Observations from Donington

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Observations from Donington

Postby pbove » Mon May 24, 2021 6:56 am

While I would rather have been racing in race 2 at Donington, watching the race was interesting. It is clear that some of the cars are clearly not giving the driver confidence and thereby reducing the driver's competitiveness. I know I've said it before, but having a car that does exactly what you want it to do and which you know won't bite you means that you can drive closer to the limit all the time which makes a huge difference over the course of a race. It would be rude of me to comment on individual cars, but I'd be happy to share my thoughts if anyone wants to PM me about theirs.

There are, however, some common observations.

Tyres
The Yoko Radials that we use start to degrade from their first usage. While the wear markers might show them to have a lot of tread depth, this does not equate to grip. If your tyres are over a season old they will not be much use for anything except being sold on eBay. Polleysport sell good second hand tyres (as used by the PRS boys) and they are relatively inexpensive, pound for pound it is the best investment you can make to increase performance. There are only four things that stop your car from sliding off the circuit and they are the tyres.

Steering
Everyone has their own preference for steering ratio, but whatever ratio you choose (or inherit) it is important that the steering moves freely without any undue effort. Being smooth is an important part of going quickly, every driver input has an impact on vehicle dynamics and as the weight distribution changes on the car, so it reacts, the result being some kind of unsettling effect on the grip. So make sure that the steering works smoothly at all ride heights, i.e. full droop, full bump and normal ride height. While you're checking the full droop and full bump also check to se whether there is any bump steer. This is when the tracking changes as the suspension is compressed or droops and should be tuned out by slightly altering the height of where the steering arm mounts on the front upright.

While we are on steering, also check the tracking. Too much toe in will rob straight line speed, too much (or indeed any) toe out will make the car feel very "pointy" although, it can be used to good effect if you're suffering from turn in understeer.

Springs
Again, this is a matter of driver preference but it does probably have the biggest effect on vehicle dynamics. The springs need to be long enough to remain engaged with the damper all through its travel, otherwise you will pick up a wheel in roll which, at the rear, can often result in the car becoming unstable, At the less extreme end this will be a wobble and at the upper end a spin.

Spring rate needs to be hard enough to avoid the car bottoming out and after that it is a matter of choice. I have always found that the stiffer you go (up to a point), the more precise the car feels. Springs are rated at 1" compression I believe - and certainly the rate rises the more they are compressed, so if you're running 200lb springs with 2" of preload the actual rate will be significantly higher - but I can't be bothered to work out the true figure, doubtless someone else will!

Dampers
I have this last, because if you haven't fixed the tyres and steering then this won't make much of a difference!

I have found that settling up dampers is a black art, particularly when you have light cars like ours with not much damper movement. The ultimate method is lots of testing - but few of us (me particularly) have the time and budget for that. The important thing is to try to work out what the car is doing in the corners and to then make small changes to the damping and note the effect. The rule of thumb is that you should work on the end with the problem (although a change on either end will affect both) and that you should try and make one change at a time.

Also, check the damper bump stops - some that I have seen are really hard (e.g. AVO) and if the car gets on those then the spring rate will dramatically increase and you will suffer from instability. Koni make some nice compliant progressive bump stops so use those. If you're not sure how much damper movement you are using then put a small ty-wrap on the damper shaft and push it down to the bottom of the damper. It will record how much travel you use.

Driving
If you look at onboard videos you will see that the quicker drivers use very few inputs into the steering wheel, the perfect corner being one turn in on entry and one steering release on corner exit - Lewis Hamilton shows this to good effect. If you see multiple inputs it is typically, because the car is not doing what the driver wants or he is over driving. Having to increase the lock is a sign of understeer, having turn in followed by a turn out and another turn in is a sign of oversteer, and so it goes on.

As you are driving a lap think about four phases of the corner, braking, turn in, at the apex and corner exit and think about what the car is doing in each phase. If this is difficult over a whole lap (and it will be) try to think about which corner feels the worst and concentrate on that one. As you get better at thinking this through then you'll start to think about what you're doing and how it is affecting the car, for example, it feels good in corners where I brake hard and turn in, but washes out in the corners where I only need a slight lift, etc. If you're not able to remember any of this as you're driving round have a look at your onboard video for any of the traits described above, it is surprising how much you can glean from the onboard.

Well done for getting this far, apologies for teaching my grandma, etc. but I hope you found something here that might be helpful.
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Re: Observations from Donington

Postby Martin Kemp » Mon May 24, 2021 10:55 am

Well done Peter.
I would add:
Check that the suspension doesn't bottom out in roll. The end in question will suddenly lose grip if it does.
Check the alignment of the rear wheels. I have come across some surprisingly bent axles. They are not as sturdy as they look.

Carrol Smith published a very handy little flip chart for analysing handling problems called " The Engineer in your Pocket", which is still available.
All his books are worth reading and you don't have to be an engineer to understand them.

Martin
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Re: Observations from Donington

Postby suebmick » Tue May 25, 2021 11:22 am

Good post Peter. You rarely get the chance to watch! It is interesting isn't it!

But I have to say that now we all have to have cameras & they must show the drivers' hands, it IS invaluable. Your driving style affects the car's handling. Much to my embarrassment & amazement I have been teaching Granny to suck eggs based on my own lessons from one of the greats of F1, Tony Trimmer, when I was in my prime & far too long ago for me to disclose!! My Darvi is very very different to any other Darvi that Maestro has ever driven in his decades of winning. The once-winner of Class B is teaching the 10-times Champion how to drive MY car. Believe it or not, it seems to be working!

Sue
Last edited by suebmick on Tue May 25, 2021 4:42 pm, edited 1 time in total.
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Re: Observations from Donington

Postby pbove » Tue May 25, 2021 12:55 pm

suebmick wrote:Good post Peter. You rarely get the chance to watch! It is interesting isn't it!

But I have to say that now we all have to have cameras & they must show the drivers' hands, it IS invaluable. Your driving style affects the car's handling. Much to my embarrassment & amazement I have been teaching Granny to suck eggs based on my own lessons from one of the greats of F1, Tony Trimmer, when I was in my prime & far too long ago for me to disclose!! My Darvi is very very different to any other Darvi that Maestro has ever driven in his decades of winning. The once-winner of Class B is teaching the 10-times Champion how to drive MY car. Believe it or not, it seems to be working! And I'm not going to tell any of you Tony's secrets!!

Sue

Not really in the spirit of my original post then Sue...... :roll:
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Re: Observations from Donington

Postby suebmick » Tue May 25, 2021 3:43 pm

True
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Re: Observations from Donington

Postby dopdog » Wed May 26, 2021 9:31 pm

Yes a good read Peter. I for one can confirm that testing is the most important part of car prep. Im sure you will all be surprised to hear but for the first time (and for many reasons) i did not test my car at all before Donny and as such ended up in the wall, on the grass and going backwards a lot. All of Peters comments are spot on and the next time you see me it will be with a car I am 100% comfortable with :?
As Sue said welcome to the formula :lol:
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Re: Observations from Donington

Postby F1300Tony » Thu May 27, 2021 11:08 am

All good stuff.
The only thing I would add is that it is worth lap time to get yourself a comfortable but tight fit in the car. That is not just the seat, but everything from the headrest, the gear lever position to the heal bar and pedals.
If you do all the races but no testing you will drive the car hard for a total of 4.5 hours in a year. In any other amateur sport you could expect to participate or practise at least 3 hours a week. I think that explains why people take a long time to get quicker and why it takes time to get back to speed after a year off.
Of the drivers I have worked with several were incapable of feeding back any useful information of what the car was doing, even though they were quick. If that is the case then changes will have to made on lap time or get someone else to test the car.
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