Getting back into track days

[Shad]

It's been a couple of years of track day drought for me for various reasons, but I'm squeezing in a couple of days before the end of the year to try and enjoy all of the changes I've made to my Caterham since the last outings.

The first of those days was at Brands Hatch on Thursday, somewhere I love visiting, despite the ~100 mile drive there in the cold and the fog. The car is a 2002 Caterham with around 95k miles on it, originally a basic Roadsport but has since become much more track focused and closer to an R300. The engine's a 1.6 K Series with forged pistons, Supersport cams on verniers, uprated valve springs, a bit of head work, Jenvey throttle bodies, and an Emerald K6 ECU. It's putting out 154hp with the airbox fitted (a must for somewhere like Brands), and 163hp on just a filter. It's a really fun engine, loves to rev, and sounds great too. The chassis is running some fairly trick suspension and the brakes and tyres are identical to a top spec Caterham 420R race car.

The last time I did a track day the engine was without the throttle bodies and ECU so it was making something in the region of 135-140hp after being freshly rebuilt, and the car was still shod with Yoko A048s on 6x13s all round. I'm always chasing lap times wherever I go and at Brands I was doing around the 54.5 second mark fairly consistently. Not too shabby, but I knew at the time both the car and me had more to give - so I've added power, grip, and cajones!

This time, with the help of a VBOX and the analysis software, I was able to push on and begin to extract quite a bit more from the car. My best lap was a 53.1 and my ideal lap (i.e. all of my best sectors) was a 52.89, which is starting to get quite close to the ultimate potential for the car at the moment. So I'm pretty pleased with that, although as always I look back and can immediately see areas to improve. Paddock, Surtees, and Clearways - these were where I was making the biggest chunks of time by either changing style or being braver.

For example, with the Caterham I've always previously felt the need to give it a dab of left-foot brake to get it turned into Surtees. But I noticed most other drivers were not braking at all, so I gave that a go and just by lifting and turning in a bit more aggressively I could make the apex and carry a bundle more speed towards McLaren. With Paddock I was finding I could brake later and harder to help rotate towards the apex, but had to be careful not to lock the front right over the initial little ripples in the tarmac in the braking zone. And Clearways - she's a cruel mistress. Any time I turned in slightly too early I would run a little wide and really struggle for grip, almost running into the gravel at one point.

So all in all, a fantastic day out and a reminder that I should really do it more often! Tomorrow I'm doing Silverstone GP which will be a totally different challenge, not least because there are a lot more corners and braking areas to get right for an ultimate lap time

There's a short video with my favourite laps here: https://www.youtube.com/watch?v=jolTdf_TNE8



And just for fun, here's where I nearly binned it at Surtees

https://twitter.com/SimonHoade/statu...93388889796608

Cheers!

[Zak33]

For example, with the Caterham I've always previously felt the need to give it a dab of left-foot brake to get it turned into Surtees. But I noticed most other drivers were not braking at all, so I gave that a go and just by lifting and turning in a bit more aggressively I could make the apex and carry a bundle more speed towards McLaren.

hello stranger, welcome home

this difference between a dab of brakes and turn in and a lift off and bit more turn in are v v different for your Caterham

on your old CRX that would be a thing I reckon.. front wheel engine braking instead of front disc braking.... especially in a high revver with lots of engine braking available...

but on your current beast you''re talking different attack profile!

agressive lift off is rear axle braking and more aggresive turn in too....

care to explain why you think it worked?

[Shad]

Hi Zak, how've you been??

You know, I seem to remember with the Honda I could take Surtees flat. But it had a better on-throttle balance and was travelling at a lower speed. Caterhams will just about always generate power-understeer to varying degrees, you have to have some weight transfer to get it rotating.

I've just got home from a day at Silverstone on the GP circuit. I was having similar quandaries in terms of dealing with understeer but today I learned could drive through it with a bit more steering input and keeping the throttle pinned. With a little help from a driver coach to review my telemetry, I've discovered a whole lot more about on-power balance of the car today, as well as being much braver on the brakes to get it rotating properly into corners.

But I'll talk about that another time...

Anyway, with today's knowledge in the bank I think Surtees could actually be an even smaller lift but with a more aggressive turn in and back to full throttle sooner to help the balance. I'll have to wait until next time to give it a try.

[Butcher]

Makes me wish I had the cash to do more track days, I feel like I barely scratch the surface of what mine can do.

[Zak33]

with today's knowledge in the bank I think Surtees could actually be an even smaller lift but with a more aggressive turn in and back to full throttle sooner to help the balance. I'll have to wait until next time to give it a try.

its the aggresive turn in I don't get... I've not driven one of those fast so I have no experience on it. With most understeerers I've tracked though, yanking it into a corner hard just causes front end drift understeer.... the push on the brakes makes utter sense ... weight transfer all day long

do you think the hard turn in just scrubs off speed better than braking?

[Zak33]

I should add.....you're a quick bloke now, aren't you? I'd be well pleased with those laps in a car like that..ie a beast.

lovely gearing too...that box suits that engine.

[Shad]

its the aggresive turn in I don't get... I've not driven one of those fast so I have no experience on it. With most understeerers I've tracked though, yanking it into a corner hard just causes front end drift understeer.... the push on the brakes makes utter sense ... weight transfer all day long

do you think the hard turn in just scrubs off speed better than braking?

I agree it does seem counter-intuitive. The way I understand/feel it is the 'flick' into the turn helps to counter the power-understeer by unsettling the car ever so slightly. It's when you ease it in and let the front wash, that's when it doesn't work. You can man-handle these cars quite a bit! The fact that the flick scrubs LESS speed is where the main gain is I think.

Trail braking and creating that weight transfer makes much more sense though. One of the biggest areas I was working on at Silverstone was my braking. Looking at the data I was all too often braking hard but not for long enough, and I'd be on throttle again slightly before the apex, which generated understeer, so I'd be off throttle again to change the attitude of the car, then back to throttle. The ideal technique is to ride the brakes right into the apex, fighting the rear of the car slightly, but letting it begin to rotate so that after a brief pause with no brake or throttle, I can get back to 100% throttle straight away and stay there. On the speed trace this gives you a nice clean V shape - a W is bad!

I'll post a clip later on of both approaches.

I should add.....you're a quick bloke now, aren't you? I'd be well pleased with those laps in a car like that..ie a beast.

lovely gearing too...that box suits that engine.

Thanks I'm very happy but until it's perfect it gives me things to work on!! I think you'll enjoy the Silverstone lap too, the gearing works well there. 124mph at the end of Hangar straight, around 7500rpm in 6th

[Zak33]

I agree it does seem counter-intuitive. The way I understand/feel it is the 'flick' into the turn helps to counter the power-understeer by unsettling the car ever so slightly. It's when you ease it in and let the front wash, that's when it doesn't work.

Could it be possible it's too stiff/hard at the front?.... or maybe anti roll bars are too stiff.

If you turn in and progressively turn in more and more doesn't it load up the tyres and grip more?

I've so very little experience with this style car and tbh even on tarmac.

But if that was a rally car, the flick would of course make sense on the loose... but then it's a permanent thing. But as many rallies are on tarmac airfields, you see more and more quick rear drivers with lots of front grip.. and I am sure they don't have to force the twitch....

having said all that.. your car looks progressive, safe and you're doing bloody marvelous laps in it, so I wil now revert to what I normally say to everyone.

Dont fiddle with the car...learn to drive it....

Which is exactly what you're doing

[Shad]

I'm a big fan of 'leave it alone and drive it'. I just make sure the starting tyre pressures are good, stiffen the dampers a couple of clicks, and get on with it. Until I reach the point where I can't get anything more out of me or the car there's so little point changing anything else. That said, you are right in that the front end is a touch too stiff. There is a slightly softer front roll bar which I might try.

Here's one where I've been flicking and keeping full throttle, where as I used to be more gentle and need to lift:



It feels understeery as hell like that but with a bit more lock it DOES grip and staying on power it does basically have good balance. It's just on the cusp of what the rear tyres will suffer.

Here's a reasonable trail brake to get the car rotating:



The lighting is a bit poor (was at the end of the day) but you can just about see me dealing with a slight kick of oversteer at the apex. Feels mega

Will post the Silverstone write-up once I've done the video...

[Zak33]

the sun setting on that looks immense :-)

Goodwood, at dawn in the frost looks like that, and the thunder of rally cars makes my skin tingle