Why are my discs warping?

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The Wookie

13,909 posts

227 months

Tuesday 30th June 2015
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Another brake engineer here, we use long motorway runs with minimal brake use for DTV generation. Typically after a hot test to create the runout.

OP, I put some Pagid discs on my parents old L322 Range Rover and they started droning and juddering within weeks. Rumour has it Euro Crap Arts are selling some Pagid Branded parts that have been subcontracted to a different, obviously lower quality, manufacturer and they appear to be tat.

Things to check before you buy your next set of (preferably genuine OE) discs are ensuring that your hub flanges and wheel faces are clean and free of any deposits or debris, and that the pistons can be pushed back into the calipers without excessive force. Also worth replacing the pin sliders (assuming it's a sliding caliper) while you're at it.

Dave Brand

928 posts

267 months

Wednesday 1st July 2015
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The Wookie said:
OP, I put some Pagid discs on my parents old L322 Range Rover and they started droning and juddering within weeks. Rumour has it Euro Crap Arts are selling some Pagid Branded parts that have been subcontracted to a different, obviously lower quality, manufacturer and they appear to be tat.
On the first point, those phenomena are a function of the "friction couple", i.e. the pad & the disc. Discs may be a simple iron casting, but the composition of the cast iron has an effect on performance.

On the second point, rebranding used to be, & no doubt is, fairly common. Manufacturers want to cover as much of the aftermarket as possible. In a lot of instances sales of a particular vehicle may be very low so it's not worth tooling up for a few dozen sets a year so they will be bought in from another manufacturer - may be the OE supplier, may be an aftermarket supplier in a country where that vehicle is a big seller. Sometimes the supplier may be a deadly rival.

Of course, if the pads are tat they could be counterfeit!

The Wookie

13,909 posts

227 months

Wednesday 1st July 2015
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Although still important, it's much more complex than simply the quality/composition of the iron, even something as seemingly inconsequential as a fractionally undersized bore centre of the disc can cause judder. Slightly off-spec air gaps or vane designs can cause drone and judder.

There is a vast amount of detail in both the casting and machining of discs that derives from a vast amount of development and effort.

I actually didn't go for the Pagid Pads, I went genuine OEM as even the alternative OEM items might cause NVH problems. I assumed that Pagid as a brand would be close enough to the OEM to be alright!