Zeus single pot. Pistons not retracting

[Grayjay66]

Back to the proper priority yesterday.. My rotors are original with 60 k and have developed a small lip along the outside rim maybe 1/32 or less. Anyway I thought perhaps the outside corners of the new pads could be riding on this lip causing the Pads to ride at a slight angle to the face of the disc and wedge the Pistons.

I filed all the pads corners and edges and tried yet again. Seems as though there is some improvement but they still do not fully release. The ever faithful dunlops do even without filing their pads. Although they are a little less faithful as one has developed a seal leak

[PeterCrespin]

You could presumably test your Zeus inverted seal hypothesis by reversing one. I believe they ARE usually slightly trapezoidal to enhance pull-back on the ID, not true square section. Could be wrong, I tend to buy complete calipers these days so it has been a while.

[Series1 Stu]

I don't understand why you would fit new calipers and not new discs. It seems to me the logical thing to do to ensure you get the best out of your upgrade. Not exactly the most expensive thing you'll ever buy.

If they are still within wear limits then you could get the discs skimmed to make sure they are running true and presenting smooth parallel faces to the pads etc.

Regards

[Grayjay66]

Well I think the slight lip on the discs was it.

Since one of the 2 Dunlops developed a seal leak, I took it off and put on a Zeus with pads filed down on the outside corners where they touched the disc outer edge.

So with three Zeus and one Dunlop,
I ran the car 8 miles today on a country road with minimal braking. At the end the discs were hot but not so much that I could not touch them as before. Interestingly enough the Dunlop side of the disc was as warm as the Zeus side. Probably not significant given the heat transfer properties of steel.

After 10 minutes at rest or so both discs were only slightly warm to the touch.

I think my next experiment will be to run the same course in my Volvo and see how hot it's discs are with a temp gun What I may be seeing is normal heat from braking. There is still some drag when the wheels are turned while on the lift , but still a tremendous improvement.

I'm really happy I don't need to spend more$ on this as Coronavirus has eroded my once comfy retirement account!

Thank you all for your thought and helpfully suggestions. I would not have guessed rotors except for a comment or two that got me thinking.

Now on to that oil leak....

[Jonny XKE]

Hi GrayJay ... slightly off topic but I have Zeus calipers. I have put on a new set of wire wheels and the wheels "just" touch the calipers. The previous owner obviously had a similar problem with the original wire wheels as he has used a grinder on them already. I could grind a bit more off but I don't want to damage the calipers. Did you have to do anything to yours?

[Grayjay66]

it looks like you have vented rotors. mine are OEM non vented. also my zeus are more similar in shape to the original series I Dunlops , so I had no need to do anything to the wire wheels.