Scott Irwin, technical manager for premium brake brand, Textar, explains why refurbished alloy wheels can have a detrimental effect on braking and what garages need to look out for.
The process of alloy wheel refurbishment, which involves stripping and blasting the wheel before painting, can be troublesome if not carried out effectively, as the thickness of the paint has an impact on the run out of the brake disc.
If the paint on the inside of the wheel is too thick, when it meets the disc, it will increase the run out causing issues such as brake judder.
To put this into perspective, normal run out on a clean hub and disc should be no more than 00.07mm.
Incorrectly refurbished alloys with a higher thickness have been known to increase the run out to 00.10mm.
To give an example of this issue in practice, a garage we work with had fitted new pads and discs for a customer, however, the car owner returned with a judder complaint.
After the Textar team got involved to help solve the issue, we found the run out with the refurbished alloy wheel fitted increased to 00.12mm and with the wheel removed it was 00.09mm.
Both measurements were above the recommended standard.
To solve the problem, the Textar team cleaned down the hub before fitting a new set of discs.
This resulted in a run out of 00.03mm however, once the refurbished alloy wheel was re-fitted it increased to 00.10mm.
After checking over the refurbished alloy wheel, it was clear to see the uneven paintwork was causing the problem.
After seeing this issue rear its head a few times now, it is important for garages to pay attention to the entire braking system, including the wheels, if a customer comes in with a judder complaint.
Signs of kerbing, tyre wear and alloy refurbishment should be checked as standard to ensure any issues are picked up and dealt with quickly, saving mechanics valuable time and in turn, money.
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