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I have a fairly new to me 2008 VW GTI (US model, aka "Golf GTI" in other parts of the planet) and am trying to figure out the specs for the brakes. Specifically, I'm trying to determine the exact size of the OE brake rotors and their wear tolerance. Searching the web I've found conflicting information. For example, one site lists the original thickness as 29.5mm and the minimum as 25.5. For aftermarket, I've found ones that are 27mm new, and 25mm minimum.

Yet, many sites list the OE brake rotor thickness as 25mm and I can't find a minimum for those. The rotors are current at 25mm, so I'm trying to determine if they're relatively new, or need to be replaced.

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  • Which model of VW? GTi is a trim level... Do you have a workshop manual ('Haynes' or similar) for the car? – Nick C♦ Feb 28 '13 at 9:22
  • Sorry, in the US GTI isn't a trim level - there is only one GTI (vw.com/en/models/gti/gallery.html), though there are trim levels of GTIs (eg Fahrenheit). I didn't realize the GTI monicker is a trim level in other parts of the planet and apologize for not indicating the car is a US model. I don't have a shop manual for it - there are many brands of those, do you know of a good one? Thanks – user1337 Feb 28 '13 at 17:26
  • You learn something new every day! That's the model we call the 'Golf' in Europe, with the Golf GTi being the top sporty version. I usually use Haynes manuals as they tend to be the most common over here, I don't know if they're available in the US though? – Nick C♦ Mar 1 '13 at 11:47
  • @user1337: The go-to manual is a Haynes manual, but there are others (Chilton, etc.). You may be able to find the actual manufacturer service manual (what the service technicians reference) if you know where to look. – Cᴏʀʏ Mar 8 '13 at 16:04
  • @CoryLarson Thanks. I know a lot of people use Chiltons for US cars. I've got a Bentley DVD for another car, but am not fond of it. – user1337 Mar 8 '13 at 19:36
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The specs are located on the face of the rotor. In order to see them you will be required to remove one of the front or rear wheels. I managed to find a picture showing the location of the markings. The number that's zoomed is the part number of the actual rotor. Using the part number to order the part will make it certain that you get the correct part from the guy behind the counter.

If they cannot cross reference the part number because they're systems don't support factory part numbers then a quick call to the dealership parts department giving them the part number, and asking them the specs on the rotor will get the Autozone parts guy the information he needs to hopefully get you the correct part.

If you plan on measuring the rotor to check the thickness, this is done with a micrometer and the measurement is taken in millimeters. After the part number there will be a number labeled Min. #mm this is the minimum thickness allowed for the rotor. There will also be a tolerance number (if not .3 is what I use when I cannot find the spec) and a Max.. The tolerance is used like so: if [ (Actual + Tol) <= Min ] ; then ReplaceRotor.

Hope this helps.

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