Wilwood Brake Discs
Discussion
After some overly enthusiastic and no doubt appallingly driven trackdays
I've managed to warp the front discs on my 205. Having searched high and low for suitable replacements Wilwood seem to have come up trumps in the price department - however is there a reason for this? Do you really get what you pay (or don't pay) for? All comments appreciated. 
Thanks for your comments. Decided to replace the whole system with that from the 306 Gti. Ended up with grooved wilwood discs and found some greenstuff pads in a sale - hopefully it will be a vast improvement once everythings fitted and bedded in.
I've left the origional master cylinder in place for the moment, may think about a larger replacement depending on the travel with the new setup.
Thanks again...
I've left the origional master cylinder in place for the moment, may think about a larger replacement depending on the travel with the new setup.
Thanks again...
Finaly managed to free up a Sunday afternoon to fit the new discs, caliper & pads. Everything went reasonably smoothly apart from the usual swearing and scraped knuckles trying to undo the caliper mount bolts! Noticed the two studs for locating the disc had been sheared off by the previous owner on both wheels however I don't think this is an issue?! Made refitting the wheel a little more tricky.
With everything assembled I only managed a quick test drive and was wary of being too hard on them before the bedding is complete however the main difference at the moment is the amount of travel on the brake pedal. Previously it was matched (more or less) with the accelerator which made h&t'ing reasonably straightforward. With the bigger pistons the travel on the pedal increased by a good inch or so. This may be down to the bleeding - I bought a one man bleed kit from halfords - not 100% sure about them (or maybe my ability to do everything with no instructions). Will try again one evening when the car returns as.....
driving home that evening; managed to get about 300m away from my girlfiends parents house when the car spluttered to a halt and refused to start. Back to the garage again.
Will let you know more as they are run in. Anyone any advice? Is it the usual procedure as taking it easy for the first 100-150 miles or so?
With everything assembled I only managed a quick test drive and was wary of being too hard on them before the bedding is complete however the main difference at the moment is the amount of travel on the brake pedal. Previously it was matched (more or less) with the accelerator which made h&t'ing reasonably straightforward. With the bigger pistons the travel on the pedal increased by a good inch or so. This may be down to the bleeding - I bought a one man bleed kit from halfords - not 100% sure about them (or maybe my ability to do everything with no instructions). Will try again one evening when the car returns as.....
driving home that evening; managed to get about 300m away from my girlfiends parents house when the car spluttered to a halt and refused to start. Back to the garage again.
Will let you know more as they are run in. Anyone any advice? Is it the usual procedure as taking it easy for the first 100-150 miles or so?
Read the bedding-in instructions that came with the pads. Some pads need a specific procedure and just driving gently will do them no good at all.
If the caliper size has changed enough to be noticeable at the pedal then I would suggest that the brake balance will be absolutely
ed. Personally, I'd be very wary of driving it until I knew how much the caliper size has changed by and what effect this has had on the brake balance. Look at the piston area of the old caliper (multiply by two if it is a floating caliper) and compare to the piston area of the new one. If it has increased by more than about 20% then the brake balance will be far enough out to be potentially dangerous.
If you have fitted bigger discs too then you need to look at the increase in distance between the axle and the center of the pad, see what factor this has increased by. Multiply the disc size increase by the piston area increase to get the total braking increase. More than 20% is a problem.
If the piston size hasn't increased dramatically then you probably just have air in the system. You need to ensure that the bleed nipple is at the highest point of the caliper when you bleed it, and keep going until you have fresh fluid with no air bubbles coming out.
You should also be aware that bleeding the brakes is quite hard on the master cylinder because it uses far more travel than normal and it is not uncommon for the seals to get damaged when you do this, this could lead to a soggy pedal.
If the caliper size has changed enough to be noticeable at the pedal then I would suggest that the brake balance will be absolutely
ed. Personally, I'd be very wary of driving it until I knew how much the caliper size has changed by and what effect this has had on the brake balance. Look at the piston area of the old caliper (multiply by two if it is a floating caliper) and compare to the piston area of the new one. If it has increased by more than about 20% then the brake balance will be far enough out to be potentially dangerous. If you have fitted bigger discs too then you need to look at the increase in distance between the axle and the center of the pad, see what factor this has increased by. Multiply the disc size increase by the piston area increase to get the total braking increase. More than 20% is a problem.
If the piston size hasn't increased dramatically then you probably just have air in the system. You need to ensure that the bleed nipple is at the highest point of the caliper when you bleed it, and keep going until you have fresh fluid with no air bubbles coming out.
You should also be aware that bleeding the brakes is quite hard on the master cylinder because it uses far more travel than normal and it is not uncommon for the seals to get damaged when you do this, this could lead to a soggy pedal.
leorest said:
... Look at the piston area of the old caliper (multiply by two if it is a floating caliper)...
If the caliper is floating, the load fron the piston applies to both sides of the disc so you get twice as much friction, you also get twice as much displacement. It acts more-or-less exactly as if you had two opposing pistons in a non-floating caliper.
GreenV8S said:Ahh. So it's more to do with the volume displaced than the area? I would never have spotted that.
... Look at the piston area of the old caliper (multiply by two if it is a floating caliper)...
If the caliper is floating, the load fron the piston applies to both sides of the disc so you get twice as much friction, you also get twice as much displacement. It acts more-or-less exactly as if you had two opposing pistons in a non-floating caliper.
Thanks
Leo
I've got green stuff on the chim and one thing i've noticed is that they are very unpredictable when cold... when hot their fine and pull up nice and straight...
when cold... somtimes you dont think it'll stop, sometimes it excellent, sometimes it pulls left sometimes right.... I've heard this from others as well
At first i though there was somthing wrong so tried a different make of pad. everything fine... a 2nd set of greenstuff and same again...
when cold... somtimes you dont think it'll stop, sometimes it excellent, sometimes it pulls left sometimes right.... I've heard this from others as well
At first i though there was somthing wrong so tried a different make of pad. everything fine... a 2nd set of greenstuff and same again...
I've noticed the same effect at much higher temperatures too. GreenStuff are good because they seem to get more and more grip as they get hotter, but at the start of a session going from 'warm' to 'hot' you can definitely feel them click in after a couple of heavy applications and there's often a noticeable pull when this happens.
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