Which brake upgrade?
Discussion
Oh let me be the first - disks dont warp but they do suffer fron hardening - if you hold your foot on the brake after stopping with hot pads they heat up a small area of the disk which can harden...then it wears differently to the rest of the disk and you know the rest.
Not an expert but I love repeating stuff I have heard elsewhere lol
ANyway, I have black diamond drilled and grooved front and rear with EBC redstuff pads. Done by the previous owner. Personally I would go with grooved but forget the drilled bit. Love the EBC reds but they do need a bit of warming up.
Not an expert but I love repeating stuff I have heard elsewhere lol
ANyway, I have black diamond drilled and grooved front and rear with EBC redstuff pads. Done by the previous owner. Personally I would go with grooved but forget the drilled bit. Love the EBC reds but they do need a bit of warming up.
Reds work fine even whem cold, they just work much better when warm is all. Greens are (so I hear) more of a road pad but I remember some people saying they wore out quickly. Probably changed now as I think they are on a new compound. Im sure someone will be along with better advice than me in a moment :-)
Imperial blue and its lovely in the sun :-)
Imperial blue and its lovely in the sun :-)
notax said:
Thanks. I think I've heard of green stuff pads - are these more for road use? Using pads which I have to remember to warm up may not be the best idea (especially if sprinting!) BTW out of interest what type of blue is your car?
I used green stuff on both my griff and cerbera both had uprated discs, and still got brake fade and that was just with road use!
notax said:I take it this question is directed at me? i cant help you with this as i sold them both about a year ago,but if i were to do it again(which i will be doing shortly) i would go for 300mm fronts with the red stuff allround.
What are you using now? And would you recommend your current set up?
I used drilled and grooved discs on mine, (better pedal feel!), and tuscan callipers (if you're going to do it do it properly). If you contact Tom at Bell Hill TVR breakers he can sort you out with a kit.
Ps use goodridge or equivalant hoses front/rear
>> Edited by phil green griff on Tuesday 23 May 20:31
Ps use goodridge or equivalant hoses front/rear
>> Edited by phil green griff on Tuesday 23 May 20:31
Some thoughts in no particular order:
Avoid drilled discs. If you're working the brakes hard then you would probably benefit from grooved discs but STAY AWAY from drilled discs. They have an extremely nasty tendancy to develop cracks when heated, which can and often does lead to catastrophic failure.
Personally wouldn't recommend Green/Red Stuff for road use. They are extremely hard on the disc if you work them hard. Normally you would expect a disc to outlive several sets of pads. If you are running GreenStuff pads it will be the other way round - that's my experience, anyway. I recommend Ferodo DS2000, or DS2500 if you find you need an even higher rating. Tarox XF is a decent alternative but personally I prefer the Ferodos.
On the disc size, I would suggest you go from the standard 240mm up to 285mm. Various people will sell you adapter plates and nice pretty split discs letting you keep your standard calipers. The increase in heat dissipation is huge - roughly 50% more than standard, and more than enough for anything you will be doing. Moving the caliper outboard also increases the amount of braking at the front wheels. There seems to be a common tendancy among TVRs to have a rearward brake bias. This means that the rear end tends to move around a lot under braking and the car will feel as if it is trying to spin if you brake really hard. Increasing the amount of braking at the front corrects this. I found that going from 240 to 285 (with everything else the same) is enough to change the characteristics from mild oversteer under braking, to mild understeer. Understeer is obviously far safer, as it means that the car will tend to straighten up under braking rather than try to spin out. However, you can have too much of a good thing and I think that over 285mm would give you problems with the fronts locking too early in slippery conditions. You need to keep the brake balance about right, the small change I'm proposing here just changes from *mild* oversteer to *mild* understeer.
300mm is too much IMO if you keep the rear brakes standard. You will find it difficult or impossible to fit the calipers inside the standard 15" front wheels. (Mine fitted, just, but it was a right pita.) The brake balance will be too far forward so you will have to change the brake balance to compensate - and that's a world of pain you don't want. Front brakes that big are unlikely to heat up as quickly as the rears so you will struggle to find a good balance of pads. Running the standard calipers would put all the heat into the outer part of the caliper potentially causing probems due to differential thermal expansion. If you fit bigger calipers this is likely to throw the balance out even further.
So anyway, my suggestion for what it's worth is space the original calipers out to take 285mm discs, fit 6-8 grooved discs and DS2000 pads and you will be well sorted.
Avoid drilled discs. If you're working the brakes hard then you would probably benefit from grooved discs but STAY AWAY from drilled discs. They have an extremely nasty tendancy to develop cracks when heated, which can and often does lead to catastrophic failure.
Personally wouldn't recommend Green/Red Stuff for road use. They are extremely hard on the disc if you work them hard. Normally you would expect a disc to outlive several sets of pads. If you are running GreenStuff pads it will be the other way round - that's my experience, anyway. I recommend Ferodo DS2000, or DS2500 if you find you need an even higher rating. Tarox XF is a decent alternative but personally I prefer the Ferodos.
On the disc size, I would suggest you go from the standard 240mm up to 285mm. Various people will sell you adapter plates and nice pretty split discs letting you keep your standard calipers. The increase in heat dissipation is huge - roughly 50% more than standard, and more than enough for anything you will be doing. Moving the caliper outboard also increases the amount of braking at the front wheels. There seems to be a common tendancy among TVRs to have a rearward brake bias. This means that the rear end tends to move around a lot under braking and the car will feel as if it is trying to spin if you brake really hard. Increasing the amount of braking at the front corrects this. I found that going from 240 to 285 (with everything else the same) is enough to change the characteristics from mild oversteer under braking, to mild understeer. Understeer is obviously far safer, as it means that the car will tend to straighten up under braking rather than try to spin out. However, you can have too much of a good thing and I think that over 285mm would give you problems with the fronts locking too early in slippery conditions. You need to keep the brake balance about right, the small change I'm proposing here just changes from *mild* oversteer to *mild* understeer.
300mm is too much IMO if you keep the rear brakes standard. You will find it difficult or impossible to fit the calipers inside the standard 15" front wheels. (Mine fitted, just, but it was a right pita.) The brake balance will be too far forward so you will have to change the brake balance to compensate - and that's a world of pain you don't want. Front brakes that big are unlikely to heat up as quickly as the rears so you will struggle to find a good balance of pads. Running the standard calipers would put all the heat into the outer part of the caliper potentially causing probems due to differential thermal expansion. If you fit bigger calipers this is likely to throw the balance out even further.
So anyway, my suggestion for what it's worth is space the original calipers out to take 285mm discs, fit 6-8 grooved discs and DS2000 pads and you will be well sorted.
Peter, thank you for your comprehensive reply. I tend to prefer a slight rear bias to my braking - I used to tarmac rally a Mk2 Escort and found having the bias set towards the rear helped set the car up for bends - admittedly I was driving a bit more sideways than I tend to in the Chimp!
Would you recommend any particular discs or suppliers?
Would you recommend any particular discs or suppliers?
Apart from warping (discuss) there is the phenomenon of "disc thickness variation" which may or may not fit with the theory about hardening, (though personally I have difficulty imagining a sitaution where you do a big stop to standstill and sit with your foot on the pedal long enough to cook the disc locally) in this case it is the overall thickness of the disc that differs around its circumference causing judder as the pads grip varys with rotation and pulsation will be felt through the pedal. Presumably this is due to uneven disc wear-resistance which possibly is a fuction of its manufacture (could this be due to the grain orientation of the crystlline structure of the cast iron???).
FWIW I am running the Tower View Racing Services front discs 283mm, spiral grooved with the caliper bracket to cope with the bigger disc, retaining the standard caliper and a set of std size rears with grooves as above. EBC Green stuff all round, which despite what others say I find extremely good for both hard road use and trackdays / sprints. My experience of them is that :
1) they wear very well,
2) are good from cold (note re: sprints) but get better with heat (I've never managed to get them to fade, even pounding round Pembrey lap after lap all day, OK not the biggest braking circuit of all time but the brakes certainly get a lot hotter than on any road use) and
3) they produce very little of the dreaded black dust even wit heavy use.
Braided hoses will improve feel greatly and are much more duarble than the std rubber / textile ones. Dot 5.1 fluid is fade resistant and doesn't require constant changing like racing fluid. I suspect many if not most instances of severe fade are due to old water contaminated fluid in calipers starting to boil, dont forget that brake fluid is hygroscopic and will absorb significant amounts of moisture.
The other thing to remember is that if you increase the front disc size significantly you will change the brake balance to more forward bias, which may end up reducing your maximum retardation.
If you consider;
the limiting factor for stopping is tyre grip (the standard brakes are perfectly capable of locking the wheels so no direct gain there) so ultimate retardation is acheived when all four wheels are just on the point of locking simultaneously. Therfore if you shift the balance either way one set of wheels will be on the point of locking (or locked) whilst the other pair will not have reached maximum braking torque, so poorer decelleration. Clearly moving the balance rearwards is an invitation for disaster on that occassion when you have to hit the brakles hard and end up in the hedge facing the opposite way, then again too far forwards and you lose the maximum effect from the rear brakes as the fronts lock up too early forcing you to ease off on the pedal. I think (and I believe it is generally accepted) that the balance on the standard later brake set up is pretty reasonable and changes in disc size will alter this.
The only real gain with larger discs etc is the increased heat capacity and therefore the amount of punishment they will absorb before getting excessively hot.
Oh it looks like Peter beat me to it!
(Only diffreence is that I am a bit of a fan of the Green Stuff)
>> Edited by tahiti450 on Tuesday 23 May 21:18
>> Edited by tahiti450 on Tuesday 23 May 21:21
FWIW I am running the Tower View Racing Services front discs 283mm, spiral grooved with the caliper bracket to cope with the bigger disc, retaining the standard caliper and a set of std size rears with grooves as above. EBC Green stuff all round, which despite what others say I find extremely good for both hard road use and trackdays / sprints. My experience of them is that :
1) they wear very well,
2) are good from cold (note re: sprints) but get better with heat (I've never managed to get them to fade, even pounding round Pembrey lap after lap all day, OK not the biggest braking circuit of all time but the brakes certainly get a lot hotter than on any road use) and
3) they produce very little of the dreaded black dust even wit heavy use.
Braided hoses will improve feel greatly and are much more duarble than the std rubber / textile ones. Dot 5.1 fluid is fade resistant and doesn't require constant changing like racing fluid. I suspect many if not most instances of severe fade are due to old water contaminated fluid in calipers starting to boil, dont forget that brake fluid is hygroscopic and will absorb significant amounts of moisture.
The other thing to remember is that if you increase the front disc size significantly you will change the brake balance to more forward bias, which may end up reducing your maximum retardation.
If you consider;
the limiting factor for stopping is tyre grip (the standard brakes are perfectly capable of locking the wheels so no direct gain there) so ultimate retardation is acheived when all four wheels are just on the point of locking simultaneously. Therfore if you shift the balance either way one set of wheels will be on the point of locking (or locked) whilst the other pair will not have reached maximum braking torque, so poorer decelleration. Clearly moving the balance rearwards is an invitation for disaster on that occassion when you have to hit the brakles hard and end up in the hedge facing the opposite way, then again too far forwards and you lose the maximum effect from the rear brakes as the fronts lock up too early forcing you to ease off on the pedal. I think (and I believe it is generally accepted) that the balance on the standard later brake set up is pretty reasonable and changes in disc size will alter this.
The only real gain with larger discs etc is the increased heat capacity and therefore the amount of punishment they will absorb before getting excessively hot.
Oh it looks like Peter beat me to it!
(Only diffreence is that I am a bit of a fan of the Green Stuff)
>> Edited by tahiti450 on Tuesday 23 May 21:18
>> Edited by tahiti450 on Tuesday 23 May 21:21
notax said:
Thanks Alan, I'll give Tower View a ring. Love the wheels on your car btw!
Cheers Chris. I think you will find TVRS very helpful. In general they like to fit the brake kit themselves, in the interests of safety and avoiding quibbles(unless you can convince them, as i had to, that you can cope with the fettling of the bracket and hub and tapping of threads that is required).
Being a non expert I think my description about why warping is not possible wasnt 100% accurate - here is my source of information
www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
Make of it what you will, I guess he's really saying bed your brakes in properly....
www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
Make of it what you will, I guess he's really saying bed your brakes in properly....
bigdods said:
Being a non expert I think my description about why warping is not possible wasnt 100% accurate - here is my source of information
www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
Make of it what you will, I guess he's really saying bed your brakes in properly....
Thanks, that's a very interesting piece, If you accept that it is authoritative then as you say bedding in properly seems to be absolutely crucial.
It does however rather suggest that DTV, due to uneven deposits and possibly cementite inclusions, is only likley to occur if the brakes are being used near to fade conditions, which wouldn't explain why "ordinary" drivers get this problem developing when they never get anywhere near cooking the brakes.
On the issue of disc problems. 20 years ago warped or distorted discs, call it what you will was not a major problem. It is only in the last 10 or so years that i have noticed it becoming more commonplace...... There used to be an old wifes tale about the likes of Volvo leaving their castings ( Blocks,brake discs etc.) outside in compounds for months on end. This was to "season" the cast as you would with timber to allow any warpage to occur before the final machining and to let it go through the heating and cooling process naturally..... It makes sence that now we are in a world where a manufacturer and indeed the retailer needs a fast stock turn over that this will now not be allowed to happen.?? Also with the removal of asbestos within the brake pads under normal conditions and with gentle braking is there more heat therefore affecting more "normal" cars and at relative low mileages???
Steve.
Steve.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff