172 Cup pulling to the Left under Heavy Braking.

[EZ Tutty]

Hey,

Not had my 172 Cup long now, but when I got it the brakes were a joke, so it had new discs and pads all round, braided hoses, fresh fluid, and new seals etc on the front calipers, (the rears are also nice and free).

However now under reasonably heavy breaking from speed (country lane type stuff) it pulls pretty sharply to the left, and I have to counter-act this with steering slightly to the right... when then locks up the front left brake.

I've checked and double checked that all sliders and pistons are free, and that the pads are free to move in the carrier and I've bled them numerous times.
I've checked for play in the wishbone bushes and ball joints, the strut and top mounts, and all seems well.

Any where I should look next?

 

[l33th3tr33]

I literally was about to ask the same thing, I went out for a spirited drive today and if you were to really plant your foot down the car would just spin. You can counter it by steering slightly to the right but that's not a very good fix really. I did notice with someone in the passenger seat it barely does it, so it may just be down to balance.

 

[EZ Tutty]

if you were to really plant your foot down the car would just spin.

That's the exact feeling I get!

 

[AlexW]

Shocks any good?

I'd also check tracking/camber/caster.

 

[l33th3tr33]

That's the exact feeling I get!

It's not a feeling, I put my foot down hard and hard to stop the car from spinning lol
AlexW 4 new shocks here, tracking done a couple months ago.

 

[EZ Tutty]

Shocks all seem fine and don't look very old.
Full geometry inc camber last week

 

[MicKPM]

Brake test it

 

[EZ Tutty]

Its looking like it might be the rear brake compensating valve... the side of the valve that controls the rear drivers side looks to be in a poor state, so the rear drivers side has low effort and because of the diagonally split circuit the front passengers side is getting the extra force that's not being sent to the back.

 

[MicKPM]

Sounds plausible... did it go on a brake roller setup which demonstrated the imbalance or are you just guessing?

 

[DannyR]

Cars will naturally pull to the left on a lot of back roads due to the shape of the road and then usually dropping at the edges.

Are you sure it wasn't just the road?

 

[l33th3tr33]

Cars will naturally pull to the left on a lot of back roads due to the shape of the road and then usually dropping at the edges.

Are you sure it wasn't just the road?

I tried mine in quite a few different places yesterday and it made no difference.

 

[EZ Tutty]

Just fitted a brand new Compensating Valve and it's made no difference at all, back to the drawing board I guess.

 

[Marz]

Thought it could be the braided lines but on re-reading I see they're brand new! I think it's a trait they all have due to the different length of the brake pipes on the diagonal split. How hard are you braking? Mine has always locked front left first but only under heavy heavy braking.

 

[onefourkrpm]

Check for play in the track rod ends and tie rods, it doesn't take much play for the wheel to wander about a bit and make the car hop about. I think the rack bushes can also produce this kind of effect.

 

[EZ Tutty]

Whilst investigating further I took the front Hoses off when I blew all the fluid out of them a small piece of crud came out the right hand front.

After flushing them and putting it all back together it appears to be braking straight again... altho I need to test further as it was raining yesterday afternoon and I couldn't hit the anchors as hard as usual.

Hoses were fitted a few weeks before I bought the car by the previous owner, guess he may have let some crap get in there!

 

[alexroberts0289]

I've got this also, I'd be very interested in whether that fixed it. It's bloody dangerous, scares the hell out of me (and my passengers!)

 

[Marz]

Mine failed MOT a while back as the BF Goodrich braided lines I had on broke down inside causing an imbalance, binned em off and went back to standard. They were less than a year old, heard of others on here having the same problem.

 

[l33th3tr33]

Whilst investigating further I took the front Hoses off when I blew all the fluid out of them a small piece of crud came out the right hand front.

After flushing them and putting it all back together it appears to be braking straight again... altho I need to test further as it was raining yesterday afternoon and I couldn't hit the anchors as hard as usual.

Hoses were fitted a few weeks before I bought the car by the previous owner, guess he may have let some crap get in there!

I doubt you'd be able to tell unless it's nice and dry, mine don't do it unless it's dry enough to stamp on the anchors, or (very worryingly) at high speed.

 

[EZ Tutty]

Just to let you know, it's sound now