How do you set up a tube chassis drag beetle?

[PLATINUMVW]

Hi everyone, we've been following Cal-look Lounge for about 6 months and from it we recently bought Andreas Abergs tube chassis “Herbie” Drag Beetle from Sweden which we have now shipped downunder to Auckland, New Zealand.

The car is fantastic and beautifully built and we are very happy with it. It had run a best of 10.19 during 2012 in Sweden.

To date we have run it at one local IHRA 1/8 mile competition event doing four passes on a prepped track.

We are running the car basically as Andreas had it setup only doing a minor wheel alignment on the rear to give a ½ degree toe in each side and not running full rpm (as a precaution while we are getting used to the car). Same tyre pressures and fuel etc

With just 2 more ¼ mile competition events (5 days total) this season we will just be playing with tuning and gaining experience behind the wheel as any alterations would probably just be counter productive at this early stage. We estimate 20-25 more passes.

During our off season we will dyno the engine as it is, so we know what we started with and then strip it for a rebuild and re dyno for comparison with different clutch/flywheel setup and alternator/vacum system. We'll also build a new gearbox and install a MSE shifter setup, rebuild the front and rear struts, replace all steering joints, maybe new rear slicks?, plus other general maintenance.

So we have no problems coping with the mechanics of the car and sorting out wheel alignments etc. Our potential problems relate to experience or “lack of” with a tube chassis. There are no other cars like this in New Zealand! So we are very much on our own!

Our general question for the forum is how aspects of a tube chassis inter relate and what is more important to pursue or experiment with for the best results? We appreciate that for all we know the chassis setup maybe perfect (“If it ain't broke don't fix it”) but we're keen to try and improve with the goal of a 9.9 - 9.99 second pass coming from mechanical modifications and chassis setup.

I suppose in short how does the Ladder bar height, Struts, Springs, Tyre pressure, Wheel alignment and Wheelie bar all inter relate to get the best results
Impossible question we know but where would you start?

The other thing we are curious about is that it has 46kg of added weight up front. Would this normally be for a weight regulation or just balance?  Would improving the rear setup (if possible) allow us to remove some of this weight from the front?  From memory the car weighs 583kg.

lastly, Is a one metre wheelstand to high? Seems to be how high it gets.

Really looking forward to the thoughts of the group.

This YouTube link is of our second run ever in the car. License run for IHRA license. Don't worry about the start it helps if you turn the fuel pump on  http://youtu.be/i4P8zpdcJk0

Thanks in advance, Nigel

[richie]

How much tow did it have when you got it? it sounds like you need that weight at the front for sure,its going to wheelie a hole lot more without it,  I did corner weight that car in norway last year and it was pretty good from what I remember.
Wheelie bar height & flex along with clutch set up will help cure the wheel stands,and if you are not running full launch rpm it is more likely to "bog" wheelie, as the clutch comes out it drops to low in the rpm and bogs and the clutch doesnt slip then as it comes back onto the power it climbs up until it hits the wheelie bars

I am going to PM you will some more info I can offer, but a light car like that will be very sensitive to any changes so try not to make too many at one time

cheers richie

[PLATINUMVW]

Hi Richie.
I'll have to check my notes at work that list what we started with and altered to. I know we adjusted the toe and camber on the right hand side mainly as it visually looked very wrong plus we were not sure how it had been tied down in the shipping container. For all we know it may have been tied down and hooked around an A Arm?  It wheel stood nice and straight off the line and at 100MPH felt good.
Thanks for the advise on the launch. I'll let you know tomorrow what RPMs we have set. From memory I think we set it at 6,500 or 7,000 launch with Max RPM of 8,000. We were trying to be conservative as we didn't want any damage first time out. One thing we did learn on our first runs it that you can't really drive it to conservatively, it needs to be driven firmly almost in anger for it to "work"
We will corner weigh the car next week at the competition meet we are going to.
Don't worry about us altering things radically. We would prefer to alter nothing unless we have a good understanding of what we were trying to achieve. There will be no random changes for changes sake hopefully just carefully considered alterations hence my questions here.
Cheers Nigel

[richie]

I was just thinking that it would need the cornerweights checked, cornerweighting is good,as it now has a different driver it is most likely to need a little adjustment

cheers richie

[PLATINUMVW]

Checked today and had basically just changed the camber on the right hand rear wheel.
Lowered our wheelie bar a little bit today getting ready for the weekend. We'll try a run or two with it a bit lower and see what happens.