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DeanH

Brake Judder/Steering Wobble - Warped Discs?

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As above really - I have brake judder and steering wobble at 40mph+, as well as the brakes biting when coming to a halt at low speeds.

This points me to warped discs, but why? Are there any common faults with the Lupo that cause discs to warp?

Is there anywhere I can buy a decent caliper refurb kit which includes a piston if it's the pistons that are sticking?

I've checked over the pads and there doesn't seem to be any excessive wear from side to side or pad to pad.

Edited by DeanH

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Could use be cheap discs/pads. Is the wheel wobble only under braking or actually driving over 40? If the latter then that could be a wheel balance issue.

I’d not get too carried away throwing bits at it, get it stripped and clean up the calipers/carriers, replace the discs and pads and go from there, if you find the pistons are seriously seized up you’d be better off getting new ones, can’t be that expensive, but in my experience it’s not very common that a front caliper can’t be freed off.

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Was it like that before the new ball joints or just since fitting them? i.e everything tightened back up.

If it feels like one wheel then swap the wheels around and see if it changes it. Otherwise it is basically look for seized / sticky carrier sliders or pistons etc. you can check run out on disks too.

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7 minutes ago, Sausage said:

Was it like that before the new ball joints or just since fitting them? i.e everything tightened back up.

If it feels like one wheel then swap the wheels around and see if it changes it. Otherwise it is basically look for seized / sticky carrier sliders or pistons etc. you can check run out on disks too.

No, present before and after the ball joints.

Everything's tightened up just fine and I'm all balanced and tracked up with two new tyres on the front.

Not obviously coming from one side of the car either, just pulses through the brake pedal and wobbles the wheel.

41 minutes ago, Pete said:

Could use be cheap discs/pads. Is the wheel wobble only under braking or actually driving over 40? If the latter then that could be a wheel balance issue.

I’d not get too carried away throwing bits at it, get it stripped and clean up the calipers/carriers, replace the discs and pads and go from there, if you find the pistons are seriously seized up you’d be better off getting new ones, can’t be that expensive, but in my experience it’s not very common that a front caliper can’t be freed off.

Discs and pads are both Pagid, not cheap but not genuine, probably less than a year old.

Happens at all speeds I suppose but more evident at 40mph and up.

All I can think is that its from me holding on the brake at traffic lights (I've almost kicked that habit).

Just don't want to stick a new set on for them to go the same way in a couple of months time.

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You got ABS?

Make sure the carrier sliders are both moving free. Check the pads for contamination and even wear, check the disk run out (need the retaining screw for the disk present, wheel off, on a stand with engine ticking over in 1st will do with mk1 eyeball and a finger for feel or a dial gauge of you have one)

if there's run out remove disk and make sure no crap is under it preventing it from seating right.

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Pagid aren’t expensive really, and you never mentioned if the wobble was when applying the brakes or constantly even without the brakes on, just that it happened at various speeds. 

As has been said, pull it to bits and you’ll know doubt be able to answer your own questions.

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2 hours ago, Sausage said:

You got ABS?

Make sure the carrier sliders are both moving free. Check the pads for contamination and even wear, check the disk run out (need the retaining screw for the disk present, wheel off, on a stand with engine ticking over in 1st will do with mk1 eyeball and a finger for feel or a dial gauge of you have one)

if there's run out remove disk and make sure no crap is under it preventing it from seating right.

No ABS as far as I'm aware, there's no ring or sensor on my hub anyway. 

Someone has snapped the retaining screws before I bought the car, looks like I'll be getting the drill out. 

I had considered a runout gauge but they seem to be a bit more expensive than I had expected for a one off job.

2 hours ago, Pete said:

Pagid aren’t expensive really, and you never mentioned if the wobble was when applying the brakes or constantly even without the brakes on, just that it happened at various speeds. 

As has been said, pull it to bits and you’ll know doubt be able to answer your own questions.

Yeah I've no issue with replacing the parts, just didn't want there to be an inherent issue that's going to mean I'm doing it again in a month or two.

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DTI can be had for less than £20 with a magnetic base dont need an expensive one just something that can be accurate to 0.1mm which a cheap one will be. But for disk run out you dont need one, just eyeball and feel, maybe rig up a bit of wire mounted on the caliper and turn the disk by hand. 

Put wheel bolts in instead to hold the disk in place but that makes for an extra hazard on a spinning disk checking run out. The snapped retaining screws will usually need penetrating fluid (50:50 petrol and oil if you dont have any) and a blow torch, probably be able to get it moving with something then.

New disks need the anti rust oil film cleaned off with with degreasant and a bedding in procedure followed to avoid problems like snatch and judder from developing too.

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3 hours ago, Sausage said:

DTI can be had for less than £20 with a magnetic base dont need an expensive one just something that can be accurate to 0.1mm which a cheap one will be. But for disk run out you dont need one, just eyeball and feel, maybe rig up a bit of wire mounted on the caliper and turn the disk by hand. 

Put wheel bolts in instead to hold the disk in place but that makes for an extra hazard on a spinning disk checking run out. The snapped retaining screws will usually need penetrating fluid (50:50 petrol and oil if you dont have any) and a blow torch, probably be able to get it moving with something then.

New disks need the anti rust oil film cleaned off with with degreasant and a bedding in procedure followed to avoid problems like snatch and judder from developing too.

I had a quick look at runout gauges on eBay and they were coming back about £60, just searched DTI and they're £20 including a base.

I've managed to tap retaining screws out with a small screwdriver and hammer before now, I'll give that a go and resort to the wheel bolts if I can't do it. 

Won't lie I didn't use any brake cleaner or pay attention to the bedding in procedure, I'll do that this time.

Could my rear drum brakes be having an effect? I've never opened them up and have no idea what condition they're in.

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I have a similar issue with one of our TDi's in the 2 and a half years I've owned it I've changed the discs 3 times and need to again. Last time I fitted Brembo discs and changed the front nearside caliper. I have also put replacement front alloys with new tyres on the front. The car does not have abs. I'm at a loss to explain this, the car tracks straight, brakes straight and does not pull to one side under acceleration, each time I've changed discs I've bought progressively more expensive items. Once replaced the new discs work fine for 3 months or so and then a judder starts. Any ideas perhaps changing the offside caliper?

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22 minutes ago, DeanH said:

Won't lie I didn't use any brake cleaner or pay attention to the bedding in procedure, I'll do that this time.

Could my rear drum brakes be having an effect? I've never opened them up and have no idea what condition they're in.

petrol is usually to hand for degreasing, otherwise white spirit, gun wash etc. Your pads probably got contaminated by the oil film, take them out and wash them in degreasant, may as well do the disks as well. unless they are warped or glazed they will be fine. If they are glazed roughen them up a bit with sand paper, flap wheel etc.

rear brakes you wont feel thru the steering wheel and have limited input anyway, if the hand brake works fine then I'd leave them alone tbh.

 

Edited by Sausage

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30 minutes ago, weslangdon said:

I have a similar issue with one of our TDi's in the 2 and a half years I've owned it I've changed the discs 3 times and need to again. Last time I fitted Brembo discs and changed the front nearside caliper. I have also put replacement front alloys with new tyres on the front. The car does not have abs. I'm at a loss to explain this, the car tracks straight, brakes straight and does not pull to one side under acceleration, each time I've changed discs I've bought progressively more expensive items. Once replaced the new discs work fine for 3 months or so and then a judder starts. Any ideas perhaps changing the offside caliper?

There's no logic to me suggesting this but what I've read online says that excessive runout in the hub face can cause similar issues. 

27 minutes ago, Sausage said:

petrol is usually to hand for degreasing, otherwise white spirit, gun wash etc. Your pads probably got contaminated by the oil film, take them out and wash them in degreasant, may as well do the disks as well. unless they are warped or glazed they will be fine. If they are glazed roughen them up a bit with sand paper, flap wheel etc.

rear brakes you wont feel thru the steering wheel and have limited input anyway, if the hand brake works fine then I'd leave them alone tbh.

I have ordered a gauge, I'll check the brake disc and hub run-out before chucking parts at it.

Once I strip it down I'll get some pictures in case you guys can see something obvious that I'm missing.

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I've given the car an Italian tune up this morning and the judder is less pronounced which does suggest a sticky caliper

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1 hour ago, weslangdon said:

I've given the car an Italian tune up this morning and the judder is less pronounced which does suggest a sticky caliper

Three options then - new used caliper, new caliper from suppliers, or refurb the existing. Which takes me back to my original post - is there anywhere to get a decent kit to do a full caliper refurb? I've heard good things about Bigg Red before? @Sausage @Pete?

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buy a seal/dustboot from VW and break out the sand paper.

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You can buy service kits from brakeparts.co.uk inc pistons, re-manufactured calipers and other bits

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DTI gauge arrived yesterday so I had a quick check today. Found it quite difficult to get reliable readings from it but seem to have pinpointed it to the passenger side.

 

Driver side:

12 o'clock -0.34

3 o'clock -0.37

6 o'clock -0.40

9 o'clock -0.35

Range: 0.06mm

 

Passenger side:

12 o'clock +0.04

3 o'clock -0.06

6 o'clock -0.03

9 o'clock 0.00

Range: 0.10mm

 

Any glaring mistakes with that?

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if you are happy with the readings then 0.1mm is likely within limits, I was expecting more, but you could well feel it. Could also be variation is disc thickness not just run out. If you havent already I'd take it off and clean up the mounting faces, remount it and measure again though.

Check your wheel bearings for play while you are at it (wheel on, rock 12 and 6 o clock)

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1 hour ago, Sausage said:

if you are happy with the readings then 0.1mm is likely within limits, I was expecting more, but you could well feel it. Could also be variation is disc thickness not just run out. If you havent already I'd take it off and clean up the mounting faces, remount it and measure again though.

Check your wheel bearings for play while you are at it (wheel on, rock 12 and 6 o clock)

I might not have used the gauge correctly, I will have a watch on youtube to make sure I haven't made an obvious mistake.

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