ok thxs for the comments - I have new rebuilt front Calipers installed. The Pads installed easily with minimal clearance, the pins were new too, I assembled with minimal brake grease, but I will double check that the pads will still slide in and out as recommended. I have never experienced a feeling of the ABS engaging (like I have on other cars when the brake pedal feels like it's fighting back at your foot) or the feeling of the steering wheel being snatched out of my hands, just an even pull to the right under braking, the magnitude of the pull being a function of how hard I'm braking - however this does set the ABS light on the dash! Hence my thought that it's ABS system related.

I will double check the front pads, replace the outer tie rod ends this weekend and try and evaluate the front suspension bushes and ball joints and see where this takes me.

It's becoming more difficult in Michigan to test drive the XJS now, as the roads are covered in salt!! This is California car and has never seen that stuff - I intend to keep it that way!!

Thxs all, keep you posted.

 

Hi icatterm

I'm still not sure that the ABS is your problem although of course be, as uneven Braking however caused could possibly trigger the ABS light to come on and so with that in mind it could be something as simple as Air in one of the Brake Lines or Air getting in somewhere when you replaced the Calipers

As this can often happen if you are re-using the Original Metal Brake Pipes, which can be quite hard to get Air Tight if they have been disturbed when they were removed

 

Hi OB, I will thoroughly bleed the brakes again this weekend too, joggle the metal brake pipes and check the hard brake line joints for any leaks - it would be great if it were as simple as some trapped air in the line!! Fingers crossed!!

Thxs for the pointers, it will be great to get to the bottom of this one.

 

As mentioned, I'm not sure this is a "typical" ABS valve block failure issue. And the ohnms readings on the valves would seem to support this.

Sticking calipers or pistons felt more likely and that is an area that you can check.

The other area that I would be looking at is integrity of the ABS sensor wiring and also any contamination or damage of the reluctor rings at the front. So check the continuity of the sensors, and pull the sensors out of their housings and revolve the hubs to check that all the reluctor ring teeth are intact and clear.

Good luck

Paul

 

Makes sense Paul - I will do that. Thank you all.

 

Quick update on the latest - SUCCESS!

I convinced myself that the tie rod ends and lower control arm ball joints DON't have play in them, despite the perished rubber boots, so alignment issues weren't root cause.
Both front Wheel speed sensors had uniform resistance, sensor rings look complete but a little dirty..
I then bled the front brakes again with the help of my daughter on the foot pedal, while I operated the bleed nipple! Bled about a cup from each side (Previously, I'd used the pressurized brake reservoir method that I use with my Land Rovers).

Last night I fired her up for a test drive (-2 deg C), but we were forecast snow last night, so figured this might be my last chance for a while! With the engine idling and the brake depressed, the ABS light & brake light was illuminated on the dash, so I wasn't hopeful! But the warning lights disappeared as I edged out the poll barn into the cold evening air! I live on a dirt road, so the first 1/2 mile was very slow with no real braking needs but a quick dab of the brakes felt good and no warning lights! Then when I hit the tarmac and opened her up to some real speed and hit the brakes - SUCCESS - nice uniform braking! No warning lights!! What a fantastic feeling!

Thanks to everyone who posted for their hints, advice and encouragement. Very grateful.

btw - I have an unrelated question (with photo) regarding what looks like an unconnected tractor fuel filter! Should I start a new thread? Or add it to this one! (I don't blog much!) Thxs Ian

 

Ian,

Well done, you must be pleased!

It could have been the bleeding or the reseating of the sensors and wiring. Then when you started to move, the system saw integrity of the sensor resistance and turned off the lights.

Either way, great result!

I suggest you start a new thread with your fuel filter issue.

Cheers

Paul

 

ok thxs Paul - just posted a new thread!

Cheers, Ian