Juddering breaks

RoaryRati

Member
Messages
1,582
Gently breaking as approaching traffic lights in town and the breaks start juddering as if ABS was deployed - there should have been no chance of that as it was all very gentle. It happened again as approaching a roundabout. And then never did it again, even though I tried a bit more aggressive breaking later. No warning lights came on. Does anyone have any suggestions what this could be (I think it has happened once before). Many tks
 

FIFTY

Member
Messages
3,100
How is the health of the inner face of your discs? Could be that they are warped and pitted while thr outter face looks OK. Have you changed them recently?
 
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GeoffCapes

Member
Messages
14,000
New pads would be my guess. My Merc was exactly the same, changed the pads, and normal service was resumed.
Check your discs whilst you are there though.
 

safrane

Member
Messages
16,748
It may have been the MSP, esp if you were approaching the roundabout and turning at the same time.

Its not a very sophisticated system and the accelerometers can get confused at times.

If it has not done it again I suspect it was just a glitch but happy to look at the discs when we meet up in a weeks time.
 

conaero

Forum Owner
Messages
34,593
Sticking pads or calliper pistons...seen it on 3200/4200 before.

If it does not do it at hispeed braking, your discs are not warped.

Its because under light braking any stiction in the braking system resits and you get uneven braking. Under hi pressure breaking, the stiction is overwhelmed.

Alfas run the same callipers as to certain Porches. They all suffer from this.

The first thing to do is to replace your brake pads and check the SS pad guides. Corrosion of the calliper underneath them pushes the pad guides up and ideally you need to strip the callipers and remove the corrosion. If the pads are tight, file the edges so they drop in. If this does not remedy it then its a deeper issue with the pistons of the callipers / partial seizure.
 

Gp79

Member
Messages
1,393
Sticking pads or calliper pistons...seen it on 3200/4200 before.

If it does not do it at hispeed braking, your discs are not warped.

Its because under light braking any stiction in the braking system resits and you get uneven braking. Under hi pressure breaking, the stiction is overwhelmed.

Alfas run the same callipers as to certain Porches. They all suffer from this.

The first thing to do is to replace your brake pads and check the SS pad guides. Corrosion of the calliper underneath them pushes the pad guides up and ideally you need to strip the callipers and remove the corrosion. If the pads are tight, file the edges so they drop in. If this does not remedy it then its a deeper issue with the pistons of the callipers / partial seizure.

I had exactly this on my GS, pads tight in the calipers stainless guides, new pads filed for a nice fit and forum disc (thank you!) and all good.
 

RoaryRati

Member
Messages
1,582
Thanks for your ideas guys - will certainly check them out - but then to make matters worse I attempted to take the car out two days later - but ABS, (as well as the ASR and gear box warning lights) came on so I didn't as I was in a rush. Took it out later when no longer rushed - and no lights displayed............. (but on return from run-out roof failed to close - it can often be a bit tricky to open requiring a 10 mile journey before it does, but, fortunately, has always closed apart from once)