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

[Fastbrit]

Keith,

as I am not totally sure of what affect what changes  what affect on a 4 link car as in relation to bar angles can you tell me how you would set it up for ultimate ET with say twice the hp you had back then? oh and so as not to crash

i am reading "Doorslammers,The chassis book" by Dave Morgan at the moment to try and learn more but it is making my head hurt   I am much better at understanding by trying things and seeing what happens than by theory


cheers richie

Easy - drive more slowly! Oh, and post on Internet forums a lot – that always seems to make cars go faster! 

(PS – I'd start by running the bars parallel so you can optimise shock settings...).

I remember reading that book, too. Shares in Ibroprufen went up sharply.

[Jon]

Cheers all for listening to the ramblings of an old git.

Thanks for elaborating for us Keith! I think I also like the long bars your car had, do you remember if they ended in front of the center of gravity? Any thoughts on this
Just one thing, that is a swing gearbox used for mockup, right?

[Patte]

Keith i didnt say that a fourlink dont work on a vw,my point is that we can not use it the way it was design for,setting the pinionangle etc.

Who says in what way a four-link should be used? Four link technology has been used on all kinds of cars for many years – look at every Grand Prix car in the 1960s and early '70s – they all ran four-link at the back. More than anything it's a simple way to offer a no-bind, yet adjustable, way to locate the rear wheels/hubs. That a V8 live-axle car can then use it to adjust pinion angle is a bonus but not necessarily the whole raison d'etre behind the four link. Just my 2c.


Cheers all for listening to the ramblings of an old git.

Good point Keith ,there are more ways to use a fourlink than just to dragrace 

But there is still the problem with the power that lifts the whole chassis when its transmitted thru the
solid mounted tranny but with a live axle it plants the tires to the track trying to lift the chassis making it a diffrent ballgame
adjusting it with shocks and springs,instant centre,bodyroll,antirollbars.
Im probably way off in my thoughts on the matter but thats the way i see it 

//Patte

[Patte]

I think that another big issue is the need for heavy springs and shocks we need to handle
the launches,making it to stiff when we go down the track and making the tires take most of
the hits when it becomes a bit bouncy.
The V8 promods uses electronic shocks to adress this problem,setting them stiff at the start
and looser down the track.Expensive? yes, but maybe worth it

//Patte

[SteveW]

I had a chat with Chris Isaacs a couple of years ago when I first thought about building custom IRS A Arms. If we had gone down the chassis car route we would have gone 4 link IRS but we were restricted with the design being a pan car. There was an interesting thread over on UAC about rear ends which I sent Chris, I can't seem to find the other emails I had but I think this one relates most to the adjustment of the 4 link bars and what happens..

"Hi Steve, very interesting thread.  As you say, similar to what we discussed, and I like the idea of the adjustable height front mounting points.  The relevant bit on this thread is, as we were saying, that an independent suspension setup does not react engine torque through the chassis in the same way that a live axle car does.  The 'pitch rotation' which happens on a live axle car is determined by Newton's Second Law,  the 'equal and opposite reaction', whereby the drive torque rotating the ring gear 'forwards' also causes the pinion gear to 'climb up' the ring gear (due to the resistance of the vehicle mass to moving forwards in response to the ring gear rotation), thus rotating the axle housing rearwards and thus rotating the chassis through the suspension links.  (Hope you got all that!).
 
Now... with an independent suspension, the ring and pinion gear is not solidly mounted to the suspension links via a solid axle case, therefore this rearward rotation is reacted to the chassis via the transaxle case, not the suspension links (as someone correctly pointed out on the thread you sent me).  Also, with a VW which has a 'reverse' engine, ie the front of the engine faces rearwards, but which runs in the conventional direction, the pinion gear actually tries to climb DOWN the ring gear, not up (hope you got all that too!).  This will make the car squat, not lift, due to torque reaction.
 
However, as the car moves forwards (via the thrust of the rear wheels) the hub carriers and suspension links are what is pushing the mass of the vehicle forwards through the chassis mounting points, and the position of those links determines how the chassis reacts.  If those chassis mounting points are REAL high, it is easy to imagine how the rear wheels would try to 'drive underneath' the chassis, thus lifting the rear of the car, the reverse would be true with a low mounting point.  Therefore, having for example a three- or five-hole vertical adjustment for the arm chassis mounts, with the centre hole at standard height, would give the facility to tune the system for the optimum performance.
 
Interesting stuff!  I'm sure a setup like that could be done fairly easily, and give you your narrowed hub width as well.
 
Cheers, Chris"

This is a really interesting topic, for me I think the thing i'd most like to see is some wind tunnel testing or even some CAD fluid dynamics results. There are numerous chassis designs that one person will swear by and the next person will swear by another but for the most part the basic shape of the body has stayed the same. All chassis types have crashed so for me personally if I had the money I would love to stick it in a wind tunnel!

[Jon]

Also, with a VW which has a 'reverse' engine, ie the front of the engine faces rearwards, but which runs in the conventional direction, the pinion gear actually tries to climb DOWN the ring gear, not up

I'm pretty sure this is wrong? Our engine turns clockwise so when the ring gear stays put, the pinion climbs up!  But anyway,s a brilliant piece of information there Steve!


Found this on pinion angles:
"Pinion angle is a term I hear tossed about as some sort of magic incantation quite often. Let’s dispel the myth.

Pinion angle in and of itself does not affect the way a car launches. A change in pinion angle does change the angle of the four link or ladder bar brackets on the rear axle housing. So a change in pinion angle will change the angle of push and pull on your rear suspension components, but, and this is the important part, we do not want to use pinion angle as a rear suspension tuning aid."

http://www.jimobalek.com/pinion-angle/

Patte, that live axle subframe approach looks promising 

[Neil Davies]

And you never will again on my car,its going in the bin        

There are some things that apparently I cant say on the internet


Version 2 should be ready for SCC

Fair enough! At least you thought about it and tried it rather than just dismissing it out of hand. I'd like to see what you're trying next - I won't be at SCC but I'm trying to get to the rest of this season's events at Shakey - are you going to any of them?

[Udo]

Hope to see you at the august open nat. ?

Udo

[richie]

Hope to see you at the august open nat. ?

Udo

If it works I will be racing at the open nationals in august    if not I maybe looking for another cabrio body


Neil it wasnt my design or manufacture   I just tried to make it work,got to stop now before i type something I am not allo

[Fasterbrit]

Yet, like your four link, the wing also seems to be cast aside and given only passing consideration.

Matt, Ricihe wrote something about your car being nervous at the same speeds as other bugs without wings are still stable. If that is true, how can a lacking wing be the source of your problems? With all due respect!
If going middle eights and sevens are going to be done *safely* the setting out point must be as good as possible before fitting the wing... of course the wing is needed to do the numbers no doubt about that.

Why is it we feel the need to re-write the rules on how a Bug should or shouldn't work when there are already cars out there proving the point?

Jhu... I think it's difficult to compare my car too closely to others because I believe the problem of stability at the rear was exaggerated on my car because of the extra weight it carries at the rear. The wasserboxer is very heavy, I have a water radiator at the rear carrying 11 L of h2o. The 915 tranny is 20kg heavier than a bug box, 930 Cvs, huge turbo, big water filled intercooler... It all adds up. Cheers, Matt

[leec]

A car being currently built in USA by a lesser known chassis build[no offence Doug ] were they are not following the "monkey see,monkey do" path followed by so many,will be intersting to see how it all works,

then how to get the weight bias nearer a front engined car by the quickest and fastest vw style car around

The Stance on the hater maker is fantastic. Who built that chassis?

Lee

[Rick Meredith]

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I'm not a drag racer but this is one of the best threads I've read here in a while

[richie]

A car being currently built in USA by a lesser known chassis build[no offence Doug ] were they are not following the "monkey see,monkey do" path followed by so many,will be intersting to see how it all works,

then how to get the weight bias nearer a front engined car by the quickest and fastest vw style car around

The Stance on the hater maker is fantastic. Who built that chassis?

Lee

Its an older chassis that crashed a while ago,Kris repaired and updated it,and added his own suspension

[richie]

Yet, like your four link, the wing also seems to be cast aside and given only passing consideration.

Matt, Ricihe wrote something about your car being nervous at the same speeds as other bugs without wings are still stable. If that is true, how can a lacking wing be the source of your problems? With all due respect!
If going middle eights and sevens are going to be done *safely* the setting out point must be as good as possible before fitting the wing... of course the wing is needed to do the numbers no doubt about that.

Why is it we feel the need to re-write the rules on how a Bug should or shouldn't work when there are already cars out there proving the point?

Jhu... I think it's difficult to compare my car too closely to others because I believe the problem of stability at the rear was exaggerated on my car because of the extra weight it carries at the rear. The wasserboxer is very heavy, I have a water radiator at the rear carrying 11 L of h2o. The 915 tranny is 20kg heavier than a bug box, 930 Cvs, huge turbo, big water filled intercooler... It all adds up. Cheers, Matt

Turbo is over gearbox correct?intercooler tank is at the front? just trying to get it clear in my head as to the layout,I am sure we can get rid of that wing

I don't have the corner weight info to hand, but the car weighs 255kg up front and 482kg at the rear. It's got a fat ass!

I make that 34/66 weight bias,not good but not that bad,its a shame its up for sale,would be interesting to see how it reacted to adding weight to the front

Back to the subject:

we can add weight to the front to help,but what if we can make the front create the downforce on the front end to give the same effect as adding the weight but without the negative of the weight on the startline,that was one of my main thoughts on the aero thread


cheers richie

[Berger]

If the car wants to go up in the start, then it want to go up down the track as well, and as speed gets higher, the wing shape helps the "want to go up" attitude. So breaking the wing shape and making the the suspension push the car forward only, not up, I think is the key elements.

[Ragtop]

My car weighed 780 kg with the old turbo setup , the new is about 11 kg lighter. I had very similar numbers as Matt with 33/67. Should be a little better now. This is with driver, forgot to write that

[Jyrki]

For reference my '65 street car WD was 61%-39% with driver. Big battery, 12l fuel cell, 10l water tank (for intercooler) and 5l oil tank in the front, turbo above transmission, exhaust behind driver's seat and intercooler behind co-driver's seat. The ladder bar setup most likely lost some weight in the rear compared to torsion bar setup? Height of CG estimated to be 500mm from ground.
Jyrki

[Jon]

Those are nice numbers Jyrki, did you do anything to lift the Center of gravity, or did it give itself?

About chassis construction, are tests being done on flexible chassis or is rigid the way to go? The reason I ask is the Rudi's new beetle chassis.
I would think this damper was between two fixed points, but seems to me there must be some movement to justify this damper?

[richie]

Those are nice numbers Jyrki, did you do anything to lift the Center of gravity, or did it give itself?

About chassis construction, are tests being done on flexible chassis or is rigid the way to go? The reason I ask is the Rudi's new beetle chassis.
I would think this damper was between two fixed points, but seems to me there must be some movement to justify this damper?

I would think with a suspended car rigid is important,so the suspension does the work,and i am pretty certain that is the ghia chassis,and that shock is for the wheelie bar,and worked on a cantilever,he tried it on the new beetle as well but went back to conventionally mounted bars

cheers richie

[Fasterbrit]

Richie. The weight does not include my 100kg in the middle and to the right (rhd). This must also be factored in

I have never had a problem with the front end going light, even before the wing. I am pretty sure the paneling under the front end helps with this respect no end. Also, I run a homemade zero bump steer steering setup and a good amount of caster.

I personally believe cars that are setup with a heavy rake angle (nose down) are the most susceptible to dodgy handling when coming off the gas. It's all in the camber and toe change at the rear. Swing axle cars behave particularly badly with rake... Just about every Looker then!

I have done a lot of measurements of tracking and toe changes with suspension movements. With the results I vowed never to race a swing axle car with a stock steering setup. Are you guys aware that the toe change through the typical suspension movement on the track on the front (stock steering) can be close to 2 degrees? I have wheelie shots of well known cars where you can clearly see the wheels towing out massively at full suspension drop. This is why swing axle cars are prone to rolling over shortly after the wheelie. Massive toe out, wheels land, massive toe in and driver tries to correct the steering based on the momentary 'incorrect' reading from the steering wheel.

For this reason one of the single most important mods you can do to your cars is the zero bump steer steering . On my car, throughout the entire front suspension movement, there is no noticeable toe change. Night and day handling difference.

[Fasterbrit]

Omg... I have just realised I have opened a can of 'zero bump steer worms'...

[Eddie DVK]

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I'm not a drag racer but this is one of the best threads I've read here in a while

The same here.

But I don t hear anybody about using a spool instead of a lsd in the box, I read somewhere on here that a spool does strange things on the end of the strip. Or is this internet rubbish?

Regards Edgar

[richie]

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I'm not a drag racer but this is one of the best threads I've read here in a while

The same here.

But I don t hear anybody about using a spool instead of a lsd in the box, I read somewhere on here that a spool does strange things on the end of the strip. Or is this internet rubbish?

Regards Edgar

A spool is fine on a well set up car,if it doesnt go straight a spool will most likely make it worse,also its not for badly prepped tracks,it needs to be consistent all the way down or one tyre can get more grip than the other and try to turn the direction of the car,they are much stronger and lighter than any diff

[Jon]

Omg... I have just realised I have opened a can of 'zero bump steer worms'...

 

[richie]

Richie. The weight does not include my 100kg in the middle and to the right (rhd). This must also be factored in

I have never had a problem with the front end going light, even before the wing. I am pretty sure the paneling under the front end helps with this respect no end. Also, I run a homemade zero bump steer steering setup and a good amount of caster.

I personally believe cars that are setup with a heavy rake angle (nose down) are the most susceptible to dodgy handling when coming off the gas. It's all in the camber and toe change at the rear. Swing axle cars behave particularly badly with rake... Just about every Looker then!

I have done a lot of measurements of tracking and toe changes with suspension movements. With the results I vowed never to race a swing axle car with a stock steering setup. Are you guys aware that the toe change through the typical suspension movement on the track on the front (stock steering) can be close to 2 degrees? I have wheelie shots of well known cars where you can clearly see the wheels towing out massively at full suspension drop. This is why swing axle cars are prone to rolling over shortly after the wheelie. Massive toe out, wheels land, massive toe in and driver tries to correct the steering based on the momentary 'incorrect' reading from the steering wheel.

For this reason one of the single most important mods you can do to your cars is the zero bump steer steering . On my car, throughout the entire front suspension movement, there is no noticeable toe change. Night and day handling difference.

with your weight in it then it would be even better front to rear.


I wouldnt be suprised if the tow change was more than 2degrees,it can be quite bad,I think a ball joint beam car suffers less from this than a king & link beam car,but dont have any data,just my own feelings when driving them,how many people use limit straps on the front suspension? it would help with this and control the weight transfer better as well.

On the old cab the front is pretty stock,steering is all factory,no fancy single arm steering mods ,and only 1 pair of thin caster shims,seems alright to me,it doesnt have lots of rake though.

I think the answer here is to keep the front wheels in the air as long as possible then the driver cant try to correct the steering and th problem you describe doesnt happen


cheers richie

[richie]

Something else to consider is wheels,how many cars use thin alluminium dished wheels? I wont use the common name as thats not actually who makes them.When you go to chevy pattern[the most common non vw] which is alot smaller than wide 5 the wheels have the ability to flex alot more,add 500+hp and a car that moves around,at what point does the wheel flex? then to look different you decide to get a pattern cut into the wheel[star cut etc] now it is really likely to flex.
There is a reason they make SFI certified wheels

When you start to add up all those little things[steering angle change,rear camber and tow change,wheel flex,chassis flex,weight bias wrong etc] its amazing anyone gets down the track at all    

[Jon]

I'm thinking away about the drawing from the v8 boys...  first of all, there seems to be something strange going on in that drawing, as the lengthwise placement of the CG doesn't have any influence on the line between the wheels. That seems really strange.
With the weight as far back as we have it the line should be much steeper...  and I suspect that the attack point also moves as speed goes up....    think about doing a wheelie on a dirt bike (or a bug with way to little weight on the front wheels) at slow speed you need a steep angle to do it... the faster you go the less angle you need to still maintain a wheelie...  

[Jon]

Therefor we should all be racing buses... maintain your stock spindles and you wont have any bump steer at all...    now that's just crazy talk right?

[Fasterbrit]

Richie... The toe change becomes more acute with narrow beams. Drastically so, in fact...

I think your approach is the best solution; just wheelie your way down the track 

[Neil Davies]

Richie. The weight does not include my 100kg in the middle and to the right (rhd). This must also be factored in

I have never had a problem with the front end going light, even before the wing. I am pretty sure the paneling under the front end helps with this respect no end. Also, I run a homemade zero bump steer steering setup and a good amount of caster.

I personally believe cars that are setup with a heavy rake angle (nose down) are the most susceptible to dodgy handling when coming off the gas. It's all in the camber and toe change at the rear. Swing axle cars behave particularly badly with rake... Just about every Looker then!

I have done a lot of measurements of tracking and toe changes with suspension movements. With the results I vowed never to race a swing axle car with a stock steering setup. Are you guys aware that the toe change through the typical suspension movement on the track on the front (stock steering) can be close to 2 degrees? I have wheelie shots of well known cars where you can clearly see the wheels towing out massively at full suspension drop. This is why swing axle cars are prone to rolling over shortly after the wheelie. Massive toe out, wheels land, massive toe in and driver tries to correct the steering based on the momentary 'incorrect' reading from the steering wheel.

For this reason one of the single most important mods you can do to your cars is the zero bump steer steering . On my car, throughout the entire front suspension movement, there is no noticeable toe change. Night and day handling difference.

The other thing that really affects the steering is a narrowed beam. That exaggerates the arc that the steering arms pull in, so the compromise between fitting the wheels in the highest part of the front fender and the width of the beam must be factored in too.

EDIT: Balls, tree'd again!