Poor Brakes

[richdraper]

Evening all,

Can someone explain to me how sharp the brakes on the x-type *should* be!?

 I needed to pull her up a little quicker than normal thanks to some idiot cutting from the outside lane to the slip road of the M6 the other day, and ill be honest... i was scared no ABS actuation in the dry which i would have expected considering how hard i stamped on the pedal. The V6 has 300mm discs on the front and 280mm on the back, I'd expect it to stop pretty sharply, even though they're not particularly focused calipers (i.e single piston with a slider arrangement... her car is an Alfa 159 with standard Brembo 4-pots and it stops incredibly well with 280mm on the front).

I bled the brakes today, its marginally better and i do mean marginally! Will be checking out Vac system tomorrow as apparently the little one way valve degrades. thinking it might be sliders a) starting to seize b) seized already. That's one for another day (maybe next weekend) though. discs are in 'relatively' good nick although now i'm thinking about it, the rears are only 'semi shiny' on the outer surface and i do get a 'mooing' sometimes when reversing from the NSR... which suggests partially seized sliders to me.

 

any thoughts/experiences/advice is always warmly recieved!

[Guest]

Hi Rich and Welcome to the Club,

Seems you're no stranger to the oily bits and your plan looks right to me and I suspect you're right about the sliders given what you say about uneven wear. Calliper slider pins seizing is not uncommon on the Jags and I'm sure you know that you can get hold of replacements readily enough; albeit there are some gouging prices out there. So, if the Vacs working properly and the ABS is behaving itself I'd put money on it being the sliders. The only other things I can think of are old brake fluid that is either deteriorating or contaminated or some kind of contamination or break-down of the pads.

This probably won't be of help to you but good luck and keep us posted.

Cheers,

Steve

[richdraper]

Hi Steve, thanks for the welcome.

Searching through the forum there's a lot of noise about sliders, so figured it might be a good place to start, from my experience (including my own mistakes) a lot of it is down to the incorrect grease used when rebuilding. There's a few instances of swollen slider rubbers that I've found, in s-type threads which, by the way, is almost solely caused by incorrect grease... 

You're right I'm no stranger to getting my hands a bit grubby ;) owned Fiats and Alfas for a shade over 11 years, and I'm a mechanic by trade. Whilst i know a lot more than most, i know next to nothing about Jags, everyday is a school day and this weekend the lil kitty has been tying my patience. Trying to source the cause of an intermettent misfire in between housework today (I'm aware of the wiring loom service bulletin Jag released) kinda hoping i just got the plug wet although with it being on pot 3, i.e. the middle one on the rear bank, hidden under the inlet and genrally well protected, I'm clutching at straws and not wanting to get into wiring too much because of work tomorrow.

[Guest]

My pleasure.

The wrong grease is, as you say, not uncommon and few people seem to realise how even slight differences can lead to big troubles. I owned a couple of Italian motors in the dim and distant - Lancia Dedra and Thema specifically - which mostly delivered electrical problems before terminal rust got to them. Jags are not dissimilar insofar that the most frequent grumbles you will hear are typically to do with the various (too many) Control Modules, Sensors and fun and games resulting with same resulting from low battery charge.

Have you got a decent ODB2 Code Reader specific to the Jag yet? They can be a real help in diagnosing the cause of intermittent faults reasonably quickly - you would be surprised how much data those CMs hold and for how long - could be a boon with that misfire.

Good luck with the brakes and the misfire.

Stay in touch, even if its only for moral support or someone to !Removed! about it with.

Cheers

Steve

[richdraper]

I've got P1301,1303, and 1316... all misfire faults... 'random', 'cyl 3' and 'within 1000revs after start' respectively. i need something a little more bullet proof than the WiFi/BT plug in dongles, i got it to work with an 7 year old tablet but no joy on my HTC... that's been part of the headache, i've lost my OBD, only have k-line USB Lead. the first 'spare' £100 i get will be going on a mongoose lead and the Jag Diag kit. its impossible/incredibly time consuming to diagnose accurately these days without good diag kit. i'm having to run it this week and just edge my bets with taking out a cat (every bone in my body tells me not to do it, alas, i have no choice) took her out earlier on and she still sputters a little bit. im hoping shell be fine cruising up and down the M6 for 4 days.

this starting to go a lil off topic though... ill report back with brake findings, i might start another thread for misfire if it doesnt clear up this week. like i said pretty sure theres water somewhere, but time will tell.

[Guest]

Good luck Rich.

[richdraper]

right, so, mystery solved... Fluid change fixed the issue.

I'd been driving the Alfa for a few days previous to doing brake work on the Jag. Our '07 plate 159 with 4 pot calipers on the front is pretty capable of popping your eyes out of their sockets if you really stamp on the pedal. The jag, whilst not feeling like its actually doing a lot in comparision, is now strong enough to at least trigger the ABS on the front wheels in the dry so i'm happy with it for now. After all there's not a lot more you can ask of a wheel if its having ABS triggers. (i wasnt even getting abs triggers in the wet before fluid change)

I'm sure when its time for discs and pads ill be putting brembos on and actually running through the sliders, if not replacing them. It may all become little sharper than it is now, but it does pull itself up a damn sight quicker than it used to.

thanks @cubist for your input. :)

[Guest]

Hi Rich,

Thanks, though I think I did little to merit it. 

I had a Dohhhmoment as I read your reply as I'd completely forgotten to ask how old the brake fluid may be. I learned some years ago, too many to think about now, that the stuff is hydroscopic and absorbs water over time which in turn produce the spongey effect.

Ah well, live, learn and forget if you don't use it.

Cheers,

Steve

[richdraper]

goodness knows how old it was, but it was 'slightly' black (not as black as it would be if seals had failed but ill keep my eye on it) and 'slightly' transluscent... It was well overdue a change

[Guest]

I just did fluid as I'd had my calipers reconditioned - I swear the first thing out of the bleed tubing was a small pocket of water - although Oil is supposed to float - Mine had a few blobs of black too.  Braking has been far more decisive since.  But not a patch on my Mrs' 208, when I drove that after a few weeks of driving the Jag, I nearly broke our necks at the junction from our estate.

The one thing I did happen to notice was if I brake when I knock the auto box into neutral, there is a vast difference in brake effectiveness.

I agree entirely single pots on a car this size is a bit daft

Glad you're sorted Rich

[richdraper]

the thing is that, away from 'perfomance circles', the way to get your brake effort up is just to use big rotors. The X was probably designed late 90's as a mid-range saloon car. there wasn't a huge need to have multi-pot calipers on anything that 'shouldn't be driven in a sporty manor' and at that time the price of big calipers wouldnt translate as 'economical' to either dealer nor buyer, so it was left off the X.

The Alfa would have had 5years worth of tech develop before it was designed and judging by the other models at the time (3.2 V6 Breras, 3.2 V6 GT, the big heavy diesel and 4x4 systems used in the 159) there was need for some serious stopping power up front, under the 17inch wheels these 4 pots are TIGHT, the 18s were a big money upgrade, theyd already gone for the big rotor approach, and then ran out of space so the only thing to do was go for more effective calipers.

 

In all fairness, the X is no slouch in the way it stops but will always pale in comparison to more modern motors of similar class. Mostly due to the era it was built and cost effectiveness. if you wanted a sporty jag you saved up for a bit longer and got the XK... which i know has some big ol' anchors bolted on it.