Used Front Disks

[944Fripp]

I'm trying to eliminate a problem with my brakes (a light pulsing that is intermittent and happens at various speeds) on the S2.

I'm down to either dodgy disks (Pagid) or a sticking valve in the ABS pump. So, rather than shelling out lots of hard earned on either just yet a fellow PCGB member suggested asking if anyone has any good quality used disks I could borrow to check. They need to be warp free and ideally good quality (Bosch or Delco) and only needed for a 50 mile or so run. If not borrowed, will happily buy for a fair price.

Tried looking in spares listing but it doesn't work! I know it's a bit of a long shot but if you don't ask.....

Anyway, thanks for looking, hope you're all keeping safe!

 

[scam75]

Good idea to check. I can't see how warped discs can be intermittent, makes sense ABS system but not necessarily the pump. If it is the pump causing it, something is triggering it, wheel sensor, relay or ECU. Any lights on? Does it prime ok?

The pedal most definitely does pump when ABS is activated, but you should brake slower and in a straight line. Any deviation from straight when pulsing?

Could also be a stuck piston, sometimes stuck, sometimes not. That would be my guess.

Stuart

 

[944Fripp]

Good idea to check. I can't see how warped discs can be intermittent, makes sense ABS system but not necessarily the pump. If it is the pump causing it, something is triggering it, wheel sensor, relay or ECU. Any lights on? Does it prime ok?

The pedal most definitely does pump when ABS is activated, but you should brake slower and in a straight line. Any deviation from straight when pulsing?

Could also be a stuck piston, sometimes stuck, sometimes not. That would be my guess.

Stuart

Thanks Stuart. The thinking behind the disks causing intermittent issues is that it could be because of heat build up. It is less noticable when the car is/brakes are cold, it is very subtle at low speeds and not always there at high speeds so could be something only just clearing and within tolerance when cold. I also don't feel juddering/pulsing through the brake pedal at all, it's the steering wheel at high speeds and at lower speeds, it just feels like a very soft grabbing and releasing as you come to a stop experienced through the movement of the car only (nothing through brake pedal or steering).

The ABS is working fine, no lock up's, pulsing fine on gravel, I hear it prime at about 8mph, and the light goes out with no issues.

With a clean bill of health otherwise mechanically from the specialist it's down to one or the other and the disks are deffinately the easiest place to start! My back up is to buy another set of lower cost disks (Pagid or equivalent) and if they correct it I know to get some good quality ones when they eventually go again. If they don't eliminate the problem I haven't lost too much I suppose but we're into ABS pump rebbuold/refurb territory because although I can live with it for now it's a sign of things to come! []

 

[scam75]

Despite what people have said, I've found the cheap ECP Pagid discs to be fine. I have them all round. Its the Pagid pads that truly suck and are hopeless and squeal like upset pigs!

I have textar pads on front and Brembo on back and the brakes are quiet and effective. On the S2 the Brembo's would be good front and back as the pad size is the same unlike the turbo with larger front calipers.

Stuart

 

[944Turbo]

Has it been parked up for a long time (covid etc)? Wondering if your tyres developed some flat spots. Mine have in the past, usually clear with some use
Tony

 

[944Turbo]

Should add - while not intermittent exactly the flat spots did show more at some speeds than others - might also change depending on whether they are in synch (opposite sides) or not
Tony

 

[944Fripp]

Should add - while not intermittent exactly the flat spots did show more at some speeds than others - might also change depending on whether they are in synch (opposite sides) or not
Tony

Thanks Tony. That's a great suggestion. Yes, it was laid up for a while beacuse of COVID and moving house in early March. Although the problem was there before, it's not impossible! I'm taking it to a local car club meeting on Thursday so I'll pay more attention to what happens as I come to a halt and see if taking the brake off stops the grabbing or not. That would eliminate or point to a flat spot. I should say though that I only experience the juddering at speed when I apply the brakes and not at any other time.

The other thing I've been considering is that I recently replaced the front bearings whilst attempting to solve the same issue and it has reduced the juddering. Some clever soul on here suggested that the bearings were not adjusted properly or were installed incorrectly (by yours truly!!) by overtigthening the clamping nut. So, I bought 2nd hand hubs, checked the runout on them was correct, new bearings and reassembled following proper procedure (ensuring a little play against the thrust washer). So perhaps the incorrect adjustment damaged the disks: now the hubs are correct the damaged disks are still on the car. It sounds plausible enough to me that it's another reason to suspect the disks.

I'll give it a week or so and if I can't get my hands on a 2nd hand pair of disks I'll just buy another pair and hope it does the trick!

 

[scam75]

I had an issue for ages, slightly similar, it was vibration through the steering wheel, intermittent, dependent on road surface (65mph to 75mph). Turned out to be a rim with a dink in it. Got it "road force" balanced and mostly cured the fault. Have since secured a replacement, straight, CS rim from Germany, bargain price thankfully. Not got round to getting it refurbed yet to match the other rims. Need to get my suspect HG failure sorted first.......

Stuart