UKGPL Season 22 F2 Club Challenge - Snetterton - May 18

[bernie]

first thing is to congratulate John on his set ups and thank him for a job well done

Straight off I noticed  the understeer ( you could hardly fail ) I thought this was a product of the diff (all them clutches ) so tried a 45/60/2 which helped ,  then started playing with ARB's and tyre pressures so it felt better yet (to my style) but the lap times where about the same as before , though a slight improvement 

My cocnclusion was that I was now losing time gained in corner exit speed in straight line acceleration,  which is what 5 clutches gives you (spool axle) hence the question about short shifting to reduce wheelspin with a loose diff ?

maybe I should try shorter gears as well , I didnt have much time in qually and had no time spare to practise off line so hopefully will improve as the series progresses (along with everyone else) 

 

[john roberts]

My cocnclusion was that I was now losing time gained in corner exit speed in straight line acceleration,  which is what 5 clutches gives you (spool axle) hence the question about short shifting to reduce wheelspin with a loose diff ?

i think you have a misunderstanding how the clutches work , it's not the number but how they work with the ramp angles .

a 85/85/6 will have more friction than a 70/70/1

for more info on friction you could take a look at the graphs that somebody made here ..

http://srmz.net/index.php?s=6df2a4cde3b7c759e88404b614704db5&showtopic=6141&st=0&p=52295&#entry52295

john

[EvilClive]

hmmmmm.

Well I found default setups did not suit me at all...sorry John 

So yes, I changed springs..shocks...rollbars....gearbox...diff...clutches.....brake balance and steering ratio.

Of the cars I have tried so far .. Lola FVA, Mclaren, Lola BMW and Protos... they all seem pretty similar with only minor differences in setup. The exception so far, being the Protos which I find does not settle into the corners like the others, but I am still playing with the setup on that one so that migt improve.

My aim in building a setup, is to get the car to do what I expect it to do and not give me any nasty surprises like snap oversteer mid corner or locked brakes and no turn in at the end of the straight. I still have not fully mastered or understood how all the parameters in GPL interact, but I am gradually able to find the adjustment I need to correct a given problem.

One useful thing I have found is that sometimes when you have a car that insists on swinging the rear end around in a corner, it is not always a case of trying increase the grip on the rear axle. Instead I often work on reducing the grip/bite at the front, thereby removing the "pivot point" for the car to work around. The ass cannot sweep around if the front wheel does not give it a lever to work against...simples..maybe

[john roberts]

The exception so far, being the Protos which I find does not settle into the corners like the others, but I am still playing with the setup on that one so that migt improve.

well the protos is made of wood , so i guess your setup tricks woodn't (gettit ! wouldn't) work .

john

[Billy Nobrakes]

Bernie,
I struggled with the default - so I ended up building a set up by trial & error which seems to work for all the F2 cars I have driven. It's very different from the default & also quite different from my base set-up for a 65 or a 67.
If you PM me with an e-mail address I can send you my set up for Snetterton.

[EvilClive]

I'm not sure if your offer was aimed at me Billy, thanks for the offer but I have found no probs in getting the cars to behave. All have responded to my setup mods well, except for the Protos thus far.

 It does seem that the same setup will work for many of the F2 cars with just minor tweaks. I am grateful that this fun series allows us to try all the cars and compare ourselves against real competition.  Until now I have not really found the time to really experiment with these cars....so thanks Axel.

[Cookie]

well the protos is made of wood , so i guess your setup tricks woodn't (gettit ! wouldn't) work .

john

John,
So I do understand that the torsion of the Protos chasis is more than all other cars?

 

[1967driver]

Why dont post your setup ?
It's interesting for all, imho.

[Billy Nobrakes]

Clive,
My post was adressed to Bernie, per his request. Based on your performance at Outlon maybe we need to give you a different set up to slow you down a bit.
Alex - not sure how to go about posting a set up?

BTW - the Protos was an absolutle pig to set up. The handling is very different from the other cars.

[john roberts]

It does seem that the same setup will work for many of the F2 cars with just minor tweaks.

well most of the cars are very similar with weight distribution , weight and power ( most have the same engine ) , from the heaviest to the lightest the difference is only 16kg ( 67 is 125kg and 65mod 30kg ).

john

[1967driver]

Alex - not sure how to go about posting a set up?

I'm not at home now, but you can try this old site to easy obtain a publishable setup:
http://www.gplsc.net/gplsc/compare.jsp

[Cookie]

Try this Johnny Ackermann setups for Goodwood!
They are very driveable for me...

But on SRMZ! Bernie, do you still have problems with it?

[bernie]

i think you have a misunderstanding how the clutches work , it's not the number but how they work with the ramp angles .

a 85/85/6 will have more friction than a 70/70/1

Well im no expert by a long means but from what I understand you are saying that a diff with 6 clutches has more friction (i.e. more effort required to turn one rear axle before the other axle turns  ) than a diff with 1 clutch which will allow one axle to almost spin freely regardless of the other ) Or we could say 6 clutches is closer to a solid rear axle 1 clutch almost likend to a free axle ?

If we accelerate in a straight line a locked diff is always better for getting the power to both wheels because it will not allow one wheel to spin freely which is what it would do if say one wheel hit a bump and became disconnected from the road surface .

Thus losing forward momentum .

Unfortunatley a locked diff is usless in a corner because the outside wheel has to turn faster than the inside wheel , or the inside wheel (being less loaded ) will spin , losing traction , also it wants to push the car straight on (understeer )

I have seen the graphs and read the books (too many) but quite how the differential gear ramp angles work with the clutches is a whole black art to me . I thought they were used to  determine the responce time of the "bite" between the clutches

Billy[/u]

thanks I will try your set ups and anyone elses for that matter , however i always end up using my own because I think we all drive very differently (look at Clive for god's sake )

Axel

thanks for the link I have recently settled my difference with SRMZ

Any one else , your feedback is very welcome , please keep it coming   

[Cookie]

Hi Bernie,

For me those ramp angles are also some strange numbers...

The easiest way to understand a Differential is the percentage of locking!

In the Setup Manager that comes with GEM, there is allways shown the locking percentage besides the ramp angles checkbox.
By adding clutches you raise the percentage of locking

[john roberts]

Well im no expert by a long means but from what I understand you are saying that a diff with 6 clutches has more friction (i.e. more effort required to turn one rear axle before the other axle turns  ) than a diff with 1 clutch which will allow one axle to almost spin freely regardless of the other ) Or we could say 6 clutches is closer to a solid rear axle 1 clutch almost likend to a free axle ?

no thats not what i'm saying ... what i'm saying is that you cannot say by the number of clutches only ! you have to see what the ramp angles are (as cookie is also saying) .

if you use setup manger or look at both graphs found here

http://srmz.net/index.php?s=6df2a4cde3b7c759e88404b614704db5&showtopic=6141&st=0&p=52295&#entry52295

everything should become clear .

john