Brakes- big ones !!!

[Frenchracingblue]

I will start to get my head round uploading images eventually!!!!

[thanuttiscotsman]

well i dont really believe that, ive caned my 16v's around for hours on end without any braking issues, ive never had them overheat or had grease melt out of bearing lol

rossco

[Frenchracingblue]

Trust me on this, I wouldn't stick my neck out this far without evidence!! Give your bx a bucket load more grip under braking with some proper wheels and rubber, stand on the brakes four times a minute as hard as the front tyres will take, then see if they keep up. Fitting the 8 x 16s made the car much quicker through the bends than on 15s, and on the brakes, with the right tyre, but introduced a level of brake overheating i'd not seen before under sustained use. The way past a sorted elise that does the same lap times as me is to get past under braking , as a BX is so much more stable than the Elise in real on the limit braking, but he can get the power down earlier than me with his engine layout so it brings him alongside after the exit for a drag race, all fine it's engines and power to weight then. The BX then has him on the brakes every time, but only until they won't do it any more. Make the brakes bigger, you get a sustained better lap time. Fact!!!

[Gary C]

Is there ducting for the brakes?

Have you lowered the car?

Which circuit?

[Rene]

Is there ducting for the brakes?

Have you lowered the car?

Which circuit?

How many times do you hit the brakes in 56 seconds at Brands?

--
René

[Simran]

Hi there, i have fitted xantia activa 282mm discs to my bx complete with the matching calipers. These are from the Mk1 activa, the Mk2 has 288discs and this setup also fits. All you need is some small washers to space the calipers properly but its a very simple job. I enquired at HiSpec brakes on whether their seals could put up with LHM, this was at the autosport show while i was helping out with my unis stand so didnt get to hang around long enough for the guy on their stand to give his tech guy a ring to find out. I was told to ring the office later that week for an asnwer but i didnt get the chance. I wouldnt have thought it would be too difficult to source a new set of seals for aftermarket calipers to work with LHM. Ive often thought about buying a replacement set of seals for such a caliper and also trying the etst ziga did by dunking them in LHM to see what happens but i came across my xantia brakes first. I havent had much road time with them as i started bakc at uni soon after they were fitted and i dont drive the car anymore but i do know they are more powerful than standard, and if they can stop a car close to 1400kg at fast road speeds, i would have thought they would stand up to track use with good quality pads and discs. Driving style can make a big difference to the abuse the brakes get, so even though gary never had problems with his setup, this doesnt mean another driver wont. If there is more grip available, then as frenchracingblue says, alot higher temps can be generated in the discs. Large racing teams put alot of effort into setting up cars to their drivers because of the wide variation in driving style for this reason. Good track oriented wheels in 15" above will fit over the xantia discs with a minimum width of 7" as this is what the xantia came with as standard. Mine fit under 7x16 compomotive MO's with plenty of room to spare.

[Mandic]

If You really want I can make some seals, no problem. Just need accurate dimensions and that's it.

Can make just about everything.


Cheers

Ziga

[Frenchracingblue]

Hi, it would be good to know tyhe maximum working pressure of an aftermarket caliper in relation to the working pressure of an LHM brake system, with the spool valve wide open, brake pedal held down. I've had a caliper, definitlynot a HiSpec, I used those on the Fiesta and so far they are fab, they need to be with two and a half times the power of a BX 16V! But a caliper from one of the bigger companies distorted when fed from a small bore, high leverage master cylinder. was able to pull itself apart under heavy braking in race condition, just made the brake pedal springy, took all it's feel away. They got those calipers back! Anyone happen to know the valve-wide-open brake system pressure on a BX?

[Mandic]

Should be 40 bar?

[Frenchracingblue]

Hi, started on the 288mm conversion today, would appear that the disc needs spacing outwards a little - 288mm disc thicker than 283mm one i think, which is fab for heat dissipation, not for ease of fitting! The calliper needs spacing inwards a little, which is a little easier! Now awaiting laser cut stainless shims for discs, 12.9 grade bolts for callipers. Need a supplier for some nice hard M12 shims, i'm not using squidgy washers behind a calliper. Would be fab if there were a drive flange hub available with a few mm more outboard thickness from another Cit/Pug... Looks right now as if the 283mm conversion is much easier.
Have to say already that i'm eyeing up using the big calliper with a 28mm thick race disc on an alloy bell for the future on the blue car, could probably get a 320mm disc in, maybe bigger!!!!!

[Simran]

I used some cheap washers from B&Q stacked togetherbut the car hasnt really been driven at all since the new brakes have been on, i may do what you've done and make something proper up at uni that wont deform as much over time. Think its about 8-9mm if i remember right?

[Timmo]

320mm! you'll be able to do an Endo with those!

[Frenchracingblue]

Hope So!!! Just want them to never overheat on a big sticky tyre with maximum beans for a sustained period. Should have my disc spacing shims for this weekend, very tempting to try the big brakes on the blue car at Lydden two weekends away. Car was fun with Matt driving at Brands Hatch, first time out for years

[RichL]

Trust me on this, I wouldn't stick my neck out this far without evidence!! Give your bx a bucket load more grip under braking with some proper wheels and rubber, stand on the brakes four times a minute as hard as the front tyres will take, then see if they keep up.

Much as I respect Gary and Rene's racing experience, I'm guessing they arent running the same size and compound rubber as FRB which is why they arent seeing any problems with the stock BX brake system.

I remember a story from the old CCC magazine where the guys were racing a Mk2 Escort and with the addition of sticky tyres and cosworth discs, they had enough braking force that the suspension turrets were deforming.

I'm thinking of putting the green machine back on the road and I know I need new pads and probably discs. I'm seriously considering the bigger disc conversion using Xantia parts simply because I can (and I already have 15" wheels).

[Toddman]

Trust me on this, I wouldn't stick my neck out this far without evidence!! Give your bx a bucket load more grip under braking with some proper wheels and rubber, stand on the brakes four times a minute as hard as the front tyres will take, then see if they keep up.

Much as I respect Gary and Rene's racing experience, I'm guessing they arent running the same size and compound rubber as FRB which is why they arent seeing any problems with the stock BX brake system.

I remember a story from the old CCC magazine where the guys were racing a Mk2 Escort and with the addition of sticky tyres and cosworth discs, they had enough braking force that the suspension turrets were deforming.

I'm thinking of putting the green machine back on the road and I know I need new pads and probably discs. I'm seriously considering the bigger disc conversion using Xantia parts simply because I can (and I already have 15" wheels).

A very valid point Rich and have to say it is great news that the green hornet may fly again
Although I may not think a road going valver "needs" the xantia upgrade I do feel as a DIY upgrade it must be worthwhile.

I must admit I read CCC and thought what is the Citroen Car Club writing about MK2 escorts for LOL! then the penny dropped and Car and Car Conversions sprang to mind, I still have some of the old mags tucked away.

Cheers
Luke