Snaking under Braking....

[RedRobin]

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Under very heavy braking yesterday I experienced snaking for the first time. I tried to induce it again but my efforts were probably not quite extreme enough because I didn't succeed. Shaving off a lot of speed from an overtake on a B-road to go into a blind 90-degree lefthander is not as easy as it sounds to replicate.

My brake setup is AP Racing fronts and S3 rears and braking is normally very even and well planted.

At the moment I reckon it wasn't caused by any worn suspension parts/joints because it was a one off so far. The road was bone dry but might have been dusty from local farm vehicles and I think it happened as I crossed the central white line back onto my side of the road. On the road I always have my ESP on.

Tyre pressures are what they should be.

Is this a sign of anything I should be concerned about? Cheers for any ideas 

[stealthwolf]

I've had similar under very hard braking (on a straight road) and have been told it is the ESP.

[sub39h]

wouldn't this be normal for a car with a front brake bias? happened to me a couple of times with NQS at front and OEM rears

[E30Dom]

Combination of ESP and the road camber?

At least you have hard braking to compare before/after with Unibraces fitted ;) (when the bloody things turn up!)

[alackofspeed]

I'd suggest the increased front camber under braking combined with traversing the mid-road crest probably did it.

[RedRobin]

wouldn't this be normal for a car with a front brake bias? happened to me a couple of times with NQS at front and OEM rears

....Except that I've got S3 rears which are bigger (and vented) than the OEM GTI rear brakes. Also, it was on the same road that I first tested the S3 rear brake combo (though nothing quite as extreme) and I noticed how much more even and well planted the car felt with them under hard braking.

[RedRobin]

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Yes, I reckoned (and hoped) it was a touch of ESP, guys, but I hadn't thought of the road camber and road crest factors.

It was very real-world as opposed to "let's brake hard and test what happens". I had waited patiently following a car (not close) and two others close to each other in front... I knew that if nothing had entered the straight coming towards me I could easily overtake and there was just about enough room to hover momentarily and indicate ducking into the gap without bullying the driver if I needed. As the front two were travelling so close to each other and at only about 45, I very quickly realised I could keep my foot planted and overtake them as well but I would have to brake very very hard indeed to shave enough speed off for the sharp corner because by the time I had overtaken three cars my speed was high to make it through safely. I also knew that by having reduced my entry speed enough I could hug the inside and exercise my Quaife to power out of the corner - All part of the fun. It's a corner where some idiots put their righthand wheel either on or over the central white line blind into oncoming vehicles. Milk lorries can be forgiven because of their size on that road but by hugging the edge there's plenty of room.

It's good to know that it's not likely to be a mechanical problem.  Thanks, guys

[RedRobin]

At least you have hard braking to compare before/after with Unibraces fitted ;) (when the bloody things turn up!)

....Funny you should say that. It's one of the B-roads I shall be testing the XB and later the XB+UB on.  (bloody British Customs still holding things up!)

[Andy]

did this on mine  as well--just picked the car up when i had all the trouble with it--braked hard (as i forgot about the corner) and mine snaked a little as well.My set up is r32 brakes all round

[gazon69]

Hmmm i have also suffered this. Thought it was driver error.

[Andy]

Hmmm i have also suffered this. Thought it was driver error.

am sticking to the esp kicking in

[gazon69]

Sounds good to me

[james]

i have the same setup as you,  i only get it at very high speed braking.  other than that feels very planted like you day.

[RedRobin]

i have the same setup as you,  i only get it at very high speed braking.  other than that feels very planted like you day.

....When you think about it, the car is being put under some very strong forces under such hard braking and the energy has to be dissipated somewhere and that's where the ESP comes to the rescue. Camber changes, central crest, road surface slippiness, etc, all contribute. I don't want to be specific about the speed I braked from (easily viewed on my GPS digital display) and the short distance I shaved off the speed in. Put it this way, I wouldn't have gone for that move if on standard GTI brakes.

Although it slightly snaked I didn't feel any loss of control but I wasn't expecting it.

[RedRobin]

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Something else which I was forgetting is that under very heavy braking the rear end will go much lighter. And consequently action some ESP.