Ariel.Club Forum

So, a change of job and an investment opportunity have delayed my supercharger purchase for a little while.

I’m still playing with the brake bias on track and have not yet exhausted all the options.
Physics tells me that being just ahead of the point of lock up on the fronts will yield optimum retardation. So that’s what I am going for.

Bigger brakes on the back will probably give better “feel” and heat management, but I think I am some way off the skill levels required to fully exploit this marginal gain. I tend to push the brake pedal as hard and as late as I dare on track, and the front brakes are what I’m focusing on, as that’s where the moment of inertia is.

So, when I’m ready I think I’ll go with the charger and an upgrade to some better track tyres. And I’ll see if the splendid Dr Zog does brace pills these days.


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I probably wouldn't notice any difference if I swapped the brakes around Pete, 'cos I'd put the brake bias mainly to the front to make sure all wheels lock up at the same time. And anyway, if rear brakes are not important, why have them fitted at all? They must do something?

And another way to say 'move brake bias to the rear' is 'reduce the effectiveness of the fronts'...

If the Alcons have a braking factor of say 10 (benchmark) and Sports are say 6, then I have a braking factor of 16/20 across the car. The brake bias is quite a way to the rear to balance the braking, so actually the rears are working much harder than the fronts and are smaller discs and pads with floating 2 pot calipers. Whereas the more substantial fronts are somewhat retarded to compensate for the skinny cousins at the back. Isn't the strength of the chain that of the weakest link?

I'm really not expecting shorter stopping distances with Alcons all round 'cos as soon as the tyres let go, that's it. My guess is that by having the same types of brakes all round - be it AP, Alcon, 'Sports' etc. - the need to change bias is really only to compensate for uneven weight distribution and NOT compensating for less efficient braking components as well as the weight distribution, as I have it at the moment. I still expect a slightly rear bias even with the same brake set up all round 'cos of the weight distribution; so maybe the rears will always work harder because of that?

Which probably all translates to: not having to stamp so hard on the middle pedal to stop and having better braking feel 'cos both axles are much more evenly matched in their stopping abilities.

It's this kind of man maths that allowed me to convince the missus that a Nomad was a suitable midlife crisis in the first place, but I am grateful to hear from others who have experience with both set ups - I'm just working on theory. Oh. And the missus really can't give a flying fudge any more...

Ta.

I find it hard to believe the rear brakes on an Atom wear out faster than the fronts. That would suggest rear biased brake setup!

So we are all idiots and need less front end braking?

Swap your brakes around front to rear Karl. Pop the bigger ones on the rear. Give that a try and report back!

Don't forget Karl's Nomad has a higher ride height, and usually is a lot softer suspension than the atom. I suspect as you anchor on, the front will dive and the rear will go light as it pivots around the front wheel.

The Atom being lower and much stiffer I suspect has less of that.

All that's theory though, I've never driven a sports rear atom in anger, nor a sports rear nomad at speed. So the above might be bobbins.

I was sure my big alcon front and sport brakes rear were sufficient ... until i tried another atom with big alcon front & rear :
so i bought the big Alcon rear kit, this made a huge difference, really.

You feel what's going on, you feel the car sitting on the back when you apply brakes,
really this is a good improvement.

I'm in the camp you won't notice much difference. Plus you'll lose the handbrake. You have a bias adjuster so you can just adjust the bias further back and offset the braking forces like that.

The 3.5r I got just had competition brakes on rear as well as a couple of others I've seen, and fairly common on the 2/3/3.5 supercharged atoms.

The fronts obviously make a huge difference.

[mention]Winmoz[/mention] - did you go for the rear Alcons in the end?

I'm running Alcon front and Sport rear ATM and am toying of upgrading the rears now that the charger is in place.

I was under the impression that most of the braking is done at the front given that's where the momentum is, but as Rookie said today - and others have said here - the weight of the car is at the back. I was even thinking of having the 10,000 mile Alcon disc and pads moved to the rear and new put on the front, but again, Rookie reckons the rears wear slightly quicker because that's where the weight is; so overall, the rears actually work harder.

The sports caliper is a floating caliper, so moving to a fixed Alcon will increase feel and efficiency - at least on first application of the brake pedal; apparently.

I think I've got brake balance about right with the balancer wound about half way towards the rear, and I get Pete's point about the fact that it won't actually make you stop any quicker because at some point, it'll be largely down to tyre grip. But I'm wondering how much of a difference rear Alcons make to feel and overall confidence building; noting Stu, John and Hedge's comments...

Not to mention the Nomad's hydraulic handbrake that would then become a 4 pot.

Any further thoughts on this Stephen?

Ta muchly.

The rear Alcon conversion also features a larger Master Cylinder upgrade to 0.7" bore ..

FWIW I doubt you will feel much difference changing the rear calipers, but its a personal thing.

As you say there is already enough braking on the rear available via the adjustment on your existing setup. You are really chasing the feel of the braking, and fade resistance etc.

I'd be interested in someone setting their full Alcon setup 50-50 front rear and trying to drive that. I am pretty sure it would be hideous locking the rears really badly.

Please bear in mind the physics of this:
If the car and tyres are constant and Steve has setup the balance correctly you cannot gain shorter stopping distance just with larger calipers. The science of it is basically just friction in 2 places (disc to pad and tyre to road / track). Both of these need to be managed so that the tyre does not quite slip on the track, via variable friction applied to the disc. Steve can already stop / lock the rear wheels, so having even more available friction won't help the stopping distance. I would also add if you want to be picky you are suggesting to add kilos of un-spring weight to the car as the Alcon's are significant heavier than sports.

Has anyone used Yokohama AO52 the replacement for the AO48?

Thanks all. Genuinely helpful as always.


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I’ve never been a fan of Avon’s (on bikes or cars) as I’ve always found them a little “glassy”. I have loved 888s on my hot hatches (they had the weight to get them up to temp) but they always suffered from too many heat cycles.

Will definitely try the Kumhos next and am now seriously thinking about getting Alcons on the back as well.

CF seats will have to wait for a fresh business case though.


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Also agree with earlier comments that cf seats are great.

Have run 2 x sets of Kumhos on my 3.5R over last few months and agree they provide fantastic grip... but do seem to drop off after 3-4 laps at peak.

wasp wrote: ↑Mon Apr 29, 2019 8:49 am
The Khumos are a revelation. After years of A048s and R888's I could not believe how much better they were. They also grip brilliantly right up to the point where they are slicks, when those above would have given up the ghost. I'm really hoping that the Avon's on the 4 are ok as they have a really hard act to follow.

Cheers,
Stu

Thats interesting. Ive never had Khumos. Just switched to Avons on my 3.5 after always having had AO48s. I don't think Ariel have any left now. I just don't think the Avons are as good as the AO48s in terms of grip. It just feels like that to me. Admittedly Ive got the ZZS Avons, which im told are not much different to ZZRs for grip but better in the wet. Might try Khumos next