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Uneven brake pad wear


Black Hole

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My front left brake has experienced very uneven brake pad wear. I would suspect this is a sticky caliper that needs a rebuild. My car is a 2009 SV with the standard brakes. 

  • Can I confirm these are Girling type 14 brakes as used on Spitfire MKIII (and perhaps some Elan and Europa?)
  • I don't see any obvious leakage, I plan to order a rebuild kit from Moss
  • Any recommendations on brake pads. Car is primarily street driven with some AutoX and occasional track day. Moss Motors sells a pad made by Classic Gold and is listed as ceramic for the Spitfire. What are the pads Beachem sells (they areabout twice the price)
  • Any comment on the cupping of the thin pad as shown in the picture

24-11-11_Caterham 7 brake caliper_4.jpg

24-10-29 7 Brake Wear-3.jpg

24-11-07_Caterham 7 Front Brake Pads_4.jpg

24-11-07_Caterham 7 Front Brake Pads_3.jpg

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They look like 14LFs

Moss doesn't list the brand of their kits   if it worries you, Girling kits at Pegasus

If you plan to split the calipers, be aware that the seal between halves doesn't come in the kits, and if reused, it will leak

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I would never consider splitting the calipers.  I had this sort of calibers on my Europa.  I was able to remove the pistons and replace them with stainless pistons without splitting the calipers.

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On my car, a '82 S-3, the master cylinder has separate lines/circuits for the left and right front brakes.  When I ordered a new Spitfire master cylinder it had one circuit for the left and right front brakes.  The left side was worn and my brakes pulled to the left.  Rather than modify the plumbing I found a shop that rebuilt/sleeved master cylinders and had it rebuilt.  Jeff was not able to sleeve them but did an excellent job of rebuilding them.

 

http://www.karpspb.com/cylinders

 

 

I bought my pads from Porterfield.

 

https://porterfield-brakes.com/

 

I bought a kit to overhaul the front calipers from Moss Motors and it came with the O-rings.  No leaks yet...

 

Tom 

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Looks like a stuck outer piston and someone tried to loosen the dragging brake (maybe on the side of the road?) with a screwdriver. You could reinstall the caliper without the pads and pop the pistons out far enough to pull with the brake pedal applied or with air to see how bad it is before ordering parts. Brake clean aerosol and emory cloth for minor clean up. Lube pistons and seals with brake fluid and start them by hand. If they cock and won't rock back easily, apply air or pedal to push them back out a little.

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16 hours ago, pethier said:

I would never consider splitting the calipers.

 

From what I have gathered it appears splitting them is not a big deal as long as you get the crossfeed gasket that is not in the rebuild ki.

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4 hours ago, MV8 said:

Looks like a stuck outer piston and someone tried to loosen the dragging brake

 

I have owned the car since new so this did not happen. No problem with the brakes til now. I have 13K miles on the pads with about 8 track days and maybe a similar number of autocross. Not sure how fast this wear happened. I probably have about 1500 street miles (no track and maybe one autocross) since I last bled the brakes and would have looked at them. Don't recall it being uneven at that time (but I may have just confirmed I had adequate pad thickness and not noticed the uneven wear).

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The problem is caused by the pad not retracting and staying in contact with the disc, greatly accelerating wear on that pad.  The pad is not retracting for one of two reasons:

 

- the caliper piston is corroded and is sticking in the bore,

 

- the pad backing plate is tight in the caliper.

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18 hours ago, jbcollier said:

- the caliper piston is corroded and is sticking in the bore,

 

- the pad backing plate is tight in the caliper.

 

3 hours ago, 7Westfield said:

I always clean up the top + bottom of the pads on the belt sander so they slide nicely

 

Thank you. Parts on order to address these issues.

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On 11/16/2024 at 5:05 PM, jbcollier said:

The problem is caused by the pad not retracting and staying in contact with the disc, greatly accelerating wear on that pad.  The pad is not retracting for one of two reasons:

 

- the caliper piston is corroded and is sticking in the bore,

 

- the pad backing plate is tight in the caliper.

I still don't understand how a pad wears concave.

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