How to improve Xantia braking system?

DoubleChevron · Post by **DoubleChevron** » 05 Oct 2004, 06:27

Hi Guys,
I'd be bloody stunned if the Activa had different brakes to every other Xantia.
Eg: we have parked in the shed a CX2200 deisel wagon. Yep that's right a bloody huge CX wagon fitted with a tiny little N/A 2.2 litre deisel. I also have a Series II CX2500 GTi Turbo. The only difference in the brakes ???? The stationwagon has bigger back disks 'cos it's a wagon and the turbo has ABS. If the '76 CX2200 was a sedan it would have IDENTICAL brake components. This is how overbraked Citroens are.
Now, I put any $$$ on the CX turbo will stop a LOT quicker than the CX2200 wagon ... It's got bugger all to do with ABS, rather the CX2500 has wide high performance sticky rubber under it.
In the same way the Activa will have much better stickier tires under it. ie: the Activa will stop quicker simply because it has more rubber on the road, it'd probably stop SLOWER on a greasy/wet road as wider tires are a comprimise, they tend to aquaplane me readily on wet surfaces than skinnier tires.
seeya,
Shane L.

pwatson · Post by **pwatson** » 05 Oct 2004, 12:35

"Xantia mk2 2.0HDi Exclusive - 76.8 sec
Xantia mk2 V6 Activa - 62.2 sec
Saxo 1.6i 16V - 64.4 sec
Berlingo 1.8 - 73.4 sec
Ford Focus 1.8TDdi - 69.7 sec
Renault Espace 2.2dT - 73.9 sec
Land Rover Freelander 1.8i - 72.4 sec
Lexus LS400 - 69.2 sec"
One minute and 17 seconds - 80 mph to zero? I can't believe those figures! I reckon if you just took your foot off the throttle and didn't use the brakes at all it wouldn't take that long. Or am I missing something??

pwatson · Post by **pwatson** » 05 Oct 2004, 12:38

"Other Xantias, just the opposite. Good breakes cost money... Citroen had to cut somewhere, so that they could reach Xantia's competitive low retail prices... "
And I'm afraid I don't believe that either - are you trolling???

madasafish · Post by **madasafish** » 05 Oct 2004, 14:03

Those figures are just rubbish.. It means over 0.5 mile stopping distances...read any of the accepted figures..Remember Aston Martin claimed to stop from 100mph in under 7 seconds...
No doubt these figures are for ships...

Post by **Jon** » 05 Oct 2004, 14:14

I've had a quick look at this, and note the following:
Xantia 90HDi hatch 266mm discs
Xantia 90HDi estate 283mm discs
Xantia 110HDi (all) 288mm discs.
In fact, the Xantia HDi 110 and V6 had the biggest discs and pads of all Xantias. The 2.0 Turbo Activa had in fact 283mm discs.
Had a quick look and all Xantia ABS sensors are the same, regardless of engine type, just a couple of changes on year break.

activa · Post by **activa** » 05 Oct 2004, 18:20

No Jon,
Activa 2.0 or V6 year '99 have 288mm disks. The poor thing is that, in Greece at least, brake pads that are sold through the representative are of very bad quality and beside the annoying "hissing" noise they perform pretty bad...
Dimitris

Xantia Activa 2.0 Turbo

espzetec · Post by **espzetec** » 05 Oct 2004, 18:24

sorry to be a pain, but here's my 2p's worth.
brakes on the Xantia are absolute rubbish! stopping distances are very long when compared to my other cars. has been a few hairy moments in the Xantia. Better brakes are the way forward!

Panjandrum · Post by **Panjandrum** » 05 Oct 2004, 18:33

There's a bit of a conflict between this topic and:
"Hydropnuematic brakes instant lock"
http://www.andyspares.com/discussionfor ... IC_ID=9138
PJ

alexx · Post by **alexx** » 05 Oct 2004, 18:43

Well...
Problem with Xantia brakes, at least on my car, is that air somehow gets into rear brake circuit, causing odd feeling on the pedal. After bleeding, feel on the pedal is definitively better than on conventional brakes
Anyway, I tested my '98 Xantia with 6 year old Michelins (!) against '01 VW Golf with very low mileage from 100 km/h to 0 on the same part of the same road. Both cars stopped in 3.1 s.
Several months before that, tested my ex BX ('89) against almost brand new Laguna mk II, loaded with ABS, EBD, BAS and similar stuff (BX didn't have any), the car with declared stopping distance 37 m (from 100 km/h to 0). Both cars needed the same time to stop.

AndersDK · Post by **AndersDK** » 05 Oct 2004, 19:03

If the brakes on the Xantia appears rubbish - then they definately needs attention. Got to be a problem somewhere, even a screeming obviuos problem.
Apart from the dreaded springy rod between pedal and brake valve - the brakes system is exactly like the BX - which is the most superior brakes I've ever experienced on any car.

bxbodger · Post by **bxbodger** » 05 Oct 2004, 19:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">air somehow gets into rear brake circuit, causing odd feeling on the pedal. <hr height="1" noshade id="quote"></blockquote id="quote">
If it keeps happening, this is possibly a leaky sphere, slowly leaking nitrogen into your rear brake circuit.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">which is the most superior brakes I've ever experienced on any car.<hr height="1" noshade id="quote"></blockquote id="quote">
Not so much these days, drive most cars produced in the last year or two with e.b.d., etc, and the margin is significantly eroded- basically, the rest of the world has caught up!
Where the Citroen system IS superior, is in the lack of dive.

Panjandrum · Post by **Panjandrum** » 05 Oct 2004, 19:35

Sorry - previous post was a bit terse.
My point is that if it is possible to lock the brakes instantly then the ability of a Xantia with properly working brakes to stop comes down to a combination of driver, ABS, tyres and ground conditions.
And back to Thunderbird's point - the only Xantia bit of this is the ABS.
The value of ABS is partly improved control and partly that a locked wheel has a lot less stopping power than a turning wheel.
A "good" ABS will optimise this.
PJ

alexx · Post by **alexx** » 05 Oct 2004, 23:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bxbodger

<blockquote id="quote">quote:<hr height="1" noshade id="quote">air somehow gets into rear brake circuit, causing odd feeling on the pedal. <hr height="1" noshade id="quote"></blockquote id="quote">
If it keeps happening, this is possibly a leaky sphere, slowly leaking nitrogen into your rear brake circuit.
<hr height="1" noshade id="quote"></blockquote id="quote">
Indeed. I wrote about this problem a month or two ago and didn't solve it yet. In the meantime, I checked suction side of the pump, where air could get into the system, but everything seems to be ok, no cracks, leaks etc. No problems with front brakes either.
I think it is nitrogen coming from anti sink sphere. Every sphere is gradually loosing the gas, and unfortunately, from this one it's going directly to the doser valve, feeding rear brake circuit. Anti sink sphere on my car have lost only about 10 bar during 6 years, but it's about 1.8 ccm of nitrogen at atmospheric pressure per day. Obviously, some of it finds its way to the brake circuit. Occasionally, after starting the car and pressing the brake pedal for the first time, I can hear a strange sound from the doser valve, something like 'ouch', which wasn't the case on BX, with the same type of the doser valve
I think it's a design flaw of the anti-sink system. Eliminating the A/S sphere would probably solve the problem (it's not needed for anti sink system anyway). Only - in the case of HP supply failure, it would leave me without front and rear brakes.

rossnunn · Post by **rossnunn** » 06 Oct 2004, 00:00

I can remeber reading that one of the reasons Citroen stopped using the BX / Xantia setup was because if the green fluid drains out the brakes would fail - this being a load of balls because the suspension would fail first then the power steering and the dash would lightup like a christmmas tree.
A little off topic, sorry about that.

Post by **Thunderbird** » 06 Oct 2004, 00:46

I appologise but on my previous post the figures' units were wrong - not seconds but meters!
Xantia mk2 2.0HDi Exclusive - 76.8 m
Xantia mk2 V6 Activa - 62.2 m
Saxo 1.6i 16V - 64.4 m
Berlingo 1.8 - 73.4 m
Ford Focus 1.8TDdi - 69.7 m
Renault Espace 2.2dT - 73.9 m
Land Rover Freelander 1.8i - 72.4 m
Lexus LS400 - 69.2 m
Renault Clio 1.2 - 77.2 m
Seat Arosa 1.0 - 79.6 m
Suzuki Jimny 1.3 - 83.9 m
Daewoo Matiz SE (800cc!) - 82.9 m
Citroen Saxo 1.0 - 81.9 m