I'm still trying to get the feel of my new/old '98 XK8 Coupe. I've addressed most of the engine and transmission weakness areas...but I still have some concerns/questions about the condition or efficiency of the brakes.
Let me first say that the brakes work and stop the car; however, there seems to be a rather soft pedal and a lot of pedal travel to reach engagement. Is this the normal braking "feel" I should expect? This is or was a 40k miles car seldom driven over the past 10 years or so. Brakes were bled and new brake fluid added by a Jag dealer a few weeks ago.

 

Very difficult to describe how the brakes should feel! Best way is to drive other XK8's for comparison.

Did they check/replace the flexi hoses to the calipers?

I do find the XK8 brake pedal 'soft' in comparison with some other vehicles but efficient at stopping. However a 'long' pedal (lot of travel to reach engagement) is more of a concern. The brake flexi's are known to deteriorate with age and balloon up under pressure. This requires further pedal travel to apply the brakes. Worth checking as this could be a possible cause.

Graham

 

Strangely enough my XKR is the same. The car stops but there's a soft feel and pedal travel is quite low.

I know my pads are due for a change and was thinking of changing the discs, not sure if this will make a difference.

I also have a 2010 XJ and the brakes are no comparison to that in an XK8. Maybe old technology I don't know but I'm also looking for an improvement.

 

long soft brakes are a common theme for Jaguar owners.

maybe it comes from a desire that the rear seat passengers
not ever feel sudden brake applications.

 

Normally, for a soft pedal, the cure is to bleed the brakes. Soft pedal can be caused by air trapped in the system. As your fluid is new, you could go around the car and bleed each caliper in turn. I am a fan of the simple "gravity" bleed, when you just open the caliper bleed screw and let mother earth do it thing. Use a clear plastic tube to see what is going on. I always use a hammer and gently tap the caliper to try and dislodge any air. Of course, make sure you have enough fluid in the reservoir so you don't run out and introduce more air in the system. Before any bleeding, I usually pump the brakes a few times to again try and move stuff around and hopefully trick the air bubbles into travelling upwards. This procedure usually firms the brakes quite a bit.

For travel, my understanding is that it is caused by the caliper moving from the rest position to the clamping position. As the rotors and bearings wears, maybe some runout is introduced, and the caliper moves back too much, causing long travel.

Let's face it, this single piston design of the XK8 is not exactly going to give you the race car rock hard feel where braking is controlled by pressure only (and no travel). The best to be hoped for is a decent feel, making the car feel more lightweight than it really is, and get to a a point where you are not thinking of the brakes when you are braking.

When it comes to brakes, "everything" counts: pad material, wear on the rotor, bearings, brake lines (rubber vs. steel-braided), even master cylinder and booster.

Another possibility is air trapped in the ABS system. I never saw definite data on this. Some say a scan tool is required to activate the pump. I assume activating the anti-lock feature has to move the fluid, so, maybe on a rainy day and slippery surface, an idea is to to try and (safely) brake hard and activate the ABS on as many wheels as possible (not necessarily at the same time), then follow up with the bleeding. Just a random thought.

Good luck, keep us posted.