The curious case of the Atom 4 brakes

[robfitz]

If the factory don’t go for the springs any suggestions of where one could get them fitted?

I think I’ll go whole hog - springs, MC, brace and some Pagid RS14.

[reg]

So good that you guys solve all brake and cooling problems right in time for the factory to include the upgrade in my december build

Dreams are free

[reg]

I think we can now demonstrate otherwise!

Indeed. What fluid have you ended up with out of interest?

[plip1953]

I think we can now demonstrate otherwise!

Indeed. What fluid have you ended up with out of interest?

I think it's Motul 660. Definitely a good quality Dot 4.

[reg]

On the subject of fluid spoke to the factory and they say that they are now using Motul DOT 5.1, they were using DOT 4. Bought some Motul 660, after asking around.....guy who looks after my BMW uses it in all his track cars. Good shout. Was also recommended ATE TYP 200 as an alternative DOT 4+

[plip1953]

On the subject of fluid spoke to the factory and they say that they are now using Motul DOT 5.1, they were using DOT 4. Bought some Motul 660, after asking around.....guy who looks after my BMW uses it in all his track cars. Good shout. Was also recommended ATE TYP 200 as an alternative DOT 4+

In a performance context I don't think I've ever come across anyone using Dot 5.1 over Dot 4.

[reg]

With help from Ian, for which I’m most grateful, fitted RS14’s F+R, springs and larger master cylinder.

1st caliper took a little bit longer but after that it wasn’t overly complex. Deffo need an airline and clamps to remove the pistons. Once the piston is out use a sharp pawl or mini screwdriver and lever the dust seal out on its outer edge. Fit spring then coat piston in fresh brake fluid and locate the dust seal in the piston. Push back into place and repeat 16 times….or 20 times if you get distracted and forget which pistons you have done

Master cylinder swap original rear to front and the 0.75 to rear. Make sure you have paper and brake cleaner ready and put a bucket and cover around the inside of the car.

Luckily we had a pressure bleeding system which was excellent..

Drive back and it’s a big improvement over the factory ABS system. It’s quite rear biased so will be dialling that out. Pedal is at the top, bit of movement but consistent everywhere. With some heat the RS14’s are strong. When stripping the calipers there was easily 10-15 thou of float, with the springs you can feel the pad dragging but it’s so little you can turn by hand.

It’s still not as good as the Alcon setup but really it’s pointless comparing it anymore. These mods are a very big improvement on what is a poor setup from standard, looking forward to a track session to see how they perform when properly punished.

Time wise all in about 4 1/2 hours. Someone is having springs fitted at the factory, surprising for a problem that doesn’t exist (ahem) so it’ll be interesting without any other mods what they think and offer moving forwards?

The pads we removed were AP badges DS2500HD, guessing a Ferodo badged pad. They showed quite a bit of overheating, also the pistons in the caliper were all at different heights, by an obvious margin. Lastly, these dust seals and pistons have been out before, three were damaged by poor removal so had to be replaced.

[plip1953]

Drive back and it’s a big improvement over the factory ABS system.

ABS system? I presume you mean AP?

It’s quite rear biased so will be dialling that out.

As referred to in an earlier post, that's the main reason for considering one size larger for the rear. A lesser friction rear pad is another option.

When stripping the calipers there was easily 10-15 thou of float

What exactly do you mean by this? How do you measure whatever it is you measured?

[reg]

ABS system? I presume you mean AP?

No, the factory ABS system, the one where you apply the pedal and roll a dice for stopping

As referred to in an earlier post, that's the main reason for considering one size larger for the rear. A lesser friction rear pad is another option.

Might be wise, the bias has been wound well forward and the rears are still aggressive. TBH the Alcon setup was as well, it's a similar balance IMO.

What exactly do you mean by this? How do you measure whatever it is you measured?

If you used your finger you could wiggle the pad around, with the springs that has completely gone for now. Obviously fingers not calibrated in the traditional sense but I do know what a few thou feels like Not more than that, less than 0.5mm but greater than it should always have been.

[reg]

Bit of an update after driving today. Bite seems a lot better, perhaps they need more heat cycles in them, Pagid's have always seemed to take a while for me anyway. Still a bit rear biased, but will fit the DS2500's in the back for a test, and also play with the master cylinder extend the fronts and then offset the bias accordingly. But, and it's a big but, during a bit of a blast the felt exactly like the 3.5 under hard braking, which it never has done before.

Look forward to the factory reporting findings on fitting springs only [mention]HenryJS[/mention] ......

[robfitz]

Good to know - also that the factory are trying the springs

[Curves Junkie]

It may be worth bearing in mind that Alcon calipers fitted to some of the earlier Atoms all had springs fitted from the outset.

My Atom 3 from 2010 have no springs - neither front nor rear. No springs in the housing of the caliper to press the pistons against the brake disc. Only a 4 edge sealing ring and the piston - nothing else.

IMG_6190.JPG (1.62 MiB) Viewed 1557 times

[plip1953]

It may be worth bearing in mind that Alcon calipers fitted to some of the earlier Atoms all had springs fitted from the outset.

My Atom 3 from 2010 have no springs - neither front nor rear. No springs in the housing of the caliper to press the pistons against the brake disc. Only a 4 edge sealing ring and the piston - nothing else.

IMG_6190.JPG

So no springs and your ones have dust seals!!

Could it be that a different caliper was used on the 3.5 cars?

[wasp]

Just a quick update.
Fitted larger master cylinder, knock back springs and brace bar.
Did Bilsterberg and Spa.
Braking is now epic again. More force required on the brake pedal but you soon get used to it.
Maybe overkill if you don't use it on track but a million times better if you do.
The pedal remained strong and consistent every lap.
Factory Ferodo pads are not good enough for track use if you like brakes to have feel. Mintex 1144's or Pagid RS14'S would be much better. Probably others too but need to see if anyone has tried anything different.
Even for road only use I'd recommend the springs.
Cheers,
Stu

[reg]

Good stuff. Similarly mine remain solid. RS14’s need some heat in them but overall a massive improvement.