Ivaan Posted April 12, 2012 Share Posted April 12, 2012 Hi all, I'm trying to decide whether to change over from drilled and grooved front discs, to the standard plain ones, to help bring the brake balance back to the rear of my car. Does anyone have experience of changing to drilled/grooved discs from the plain items, leaving everything else unchanged. If so, what difference was made? Supposedly, the drilled/grooved one's disipate heat better, so would be more efficient. However, there's also less contact area on the disc, which will reduce braking, but against that, there's the same pressure from the calipers over a smaller area, which should do what??? Confused? I have the plain discs at home ready to go on, but I'm just after some idea of what the change will mean. Thanks, Clive Link to comment Share on other sites More sharing options...
Racing Snake Posted April 12, 2012 Share Posted April 12, 2012 Drilled are more likely to crack and not advised for heavy duty use (track days etc) YHBM Link to comment Share on other sites More sharing options...
Graham Sewell Posted April 12, 2012 Share Posted April 12, 2012 From my understanding, any braking is mainly based on the surface area between the pads and disks. So, all other things equal, drilled/grooved disks may increase braking distance due to the smaller area available. The point behind drilling/grooving disks is tio dissipate heat quicker for the next time you are braking hard. This may prevent brake fade over successive braking zones if braking frequently (eg track driving or Stelvio Pass). But, as ever, I may be wrong. Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted April 12, 2012 Area Representative Share Posted April 12, 2012 Clive, for the sake of a few minutes work I think it's easiest to change them over and have a try yourself Nick Link to comment Share on other sites More sharing options...
Drumster Posted April 12, 2012 Share Posted April 12, 2012 Strangely enough, I've just got in from the garage from replacing the dimpled/grooved discs with the standard ones. Partly through cost consideration, but also I was never totally convinced that changing from plain to dimpled/grooved really made that much difference all those years ago anyway. Also just fitted the larger surface areas Mintex 1144s (Ref MGB535M1144) to try to get more brake balance to the front. Need to bed them in after changing the brake fluid though. Not sure when I'll really be able to get this done and offer feedback..... Link to comment Share on other sites More sharing options...
Mr Locust Posted April 12, 2012 Share Posted April 12, 2012 Nick, were they grooved/drilled discs on your blue S1 Elise? You could feel the pattern through the pedal!! Clive, has Richard's handy work not sorted your balance issue? Link to comment Share on other sites More sharing options...
Ivaan Posted April 12, 2012 Author Share Posted April 12, 2012 Nick, I'm sure you're right. Probably change them over on Saturday. The twin MC helped a lot, that's to say, the rear brakes are now getting hot and doing work. I've put new standard brake shoes on the rear, which has also helped. However, the bias bar is still wound right over to the rear circuit, and the brake peddle pressure is pretty high. I think if I swap the discs, I will be able to move the bias more towards the centre. This may effect the peddle pressure needed to lock all 4 wheels. I assume once I'm able to lock all 4 more or less at the same time, front's first, then I won't be able to get the braking any better, it'll just be the feel that will improve. From this point, the braking is mainly a function of the weight distribution and suspension set up, tyres ect. Question: When changing over the discs, what should the bolts be torque'd to, and should I use any threadlock. Link to comment Share on other sites More sharing options...
Drumster Posted April 12, 2012 Share Posted April 12, 2012 Disc to hubs 22-27lbft & yes, to threadlock. Link to comment Share on other sites More sharing options...
Ivaan Posted April 12, 2012 Author Share Posted April 12, 2012 Thanks Link to comment Share on other sites More sharing options...
Drumster Posted April 12, 2012 Share Posted April 12, 2012 PS Don't forget brake calipers at 40-45lbft.... Link to comment Share on other sites More sharing options...
blade_runner Posted April 13, 2012 Share Posted April 13, 2012 Drilled/grooved discs are also supposed to give a better pedel feel, the holes/grooves allow the hot gasses generated between pad and disc escape so the pad isnt 'floating'...... supposedly! My fireblade was a prototype, so did loads of press work then was raced heavly at the hands of Alan Maynard, and Paul Harvey, the original drilled discs on the car have lasted well with no visable cracking, and I only changed the drilled fronts last year where they still had about 1/2 mm of service life left in them after i've had the car 8 years!, I bought standard discs from Canley Classics for about £13 each, clamped the old ones to them as a patern and drilled them.. proper job Link to comment Share on other sites More sharing options...
James.S Posted April 13, 2012 Share Posted April 13, 2012 You won't notice any difference other than the drilled ones are noisier and you can get a pulsing through the pedal - doubt you will over heat either. You will get better feel from race master cylinder and high ratio pedal than changing discs. Leave them on and fit a brake bias control - much better for wet as well. J Edited by - James.S on 13 Apr 2012 14:15:24 Link to comment Share on other sites More sharing options...
Graham Sewell Posted April 13, 2012 Share Posted April 13, 2012 Quoting blade_runner: I bought standard discs from Canley Classics for about £13 each, clamped the old ones to them as a pattern and drilled them.. proper job I seem to remember that you were supposed to heat treat the discs AFTER drilling and that any holes had to be radiused in order to prevent stress fractures. Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted April 13, 2012 Share Posted April 13, 2012 blade_runner - Drilled/grooved discs look the part if nothing else Link to comment Share on other sites More sharing options...
Ivaan Posted April 13, 2012 Author Share Posted April 13, 2012 Discs changed this evening. Test blat tomorrow after Qually. 😬 Link to comment Share on other sites More sharing options...
blade_runner Posted April 13, 2012 Share Posted April 13, 2012 I tapered/countersunk the holes ever so slightly as recomended by a fellow sevener who's drilled the discs on all the sevens he's owned and for his brother too... I've done 2 trackdays on them and so far so good. The original drilled discs were supplied on the car from James Whiting with the 4 pot Alcons, James used to supply the solid drilled discs, Now I'm assuming he either just drilled standard discs himself or got someone to do it for him because I noticed when drilled them that one of the holes is quite far out of the pattern. Take a look at my drilling effort here Link to comment Share on other sites More sharing options...
Violet Elizabeth Posted April 14, 2012 Share Posted April 14, 2012 Interested to hear the results :) Did you weigh them ? Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted April 14, 2012 Share Posted April 14, 2012 Certainly looks the part! Link to comment Share on other sites More sharing options...
Ivaan Posted April 14, 2012 Author Share Posted April 14, 2012 Went for a good blat this morning. The solid discs are less grabby, don't lock up so suddenly, so a lot more feel to the brake. I've also wound the bias towards the front, by a couple of turns, but can still go more. Beginning to get some real confidence in the brakes now, but there's more to come with bedding in and getting the balance right. Might need a Curborough test day soon 😬 Sorry, forgot to weigh the solid discs, but they can only be a few grams heavier than the drilled/grooved ones. Edited by - Ivaan on 14 Apr 2012 19:55:14 Link to comment Share on other sites More sharing options...
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