JAG IRS brake shudder

[ollykiwi3]

Jac Mac - I don't believe its this kind of sensation with the u-joints. it goes away with more pedal effort and only with light pedal presure. again, this only happens at low speed around20-30mph. I will try new pads fisrt and then single out the front and rear end once back on the road.

chanmadd - yes all bolts are tight, and the rods are also tight. although I did find the fulcrum pivot mount loose, but cant see how that affects the brakes as they are on the diff head. that's all fixed now, but again, cant road test for another couple months.

motorhead- both sets of pads are exactly the same, both wedge shaped with the same amount of wear and on the same plane. the calipers cant be misaligned as the pads would have wear on opposite sides. one side thick, and opposite thin. these are both thin at top.
its as if the top is wearing faster than bottom. so like a I say, I think the piston is now not sitting square on the pad. don't think all four pistons could be cocked? seeing as all are the same.
have had a look underneath while operating, and there is a little soak up required when applying brake but not sure how much is too much. replacing calipers is expensive here and will be a last resort.
wish I had of recorded it before I took car off the road.

[RICK LAKE]

ollykiwi3 Olly I got a real problem with this problem. I have never had calipers cause a braking problem unless the sliders where no good. Brake pads will cover a number of problems.
I believe you said this has been happening for a long time. I am thinking you have a hard spots in the rotors or rotors. Take them to a machine shop and have them resurfaced. Tell them you want new bits on the machine and the main shaft checked for true. Less than .001" on the brake machine. Resurface both rotors. Clean both stub axle surfaces with 3m wheel. After cleaning install your dial indicator on each stub shaft and check for out of round. Both should be under .002", if not have machine true. Install the rotor and recheck the out of round with the rotors bolted to the stub axles. Again shoudl be less then .002" I checked my jag set from XJ6 and I have about .0017" play all the way around. My does 95% track and auto cross. New pads and same rotors I installed back in 98 and then change pads and resurfaced rotors in 2006. I would change the rotors if nothing shows up. China steel is crap. If this doesn't fix the problem, Go to Jag and find a good tech and see what he said. Can you go 20-30 in reverse?? See if the schutter is there. What happened with the parking brake test?? This should give you the same feedback as rear brakes?? Good Luck Rick L. Ps have an old service manual for Jag, going to look up info and see if any thing will help.