dandan Posted August 11, 2010 Author Share Posted August 11, 2010 The braking torque is the twisting action caused by the drum or disc on the shoes or caliper anchors during the application of brakes. The amount of torque is determined by the effective axle height and stopping force between the tyre and road surface. Brake torque on the front wheels is absorbed by the knuckle and suspension control arm. In rear, it is absorbed by the axle housing and the leaf spring or control arm. Braking torque during an emergency stop is much higher than accelerating torque at full throttle. Brake supporting and anchoring members must, therefore, have sufficient strength to withstand these high braking loads. http://www.the-crankshaft.info/2009/09/braking-system.html If you have a read and see what you are trying to establish is possible given the variables and fixed data -and the only data you have ie the size of the discs and area of pads to use for comparrisons Look at the brake bias bit in particular I read it - what is it about the brake balance that you makes you say "Look at the brake bias bit in particular"? Once again I think I am missing the point of your post, sorry. Quote Link to comment Share on other sites More sharing options...
paul mac Posted August 11, 2010 Share Posted August 11, 2010 It is brake torque but that is only related to clamping force by the coefficient of friction. For comparison's sake it can be thought of as the same thing if the coefficient of friction is constant. For my numbers I was using a shade under 0.4 but it doesn't really matter as I am not looking for absolute values - only relative values between different setups. What I was really doing was investigating brake bias on big brake kits to see how far they deviate from OEM and comparing that to my options for my own custom made kit. To get the brake bias you need the front and rear braking torque but once again - only in relative terms. i'm with it now Dan and i can only commend you on your approach here to quantify this topic, i have long suspected what you have found and posted my suspicions here http://www.mkivsupra.net/vbb/showthread.php?t=137208&highlight=big+brakes, hard figures are beyond argument, i also kind of killed this thread http://www.mkivsupra.net/vbb/showthread.php?t=168382&highlight=big+brakes at post #41 Quote Link to comment Share on other sites More sharing options...
jevansio Posted August 12, 2010 Share Posted August 12, 2010 I've just read this link: http://www.carbibles.com/brake_bible.html Does anyone not feel it a little unfair that we are "rating" these different brake setups against each other based on the force the piston can apply when in reality there is a lot more at work. Quote Link to comment Share on other sites More sharing options...
dandan Posted August 12, 2010 Author Share Posted August 12, 2010 (edited) I wasn't rating them Jay - I was trying to decide which to buy. To truly rate them you'd really have to go to town with caliper stiffness, noise, dust, weight, inertia, heat transfer (good or bad), wheel size limitations etc etc. I don't have the time or money to buy all those kits and do the testing. If anyone wanted to help then I'd be happy to organize some tests to quantify some of the stuff but to be honest I don't think anyone would be interested. Something to bear in mind that has a massive effect is the pads....but in reality pad selection makes no difference here as you can pretty much use any pad in any kit so it's irrelevant. Edit: To kind of answer your question..... I think it is more than fair to compare these kits based on available braking torque (or piston area and effective radius). With an appreciation of caliper stiffness (and a detailed knowledge of the two piece floating/fixed design of every kit here) I had more than enough info to decide what to do or which to buy. Without the braking torque and bias figures I could not have made any sort of informed choice. Edited August 12, 2010 by dandan (see edit history) Quote Link to comment Share on other sites More sharing options...
jevansio Posted August 12, 2010 Share Posted August 12, 2010 Trouble is if you are using these numbers to "decide" what to buy, is that in itself not flawed when you have discounted so much of what constitues a brake kit that performs to your needs? EDIt sorry I see you mean as additional info, not soley on these nubers Quote Link to comment Share on other sites More sharing options...
jevansio Posted August 12, 2010 Share Posted August 12, 2010 PS I think we do need a day out test where we measure actual stopping distances of various setups at different speeds on different tyres Quote Link to comment Share on other sites More sharing options...
dandan Posted August 12, 2010 Author Share Posted August 12, 2010 i'm with it now Dan and i can only commend you on your approach here to quantify this topic, i have long suspected what you have found and posted my suspicions here http://www.mkivsupra.net/vbb/showthread.php?t=137208&highlight=big+brakes, hard figures are beyond argument, i also kind of killed this thread http://www.mkivsupra.net/vbb/showthread.php?t=168382&highlight=big+brakes at post #41 Brakes are very subjective. Like suspension setups, people want different things and within the limts of road tyres and road usage temperatures it is very difficult to generate a real life comparison that anyone could understand or buy into as everyone places importance on different things. Some like massive initial bite as it fills them with confidence, some like to save money, some like constant braking throughout a stop, some like that braking force to increase through the stop. Some can live with noise, some hate removing monoblock calipers to change pads Some people just want to fill their wheels and have nice colours in there. Some like a particular brand so it's hard to come up with anything meaningful. I wanted to know where to best spend my money for improved performance. In my mind that "performance" is a combination of balance, weight, caliper stiffness and pedal feel, noise, serviceability and reliability. Quote Link to comment Share on other sites More sharing options...
dandan Posted August 12, 2010 Author Share Posted August 12, 2010 Trouble is if you are using these numbers to "decide" what to buy, is that in itself not flawed when you have discounted so much of what constitues a brake kit that performs to your needs? EDIt sorry I see you mean as additional info, not soley on these nubers What I didn't want to do is post up a list of my perceived advantages and disadvantages to everyone's brakes.....far too contentious and probably wouldn't sit too well with the vendors If I were to be buying a kit I would consider weight, stiffness, disc internal cooling design, piston material, caliper material, piston area, effective radius, seal design, disc and pad availability, reputation of parts on same cars (not in F1, Indy etc etc), floating design, noise and wheel limitations. I could post up lots of information and facts on what Brembo, KAD, AP, Alcon and a few OEM systems have to offer in those areas but I don't really want to as people will get a bit defensive about what they have and which factor is most important to them. Quote Link to comment Share on other sites More sharing options...
jagman Posted August 12, 2010 Share Posted August 12, 2010 Hence my perspective comment , in relation to all variables the size of the caliper almost becomes meaningless, differences with calculated bias of 1-2 % compared with 15% friction pad weight shift changes . Ultimately the best kit has the best heat removal ability and thats a job to compare ,and pad selection is a biggie . expensive BBK and cheap tyres also a bit daft! Quote Link to comment Share on other sites More sharing options...
jevansio Posted August 12, 2010 Share Posted August 12, 2010 What I didn't want to do is post up a list of my perceived advantages and disadvantages to everyone's brakes.....far too contentious and probably wouldn't sit too well with the vendors If I were to be buying a kit I would consider weight, stiffness, disc internal cooling design, piston material, caliper material, piston area, effective radius, seal design, disc and pad availability, reputation of parts on same cars (not in F1, Indy etc etc), floating design, noise and wheel limitations. I could post up lots of information and facts on what Brembo, KAD, AP, Alcon and a few OEM systems have to offer in those areas but I don't really want to as people will get a bit defensive about what they have and which factor is most important to them. Oh I know bud The only reason I brought anything up is that UK spec brakes have this "reputation" of being unbeatable, and unsuspecting readers will take this "braking force" as being the deciding factor of how good a brake system is. I guarantee in a future argument on how good UK brakes are over BBKs the data in this thread will be brought up Quote Link to comment Share on other sites More sharing options...
Terminator Posted August 12, 2010 Share Posted August 12, 2010 (edited) As long as anyone reading this thread is aware of the numerous factors that influence brake performance, there should not be a problem. The increase or decrease in braking torque and shift or otherwise of brake bias, is very useful information, which up to now has not been available, and is infinitely better than the seat of the pants "these brakes are amazing" recommendation. The full UK setup is an excellent braking system, this thread least gives a comparison of brake torque and bias against a benchmark standard that we have not had before. I hope this thread gets tidied up and put in Tech FAQ with the appropriate health warnings and perhaps links to some of the excellent technical information that has been added. If the information collated stops one person making a drastic and possibly dangerous choice of brakes, it will have been more than worth while. When members start asking questions about possible brake buys, we have some where to point them for objective rather than subjective information. This thread, when combined with other research I carried out, has certainly reassured me that my choice of callipers and discs has not altered brake bias. Edited September 6, 2010 by Terminator (see edit history) Quote Link to comment Share on other sites More sharing options...
Ian C Posted August 12, 2010 Share Posted August 12, 2010 I'm keeping an eye on this to poach for a tech article, don't worry Quote Link to comment Share on other sites More sharing options...
dandan Posted August 12, 2010 Author Share Posted August 12, 2010 I have the data in more sensible formats (see example below) which I can post up as well but I was waiting for at least the "AP Race" and "Brembo C" rear caliper info to surface before I do that. I also want to double check the numbers as it was some time ago that I put the bulk of this together If "we" wanted to make a useful BBK type thread (rather than opinion based feelings about how good certain setups are) I could post up some facts about piston materials, float mechanisms, bridge design etc to give people an appreciation of how various kits differ. No opinion or recommendations....just the technical differences so people could weigh up which feature/design element/colour is important to them. That could take some time though! Quote Link to comment Share on other sites More sharing options...
TLicense Posted August 12, 2010 Share Posted August 12, 2010 Do it Dan, do it. Quote Link to comment Share on other sites More sharing options...
Wez Posted August 12, 2010 Share Posted August 12, 2010 More graphs, everyone loves a good graph Quote Link to comment Share on other sites More sharing options...
Terminator Posted August 12, 2010 Share Posted August 12, 2010 More graphs, everyone loves a good graph Oh yes now you're talking:p Quote Link to comment Share on other sites More sharing options...
Ian C Posted August 12, 2010 Share Posted August 12, 2010 Graphs Quote Link to comment Share on other sites More sharing options...
dandan Posted August 16, 2010 Author Share Posted August 16, 2010 Do it Dan, do it. More graphs, everyone loves a good graph Oh yes now you're talking:p Graphs You guys crack me up - gotta love a good visual aid! I'll be off work for a few days near then end of the month so I'll try to put something together then about the various float configurations and materials. I have enough info and pics to explain the floating mechanism on the Brembo GT kits, Alcons road and race kits, various AP setups and a couple of others. If somebody wants to purge it or amend it for some sort of FAQ type thread then that's fine by me. In the meantime if anyone can help with the following it would be great as I could get a more complete list uptogether. 1. Brembo BBK rear caliper piston diameters 2. Brembo BBK rear caliper pad depths 3. AP race rear caliper piston sizes and pad depth (as per Whifbitz AP BBK) 4. K-Sport - any of the rear caliper piston diameter and pad depths 5. Stoptech - do any of you chaps with Stoptech kits fancy chipping in? Quote Link to comment Share on other sites More sharing options...
GlennK Posted August 20, 2010 Share Posted August 20, 2010 One other useful thing to add to the comparison table please: Weight deltas (+,-) wrt UK F,R brake kits Thanks Quote Link to comment Share on other sites More sharing options...
Wez Posted August 20, 2010 Share Posted August 20, 2010 One other useful thing to add to the comparison table please: Weight deltas (+,-) wrt UK F,R brake kits Thanks very useful indeed. Quote Link to comment Share on other sites More sharing options...
dandan Posted August 20, 2010 Author Share Posted August 20, 2010 Good idea - this will need members to post up info though. I have all the weight info for OEM and Alcon 4 pot and 6 pot monoblocks...nothing else though. Quote Link to comment Share on other sites More sharing options...
dandan Posted August 27, 2010 Author Share Posted August 27, 2010 (edited) All these setups (Brembo, AP, Stoptech, Alcon etc) have subtle differences and it's not easy to tabulate it all but I think once I have jotted some of it down it'll be easier to pick out the obvious stuff to compare in a few tables along with some supporting text and images. ....Data below is for example purposes only..... Brembo GT Monoblock Complete kit weight for front axle: 28kg Complete kit weight for rear axle: 25kg Disc Size Front 356mm Rear 345mm Brake Torque and Bias Calipers and Materials Cast aluminium monoblock front caliper Six chrome plated steel pistons - 36, 30, 28mm diameter Front bare caliper weight (no pads or mounting brackets) ??kg Front caliper weight including pads and mounting brackets ??kg Steel mounting bracket Cast aluminium two piece bolted rear caliper Four chrome plated steel pistons - 32, 30mm diameter Rear bare caliper weight (no pads or mounting brackets) ??kg Rear caliper weight including pads and mounting brackets ??kg Steel mounting bracket Float Mechanism Float in disc Oval hole in disc (typically an 8.15mm by 10.25mm) Round hole in bell Bobbin passes through disc and bell transmitting torque from one to the other Bobbin pushes through from front of bell and has female thread (like a nut) Bolt comes through from rear of disc and screws into bobbin Bobbin is longer than the combined thickness of the disc and bell so bolt “does up” against the bobbin and the disc and bell are left to rattle freely sliding back and fro on the bobbin McLaren anti rattle shim (usually on back of disc) included on alternate fixings (regular washer used elsewhere) So.....would this info be useful/welcome? Anything else people want to know? Edited August 27, 2010 by dandan (see edit history) Quote Link to comment Share on other sites More sharing options...
Wez Posted August 27, 2010 Share Posted August 27, 2010 I would say so yeah, great write up matey Quote Link to comment Share on other sites More sharing options...
Kirk Posted August 27, 2010 Share Posted August 27, 2010 Definatly a most useful thread for people who research before buying Quote Link to comment Share on other sites More sharing options...
dandan Posted August 28, 2010 Author Share Posted August 28, 2010 OK cool - I'll knock something up with this sort of info. If we can convince any members/traders to take a few measurements we can end up with a very complete comparison somewhere down the line... Quote Link to comment Share on other sites More sharing options...
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