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[Migalot]

Hi All,
This is a bit puzzling. For some time, the car has been pulling to the left under braking and the pedal felt a bit spongy.
A medical episode meant I wouldn't be driving for a while, I took the opportunity to have a mechanic friend do a complete check.
The wishbones are fine (with polybushes!). The brakes have been bled properly (pedal nice and firm, now). The front springs and shockers have been changed. The calipers work fine (though they weren't changed). The front tyres have been changed and the tracking done (including the caster angles!).
The car rides beautifully now, but under light braking it still pulls a bit the left, whereas under moderate/heavy braking, it stops straight and true.
The mechanic (and I!) are totally baffled by this.
Any ideas would be gratefully received!     

[Doctor Gollum]

Sticking caliper/pads. Might even be on the right front, binding under light pressure.

Don't dismiss the rears too.

[polilara]

After having changed cheap wishbones to my Omega after a while braking started to to pull to one direction. At the same time steering wheel turned slightly to opposite direction. Root case was damaged rear bushing of one wishbone. I bought "Better ones", then Ok.

[cam.in.head]

pulling to the left means that the right side isnt working as it should . because it brakes well under hard braking but not light i would be suspecting either the caliper piston or sliders are not quite as free on the right compared to the left,  i would remove both front wheels and compare the ease of moving the caliper back. a good caliper should move by hand or gentle leverage only. if you find no difference reassemble ( swapping front tyres left to right if theyre not rotational !) then as DG  suggest check the rear brakes .
i assume obviously that the disc and pads are identical side wise !

[Migalot]

Thanks Guys!

Having new calipers fitted on Tuesday. Front only for now – will keep an eye on the rears.

[Migalot]

Had new calipers fitted, having waited for a few days for some to come from Autodoc. All fitted, but car still pulls to the left under moderate braking. Should I have had brand new pads fitted. Existing ones are not that old and have plenty of meat left, but perhaps the sticking has caused uneven wear.

Getting a bit fed up with this. Only other thing that has been suggested is a faulty ABS unit.

Any thoughts? 

[cam.in.head]

shouldnt have damaged the pads but as suggested check the rears . they get stuck in the caliper very easily and need removing and cleaning if so . making sure pistons are all nice and free  too .
alsk wirth checki g tyres . a low tyre ( lower pressure or tread) can cause a slight pull ! thats why insuggested swapping them on reassembly

[YZ250]

………..
The wishbones are fine (with polybushes!).
……….
Any ideas would be gratefully received! 

What about the wishbone rear bush as suggested on a previous post above, have they been checked for equal deflection. Once you’ve checked the rear brakes as suggested it might be worth looking at the rear bush. I’m just thinking that under light braking a weak left vertical bush could cause a slight steering change but moderate to heavy braking would push both rear bushes to their limit, so the braking would be equal. I’m just throwing suggestions in the pot really so you can get to the bottom of it.
As far as the abs module goes, if you bleed the right hand caliper and the fluid comes out at the same rate as the left hand caliper, then the fluid is getting past the abs pump ok. If it wasn’t, you wouldn’t have equal braking under heavier braking, and you would definitely know if it was starving the right hand caliper of fluid.
Good luck sorting it. 

[Doctor Gollum]

How old are the flexible brake hoses?

[jb]

Many years ago I had the same issue,it turned out to be the wishbone rear bush....recommend you have it checked again with real force applied

[Migalot]

How old are the flexible brake hoses?

No idea. 

[Migalot]

I suppose what I need is an Omega-competent mechanic who can take my car and sort it.

I'm into my 70s and no longer able to do work on the car.

Where can I find such a person?

 

[Doctor Gollum]

How old are the flexible brake hoses?

No idea. 

As they degrade, they constrict internally eventually acting as one way valves.

Poor fluid maintenance won't help.