Red Bull RB6

[747heavy]

o.k. so we talk about the re-positioning of the front calibers.

from F1.com

After several reliability issues, Red Bull's chief technical officer Adrian Newey has changed the positioning of the RB6's front brake calipers. Instead of the horizontal position, which lowered the suspension's centre of gravity, he's moved the front calipers back to the more standard vertical position. The previous positioning had led to occasional mechanical failure due to greater movement of the brake pistons, pads and discs. This was a change planned for 2011, but the team took the decision to run with it for qualifying and the race in Japan.

not 100% sure what they want to say with the highlighted part, but it sounds a bit like flexure in the wheelbearing/upright to me - under lateral/cornering load.
I can see, that this causes some problems, but not sure why it would lead to mechanical failures. It also seems to be only a problem at the front, as they keep the position at the rear.

[Michiba]

o.k. so we talk about the re-positioning of the front calibers.

not 100% sure what they want to say with the highlighted part, but it sounds a bit like flexure in the wheelbearing/upright to me - under lateral/cornering load.
I can see, that this causes some problems, but not sure why it would lead to mechanical failures. It also seems to be only a problem at the front, as they keep the position at the rear.

Perhaps it is due to the torsional load on the the wishbones. I'm thinking that at the 6 o'clock position, there is more load on the lower wishbone resulting in the failure. However at the 9 o'clock position, the load is distributed between the two wishbones making it more reliable? Just a guess.

[Belatti]

I have followed RB6 development through the first pages of this thread, but after 127 pages I dont know what has been said or speculated -or not- about ride height and downforce. I remember the matters involving dampers and gas pressures and I could hardly believe at that time that there was the secret lying. Now I was reading something that made me remember the Red Bull case:

If a lot of rebound damping is used the suspension will be dynamically pumped down which can improve the aerodynamic downforce. If there is enough ”aero” gain it can more than offset any loss of grip due to slow rebound recovery. When this approach is used compression damping is generally reduced at the same time to help the pumping down.

[Sean H]

o.k. so we talk about the re-positioning of the front calibers.

not 100% sure what they want to say with the highlighted part, but it sounds a bit like flexure in the wheelbearing/upright to me - under lateral/cornering load.
I can see, that this causes some problems, but not sure why it would lead to mechanical failures. It also seems to be only a problem at the front, as they keep the position at the rear.

Perhaps it is due to the torsional load on the the wishbones. I'm thinking that at the 6 o'clock position, there is more load on the lower wishbone resulting in the failure. However at the 9 o'clock position, the load is distributed between the two wishbones making it more reliable? Just a guess.

they were talking about the reliablity of the brakes, they have had several caliper issues this year.

[Tim.Wright]

At a rough guess, I'd say there were some compliance issues with the brakes down low.

Can't guess at how exactly but it would be something imposed by the geometry. Though, if anything I would have thought the caliper mount would be stiffer since it is closer to the wishbone mount.

Tim

[marcush.]

a low positioned caliper will SEE all flex in the bearing /Hub/Disc flex under vertical /lateral load. so if you got some slack or flex in the bearing system the disc will inevitably make contact to the pads...knocking back the pistons and create additiuonaldrag and wear on the brakes....
Knocked back pistons is effectively a long brakepedal on first touching the brakes...definitely not something a driver would like.
Not to talk of all debris falling into the brake caliper -read wheel change during hot pitstops-

[marcush.]

I have followed RB6 development through the first pages of this thread, but after 127 pages I dont know what has been said or speculated -or not- about ride height and downforce. I remember the matters involving dampers and gas pressures and I could hardly believe at that time that there was the secret lying. Now I was reading something that made me remember the Red Bull case:

If a lot of rebound damping is used the suspension will be dynamically pumped down which can improve the aerodynamic downforce. If there is enough ”aero” gain it can more than offset any loss of grip due to slow rebound recovery. When this approach is used compression damping is generally reduced at the same time to help the pumping down.

In the night race you could clearly see how quick especially the RBR 6 was changing attitude -rideheight-at the rear into the corner.No ways they are running a rebound biased setup.
Also the lots of rebound setup will hurt mechanical grip...which they are strong as well...the Redbull looks very compliant .
I´d think the Sauber was tightened up maybe the Mclaren as well if thats just rebound or more spring related ..hard to see on TV..

[aral]

a low positioned caliper will SEE all flex in the bearing /Hub/Disc flex under vertical /lateral load. so if you got some slack or flex in the bearing system the disc will inevitably make contact to the pads...knocking back the pistons and create additiuonaldrag and wear on the brakes....
Knocked back pistons is effectively a long brakepedal on first touching the brakes...definitely not something a driver would like.
Not to talk of all debris falling into the brake caliper -read wheel change during hot pitstops-

I agree with the possibility of debris lying in the horizontal caliper, but in relation to knock back. Surely if the pistons are knocked back, then there would be LESS drag . After all, road cars, and most racing cars, have a system to pull back the brake pistons, so as to REDUCE drag.

[marcush.]

errm yes ..but to knock back the pistons you will first neeed to touch the pad heating it up....so drag is at least in cornering extended.For sure on the straights you are correct.On the other hand you don´t know if the knock back of óne side of pistons will not leadd to the other side of the calipers piston to pop out the same amount.before fluid is transferred into the reservoir..so you got knock back on one side and potentially a extended pistonset on the opposing caliper pistons...

[747heavy]

a low positioned caliper will SEE all flex in the bearing /Hub/Disc flex under vertical /lateral load. so if you got some slack or flex in the bearing system the disc will inevitably make contact to the pads...knocking back the pistons and create additiuonaldrag and wear on the brakes....
Knocked back pistons is effectively a long brakepedal on first touching the brakes...definitely not something a driver would like.
Not to talk of all debris falling into the brake caliper -read wheel change during hot pitstops-

Yes I can following your reasoning Marcus, it is along the lines which I have in mind (the pad knock back part).
I´m still not sure, why this would lead to "mechanical failure" and why it is not the same on the rear.

Maybe they will change the rear caliper position for next year, and just had time/resources for one change at the time - pure speculation on my part.
Just interested in the technical explaination.

In this case the "real problem", if you like to call it like this, would not be in the calibers/brakes, but more in hub stiffness (upright/wheelbearing etc.)

Cheers

[marcush.]

I have an idea on that :the slot for the disc in the Brake caliper is obviously just clearing the disc.So if your flex is too much the disc will start to grind on the caliper ..and something will start to give....it may not only be pad knockback then.

[747heavy]

yes, thats a very good point, and a possibility-IMHO
So why only on the front?
more sideload or better/stiffer wheelbearings/upright in the rear?

on the other hand, if you mount your caliper like this:



you would move the point of the dics, with the largest lateral deflection,
even closer to the narrow "slot" in the caliper - No??

[mep]

Maybe pushrod related.
You have wishbone mount, pushrod pick up and brake mount in roughly the same area at the front. Could cause some lack of space and trouble to get a stiff upright.

[marcush.]

So what have we got on the front we don´t have at the rear ?
Steering action
More brake force
No Propulsion
Less Weight
higher CoG
pushrod/ pullrod

add as required..

my feeling is brake force and steering activity on corner entry may have an effect..but who knows...maybe you are right and they simply started where they had more issues till now and will do the same on the rear time permitting.

or maybe they can reuse the new part on the RB7?

[AbbaleRacing77]

a low positioned caliper will SEE all flex in the bearing /Hub/Disc flex under vertical /lateral load. so if you got some slack or flex in the bearing system the disc will inevitably make contact to the pads...knocking back the pistons and create additiuonaldrag and wear on the brakes....
Knocked back pistons is effectively a long brakepedal on first touching the brakes...definitely not something a driver would like.
Not to talk of all debris falling into the brake caliper -read wheel change during hot pitstops-

WIth the amount of negative castor they put in these cars wouldn't that shift the most load to a more vertical position? Similar to where they are mounting the calipers right now? And wouldn't the use of a floating brake disc and floating pads eliminate this problem anyway? Pretty much all modern race cars use floating discs to eliminate most of the drag. Im not positive but it seems like your reasoning could be avoided by some relatively not so new technology. Especially by a modern f1 team. Honestly im puzzled by this and cant figure out why they have problems mounting the brakes like this. If i had to guess i would say that there's a problem evacuating heat and debris from the caliper and wheel, and the reasoning for not changing the rear calipers is probably because they have much less work to do then the front calipers with most of the bias being toward the front.