The brake pedal on my 2005 XK8 with Brembo's feels very much softer than my 2001 XK8 did with standard brakes.

No problem with the way the car stops but it's certainly different. Not spongy the way brakes are with air in the system - less feel of resistance when pressing the pedal.

Is this normal?

Graham

 

cold. Add heat into the disc/pad and it should improve. How much wear on them?

 

I would check the brake fluid. Look at the brake fluid, the darker it is the more moisture it has absorbed, it should be yellowish. Brembo brakes are performance brakes which means they get really hot due to the extra pistons on the calipers and the migger braking surface. If the brake fluid hasn't been changed in a while, Jaguar recomends every 2 years if severe driving, that might make your pedal a bit low. I also recomend using Motul DOT 5.1 which is awesome for that car.

 

Supplied and service by the same Jaguar dealer from new. Discs are good. Pads were changed at last service and have done just over 4K miles since.

Are you saying Brembo's need to be hot before braking at full efficiency?

Graham

 

The fluid should have been changed at the recommended intervals by the Jaguar dealer but I have no way of knowing the PO's driving style.

Good plan to flush it. That removes any doubt about the deterioration of the brake fluid.

Checking out Motul DOT 5.1 on the web shows it's fully synthetic long life. No special precautions to be taken when switching to it from Jaguar non-mineral polyglycol DOT 4?

Graham

 

My XKR brakes are normal feeling, they don't have a soft feel. I have an XJ8, they feel just the same. The Brembos use a smaller diameter brake hose than normal, should decrease the softness, not increase it. If yours do, they probably need bleeding. I use ATE Racing Blue DOT4 alternating with gold at change times. I change fluid at least every two years with the alloy calipers. The last thing you want is water in these babies! If they get any aluminum oxide going in all those pistons and bores, there will be a second mortage to replace them!

 

That's very useful you can compare the two cars and don't feel any difference in the pedal. It emphasises my need for a fluid change.

Have you had any reason to change the flexi hoses? Your comment about the diameter has got me thinking about the possibility of one ballooning under pressure although I haven't seen this happen for many years.

Graham

 

Another possibility ...

Water in the system would be bad for other reasons, but it would not explain softness in the pedal (unless you got things hot enough to boil it; not likely on the street). This is so because water, like brake fluid, is incompressible.

Pedal softness = compressibility. Could be air in there, but that's easy to identify because the pedal can be pumped up. The hoses have been mentioned. How about a pad material different from what you're used to from the XK8? That, or a different level of power assist seem like the most likely sources of a softer pedal feel.

 

I have always thought that the pedal on my XKR felt a bit soft, especially compared to my Jeep Liberty.
Will get a fluid change at next service.

 

My Brembos feel normal. I wasn't aware they needed special treatment re. heating up. In fact, seeing how massively expensive they are to replace, I try to use them as gently as I can!

 

I'm reasonably confident there's not water in the system because this usually shows as condensate on the inside of the filler cap. Had a look just now and there's no signs of this. Pedal doesn't pump up which near enough discounts air.

The possibility of power assist being different was something I hadn't considered. Checked the Parts Manual and it's the same part number for both the standard brake systems and the Brembo system. That's not to say the servo couldn't be faulty.

Pad material is likely to be different. I've always used aftermarket pads (Ferodo or Mintex) and this car will definitely be fitted with whatever is Jaguar supplied because it has been serviced exclusively by the dealer until I purchased it in November. I'll have a look at what pads are available as an alternative. This also gives me a chance to get round the dust problem. The black brake dust wasn't too much trouble with the Impellar wheels on my last XK8 but the Sepangs on this one are tougher to keep clean.

Thanks,
Graham

 

Fitment on Brembos, I dunno, but have been very happy with Akebono ceramics on my XK8, both performance and the lack of dust.

Somebody had told me that these would feel more "wooden" than stock, and they do. Now: if you ask me to define "wooden", I'm at a loss. Sort of like Potter Stewart's definition of pornography: "I can't define it. but I know it when I see it".

Good luck ...

 

Tell me about it. I try to give mine a quick wipe down every 100 miles or so to keep them clean. But I think that's precisely why they are so classy: a bit like a beautiful girl in a white dress, people know the work it takes to keep them looking clean and so appreciate them all the more.

 

I've got an aerosol of AutoGlym Alloy Wheel Seal to try as soon as it warms up enough outside to encourage taking the wheels off for a thorough clean and polish:

Autoglym Alloy Wheel Seal at the Autoglym Shop

If this allows brake dust to be hosed off instead of needing a scrub with a wheel brush, it'll be worth the effort.

I'll let you know if it's any good.

Graham

 

G why are you using the brakes so much?

Ettore Bugatti said "I make my cars to go not to stop".

Chip the ice off your wheels and test the Autoglym then get back to us.

My Green Brembos seem to be fine, great brakes, nice and hard feel!

Sorry about your 'softness' problem.

cheers from the Siberian Alps,

It's all the way up to -10c today....balmy.

jj

 

JJ,

You have Green Brembos - is that the writing on the side of the calipers or the pad type?

I've been going through the threads on brake pads and one of your posts mentioned Akebono only being avalable for rears and backed this up with a eMail from the manufacturer. Did you bottom out what's available and what fits? It appears to be a choice between original Brembo, Akebono or Hawk.

Hadn't realised these things were so expensive. I'll be following Bugatti's advice on braking.

GGG

 

To be honest I dumped my Brembo's - squealing, dusty and starting to rot on the backside of the caliper - standard equipment on the XJR100. I tried a few pad makes, Ferodo (Jaguar use them too) where the happiest.

Sounds like a flush and some DS2500 pads might give a better pedal. All Brembo equipped cars have BF Goodridge stainless steel braided hoses, so flex pipe bulge is b.s.

I now use Alcon monobloc calipers all round, these do need an initial poke to introduce heat, but christ do they bite. How about 120-0 in under 5 seconds, fearsome stopping power.

 

G;

That's the paint.



No go on the Akebono's, too bad.

I have the Hawks book marked, only $250 for a set in the US.

Let me know if you find them in the EU please.

Do you have any friends coming over from there?

How urgent is this, I have family and friends coming from about March on from the US and will have them bring me a set for future reference.

There is also "Red Stuff Ceramic" that get's high marks, you can check them out on TireRack.com

Try this thread for some useful info if you haven't seen it:

https://www.jaguarforums.com/forum/x...st-hell-66277/


Let me know too if you use the Autoglym....my wheels are clean right now and it is not going anywhere soon...so I could try it too.

cheers,

jj

 

That's some stopping power - I'll be sure to leave plenty of room following any black XJR's along the M6 or M62!

Thanks for the info on the hoses being Goodridge stainless. That's another possibility I should be able to strike off the list.

Graham

 

Stay away from Bad Stuff, sorry Red Stuff. Have obviously not so good experiences with them on the Brembo brakes we have. Hawk ceramics are very good in bite and low dust, am now on my 4th set.