What is really the problem using a beetle as a drag racer?

[Stripped66]

What do you consider inappropiate driver input or overreaction?

Inappropriate input would be steering input when no steering input is necessary, and overreaction would be more steering input than necessary in reaction to the situation.

The steering wheel simply takes movements of a lever-system (our limbs) and restrains it to circular motion. The total input to the steering is a function of the angular movement of the joints in our arm and the inverse of the diameter of the wheel. And, while a drag race is not a slalom, how many crashes are related to too much steering input? Do we simply say, "he got out of the groove" and we think no more? How do you get out of the groove? Why couldn't you get back into the groove as easily as you got out of it? The fact of the matter is VW drag racers often put cars into the wall at speeds slower than where aerodynamic issues would otherwise come into play; I'd argue that some of these crashes are linked to steering inputs, and that at much higher speeds where aerodynamics contribute to upsetting the stability of the car, steering inputs are even more important. All I'm pointing out with the steering wheel size is it's ability to amplify the movements of the driver and contribute to an overreaction. If there's not a happy medium then you can postulate to use the smallest steering wheel possible.

[Jon]

I read somewhere that if you wanted a circuit racing car to become more stable (when it comes to cornering) one could lengthen the wheelbase, as the stability is the result of the relationship between length and axle width. (as I read it)
Now we usually don't want to make our bugs longer than they are, but if you go with a narrower axle width you should gain the same...??  Think of those small Mazdas and starlets....  not long... but very narrow.
I just thought it was interesting...

[Fasterbrit]

The low speed crashes are more often than not directly related to the steering toe changes and steering input from the driver. As mentioned  earlier, a stock Vw steering setup experiences EXTREME toe in and toe out at launch and when shifting gears. And wheelies? Absolutely massive toe change. A driver often tries to correct steering in a split second based on an input from the steering wheel which is in a perpetual state of flux. That's why they often end up on their roof inexplicably and only just passed the sixty foot... Driver error based on incorrect feedback from the steering. A lose - lose situation that is easily remedied by the Pro-Stock type steering.

Sort out the steering on your racecars, then address the aerodynamic issue present above 125 mph on Sedans and then, as Martin experienced, you can drive thru the top end at 150 mph with one hand on the wheel.

[Shag55]

Very good reading guys. Can't want to see what everyone comes up with. New times, new ideas = changes for the better I hope!

[Martin]

Very good reading guys. Can't want to see what everyone comes up with. New times, new ideas = changes for the better I hope!

I think that's the Idea really, to make the VW world a lot safer place.

There are so many suspension dynamics and aero dynamics we are trying to understand and equate into a better, safer car.

I think a lot of people are not looking at the basics first, how many out there has actually made/used a bump steer gauge to measure the bump steer in the front ends over its suspension travel? and have you considered how much travel you might need down the track?

I also think there is no best rear suspension, just one set up correctly.  eg red baron - swing axle hitting 170mph+,  Hater maker - irs also hitting 170mph+ so i don't feel theres and argument for ether, just what your more comfortable with.

Personally I'm willing to put my finding out there for the benefit of the VW world that Ive grown up in. I don't get as many runs in as some, but i acquire more data in 1 run than most get in a year.

Speaking out loud, i feel that if a car has gone through all the BASIC suspension setups and there is no bump steer, and the Castor, camber and toe for all 4 wheels is correct and the car gets the power down in the 60' and is happy in the 1/8 (120mph+) then after all that its getting fucked up past that point you really need to be looking at the aero side of things. as them forces can be massive (who has stuck there head up past the windscreen on a bike at 150mph +? there will be a few of you )


As ever guys, we just want fast / Safe VW's out there.


Martin

[Andy Sykes]

This is great info for me building my car so thanks for that, what would be the good attributes of a front air dam

Cheers andy

[Martin]

This is great info for me building my car so thanks for that, what would be the good attributes of a front air dam

Cheers andy

You want to try and stop as much air from getting under the car as posible, but if your racing MSA then take a look at the rule book as there is a limit to how low you can be, i think (looking towards Jim Smith) its 3"

Martin

[Berger]

I think Tor Oyvinds achievements this weekend, 8,02 and 281km/h is a good reason to bring this topic up again!

The new wing seams to work well, and I am pretty sure it is because of it`s high position, actually working where the air leaves the roof breaking the wing effect.
Also worth noticing is that this car does not have a raised tranny and much closer to stock ride height that any other beetle racing in the eights.



<a href="http://www.youtube.com/v/SVKvNhbfbi4" target="_blank">http://www.youtube.com/v/SVKvNhbfbi4</a>

[BeetleBug]

I talked to Skinne about the new wing at Kjula and he told me that they noticed that the car started to lift the rear after mounting the front splitter. That was the reason for mounting the new wing, to increase the down force. Also worth noticing is that the driver did not pull the brake chute after crossing the finish line.

-BB-

[Jon]

I'm having a good time reading Herb Adams Chassis Design book in the evenings. It has a good section on IRS rear ends, and according to that, on a IRS car the laderbar/fourlink would handle only 25% of the force that an normal live axle would see.
But on a 1000hp car that is still 250hp! The book is a great read on many other topics as well, even if most of the information is about circuit racing. 
 

[Airspeed]

, even if most of the information is about circuit racing. 
 

Which book is that again? 

Kalle, the pic you took of Skinne's rear end is probably somewhat exaggerated by the wide angle lens and close-up standpoint?

[BeetleBug]

Kalle, the pic you took of Skinne's rear end is probably somewhat exaggerated by the wide angle lens and close-up standpoint?

Nope Walter, no such fancy thing. I´m standing 2 meters from the car with a simple Sony camera.

Here is the builder and the tuner standing next to the car in the staging lanes:



Behind them is the Volvo that won the 4to6 class with a 7.62 run on a 7.60 break out. Basically a HUGE Holset HX80 with a Volvo wrapped around it.

And the front splitter:



Best rgs
BB

[Airspeed]

Tnx mate, excellent pics and your right, that is a HUGE wing from all standpoints!

[richie]

I think Tor Oyvinds achievements this weekend, 8,02 and 281km/h is a good reason to bring this topic up again!

The new wing seams to work well, and I am pretty sure it is because of it`s high position, actually working where the air leaves the roof breaking the wing effect.
Also worth noticing is that this car does not have a raised tranny and much closer to stock ride height that any other beetle racing in the eights.



<a href="http://www.youtube.com/v/SVKvNhbfbi4" target="_blank">http://www.youtube.com/v/SVKvNhbfbi4</a>

Looking at that picture to me it seems that the width of the wing proberly helps as much,if not more than the height as there is so much of it out in relatively clean air,particularly the spill plates being right out there.

Raised trans is only really a swingaxle thing anyway,IRS doesnt need it in the same way,when you lower the swingaxle springplates the wheels go into horrible negative camber,raising the trans helps cure this..
Now there center of gravity must be alot higher than most quick cars I agree,my old cab doesnt have a raised trans or torsion raise etc so will suffer similarly,its nearly time to drag it back out again,as someone wrote to me and told me after the success of this car this weekend


"put too much power to a factory IRS car and see what happens"   sounds like a good plan to me

[Russell]

wow that front spliter is low.....

[Eddie DVK]

I think the wing and splitter on skinnes car sure helps it to "keep" it on the ground for his new record, but what amasses me is, this is a heavy almost all steel car... So is it not that this weight is helping it to keep it on the ground.....
Now days there is a lot more powerfull engines, and we keep trying to save a lot of weight, for better power to weight ratio,
maybe to much weight?

just a thought.

[Patte]

After a long summer of no racing i have decided to make some changes to the Fasty making it steadier at speed(i hope) 

This thread has brought out some really good input from experienced drivers and after  seeing what Skinne has done to
make the beetle not to be all over the track, i think i will do a little bit of everything to make it fun to drive at 150+mph again 

I have increased the caster angle to 10 degrees.
Changed the steeringwheel from a 12" to a 14".
Making a frontspoiler/splitter.
Mounting an adjustable  roofwing in combination with my rearwing or a 2plane wing on the engine lid.
Make a serious attempt to make the clutchless shifting work.
Move the lever for the chute so i don't have to take my eyes off the track to  see it 
Take care of the small bumpsteer i have.
Move the turbo and IC forward.
Add some bars at the rear

I have probably forgotten a few things 

[Berger]

Will be good to see you racing agian Patte!

Stian "Tekken" had some good arguments for having all the wheels (especially the rear) at zero degree to-in. If he is on this tread he might explain, I`m not so good at referring this in english. Anyway, it might be worth looking into also.

Good luck with the changes

[Airspeed]

Stian "Tekken" had some good arguments for having all the wheels (especially the rear) at zero degree to-in.

I could understand the reasoning behind that. But...static alignment means 'nothing' as opposed to what happens when the car 'digs in' on the launch and on acceleration.
Seeing what happens to toe when the suspension moves up and down could be whats most interesting.
Maybe making the suspension keeping its set toe angle at the full suspension arc is what matters?

[Berger]

Stian "Tekken" had some good arguments for having all the wheels (especially the rear) at zero degree to-in.

I could understand the reasoning behind that. But...static alignment means 'nothing' as opposed to what happens when the car 'digs in' on the launch and on acceleration.
Seeing what happens to toe when the suspension moves up and down could be whats most interesting.
Maybe making the suspension keeping its set toe angle at the full suspension arc is what matters?

What matters as I understand is to have zero to-in at high speed. Reason for this is the high traction the slicks have, and to-in makes them sideways unstable. Hard to explain, sorry my vocabulary is to bad.....Richie, help?!?

[tikimadness]

Stian "Tekken" had some good arguments for having all the wheels (especially the rear) at zero degree to-in.

I could understand the reasoning behind that. But...static alignment means 'nothing' as opposed to what happens when the car 'digs in' on the launch and on acceleration.
Seeing what happens to toe when the suspension moves up and down could be whats most interesting.
Maybe making the suspension keeping its set toe angle at the full suspension arc is what matters?

What matters as I understand is to have zero to-in at high speed. Reason for this is the high traction the slicks have, and to-in makes them sideways unstable. Hard to explain, sorry my vocabulary is to bad.....Richie, help?!?

You're on your own now Berger Richie is all alone in bitburg right now
Thanks for that info, really thought that toe-in was the way to go. Putting it on zero now.


Michael

[Ragtop]

I run zero at the rear and 1 degree toe in at the front.

[Patte]

Will be good to see you racing agian Patte!

Stian "Tekken" had some good arguments for having all the wheels (especially the rear) at zero degree to-in. If he is on this tread he might explain, I`m not so good at referring this in english. Anyway, it might be worth looking into also.

Good luck with the changes

Thanks 

I run zero toe-in at the rear and 1mm in the front.
With the IRS ladderbar design i use there is no changes in the toe-in when it moves up and down,but under load i have no idea what happens   
It probably is a lot of toe-in at takeoff

[Fasterbrit]

I run zero toe at front and zero rear. Car always went nice and straight.

One thing you guys really need to do stop drastic rear toe change is to tie the torsion bar housing into the roll cage in at least three axis
If you ever get a chance to see a floorpan separated from a body, push the torsion housing with your foot. See how it flexes badly. Now imagine the only thing holding it is a piece of 18 guage steel where it attaches to the body them picture what 200+ horsepower is going to do in terms of flex... All that flex = toe change and a car that 'rear steers'.   

Sorting the front end so that it zero toe changes over full up and down movement is much more simple. Do away with the twin steering arm setup from the steering box and run a single rose jointed tube from the steering box to the farthest spindle then link the two spindles with a rose jointed tube. This is a popular mod in the US, though strangely not here in Europe. I will say it one more time then I'll shut up for good as I'm probably boring the piss out of you guys... Do this mod, you will never look back

[JamieL]

good point well made. 

[Jyrki]

I trust everyone that zero toe-in is good (or best).
In the '65 street car I had very little (maybe 1mm) toe-in in rear, and 2-3mm toe-in in front. Torsion bar housing was tied to roll-cage, then later moved on to ladder bars. With the ladder bars it went straight, was very easy to drive and felt safe at 230+km/h.
Jyrki

[Airspeed]

One thing you guys really need to do stop drastic rear toe change is to tie the torsion bar housing into the roll cage in at least three axis
If you ever get a chance to see a floorpan separated from a body, push the torsion housing with your foot. See how it flexes badly. Now imagine the only thing holding it is a piece of 18 guage steel where it attaches to the body them picture what 200+ horsepower is going to do in terms of flex... All that flex = toe change and a car that 'rear steers'.   

Good point Matt! I never thought about it that way.
Would running torsion bars be any different then running coil-overs with IRS in ^^ that respect?

[Andy Sykes]

I would think it would mark no difference weather you run run torsion bars or not the force on launch will be the same on the torsion tube
IRS may spread the load though down the tunnel
Cheers andy

[Fasterbrit]

Like Andy says, if you put load onto the torsion tube - whether it be thru torsion bars or IRS points - it will still flex unless supported.

I am glad that Skinne's car has awakened people's interest in aerodynamics, I was beginning to think I was flogging a dead horse on here with my own personal experience. Play it safe folks, a standard VW sedan will start to take off at speeds around and above 125 mph. this is serious stuff, not to be taken lightly. Martin Taylor's data should also be studied and accepted as hard evidence as to what happens to a Bug's rear end at speed without a wing and then with a wing. Read his post several pages back. Very
Educational.

It's a shame that Richie's cab doesn't fall into the same aerodynamic category as the rest of our cars, as data and results from aerodynamic aids on his car would be interesting juxtaposed against a Sedan's. However, the two shapes are poles apart so comparing a cabrio with a Sedan is like comparing apples and oranges. Still would be interesting to hear Richie's aerodynamic results from any mods. Rich, you have any info you can share?

Cheers, Matt

[Lids]

Matt, richie has a bloody big wing on his car already, he pretends its his hood