Badiguana said:
I picked up a set of K3 calipers and a K5 master cylinder on ebay really cheap, have you any idea if the 2 are compatible? I'm currently running the MC on my standard K4 calipers, the braking is really good but sometimes I get some strong vibrations when braking on uneven surfaces..
Is it worth doing?
There is no reason why they shouldn't be compatible. I've run stronger MCs (Brembo 19/20) with both types of calipers with no issues. Question is: do you get the same vibes when braking hard on smooth surfaces? A slightly warped rotor, glazed pads, unbalanced wheels or worn tires would exhibit the kind of problem you've noticed, to differing levels. Overly hard front suspension damping might also be the culprit.
You will need to isolate the problem first. What pads are you running, and have you checked you rotors for straightness? How old are your tires and when were they last balanced, and how often do you have your tire pressures checked? Is your suspension properly set-up? When were they last serviced?
Check if the pads are glazed (appearing shiny across their surface). Remove them and sand them down with fine grit sandpaper before replacing them in the calipers. Alternatively, if you have a different set of pads (stock for instance) run them for awhile and see if the vibes return. I always place a
very light film of high-temp copper greas on the back of the pads to help keep things quiet. You might want to try the same.
Let us know how it turns out. :cheers