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hueb

Original Poster:

44 posts

104 months

[news] 
Monday 15th October 2012 quote quote all
Hi guys. I'm sure this will have been discussed in much depth before but.....last weekend took the TVR wedge 450 to my local track for four 8 lap sessions. Weather was around 28 degrees (this being in Oz by the way!) Had a ball but after several laps of each session & at certain corners after some heavy braking before, experienced pedal nearly to the floor to slow the car down. Down the following straight the pedal feel would again return on the next corner.

I've got the standard Granada vented disks with 4 pots on 15" wheels & original brake hoses. Before the track day, changed the fluid to super Dot4 & fitted Mintex 1155 pads.
For those that have experienced similar, are there any recommendations / suggestions to help improve matters? I'm also looking into putting in extra air ducting direct to the disks. Cheers Clive

atom111

903 posts

111 months

[news] 
Monday 15th October 2012 quote quote all
Are the original hoses braided?

I suffered fade on my MINI upgraded discs, pads, fluid and replaced hoses with braided and that sorted fade for me.

Pumajay

555 posts

90 months

[news] 
Monday 15th October 2012 quote quote all
yeh i had fabe on my first day but i just replaced the fluif to motul 600 amd that cured it for me, its just overheating of the brakes/fluid that causes it so some cooling would help

fushion julz

382 posts

59 months

[news] 
Monday 15th October 2012 quote quote all
Fading brakes will be due to the pads/shoes overheating to outside of their optimum working temperature.
The solution is to a) upgrade the pads and b) to ensure their is a supply of cold air to cool the brake discs at the front...You could remove the metal backing plates to the discs and direct some air through some ducting from the front of the car.
If the discs are solid, then upgrading to ventilated discs will help, too.
Cross-drilled discs are *suppossed* to aid in cooling, but I've not found that in any way effective and it does mean the disc is more prone to cracking.

Braided lines will help with pedal feel and effort as the PTFE hose flexes/expands less than rubber, especially when contained by a metal braid. This won't have anything to do with pedal fade, though.

The brake fluid is important as you don't want it boiling...A decent road-spec, high braking point fluid (ATE Super Blue or AP551, for example) will be fine..Boiling brake fluid means that either the pedal will go rock hard and there will be virtually no braking effort at all or it will go "long" and soft, again with very little brake effort. The fluid, once boiled, also has a lot of air absorbed in it and, not only does it take a while to cool enough to regain effectivenes, it also has a reduced hydraulic effectiveness (due to the absorbed air)...Much worse than overheated pads (which cool pretty quickly in the airflow).

MuZiZZle

485 posts

76 months

[news] 
Monday 15th October 2012 quote quote all
fushion julz said:
Fading brakes will be due to the pads/shoes overheating to outside of their optimum working temperature.
The solution is to a) upgrade the pads and b) to ensure their is a supply of cold air to cool the brake discs at the front...You could remove the metal backing plates to the discs and direct some air through some ducting from the front of the car.
If the discs are solid, then upgrading to ventilated discs will help, too.
Cross-drilled discs are *suppossed* to aid in cooling, but I've not found that in any way effective and it does mean the disc is more prone to cracking.

Braided lines will help with pedal feel and effort as the PTFE hose flexes/expands less than rubber, especially when contained by a metal braid. This won't have anything to do with pedal fade, though.

The brake fluid is important as you don't want it boiling...A decent road-spec, high braking point fluid (ATE Super Blue or AP551, for example) will be fine..Boiling brake fluid means that either the pedal will go rock hard and there will be virtually no braking effort at all or it will go "long" and soft, again with very little brake effort. The fluid, once boiled, also has a lot of air absorbed in it and, not only does it take a while to cool enough to regain effectivenes, it also has a reduced hydraulic effectiveness (due to the absorbed air)...Much worse than overheated pads (which cool pretty quickly in the airflow).
Basically as above!

I'm looking into ducting for my (don't laugh) saxo, a guy on our forum can run steel wheels with air ducting and return better results than no ducting on a more open wheel.

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framerateuk

1,504 posts

70 months

[news] 
Monday 15th October 2012 quote quote all
I had good results on my Megane 250 by upgrading the pads, and using some RBF600 instead of the standard fluid. In fact, the RBF600 on it's own with the standard pads did a great job.

Johno

7,616 posts

168 months

[news] 
Monday 15th October 2012 quote quote all
You may also consider your braking style, shorter, harder application will be better for them than prolonged periods of lower force application. Agree upgrading is the ultimate way forward as circuit driving puts a different demand on the brakes, but aplication will also play a role.

PhillipM

3,663 posts

75 months

[news] 
Monday 15th October 2012 quote quote all
Soft pedal is fluid fade rather than pad, so some ducting to the caliper may help, some pads transfer a lot more heat to the claiper than others too, stainless shims behind them sometimes help slightly.

hueb

Original Poster:

44 posts

104 months

[news] 
Tuesday 16th October 2012 quote quote all
Thanks everyone for your comments. As I've only got Castol super Dot4 in there at the moment, I'll upgrade to Motul. Plus I think it's probably time to upgrade brake hoses to braided ones & also to improve air-cooling (which would also include removing the metal backing to the discs). I noticed many of the cars at the last track day I went to had some serious 3" air ducting towards the brakes.

fergus

5,160 posts

161 months

[news] 
Tuesday 16th October 2012 quote quote all
Johno said:
You may also consider your braking style, shorter, harder application will be better for them than prolonged periods of lower force application.

Agree upgrading is the ultimate way forward as circuit driving puts a different demand on the brakes, but aplication will also play a role.
thumbup

Changing your braking style will allow you to probably stick with your current setup, until you're going a lot quicker. Upgrading your braking hardware just allows the driver to get away with "less than optimum" braking technique without suffering any deteriation in braking performance.

If any professional drivers attend any trackdays you are at, watch how they can peddle a *very* stock car quicker than an averge driver in a much quicker car, and still not suffer from fade, etc.

PS if you install ducting, you need to point it at the centre of the disc to let the air flow through the vanes. Pointing it at the surface will do very little to dissipate 500-700 degrees C of heat.

HokumPokum

1,035 posts

91 months

[news] 
Wednesday 17th October 2012 quote quote all
fergus said:
thumbup

Changing your braking style will allow you to probably stick with your current setup, until you're going a lot quicker. Upgrading your braking hardware just allows the driver to get away with "less than optimum" braking technique without suffering any deteriation in braking performance.
think this is key.
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