Brake calliper mount bolt size.....???

[Experiment 27]

Hi desperatly need help,changed the rear rotors had a awful time trying to get the brake caliper mount off >< resulting in destroying 2/4 bolts.
Can anybody tell me the thread size of them they are not M8 or M10

[vwcabriolet1971]

Might be M9. VW do use some non-preferred std. screw thread sizes in critical areas ( space constraints). If you need new bolts I would order them from VW - don't try to use standard bolts.

[olds_kool]

metric fine thread, (m8 if i remember correctly), coil on thread is half the size of a normal bolt, about £3 from audi or 20p from any fastener company

[vwcabriolet1971]

By ordering from VAG it can be assured that the Bolt is the correct size, the correct thread pitch and the correct high tensile strength grade. Ordering bolt from a fastener stockist is fraught with danger ( brake caliper bolts shearing ?). If the recommended tightening torque for a high tensile bolt is applied to a lower grade strength bolt then it will likely shear.
In my experience Fastener stockists do not stock fine thread bolts as they are non-standard sizes.

[olds_kool]

never had any problems using fastener companies, as long as you take the bolt with you they will match it
metric fine is common in industrial use where vibration/space is an issue

[vwcabriolet1971]

I agree that the larger Fastener suppliers may have the correct bolt in the correct length but there's not many of these companies about these days and to waste time and fuel to pick up a few bolts to save a couple of pounds seems to me to be a bit pointless. Also I doubt you could get a high tensile M8 fine thread bolt for 20 pence. Also most specialist suppliers will only sell a minm. quantity - normally at least 50 in this size. Unless you've got a specialist fastener supplier close to your doorstep who will sell in very small quantities, I would stick with the VAG parts assuming they are within reasonable travelling distance.

[Experiment 27]

Hi guys ty for all ur advice and help, contacted a vw dealer got the bolts. If anybody has the same problem the part number is : N90688901