Who has worn out their brake discs ?

[PAJ]

I know that the Alcon brakes for the Atom aren’t a cheap part, but who has worn through a set of discs ?

The cars are obviously pretty light, is it even possible to wear out a set of discs when you have 90% road use, and are they as scary expensive as I imagine .

[John Scherrer]

In 2013, Tom mentioned they were £395.10 + VAT per pair.

He said that they were rarely needed to be replaced unless accident damaged or run very hard with the wrong pad material.

[K20A2]

I can confirm, that the price is still the same (status August 2017).
I unfortunately need 4 new ones, which is not because they are outworn, but because they are vibrating.
As obviously almost nobody has any problems with the Alcons I am a bit afraid, that the discs may not be the reason for the vibration thouth...

[smokin]

I unfortunately need 4 new ones, which is not because they are outworn, but because they are vibrating.

This sorted, and transformed, my braking
https://www.ariel.club/forum/viewtopic. ... 65#p260965

[911tom]

Yeah all mine were replaced last year when my car was in for a service as they were a bit warped. I do find on the roads I hardly touch the brakes as the car is so light. As soon as you come off the throttle the engine brake slows you down quite a bit. Even when driving hard I suspect I am only using 50% of the braking force available.

[wasp]

Even when driving hard I suspect I am only using 50% of the braking force available.

I was definitely in this camp, as apart from anything else, I never wanted to risk not making a corner. Then, I had an instructor on board at Spa a few years ago. He took me out of my normal comfort zone with braking at the end of the Kemmel Straight. The Atom can apparently brake from 145-150mph to 45mph in less than 100 metres, lap after lap. Quite amazing things these Atoms.

Cheers,
Stu

[phil4]

Quite amazing things these Atoms.

It was only when I did a track day at Castle Combe, that I realise quite how good the brakes are when everything's up to temp.

On the road, the brakes never seemed amazing to me, and indeed a lockup was never too far away.  Once the tyres and brakes are nicely warm on track though, the stopping power is amazing, very much like hitting a brick wall.

I was astounded at the difference, like chalk and cheese.... I'm almost amazed they're the same components.

[phil4]

I wish I'd remember this thread.

In for service this year, and my rears have been replaced due to being warped. Price was as per earlier in the thread.

Stumps me how with 6500 miles and 3-4 light trackdays (If you've seen me drive you'll realise I'm not that fast) the rears of all things can become warped.

Perhaps I should have asked them to fit the new AP discs they're using on the Atom 4, rather than ones made of cheese.

[John Scherrer]

Nah Phil - Ariel just need to get rid of a shelf full of old parts !

Only kidding !

[Winmoz]

I have replaced a lot of discs in my track toys over the years, but have never actually managed to warp a disc. My issues have stemmed from leaving the pad in contact with a hot disc for too long, creating a raised deposit area. Sometimes this can be skimmed off, sometimes it can’t.

This has happened with AP, Alcons, etc and has taught me the wisdom of a cooling down lap and how handbrakes are evil when it comes to paddocks.

Perhaps I just need to drive harder?


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[cvjoint]

I cracked my first set. I haven't checked thickness to see if they were still in spec, but the slots were still plenty deep. Got 3,500 miles on them. Of all cars I've had the Atom is the most gentle on brakes, and by an incredible margin. On the C7 Z06 for example, I would crack a set of rotors in just 1,000 miles and they were massive 15.5" iron slugs.

[Anon]

Stumps me how with 6500 miles and 3-4 light trackdays (If you've seen me drive you'll realise I'm not that fast) the rears of all things can become warped.

If discs are to be warped then it makes sense the rears over the fronts because there is no weight at the front and I suspect more braking is needed on the rear than the front as for the front there is little weight transfer. This also surprises me when I see Atoms for sale some on a budget decide to have Alcons on the front but sport brakes on the rear. It should be the other way around. Warping brakes is normally due to them overheating. Just wondering if the AP racing brakes will be better.

[phil4]

If discs are to be warped then it makes sense the rears over the fronts because there is no weight at the front and I suspect more braking is needed on the rear than the front as for the front there is little weight transfer. This also surprises me when I see Atoms for sale some on a budget decide to have Alcons on the front but sport brakes on the rear.

Hi Simon, now I might be completely wrong with this... but I think you've got something a bit wonky. When you press the brakes on pretty much any car or bike, including the Atom, it's the front wheels that do most of the braking. The weight of the vehicle transfers to the front of the car, pushing the wheels into the tarmac allowing much much higher braking force. Conversely, as there is now very little weight pushing the rears tyres down, you'll want very little braking force on the rears, or they'll lock up.

If you look at almost any motorbike, but especially sports bikes you'll see this stark contrast, you'll usually find two massive rotors at the front, and one tiny rotor at the rear.

at the front against as the rear.

Sure the atom is a bit less extreme than the bike pictured, but this shows you how the weight transfer means there's less point having massive rotors on the rear... you'd just lock up the rear wheels.

And that's also why you see the budget minded spec'ing sports brakes on the rear... because they do much less braking, and as such having less braking effort would be less noticeable.

[Peter255]

Phil is correct more braking is required at the front even for an Atom.

Many Atoms (mine included) have big brakes front and smaller sports on the rear. It is NEVER the other way around on any Atoms. You may have Alcons all around but never only at the rear.

Weight transfer forward under braking has a strong effect even on an Atom. This means even with a light front end you can make use of more braking at the front.

This can be seen when the front of the car dips under braking as it is pushed down. This force can be utilised by bigger brakes on the front. The suspension dive effect is quite visible in my old Atom 2, but has been largely dialled out of the Atom 4 from what we have been told.

Warping is usually due to un-even cooling and thus contraction of the metal discs. Winmoz is correct in his cool down technique!

[Anon]

A bike is a very different applicatuon because weight transfer is the rider himself as he is almost on the front wheel.

It makes no sense to me putting bigger brakes on the front when all the weight is at the back. If this were an issue we would see the same thing as on bikes, but we don't, disks are often the same size with same.

I don't like arguing on an internet chat forum so lets agree to disagree!