How bigs too big ??
Discussion
Afternoon guys. Just needing some advice on how big i can go with the front discs. Whilst i know it will drastically improve the brakes the reasons are purely cosmetic. ( Shallow i know, but hey !! i bought it because its loud and brash and gets you noticed.!!!!)
and the brake discs look proper feeble . I have 17" alloys. Ideas of costs and from where would be good, even used parts if any of you guys have any....
Cheers in advance, Steve.
and the brake discs look proper feeble . I have 17" alloys. Ideas of costs and from where would be good, even used parts if any of you guys have any....
Cheers in advance, Steve.
V8, thanks for the advice. I think that under moderate braking the rears will be unaffected whilst under heavy braking the weight transfer will allow the fronts to be used heavily. The rear will only act as a ballance.???? I think??....... If not i suppose i might have to consider rears as well........
parrot of doom said:
Bigger discs on front = more stopping power = front slowing down more quickly than rear = spin.....
Errrm.... Isn't the danger when the brake bias is towards the rear and the back wheels lock up before the font. This causes the back tyres to break traction sending you backwards through the hedge?
sparkythecat said:
Bigger discs on front = more stopping power = front slowing down more quickly than rear = spin.....
Errrm.... Isn't the danger when the brake bias is towards the rear and the back wheels lock up before the font. This causes the back tyres to break traction sending you backwards through the hedge?
Better brakes on the front will notpromote a spin. Too much braking at the rear, causing the rears to lock before the fronts, is what usually causes problems.
My Griffith (500; standard brakes) has slightly too much rear bias for my liking, so better front brakes would be quite desirable.
It is very important that the front and rear brakes are correctly balanced under all conditions. If you can follow simple physics the calculations are fairly simple to do. But don't even think about tackling an upgrade unless you have got the calculations clear in your head, because the brakes aren't going to balance themselves by accident and if they aren't correctly balanced the car can be dangerous. Too much braking to the front means the car understeers under braking, and also doesn't slow down as much as it should. Too much to the rear means the car ovesteers under braking, and doesn't slow down as much as it should. If you get the setup wrong you can even have a car that understeers under light braking and oversteers under heavy braking. Not something to be messed with casually IMO and certainly not a fashion accessory.
>> Edited by GreenV8S on Wednesday 10th August 20:43
>> Edited by GreenV8S on Wednesday 10th August 20:43
GreenV8S said:
It is very important that the front and rear brakes are correctly balanced under all conditions. If you can follow simple physics the calculations are fairly simple to do. But don't even think about tackling an upgrade unless you have got the calculations clear in your head, because the brakes aren't going to balance themselves by accident and if they aren't correctly balanced the car can be dangerous. Too much braking to the front means the car understeers under braking, and also doesn't slow down as much as it should. Too much to the rear means the car ovesteers under braking, and doesn't slow down as much as it should. If you get the setup wrong you can even have a car that understeers under light braking and oversteers under heavy braking. Not something to be messed with casually IMO and certainly not a fashion accessory.
All very well if you have dual m/cyls and a bias bar, or a proportioning valve, but slightly academic if you are running a standard hydraulic circuit and are limted to mixing-and-matching standard components.
And what's this talk of understeer and oversteer under heavy braking?! Heavy braking should be done in a straight line, so steering doesn't come into it!
I never trust calculations, anyway - they are fine to get the basic sizing of the brakes right, but tuning is better done with the bias bar on the track, not with a pocket calculator. The physics of it are far from simple, too, when you take into account dynamic weight transfer, especially if you are in the habit of braking deep into corners
...in any case, optimum balance will vary dramatically according to surface and weather conditions. For a road set-up which is intended to give a good 'average' for all conditions, I'd much rather have a definite bias to the front; my Griff borders on too much rear bias, so I think there would be a fair tolerance for upgrading the fronts without causing problems the other way.
Thanks for the answers mutant rat and everyone upto press. Just dont understand the reactions to uprating the front discs/calipers. Other threads on the site lead quite favourably towards different pads and discs ?? surely this would create the same issues and problems over front to rear bias as simply going bigger on the discs.?? As far as the discs not been a fashion accessory, am i the only person on pistonheads to want to change something so it looks better.?? Maybe not me thinks !! I come to TVR from motorbikes. Some would stand up severely if the brakes were applied mid corner, others were not as bad. You had to adapt your riding accordingly.Some could be considered dangerous, but when you were aware of how they were going to react there were no nasty surprises The same would be said for a car that had more front brake bias than another. Adaptation. Know the characteristics of what you drive..... I dont want to go above 280mm, dont want fancy 6pot calipers, i just want the brakes to look better than they do through the alloy with the added benefit that the brakes will also be better....
Mutant Rat said:
All very well if you have dual m/cyls and a bias bar, or a proportioning valve, but slightly academic if you are running a standard hydraulic circuit and are limted to mixing-and-matching standard components.
And what's this talk of understeer and oversteer under heavy braking?! Heavy braking should be done in a straight line, so steering doesn't come into it!
I never trust calculations, anyway - they are fine to get the basic sizing of the brakes right, but tuning is better done with the bias bar on the track, not with a pocket calculator.
I don't quite agree with that. You don't need adjustable balance bars and bias valves to get the brake balance correct. This just makes it easier to get it right without changing components.
The question of understeer and oversteer is far more relevant than you suggest. It determines what happens when you apply the brakes. If the brake balance is correct then you achieve maximum steady state braking in a straight line under all conditions, and braking in a corner doesn't upset the steady state balance of the car. The steady state balance of the car isn't the whole story, there are important transient affects to be considered too as you point out, but getting the steady state balance right is a good starting point. To achieve this requires a solid understanding of the theory.
The general advice that you should brake only in a straight line is sensible because it removes complicated transient effects that not all drivers are competant to cope with. But with properly set up brakes, braking in a corner is not fundamentally a bad thing to do.
Put another way, if you brakes are set up so the balance is only right in a straight line in dry conditions, then it will be potentially dangerous if you have to brake unexpectedly in other circumstances.
And the answer to my question is !!! Blimey guys, I only want to know where and how much i can get some larger discs for. !!! I drive the car well within its and my limits. I dont do track days and if im driving in the rain its because ive been caught out !!! I drive at a conservative speed and enjoy the feel and sound of the car. If the need arises to up the pace i am more than capable of controling the car. I just want larger discs.!!!! Mad Mitch said:
And the answer to my question is !!!
Sorry to be tedious but this is my whole point. Changing the size of the brakes has a big difference on the safe handling of the car, easy to mess up, hard to put right. If you're doing it for looks (don't want to judge, but that's the impression I get) and think you will just bolt on some bigger brakes then I think you're heading down a very dangerous path and I advise you to think twice.
THanks for your concern V8S. I value all advice given. you comented on a previous post that the 280mm upgrade was an ideal conversion for the early chims. Has something changed.??....Stegefal, thanks for your advice, i will ring them. The wheels are tsw 17" reflex. I am however about to change them for 17" wolfrace asia tec Suzukas.I will post pics when they are fitted.Steve.
At last an idea of price Jellison,thankyou.... Was that for callipers and discs or just discs ???.
Wheels too bling for you are they. Just as well i didn`t ask for your opinion then isnt it !!!... It would be a strange old world if we all liked the same things mate...The reason i was straight about the fact that it was the looks of the brakes was that i dont need someone telling me i need brakes suitable for a lap le mans !!!..... it is easier when asking advice from the people who should know to be honest with them rather than bullshiting to avoid a bit of sarcastic banter..... Wheels match the " 2 fast 2 furious " badge on the back....
Wheels too bling for you are they. Just as well i didn`t ask for your opinion then isnt it !!!... It would be a strange old world if we all liked the same things mate...The reason i was straight about the fact that it was the looks of the brakes was that i dont need someone telling me i need brakes suitable for a lap le mans !!!..... it is easier when asking advice from the people who should know to be honest with them rather than bullshiting to avoid a bit of sarcastic banter..... Wheels match the " 2 fast 2 furious " badge on the back....
MadMitch,
With 17" wheels you can fit the AP 330mm Front brake kit - although budget around £2000 - probably overkill for road use - But ideal for track driving.
Ive read/heard the many debates re Brake imbalance and can only speak from my own experience
- gained driving my Chim - on the road and over 40 track days (plus other track time in faster Tivs).
The last six or seven Track days in the Chim,post brake upgrade, have been a revelation.
Confident stopping power , with lots in reserve , no fade, no imbalance fr to rr , no hint whatsoever of tendency to spin.
In fact even TRYING to unsettle the car by braking mid corner (Playing on an airfield - Not a Circuit) did 'nt cause any spinning - although im sure ,eventually ,i could have
.
Must point out ,though, i have 235 section front tyres (255 section rear) which - giving a greater footprint and better grip - should make the best use of the greater breaking effort.
Rear brakes on mine are drilled and grooved discs, but of standard dia - running mintex 1144 pads.
Looks aside , i found the Standard brake set up perfectly good for road use ,but not really up to the job on a car which spends (too) much time on Tracks.
This of course is MY experience only - Big brakes on other Chims may upset the balance in extremis,i dont know.
Anyway ,hope this is of use.
p.s , they look the dogs bollox as well
With 17" wheels you can fit the AP 330mm Front brake kit - although budget around £2000 - probably overkill for road use - But ideal for track driving.
Ive read/heard the many debates re Brake imbalance and can only speak from my own experience
- gained driving my Chim - on the road and over 40 track days (plus other track time in faster Tivs). The last six or seven Track days in the Chim,post brake upgrade, have been a revelation.
Confident stopping power , with lots in reserve , no fade, no imbalance fr to rr , no hint whatsoever of tendency to spin.
In fact even TRYING to unsettle the car by braking mid corner (Playing on an airfield - Not a Circuit) did 'nt cause any spinning - although im sure ,eventually ,i could have
. Must point out ,though, i have 235 section front tyres (255 section rear) which - giving a greater footprint and better grip - should make the best use of the greater breaking effort.
Rear brakes on mine are drilled and grooved discs, but of standard dia - running mintex 1144 pads.
Looks aside , i found the Standard brake set up perfectly good for road use ,but not really up to the job on a car which spends (too) much time on Tracks.
This of course is MY experience only - Big brakes on other Chims may upset the balance in extremis,i dont know.
Anyway ,hope this is of use.
p.s , they look the dogs bollox as well
Cheers for that whitechimp..... Thats all i needed to know, and yes, i bet they do look the dogs dangleys!!! The debate no doubt will rage but the conclusion from the upgrade you have is that provided a reasonable level of braking is achieved at the rear the fronts can be something very serious without major adverse affects...... of course all cars are different and you can only spaek from personal experience and nothing you have said should lead me to believe this set up would be safe on my vehicle.....
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