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MG MGF Technical - Brake upgrade
|I have had my 'F for five months now, and I am very pleased with most things. One failing however is the brakes. I find that they suffer from fade, so am considering an upgrade.|
In the latest issue of EMG my eye was drawn to the EBC Greenstuff pads and Turbo-Grooved discs for the front of the car.
The prices seemed reasonable and I planned to buy and fit them soon.
The problem is that a friend fitted the same discs to his 306 D Turbo (hmmmm), and said that because the disc have dimples rather than fully drilled holes, an noise occurs upon braking. Presumably this is the air being squeezed out of the dimple as it passes the pad.(??)
Can anyone confirm or dispell this rumour so that I can get my new discs and pads? Alternatively, are there any other disc/pad combinations (I would rather have the kevlar pads in order to reduce brake dust) suitable for my car? I have a '97 P MGF with OE 15" wheels.
I hope you can help.
|Rich, I've got Rover Sport disks fitted on mine, together with Mintex 1144 pads. (About the same level as the greenstuff, "fast road"). Also got stainless steel hoses as well. All in all, it transforms the brakes and because the disks are groved, you don't get any of the fade you have experienced in the past.|
Got mine fitted by Techspeed in Leamington Spa (not a million miles from you). Can't remember the costing, but if you give Roy a ring on 01926 632066 and mention my name and he'll be able to quote you for the same kit.
Dave Livingstone also has the same setup as me. The only down side of the harder pads is that they tend to squeak a bit when in stop-go-stop-go traffic.
|Happy to endorse Steve's comments about the grooved disks, Mintex 1144 pads and braided hose setup from Tech-Speed. An improvement over standard brakes, no fade on the track and only marginal warming required from cold (probably one gentle brake application enough to bring them up to working temp).|
|To put the "less expensive" route:|
You don't have to replace the disks! You can just fit EBC Green/Black (I seem to remember seeing they've introduced Green for the back as well now?) onto standard disks and that works quite well. Mintex is another option (I think Rob has tried this option...)
I currently have EBC Green on the front and Black on the back and they work well. Maybe a little less bite when its cold until they warm up a bit. No problems with fade "parading" at Silverstone this year (last year I got quite frightened by the fade!). B&G and others do them for quite reasonable costs and they're easy to DIY fit (in the FAQ).
Will the Insurance people be "interested" if you change the disks - mine don't care what type of pads I fit...
Another option is the "big brake" type of kit that Roger helped someone develop (can't remember who right now...)
|Neil, problem is that pads alone will not cure brake fade. The Grooves in the disk vastly reduce fading (I've never had it since).|
|Steve, the grooves aren't there to aid cooling- they are there simply to shift brake dust generated by the pads from the friction surface. Cross drilling is supposed to aid cooling- I suppose I don't doubt that, but I do fear for the strength of the discs as a whole.|
Grooved and/or drilled discs do generate more noise- the removal of material from the smooth surface of the disc generates vibrations when the pads are pushed up against them... Nothing to worry about- but some may find it marginally irritating.
Richard- are you sure your car is suffering from fade? In my experience it is very hard to get the brakes (even standard OE ones) so hot so as that the pedal falls to the floor... What exactly are the problems you are experiencing with the brakes?
EBC green stuff pads aren't bad- less dust in road use- but when they get hot on the track they billow dust big time. EBC black stuff pads I wouldn't bother with again. Fortunately, greens are now available front and rear.
My preference is towards Mintex pads- 1144s as Steve and Dave have are excellent, whilst 1177s are remarkable :o) The latter are very expensive- for the road I wouldn't bother with anything more abrasive than 1144s.
|Rob, I wasn't on about cooling, I was on about the fact the fading can also happen when a layer of gas builds up beneath the pad under heavy braking, which reduces the effectiveness of the pad. The grooves help the clear the gas also keeping the brakes clean, as you say.|
At least that's as much as I understood it, can't remember where I heard that from now, it may have been Roy @ TS.
Anyway, booked in for next Wednesday :)
Now to organise a rental car, again! :(
|I hope the bill will not be too damaging Steve!|
Regarding brake fade, remember that fade is caused by over heating of the brake fluid, causing it to boil and evaporate in the caliper pistons. As gas is more compressible than fluid, the brake pedal starts to become spongy, requiring more pedal travel to produce the same effect.
The question of pads is a slightly complicated question- with different materials having different thermal condition properties- and many high performance pads actually require more heat to actually start working properly.
Two simple approaches to brake fade:
1. fit larger or better ventilated discs- either approach will increase the surface area of the disc to radiate the excess heat;
2. uprate the brake fluid. Dot 4 spec is fitted as standard. As I tend to do more sprint/ hill climb/ track day kind of driving in my 'F, I have Dot 5 brake fluid which is more resistant to heat insofar as it has a higher boiling point.
Other options include installing cooling ducts etc- but this is more than is needed on a road car.
I have never heard a 'proper' explanation of brake fade but I thought I was experiencing it. The situation is:
when braking heavily, ie:when slowing quickly from a high speed, or when attempting to stop in a short distance, the car brakes extremely well to begin with, but the braking force seems to die away rapidly. This can be quite unnerving when you are approaching a roundabout at speed and the car decides it is just not going to slow down as much as you want! This has resulted in the car locking up, particularly when approaching a junction too fast. I know the solution is to slow down, but on the occasions when I give the car some stick I want to be confident it will stop.
From everyone's comments it seems that I may be suffering from the layer of gas build up that Steve mentions.
As an aside, do Techspeed have a website? I am fairly new to the 'F scene and have not looked into any of these upgrades before. I am also interested in the lowering knuckles and their effects. It would be interesting to see what they have to offer. Do they have a shop area?
Thanks again for your help.
|Rich, their website is http://www.tech-speed.co.uk There's not that much info on there, but the basics will do. Don't bother emailing them, they don't seem to respond to it quickly, best thing is to give them a ring. |
>> I am also interested in the lowering knuckles and their effects <<
Techspeed are also the ones to talk to about this. I know others do sell the knuckles alone, but I used TS for lowering mine and I've (touch wood) had no problems with increased tyre wear or other such stuff.
|Having just had my car back from a 60k mile 'renovation' I totally concur with Steve's endorsement of Techspeed.|
The car drives better than new, the suspension is pleasingly taut with practically no deterioration of ride quality. The brakes are superb (Rover Sport grooved discs)- and the Mintex pads give their usual excellent bite :o)
Techspeed don't sell knuckles- they actually machine the ali pistons in the hydragas spheres- this is how Rover has lowered the Trophy 160 and avoids potential long term problem with electrolytic corrosion between two different metals (mild steel and aluminium).
There are few problems with lowering a car on knuckles- inner tyre wear is rarely a problem if the tracking is set correctly (or you use the BBS tracking settings). 330 mm is usually the lowest practical height with respect to speed bumps.
If you are lowering your car, I really would urge you to consider uprating the dampers- again TS use high quality non-adjustable Bilsteins that are perfectly suited to the 'F.
|>> they actually machine the ali pistons in the hydragas spheres <<|
Ah, finally someone has been able to get the info out of TS!! They wouldn't tell me or Dave I think how they actually lowered it.
I thought they used their own knuckles.
My car is lowered ( knuckles ), but tend to think the suspension bounces around alot when going over small 'lumps'/bridges etc in the road. Looking at the manual it seems very easy to replaces the shockers, does that give the same tech speed setup as you have, or put another way would new shocks alone tighten up things noticably in my case.
Another question, I'm sure I've read in reviews that fitting the bigger disks ( option on 16"/VVC wheels only ) make lock-ups very easy indeed and in fact hamper fast approaches etc as the bite suddenly kicks in. Whats your view with your setup ?
|Bob, yes, I do think that some uprated dampers would be a good investment- tauter dampers really do tie the car down a good deal more, so whilst yo still feel the bumps, there isn't the bounce.|
But there is a pitfall here- go for too stiff a damper, and you will crack the damper upper mounts as they were originally designed with only minor suspension loads in mind. Adjustable shocks on reasonably soft settings seem to be okay, and the wealth of experience with the TS specified dampers indicate that these do not cause problems either- all worth considering.
Regarding big brakes, yes you are quite right about the 'balance' of the brakes. I've driven a car with HJW 280 mm front discs and compared it to my own car with standard sized discs and Mintex 1177 pads. Both Paul and I were agreed that my car had terrific stopping ability pulling up all square with no evidence of premature locking. The big brake conversion however prematurely triggered the ABS and felt dissappointing in comparison.
This experience seems to dove tail with a number of people's reports that it is very easy to over-brake the front of the MGF- primarily because there is relatively little weight over the front wheels. If larger rotors are required, then the MGF Cup car approach of larger discs ALL ROUND would be a far better solution IMO- and should provide a car with a well balanced braking system.
Unfortunately, the vast majority of big brake 'kits' only come with larger front rotors... :o(
|Aren't the standard dampers "rebound only". I presume the aim is that bump on a front wheel causes rebound on the opposite rear due to the hydragas link and vice versa...|
|Exactly right Neil. I was genuinely shocked to find out how easy it is to compress the dampers by hand, yet trying to re-extend them was pretty hard work.|
Most dampers do not work in this fashion- or at least not to this extreme. Therefore any replacement damper will make a difference- the key lies in their tuning.
FWIW I am reliably informed that the Trophy 160 dampers are practically identical to 'our' standard dampers...
|>At least that's as much as I understood it, can't remember where I heard that from now, it may have been Roy @ TS<<|
It could be from the EBC 'Users guide': In their 'Brake Fade Explained' section !
|>>>>>If larger rotors are required, then the MGF Cup car approach of larger discs ALL ROUND would be a far better solution IMO>>>>|
I'm afraid that isn't quite true Rob. The Trophy for the ideal example has the 304mm front discs AND a 4 pot with a greater pad surface area and better clamping than the standard 240mm single piston slifder caliper. At the rear remains the same common 240mm discs and calipers.
The 280mm disc conversion has two problems to overcome...
1, the correct balance of pad friction material which will provide the response which is often lacking because carrying over the pad materials used before is often not too successful.
2, there is a degree of extra flexibility of the caliper on the extended brackets in addition to the flex which is common to all sliding calipers. This is solved by having calipers with pistons clamping from both sides of the disc. The 4 pot caliper is also more rigid as an assembly. This flex will induce a degree of lazyness to the way the brakes performa nd so initial response is dulled. I am working on reducing this initial dead feel.
Can't wait to see your car at the next roadster's meet
8-) Couldn't make it last Thursday as I couldm't get away from work.
Bags first for a ride in the passenger seat.
Raj Jena P58 NVF
This thread was discussed between 18/07/2001 and 22/07/2001
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