Brakes- big ones !!!

[Frenchracingblue]

Hi, not been here for a very long time, Blue racer is coming out to play for the first time in years, Mot'd again now, just as fun to drive as ever. Anyone fitted large front brakes to a 16V? I have my own plans but am curious to know what others have done

Also have a few photos I can upload, not sure how to do that. Doh!
Cheers

Peter

[Mandic]

Use this: http://imageshack.us/

As for the brakes, problem is that LHM and DOT seals are not compatible. If You fit bigger brakes on (from other cars) You'll need to change seals.

Other Citroens have more or less similar brakes as BX. Besides, with 160HP I reckon std. ones with some better pads are adequate.

Cheers

[Frenchracingblue]

Hi, granted the standard setup's ok for road use, but even with Ferodo DS pads the discs go off on track after a while, car needs a disc much bigger and thicker with a bigger pad area to offload all that heat. I started on a little experiment back in 2002, which started well and all looked very encouraging, got sidetracked though!! About to pick it up again next week.
Will update as progress goes on.

Thank you for piccy link, will give it a try.

Peter

[Toddman]

I am pretty sure there is some info in the members area, Simran IIRC has fitted the Xantia setup but they won't fit under std rims.

Cheers
Luke

[surjit25]

Since the 16V has the same disc as the Xantia just change the
calipers , they really stop well. , I use ori 14in and they just clear
the calipers by an mm or two.

[Vanny]

Xantia activa (and possibly V6) discs are 20mm wider accross the diameter and hence why you need bigger rims for the calipers to fit under.


Does anyone have any actual proof that DOT seals aren't compatible with LHM? LHM is after all simply mineral oil and hence the rubber hydraulic pipes are nothing more than rubber fuel hose. I must admit that i have always been told and told others that DOT and LHM seals aren't compatible, but i've never seen/heard of any actual proof.

[Gary C]

Have found standard discs and pads to be fine for racing. Competition compounds are usually too soft and either break up or glaze. Giving the std disc and pads a good going over with emery before each track session helps.

[Mandic]

Does anyone have any actual proof that DOT seals aren't compatible with LHM? LHM is after all simply mineral oil and hence the rubber hydraulic pipes are nothing more than rubber fuel hose. I must admit that i have always been told and told others that DOT and LHM seals aren't compatible, but i've never seen/heard of any actual proof.

They aren't, for sure!

For DOT oil, seals from EPDM rubber are used, and for mineral oil NBR rubber must be used.

Otherwise seals expand and seize. I have thrown EPDM seal in LHM and it expanded like 5 times. Haven't done it the other way around.

Cheers

Ziga

[Rene]

I ran standard size Black Diamond grooved discs with EBC Green Stuff for 18 months. They lasted 9k miles and I was quite hard on them. The stopping power was tremendous, if a little rough under extreme braking, I mean 100+ hard stopping. The pressures inside the BX caliper are tremndous, 40 tons I believe and possibly the pads were being ground into the grooves. That's what it felt like, could possibly be the ABS coming in.......... I'd certainly not go for grooved discs again, Gary has proved what standard discs can do, but with a bit less extreme work than Gary's I think soft pads work well.

--
René

[Frenchracingblue]

Hi, need to try to do this without being impatient!! Fact: If you leave braking to the latest possible moment on every corner on a circuit that doesn't give you cooling distance between corners, then the brakes will rise in temperature beyond the working range of either the pad or the disc. about 6 laps round Lydden will see a BX's front brakes off the scale, unless one adopts a fitment of new discs and Ferodo DS pads every race, and that's £129 or so on top of the entry fee every time out, I know because I've run a TVR griffith using exactly that method, because the regs won't allow a bigger brake to be used. We also had to run front hubs made from super high quality alloy and bearings running in melt proof grease otherwise the grease ran out of the bearings to make black radial spray all round the front wheels.

The BX does exacty the same, so therefore if you want to keep braking hard lap after lap you need brakes that can offload enough heat into the disc to keep within limits - that means a big disc, limited by rim size with whatever caliper one has to use, as thick as possible to maximise cooling to the airstream, not the front wheel bearings! The caliper piston dust seals on our car used to turn to powder, from heat conducted and radiated from the piston and pad, I think that's an indicator of how good the brakes are efficiency wise, in turning kinetic energy into heat, but the heat needs to be got out of the components that are being heated by the job of braking, if the brake is to be asked to keep repeating the action. The ONLY way one can keep a BX going flat under full race conditions (without spending on an expensive engine) lap after lap after lap is to be kind to the brakes, thereby wasting the car's best feature in generating a good lap time. I've just fitted £1350's worth of front brakes on a fiesta weighing considerably less than our BX to cure exactly that problem, now you can give it hell all the time, not just for five minutes. the BX has to be sorted with a budget of nothing, by comparison! I posted here having tested something out with bits borrowed - with permission- from a taxi, so i arrived at a potential solution in 2002, just wondered if anyone was using it, or anything else? I have a set of Xantia 288mm calipers on their way now, want to see whether one can space the caliper mountings bolts inboard, or to move the disc outboard, before I order the wheels, that's as far as I got in 2002! Have also been told that there is a 305mm four stud front disc on the 406V6 coupe, normally run with a brembo caliper. getting a bit big to run without a bell though, would need caliper adaptors too rather than concentric bolt or disc spacing, so all gets expensive and fiddly. Am hoping that the Xantia disc might just stay cool enough to use road pads too. We'll see!!!!!!!
Cheers

[Rene]

I hate to argue here but, as Gary C said, we ran Bertie the BX for 4 seasons on standard Citroen pads and discs on most of the circuits in this country. We didn't have glazing or overheating problems at all.


copyright Ian Hardy 2004

I've seen Gary outbrake ex-BTCC Integras and cars with much more expensive set-ups. Brakes were always one of our big advantages over the opposition, even the lighter cars.

When we were with the Dunlop Max Sport Cup, the leading Astra went through a stage of melting everything with brake heat, including his cv boots at Snetterton!!! So while there IS a problem with some cars, not the BX.

Those Brembo calipers are great, but won't you run into fluid problems with the LHM? But if you find a set, let us know, as we want a set for the Xsara.

--
René

[Toddman]

I was told a long time ago that the LHM seals were not compatable with standard brake fluid but I never had any proof, I trust the guys I use and they have been racing citroen since the days of the DS.

Anyhow I have always been a fan of the std braking setup on the 16v and am a firm beleiver in that a decent set of discs such as Bendix and pads like Tekstar will show up much more expensive set-ups.

The good news is however that fitting the Xantia discs and calipers like Simran has done is a cheap modification and should ass suggested aid cooling and braking force. Here is the thread - http://bx16valve.co.uk/forum/viewtopic. ... c&start=45

Cheers
Luke

[Frenchracingblue]

Hi, please read the post carefully, I was advised of the existance of a 305mm disc, that would normally go with a Brembo caliper on a 406, it's the disc that grabbed my attention, just the disc. Anyone that cant overheat a BX brake needs to try braking harder, then keep braking later and harder, on 8 x16 rims with sticky tyres, keeping a modified elise at bay. take it from me, the brakes will go off in the end unless you are either kind to them or spend on DS pads all the time. just gets too expensive, the ones that didn't go off lasted 40 minutes on track. My car started scorching thepaint on the wheels after a while.With 15s and 195 tyres, it limited how much force one could apply under braking without locking up, so was less of a problem, but I'm not limited by the kind of race wheel and tyre restrictions that Gary is, so ran the car with 8x16 compomotives made for the car, and 215/40 x 16s on the front. with the right tyre the braking improved immensly just because of grip and consequent later harder braking, so the brakes went off faster because they couldn't disperse the extra heat for a sustained period. The BX has massively powerful brakes, and the way the suspension works makes it possible to really stand the car on its nose if you can find the grip. But you can't escape physics, however hard you try. Thank you for the link!!!

[Frenchracingblue]

[Frenchracingblue]