Hi
I am new.to the forum.but felt the need to join a well established one to see if anybody could.help me

I have had my wheels refurbed and.checked for any buckling.and.rectified had the tracking done balancing carried out and changed the discs and pads only a month ago but after a month my steering is shaking again on braking, has anybody had ths issue on their xj as it is driving me mad and I don't want.to put another set of discs and pads on in case it happens again

Can anybody help me
Regards
Steve

 

Check out this video. It may not be the rotors.

 

The lower front suspension arm "banana arm" inner bushes do wear out and cause vibration on braking. (they are there to cope front wheel braking forces) When these bushes get soft, they change the wheel aligment during braking and that cause vibration.
These arms are quite cheap (even OEM Lemförder) and easy to change. 4--Wheel aligment needed afterwards.

Also:
Measure if your disks have warped.
The service manual gives these values:
Maximum front brake disc runout (installed) 0.075 mm ( 0.003 in)
Maximum rear brake disc runout (installed) 0.09 mm ( 0.004 in)

Note: There are manufacturers who do not make good quality disks and they can warp just by few weeks of usage. Specially if your calibers are stuck and do not release the pads from disk surface. (one side get hot, other stay cool. Warping happens by heat difference in different sides of mid-duct cooled disks.
XJ is still big and heavy car. No-name disk may perform well in light citycar without problems, but not nessesarly on XJ.

Seen also pirate manufacturers packing just crap disks to the quality brand packages and sell these as premium products. (at least one big major aftermarket car part supplier been catch for this. Naturally they blame their supplier...)
When you purchase new disks, choose quality brand and verify that you have installation / warning leaflets etc inside of boxes what are included in original manufacturer products but pirates leave out.

https://www.ferodo.com/en-ae/support...unterfeit.html

https://www.brembo.com/en/company/ne...ognizing-fakes