Jackwebb motorsport big brakes

[SLR No.77]

You don't need vented discs.

[K7 VCT]

Ok great.

What about the master cylinder ?

 

[Richard Price]

I’m surprised to see reference to using DS3000 pads.

looking at the spec of these pads, they don’t look like a sensible choice for anything other than racing or track days. Their optimum operating temperature looks to be between 450 and 700 degrees C ( from the discs between dull red and bright red!), but, at cold, could have only half the stopping power.

For road brakes (as, indeed, a sprint/Hillclimb use), you need pads with a much flatter temperature/friction characteristic  so that you know what is going to happen each time you press the brake pedal.

likewise, if you wish to improve stopping power, it’s important to retain reasonable front to rear balance. If the fronts are too powerful, you’ll simply lock up the fronts easily , but not necessarily slow down any better. Do not under estimate how much of your overall stopping power comes from the rear brakes!

   

[elie boone]

The 7 i build with Hi-Spec all round uses the std master brake cylinder. you can have Hi-Spec front brakes with vented rotor, it's about 85ish for the rotor and 75 ish for the alloy bell, you will need vented rotors on the short and twisted tracks if you have more than +/- 150 bhp. I could dig up the part numbers for both parts.

[rj]

Do not under estimate how much of your overall stopping power comes from the rear brakes!

+1

I fitted uprated fronts and upset the balance. I had no faith in the brakes until I repaced the rear pads with CL Brakes RC8s and added a brake balance valve. This is, by far, the best modifcation I've done for ages.

[K7 VCT]

Thinking about leaving the standard set up, so many variations and variables to consider.

[Drumster]

Just to add another view.....

My 7 (200bhp 'boat anchor' Zetec) still uses the standard brake calipers with the 'larger' Mintex 1144 pads on the front and Ferodo FDB398 pads on the rear but with the AP uprated racing master cylinder.

The car is used for sprinting, hillclimbing and touring and I certainly don't have any trouble in stopping the 7 in a hurry and I'm happy with the balance of the brakes. After 20 years I'm still not tempted to invest in the uprated front brake set-up and it's probably the only upgrade I haven't made.

That's the problem with our 7s, there is no one single 'right' answer as we all have different opinions, uses and driving styles.

[7 wonders of the world]

DS3000 do have a consistent torque curve and offer reliable consistent pedal hot or cold - much better than than the previous 1144 pads.

 

[Richard Price]

"DS3000 do have a consistent torque curve" 

 

Ferodos own website would suggest otherwise:-

 https://www.ferodoracing.com/products/car-racing/racing-brake-pads/ds3000/y

They certainly look like they would work better and better until the discs are just starting to glow, at which point, they'd remain stable until the discs are bright red. As the friction changes by over 20% between 100 and 400 degrees, if the rears don't change at the same rate (where it is highly unlikely will....), then the front to rear bias will be adversely affected.

[7 wonders of the world]

Unless you start using temp paint for monitoring and playing with ducting etc then you will always have an imbalance at some point front to rear.

Many switch the front pads to 1144 without a thought for whats pads (and their characteristics) are in the rear, I've yet to see any firm evidence of what material CC use in either the std or blue spot pads, and then there's the big brake kit...... and how that affects the bias.....

DS3000 from my real world experience gives a better initial cold feel than the 1144 and the pedal does get better and more confidence inspiring as they gain heat.

I've tried many combinations and have a set of front DS1.11 to try, though my concern with these is they may offer a little too much at lower brakes temps that could promote premature locking on cold tyres / damp roads.

Might be good for sprinting / hillclimbing though....

 

[bluenose]

I have Hispec Ultralite 4s with standard disks and Mintex 1144 pads and standard rear brakes and the same pads as Chris Alston.  Car seems balanced and is fine for roads round here and on track.  I have the updated master cylinder.  My car is light at 460kg.  I agree with Chris that the car is ok on standard calipers, I just wanted the far lighter weight of the Ultralites to save on unsprung weight.  I have heard from posts saying that on overseas trips where there are loads of hairpins etc the Hispecs do not perform and I suspect this is probable true and vented disks and bigger 4 pot calipers would likely work better but for most of us it is not usually needed.  

As for HiSpec customer service, I have heard stories and again cannot comment as I had no issues although my dealings with them were quite a while ago but HiSpec have been used on the Levante and other cars so they must be doing something right.  

 

 

[7 wonders of the world]

No reason the brakes should not work on the alpine descents...... unless your getting fade or vapour lock...?

Both of which can be avoided with correct material and fluid choice.

[CageyH]

Surely it depends on the speed of descent, the force used in braking and the capacity of the brake and pad to cool effectively before the next hard brake application as well as the fluid etc.?

[7 wonders of the world]

isnt that what I said though.....?

      - unless your getting fade or vapour lock..

[CageyH]

A ventilated disc will cool more efficiently compared to a solid disc.

It is an extreme case as normal use should not see much of an issue on standard brakes.

[7 wonders of the world]

But unless your experiencing either fade or vapour lock - irrespective of what brakes are used, you have no problem.....

 

[aerobod - near CYYC]

I think with normal road use solid disks would be OK, but for track use it is definitely beneficial to have 4-pot fronts with ventilated disks and high temperature fluid (I use RBF600) to avoid problems, especially when using slicks. I also remove the plastic wheel centre caps during that sort of hard use, as the wheels get hot enough when you can achieve 1.5g stops from 170 to 80km/h with the AP brakes, causing softening of the plastic retaining tabs, I got black flagged once for one of mine flying off and almost hitting a marshall ;), he did bring it back to me though, so I could see how the tabs had softened and distorted.

[CageyH]

If you suffer from brake fade part way down a mountain, it is not a good situation to be in with regards to enjoying yourself.

I still run standard front brakes and M1144 pads on the front, and have never really had a serious issue, but I have not done many track days.

[Simon.Rogers]

Richard.  The DS3000 work brilliantly from cold and great when hot also.

Always with consistent feel through the pedal.

They last for ever - in fact thats the one draw back they may well last longer than the discs!

I did have to swap back to 1144 in the Busa as they were too aggressive for a car with little engine braking but the 1144 only gave me confidence for a couple of big stops using the slicks.  You can really smell them at the top of the hill at Epynt for example. 

I now use the DS2500 a happy compromise. 

[Richard Price]

Simon, are you saying that the DS3000's worked better from cold ("brilliant"), but did not improve with temperature? Or that they get better with temperature?

"I did have to swap back to 1144 in the Busa " - are you saying that you ran DS3000's when you had the K, but swapped to 1144's after going 'Busa?

What pads have you/do you run in the rear?

Whilst I'd really like to apply a lot more science, my own observation is that heat is built and retained significantly more in the rear brakes than the front (with AP's on the front, and standard Triumph/Ford rears) after a few big stops, my front wheels are cool, and my rears significantly warmer. I'd wager that most lost stopping power is associated with loss of rear braking power due to fade (or a mismatch between the front and rear heat/friction characteristics, and the rate at which each axle builds heat) .

Ideally, for a sprint/hillclimb car, we need the stopping power to be the same cold as it is hot (or, as similar as possible). Additionally, for each axle to provide the optimum stopping torque to the tyres. However, that optimum stopping torque to each axle is affected by so many variables. As you know, my feeling is that very few cars optimise the rear brake performance. If weight is removed from the front of the car, the available front stopping power is reduced, and fitting wider rear tyres increases the rear stopping power.Therefore, what works with an Iron blocked Vauxhall XE, is not going to work with a K, and less so again with a 'busa... 

[Richard Price]

K7 VCT,

'sorry about the hijack of your thread!

With reference to your question about master cylinders. The AP "uprated" master cylinder has a piston area something like 1.69 times greater than the standard master cylinder. Therefore, for the same stopping power, you need to apply 1.69 times more pedal effort, but, you'll also get a corresponding reduction in pedal travel. 

If you fit an AP master cylinder with standard calipers, you'll need to apply more pressure.

If you retain a standard master cylinder with AP calipers, then, as the AP calipers have more piston area, you'll have a longer pedal requiring less pedal pressure.

'to your original question. I'd also ask what you are looking for? 

I've seen so many times that folks complain of a soft pedal on trackdays, and then report that fitting big fronts has "cured" the issue. I'd suggest that the big fronts have masked the problem rather than cured it! I'd suggest that a soft pedal is far more likely the result of boiling fluid in the rear calipers. Fitting big fronts, moves the bias towards the front making the rears work less hard, make less heat, and so don't boil. However, the overall stopping power has actually been reduced. Its easy to lock the fronts, way before the rears are ready to lock. Better brake fluid is a far cheaper solution to cure fluid boil.

[Simon.Rogers]

So I pretty much agree.

 

The rear of the cars is under braked. I now have DS3000 rear and 2500 front.

 

I have sold a significant number of pads to customers with the same pads front and rear - be that 3000, 2500 or 1144.

 

Yes the 3000 worked brilliant on the K but grabbed a wheel on the Busa which is as you suggested due to loss of weight.

 

I have never had brake fade o track but neither have I measured anything.

 

I am currently working on a complete new wishbone, upright and brake kit.

[7 wonders of the world]

Richard,

If your looking for a 'flat line' with regards to Mu then take a look at DS1.11 - as I mentioned previously they could be great for sprints and hillclimbs, cant offer any feedback on these though as there still in the box !

A lot depends of your preferences and how you like the brakes to feel - we're all different.

DS3000 work for me, much less dust than 1144 and no where near as smelly -  whilst on 1144's SWMBO once asked it it was me who had made that smell.... she wasn't convinced it was the pads     

 

[Simon.Rogers]

DS1.11 didn't work for me. Too much like a Pagid. Too grabby.

[Simon.Rogers]

I think it's all about improving the rear to front balance.

That's what I am working on.