and I re-bled the entire braking system while running the ABS pump.

I have two theory's

Theory 1 - I've pulled some air or grubby fluid out of a passage within the ABS pump into a line somewhere? I pulled 500ml (half a quart) out of each corner starting with the rear left side (furthest away from the M/C) and finishing with the front right side (closest to the M/C)

Theory 2 - Geometry issue caused by the new ball joints and generally having the suspension apart?

Anyone got any other ideas? Need to get this sorted this weekend as it's due it's annual MOT in the next week or so where braking etc is tested.
 
I would look for a problem with your left front brake assembly. Sounds like it's not working up to snuff. An alignment issue would pull with no brakes applied.
 
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Maybe have the alignment checked.
Do the wheels seem to spin freely and evenly all 4 corners?
What does MOT do to test the brakes, just drive it?
 
Oh, I didn't read the whole thread, but l see it has rear drums.
Are the rear drums adjusted evenly?
Did you make sure the rear wheel cylinder (s) are not frozen?
I'm not sure if you replace the wheel cylinders again I didn't finish reading the whole thread.
But if one of those wheel cylinders is Frozen and not doing its job and the other side is that could make it pull.
 
So you were breaking pretty good pretty hard I mean and you had a pop out of the left rear did you pull that all back apart and check it out? If not that's what you need to do. Also yes make sure you check those wheel cylinders the one isn't Frozen that's often overlooked.
When you take the drum off you can stick a thin screwdriver alongside the pin that protrudes from the wheel cylinder and pushes on the brake shoe, and push in on either side both sides in other words and make sure that piston is moving in each side of that wheel cylinder.
You said when you pulled the emergency brake slightly you had a grinding noise back there I don't know if you ever got back into there and checked everything out? But again I would check those wheel cylinders back there.
 
I really should have added more detail to the start. :ROFLMAO:

Still no idea what caused the pop. We have stripped both rear drums and they are absolutely fine. Maybe the shoes re-centreing with the extra brake force from the now-fully-bled brakes?

We've jacked up each corner, span each wheel by hand and tested the brakes that way. Each wheel stops abruptly. No signs of any dragging either.

I took it out for a drive and checked the temperature of the disc/drum on each corner. All seems to check out. None noticeably cooler.
 
So you were breaking pretty good pretty hard I mean, and you had a pop out of the left rear did you pull that all back apart and check it out? If not that's what you need to do. Also yes make sure you check those wheel cylinders the one isn't Frozen that's often overlooked.
When you take the drum off you can stick a thin screwdriver alongside the pin that protrudes from the wheel cylinder and pushes on the brake shoe and push in on either side both sides in other words and make sure that piston is moving in each side of that wheel cylinder.
You said when you pulled the emergency brake slightly you had a grinding noise back there, I don't know if you ever got back into there and checked everything out? But again, I would check those wheel cylinders back there.
Still need to check the wheel cylinders the way l stated. One piston could be frozen and not the other.
 
Sounds like there is more wear on some suspension bits on one side of the car than the other. When you brake lightly, the right wheel toes out a little so that the car pulls to the right.
That's why l say have the alignment checked too. The alignment man can tell you if there are worn
suspension and or steering bits.
 
I’ve been embarassed before to discover uneven tire pressure by even 2psi can cause this, especially if youve altered wheels, tires, scrub radius, etc.

After that, I’m looking for sticking caliper pins/slides…. Along the thought that one is making contact before the other.

After that I’m looking to see if there is play in bearings which might allow the rotor to bump the pads on one side to retract, while the other doesn’t flex as much (not kidding, seen it). Theres a reason subaru uses larger than normal spacing between their front bearings, something from their rally lessons learned… you can sort of test this by driving over really bad surfaces and then applying the brakes. The really bad surfaces will cause greater rotor deflection.
 
I’ve been embarassed before to discover uneven tire pressure by even 2psi can cause this, especially if youve altered wheels, tires, scrub radius, etc.

After that, I’m looking for sticking caliper pins/slides…. Along the thought that one is making contact before the other.

After that I’m looking to see if there is play in bearings which might allow the rotor to bump the pads on one side to retract, while the other doesn’t flex as much (not kidding, seen it). Theres a reason subaru uses larger than normal spacing between their front bearings, something from their rally lessons learned… you can sort of test this by driving over really bad surfaces and then applying the brakes. The really bad surfaces will cause greater rotor deflection.
No, makes perfect sense,
 
Sounds like there is more wear on some suspension bits on one side of the car than the other. When you brake lightly, the right wheel toes out a little so that the car pulls to the right.

This is kind of what it feels like. I did have the lower arms off both sides to replace the ball joints and the fault didn't present itself until the recent round of 'work' last weekend.

I've got a few free hours Sunday. I'm going to strip each brake back down. Inspect every part of the brakes and re-bleed. I will also just have another visual check on the front suspension that I've had apart and ensure everything is tight.

If that doesn't solve it then I may have to throw in the towel and get someone else to take a look. I may even take it to be checked on the brake roller and get wheel alignment done to see if it can throw light on the issue.
 
Does it have control arm bushings or strut rod bushings?

Control arm bushes I believe. Unsure what the 2nd item is?

Bushes have done 110k but they looked good to me. The issue certainly wasn't present before I started working on the car this last weekend. It always broke straight and true, even with it's weird pedal.
 
IMG_20230205_090700.jpg


LH wishbone, rear bush. Seems I neglected to do it up. Amazed it's still there.

Lesson learned here, don't get stressed and rush when your Wife is nagging you to hurry up because the kids are playing up.
 
LH wishbone, rear bush. Seems I neglected to do it up. Amazed it's still there.

Lesson learned here, don't get stressed and rush when your Wife is nagging you to hurry up because the kids are playing up.
So, you found it loose all on it's own? So, it fixed the pulling under light breaking?
 
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