So bigger master cylinder, bigger calipers, bigger pads and bigger discs have no advantage apart from better cooling?
Something I have been wanting to post for months and keep forgetting. It's not your brakes that need changing its your tyres. If you are having problems locking up the front wheels then get those weedy legs down the gym. I have never had a problem with 239mm brakes fading or failing (regardless of what you say about 8v's not being fast enough...they do 120mph!) I have on the other hand lost grip and all braking ability with sh1te tyres
Tyres are a major factor in braking. The way i always understood it is also braking performance will also be better with bigger brakes discs, bigger calipers and good quality pads. Its a simple principle of a bigger contact friction area means the wheel will stop quicker, also as mentioned previously bigger discs will mean better heat dissipation, which will give better resistance to brake fade. I agree that the set up on most golfs is perfectly adequate, if not better than adequate. Probably in most cases the stock system just needs a bit of loving care Edited by: vwpolo2000
Also the condition of the shock absorbers as well the tyres is vitally important when it comes to stopping distances.
Another suberb thread. So much knowledge has been aired over the last few months in particular. Keep it coming! Cheers
I have always though that the bigger the disc the greater the stopping power, i'll try and explain the best I can it's like if you drive a car with no PAS and a tiny wheel it is hard to turn whereas if the same car has a larger wheel fitted it is easier to turn due to leverage. If I can transfer this principle over to brake discs and callipers, just like that!! Therefore the greater the distance between calliper and the centre of the disc the more 'leverage?' and therefore greater braking force I'm totally wrong are'nt I Pete Edited by: Peter
Also we seem to be missing the fact that yes big discs = larger cooling area, but if the pad area is no bigger then its not gunna make a difference to the braking force. Take Audi S4 twin turbo for example, big discs as standard, v similar size to the porsche big reds that many upgrade to, yet the brake pad size of the s4 is cack all, in fact its 4 little motorbike sized jobbies rather than the big porker jobbies. Also old dubs use a cack single piston sliding caliper, its hardly the greatest engineering solution to great braking, 4 or more pistons being a better & more even distribution of braking force. Then again older TVRs Chims & Grifs only used 240mm discs& a sliding caliper & they had 1000kg & over 250+bhp & they are ok on road, so 239 is not that woefull on a 950kg golfy if useing decent discs/pads/braided lines & new fluid
On my mk3 8v, I'm happy with the braking force, but I have got them to fade a few times on the road during spirited driving, so i wouldnt be happy going to a trackday with my current 280s. The main reason I'm looking to go to 312mm (if it all fits under my wheels) is because of the cooling aspect really, I think the 288mm caliper has a larger pad contact area than my 280s, so a bit more force would be good, but really I want my brakes to last long when pressing hard, and give me the option of doing a trackday without going to mush after 2 laps. Also, is Dot 5 the fluid to go for when using larger setups like 312mm?
I think the 239's are fine on my 8v. I drive to work everyday down a dual carriageway with a series of roundabouts, this gives you the 90-100 down to 30/40 scenarion about 4 times in a row. Maybe its more extreme on the track but I find them to be fine. The only time I've experienced brake fade, was when the pads were really worn. I've been able to lock mine up at 80 as well, nearly missed a turn off on the main road. I've driven an audi A6, and the brakes on that are very good, but in my opinion the reason they feel better is that they are assisted by a powerful master cylinder/ servo, and big wide tyres so you don't have to put a great deal of effort into pressing the pedal. This is fine in a car with ABS, but I think the golf has a better/ more progressive and controllable feel. Would having a bigger master cylinder give a similar feeling to the audi?
no it'd maKE IT FEEL HARDER, YOU NEED A BIGGER SERVO TO GET THE OVER ASSISTED MODERN CAR FEEL. I bigger M/C will just reduce the leverage and pedal travel. sorry about the caps, think my keyboard is going through puberty...
You want DOT5.1 not DOT5 but DOT4 is normally sufficient. If you want cooling and to reduce fade why not spend less money and buy some ducting from B&Q, and use fluid and pads which can take the heat better.
I've got Pagid FR pads front and rear, and brembo max discs front, solid brembo's rear, on Dot 4. 5.1 has a higher boiling point, so would that would stop the fluid being 'the weakest link' in my setup? Are pagid FR pads not good enough? I'd just feel better about having larger discs, and for the money I think 312s arent a bad deal at all. Could probably sell them for nearly as much as I will pay for them also, after using them for a year or 2.
Good enough for what? They're a fast road pad, obviously, if you want to hammer round the track for a few sessions then perhaps you should consider something else. 312s to replace a 280 set up made a significant difference according to one owner.
so pagid FR with the 312s on a mk3 will be good enough for hammering round a track? The 280's with pagids and dot 4, is just about good enough for fast road use, would be utter crap on track, I'm quite sure. Who do you know who has the 312mm setup edc?
You must have a problem with your braking S1mma if you're fading 280's like that on the road. I'd recommend going to a better fluid and ensuring it's fully flushed through the system after fitting some braided hoses. It's also possible you've got some air in the system as it is. I mean seriously, my 239's were fine on track at Combe so 280's should be able to handle it easily. I know the Mk3 is heavier but not that much heavier. Joe
it is possible that i've got air in the system, I've only experienced fade when really pushing very hard on empty dual carridgeways with roundabouts every km or so, constand braking from high speeds (A264 west sussex). Not really at any other times, but would do on track i'm sure. May have to check for air in the Dot 4, and maybe go Dot 5.
brake fluid absorbs water over time that boils at a much lower temp than brake fluid and giving you the feel of air in the brakes. You can bleed it all you like and see no air coming out. Change it and flush it thoughly, you'll notice the diference.
I'd go for something like Castrol Response Super DOT 4 rather than a DOT 5.1. It's about 10 a litre. Up from that is ATE Super Racing Blue which is also a DOT4 and very good but is 20 a litre. Joe
I have got a Mk 2 Driver with a 2 litre engine in it, and it has got 239mm front discs, with the standard drums at the rear. It has got Goodridge braided hoses, had the fluid changed in March, new pads (Pagid Fast Road) and GSF Vented discs (Zimmerman). The braking system is in good order. As is the suspension (lowered 40mm), and the tyres (Eagle F1s). Tonight I got severe brake fade after doing about 10-12 roundabouts on the Bristol Ring Road (1 roundabout approx every 1-2 miles) going from 90 to 20 or 30. I pressed the pedal, I pressed harder and still nothing. It was lucky I was anticipating it, and left plenty of room. Scared myself silly though. Do I go for better discs (such as Brembo grooved) in the 239mm size, or go for 256mm or even 280mm discs? My wheel size is 14" (steel wheels) and I won't be getting bigger ones. Bearing in mind that if I upgrade the disc size, I will still have to do something to the hubs etc, so should I go for the biggest now? Shall I leave the rears as drums, as they don't do much work (and they don't sieze like GTi calipers). Thanks Steve
