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

[Jon]

Getting rid of bump steer is a matter of playing around with the placement of the inner rose joint. If you do, you get rid of it the same way for both sides.
The lengths of the steering rods does NOT affect bump steer on a trailing arm front suspension, so don't change them, and DO NOT fit a single rod from one spindle to the other!

The reason I say this because I'm seriously worried for the safety of the drivers of cars with the JCL conversion, as it WILL reproduce the bump steer (however minor) from one spindle to the other, thereby making the making the car steer.
I think all will agree that having toe in or out during suspension travel is minor problem compared with a car that actually turns the wheels the same way while you are racing. But when only one wheel is going thru a bump that's when the single bare is really going to bite you, since it then will produce the bump steer (you do not have independent suspension anymore). The reduction of bump steer you may or may not get with JCL set up comes from playing with placement of the rose joints... and NOT the length of the bars.

Stay safe.

[Fasterbrit]

Jhu... Do you have any experience with the steering mod or are you speculating? If it's speculation, please can you elaborate on your theory and explain why I have had amazing experience with it both on the track and on many air ride systems I have done for the street?

If you have actual experience with the steering mod, please can you give us your findings and explain how the car failed you and in what respect?

Having done thousands of street miles and 100's of track passes myself, I find it very hard to believe you dismiss this mod as dangerous. We even towed an Eriba Puck from Cornwall to European Bugin slammed on air with the steering mod. It handled perfectly the entire journey, including over cobbled streets whilst towing. I am very interested to hear your own personal experiences, as I am pretty sure you must have got something wrong on your install... Done correctly, the mod is awesome. I fail to see how you call it dangerous  

Yours very interested and intrigued, Matt

[Fasterbrit]

Getting rid of bump steer is a matter of playing around with the placement of the inner rose joint. If you do, you get rid of it the same way for both sides.
The lengths of the steering rods does NOT affect bump steer on a trailing arm front suspension, so don't change them, and DO NOT fit a single rod from one spindle to the other!

Jhu... I totally disagree with the above statement. The length of the steering rod totally affects bump steer and is simple physics.  The shorter the steering rod from the steering box to the spindle, the more acute the angle of steering rod. The greater the angle, the greater the multiplication of movement at the spindle when the car hits a bump. This is why cars with narrowed beams are so much more susceptible to bump steer: because the steering rods are narrowed and their respective angles become acute!  

Another point I need to clarify is your understanding of the single tube running from spindle to spindle. When working on your theory, do you take into account the movement afforded by the rose joints at either end? These allow a great deal of independent travel side for side before locking out. On my race car I can jack one spindle four inches in the air before any kind of lift at the other side, so the suspension is still independent to a massive degree.

I would never personally recommend any mod that I thought would in any way to be dangerous. Nor would I ever champion anything I haven't personally tried and tested for years myself. My background in engineering started at college aged 16 years old and I have been working in the historic race car industry for over 25 years, so I have a good deal of experience. Sure, there are plenty of ways to mess such an install up; it's all down to correct conception, design and execution. Do it right and it's an awesome mod.

The proof in the pudding is in the tasting

[Eddie DVK]

This is how Remmelemotorsport support the torsionbars.
http://remmelemotorsport.com/bodengruppe.html

[Jon]

It's not speculation, what I'm saying is just facts.

Once you understand the geometry of the trailing arm front suspension you will see that there is only one given design that will cancel bump steer.
It's only really simple math's, I have showed "my" formula/method/findings to multiple engineers and they all say it would take a good engineer about 10 minutes to figure it out. Yet no one does??
The solution is just too simple I guess.

Nothing has changed in the 12 years since I figured this out, it's the same stuff I showed you on the airport. Since that time I have made a model of this and shown it to big names in our industry to get a bolt on kit into production. They all tell me, that they have newer seen it solved before, but I know that the boys in Wolfsburg knew, and some of their cars came of the line without bump steer . But common practice with these cars reinstate bump steer in a BIG way.
With the model in hand it's really easy to see that it works, and how fragile/exact the placement of the components must be to work. 1 mm off in either X or Y axis and you have bump steer (this is also why it's close to impossible to get it right with just testing.

I have shown this model to some of the contributors to this thread as well, and the reason I did that is that I feel that I have to show them, so they can remove one of the hidden dangers of our cars.

The trailing arm front suspension may be significantly flawed in the way it deals with corners, but its the only front suspension on the marked that will allow you to cancel any and all bump steer. That makes it IDEAL for dragracing, and with this in mind fitting STRANGE components is downgrading the bug as a dragracer.


And finally Matt, I'm not saying that your stuff isn't reducing bump steer, what I'm letting you know Is that the reason you get better results has very little to do with the lengths of the steering arms, and nothing to do with the parallel bar.

Best regards
Jon Hroar Ulstad
+4792495271

[Lids]

This is how Remmelemotorsport support the torsionbars.
http://remmelemotorsport.com/bodengruppe.html

Because the gearbox and engine hang off the suspension the back of the car is a cantilever.  Any bracing will only reduce downward flex not prevent it.

The heavier the gearbox and engine the more this becomes a problem.  The only solution is to stop it been a cantilever and provide support at the very back of the car.  Ideally from underneath!

[Fasterbrit]

Jon I respect what you say and I recall our conversation at the airport fondly. But a fact becomes a fact only when it is proven. Until then it is speculation. If your mod is so amazing why have you not seen it through to some kind of development, even if just on your own car? 10 years plus is quite some time to have at least one modded car, surely? If you have the answer to the problem then it's a sure-fire seller as a product.

I am not trying to dismiss any mod you may have devised, in fact I actively encourage a simple solution to a well known problem. My issue is perhaps that you say the mod I have done is dangerous and you actively discourage others from doing so based on your own theory. I wish I could let you drive some of the cars I have built with this mod. Ten year's of nothing but positive feedback from proven experience, to me goes a long way to becoming fact.

The simple physics of the steering rod length can be proven by this simple test: take a 12" rule and place on a piece of paper. Draw a line beneath the rule along its entire length. Now pivot the rule from one end to raise the rule two inches at the other end.  Draw vertical line down from the raised end of the rule so that the vertical line touches the line that you drew originally beneath the rule.  Measure the distance from where the vertical line touches the horzontal line to the end of original line and note measurement.

Now do the exact same test, with a six inch rule and compare the two noted measurements! Quite a difference and still with only two inches of movement. Now this 'measurement' is the direct effect on movement of the spindle and turning of the wheel. So you can see that by narrowing the steering rod by half, you increase the turning movent of the wheel drastically for the same amount of wheel travel.

Converesly, lengthen the steering rod and the effect it has on turning the wheel during suspension movement is reduced. Hence running just one long steering rod from the steering box and doing away with the troublesome short steering arm. It really is that simple folks...simple math and physics that can be proven with a rule and paper. Try it yourself and the cause of the problem is immediately obvious and hence the solution is staring you in the face

[Jon]

Jon I respect what you say and I recall our conversation at the airport fondly. But a fact becomes a fact only when it is proven. Until then it is speculation.

Both you and I have engineering background, so I know you will get this; when you project to build a draw bridge, are the plans speculations until the bridge is built?  Surely not?
What I did was good old fashioned engineering work.
 

If your mod is so amazing why have you not seen it through to some kind of development, even if just on your own car? 10 years plus is quite some time to have at least one modded car, surely? If you have the answer to the problem then it's a sure-fire seller as a product.

Quite frankly I don't understand this question??   My personal life has nothing to do with me figuring out how to do something? I know lots of stuff that I don't go out and build. THAT being said, I fitted a Porsche rack n' pinion some months after I figured this out... But I have not driven my bus since. The years up to 2008 I spent trying to teach away my findings, I would say without ANY luck! I have discussed this in many forums and made drawings and flash animations. But the solution is TO simple, no one takes my word for it.... It kind of a leap of faith... "it must be harder" you can see it in their faces
 
All I have is the answer, someone else must take care of the development, because you want it bolt on, and it CAN be. Many people have signed nondisclosure contracts and seen it, but no one starts doing the work. There are many reasons for this probably, but the biggest point, I think, is that most of the Volkswagen owners don't even know what bump steer is. So will it sell?
 
 

My issue is perhaps that you say the mod I have done is dangerous and you actively discourage others from doing so based on your own theory.

This is something I have given a lot of thought! And I have kept my tongue many times you have mentioned the JCL solution in the past.
But I don't think I would sleep to well if one of these 9 8 or 7 second cars got built with that solution AFTER this thread, what if a car crashed? This thread is very much about keeping these guys alive. So no stone should be left unturned IMHO.
But like I say, I'm not saying your stuff is not working (except the parallel bar) , you get it better every time your adjustments makes the total geometry come closer to "my" layout. Again, I have only rediscovered what Volkswagen knew/did, but omitted from our favorite car.
 

you actively discourage others from doing so based on your own theory

I can see that this is seems seriously over the top, but "my" theory is along the lines of a statement that says "the center of a perfect circle is in the middle",  and you are saying that you have found a "second center in the circle". Unless your new center is on top of the old center, with incredible luck, it's just wrong.  I take no risk in saying this.
 
 

The simple physics of the steering rod length can be proven by this simple test: take a 12" rule and place on a piece of paper. Draw a line beneath the rule along its entire length. Now pivot the rule from one end to raise the rule two inches at the other end.  Draw vertical line down from the raised end of the rule so that the vertical line touches the line that you drew originally beneath the rule.  Measure the distance from where the vertical line touches the horizontal line to the end of original line and note measurement.

You are absolutely right, this is a great way to reduce bump steer, but it's has no part in getting rid of it... at all.  In fact this line of thought is what has concealed the right approach since the 1930's.
 
So, short getting it right, I too suggest as long steering arms as you can fit. Just don't mount the parallel bar.
 
Best regards,
Jon Hroar
004792495271

[Andy Sykes]

these pictures may be of some interest if you havent seen how thin a gauge the frame horns are and also the torsion tube





cheers andy

[Sepi]

This last page debate between JHU and All Torque caused some questions on my nervous mind if I'm doing now some hazardous set-up with this R&P steering system to my beetle... Any comments or experiences, please!

[Jon]

That looks fine to me at least.

[Peter Shattock]

Good to see some debate going on here without anyone throwing their rattle out of the pram!

Interesting topic and given I do have the straight rod linking the trailing arms it is one I have a particular interest in.

Like Matt I have been impressed with the way the car drives since converted relative to the way it drove before. That said I appreciate it does not resolve the bump steer in its self but as Matt has explained it certainly reduces its effect. When I first did the modification I found that as Jon suggests the tie rod location at both ends (pitman arm and trailing arm) was critical. That said I only adjusted them in the z plane (up and down). I've stuck with the standard x y locations at each end.

when I set it up I plotted the change in toe in / out with a laser mounted on the hub pointing to a wall about 1.5m away. At first it was all over the place but with some adjustment I got to a point where there was no noticed change in toe it just followed the vertical line I'd drawn on the wall. I did all this with the long arm but didn't even try the short arm as I was not planning on using it. But at this point I was thinking great no bump steer. So I just joined the two trailing arms together and off I went.

Jon are you suggesting if I had tried the short arm I could get the same result?

The planes of movement at work at the same time are quite complex in my mind but I'm no engineer.

Peter

[Jon]

Jon are you suggesting if I had tried the short arm I could get the same result?

If you look at the shape of the stock pitman (sixties linkpin) arm you see that the pivot points are not placed the same distance from the axis of the steering box. This is a problem, if you get them the same distance from the axis the rods will work more or less the same.
Why more or less?, because if you don't have it quite right you have some bump steer, a long rod will then help you (like Matt said). The short one will not help you as much. So they will not work quite the same.
But when you get the placement of all the components RIGHT, you don't have any designed bump steer, so you don't need help from the lengths, and therefor you can run them as sort as you like. Or like stock.

To me, the big gain is that the wheels operate separately, I feel that is a safety point. 

PS. I'm also no engineer, I only took the first two years, and moved on to areas where my creative brain has better use.     

[freakpower]

This last page debate between JHU and All Torque caused some questions on my nervous mind if I'm doing now some hazardous set-up with this R&P steering system to my beetle... Any comments or experiences, please!

I am curious about this set up. It looks good!
Is it a kit, or is it someting you have put together yourself.

[Martin]

i feel as if i must chip in to this great thread again,

I can only comment on my own personal finding and as ive said before I'm willing to share with my fellow VW friends.

My car suffered from Bump steer a long time ago, you could 'feel' that steering was going to extremes and the short arm of the system was pulling in the wheel, effectively making the wheels toe out.

after a trip to JCL with a buddy, Jimmy showed us his way of steering. Link the two stub axles to each other to control toe through the entire movement of the suspension, then link one stub axle to the steering box (the long arm) keeping the long arm parallel to the linking arm at ride hight.

We took this information away with us and made it work on our cars, the transformation was amazing, you could twitching from the wheelie disappeared and the whole feel was so much better than before.

now i know, if one side of the suspension is fully compressed and the other is fully decompressed then the toe will alter by a small amount, but lets be honest if the front suspension is like this on a 9 second run, something else has gone very wrong and your going in the wall!

after driving the car on the road and getting a little err sideways a few times, the steering feels so natural, i have no fear of not knowing where the car is going. the feedback is on a par with my 911, may be a little better....


JHU, has shown me his idea, and yes i have signed his papers to keep it to myself, when i do finally get time to tinker i'll build it up and put it through its paces. but until then the system I'm running at the moment gives me great confidence and feel and have no reservations about taking the car past 150mph (its been to 149 already).


The creative pool we have going is working great, just look through the speculation and look at the facts.


arnt vw guys great


Martin

[Shag55]

Shure would be nice to see some pics or scetches of these ideas guys. I'm not totally following you. I am at the point on my car where I'm ready to do the steering and am very curios as to your findings.

My buddie did the single bar that JCL recommended. He didn't like it or wasn't set up right and ended up putting it back to conventional.

[Peter Shattock]

Thanks Jon,

Before really thinking about it I always assumed the offset of the inner tie rod points on the pitman arm was a very intentional design feature to do with steering geometry not a potential design hindrance.

I can see that it would be possible to site the pitman arm inner tie rod point at the centre of what would in effect be the base circle described by the arc of the outer tie rod point, sort of like a cone on its side, the tip of which being the pitman arm tie rod and the base being the outer tie rod as it travels through it arc. Is this is the point you are making?

Unfortunately I don’t have the car at home to just go and have a look at the moment, and I’m much better at looking at things to understand how they work than mathematics, but if you were able, would it be possible to swinging the torsion arms and stub axel and outer tie rod 360 degrees to describe a true circle or is there some kind of cam effect going on, I’m sure you can see where I’m going with this if there is.

The other potential issue is the relationship between the inner and outer tie rod as the pitman arm and outer tie rods move to turn the car. Needless to say if the tip of the cone and the base circle move at different rates this would I assume cause bump steer again (not that the straight link rod does anything to help this) as the inner point moves away from the centre of the base circle.

I understand the point of independence of each steering arm as this must be preferable, but in practice and for what ever reason like Matt and Martin have said I have not had a problem. There are some older production cars with the straight rod steering arrangement, so I’m not sure its such a fundamental problem, but I don’t suppose any of these exist on modern cars given they all use racks rather than boxes now.

Interested to know what you think, but whish I could just go and have a look at the car in the garage (with a cup of tea of course, the drink that powers the nation).

Peter

Ps  Freakpower, if what I’ve said above is correct the rack looks good in principal but be careful where you site the inner pivot points!

[Jon]

You are on the right track Peter, you understand it so much better when you figure it out yourself... now you see how fragile this system is, and how ingenious VW has constructed the front suspension (seen from this standpoint(and this standpoint alone)).

Regarding the pit man arm thing, the split bus doesn't have this "feature", I suspected it could have something to do with ackerman, but I have found nothing in my books supporting this theory.

When thinking about this it always helps me to remember that the tubes in the beam are parallel.

The straight rod arrangement is used exclusively (from what I have seen) on solid beam suspensions. This means the spindles keep their relationship to each other during suspension travel, and therefor will not suffer from the solid rod.

[richie]

As I was away racing when the last couple of pages were posted I thought i would take some time today and have a read back through it all,somethings stuck out to me, and as I was asked/mentioned in my absense heres some thoughts I have from this year,first this still bugs me

I have never had a problem with the front end going light, even before the wing.

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.

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.

Really? you seem to be suggesting this is an improvement,then wrote this below

One thing I can certainly vouch for from my experience was the fitting of a wing - it made a night and day difference to my car. Before the wing the Oval was so unstable at speeds above 130 mph that it made me not want to drive the car above 125 mph; it was just too dangerous - the back end became so unstable and the car started to 'steer from the rear'.
 

Again,really?   

 I am not dissing the wing or any other mod i haven't tried, but from your 2 quotes it does seem like there was something else going on with your car,if it was that dangerous how could you recomend the steering mod you used,is it only safe when used in conjunction with a wing? plenty of cars without out it go straight at 130+
I am not attacking you at all Matt, but you are in a position as the technical wiz on Volksworld magazine that people will look up to you and trust 100% everything you write or say, to me this means you have to be 110% certain that something works before saying so,

and you seemed upset that people werent taking any notice of supposed data posted up by someone else that backed up your claims, anyone can post claiming something they learnt, hell i think everyone should cut the roof off there cars to make them safer   but without actually seeing data why would anyone believe it? and in the real world data is taken from 100s of passes, not 2 passes in 3 years, no one cares what a 18 second car does,its not relavent to this topic

As for my own findings this year,well I didnt get enough track time to try the aero mods I have for my car,I want to get another 20-30 passes with the car as it is,assess that data, see if there are any patterns then make the changes to see what happens and go from there, I can say i finally have a decent handling car and it is still far from perfect,time and parts availability meant I had to just make do with some things this year, I will make a couple of minor changes ready for next year and go from there, I have said this before but will say it again,I am NOT trying to build an 8 second car, that has been done lots of times now, I am trying to build a quicker than that car so the developement might not be as quick as some expect, it is a huge learning curve for sure and apparently I don't know anything which slows it down even more.     

.

I have looked at Jons ideas,i see some positives there and if it gets to a stage that there is a "kit" available I would like to test it on my old cabrio for sure as if we can make that car go straight run after run ,that should be enough proof for anyone

I am nearly at zero tow at the rear now,and 1 degree at the front to add that to the other info posted.


Finally for now,Stretch very true, but how often do you get you tyre pressure gauge checked or calibrated?   


cheers richie

[Fasterbrit]

Richie...

As I developed the car over the years I learnt a lot of info. The steering mod worked fantastically and cured the front end. When I started to get to speeds of 125 mph + the aerodynamics of the rear end began to take over - nothing to do with the steering - and started to make the rear end 'shimmy' as in feel really loose and wobble. The faster it went, the more prominent the problem. The wing totally cured this and made 145 mph a 'one hand on the wheel and no chute deal' as opposed to a 'grip your butt cheeks, pull the chute and hope for the best.'

I like to isolate problems and address them as separate issues, and I only ever change one thing at a time and test it. Again, as I have stated many times, all my posts are based on personal experience. Perhaps the rear end on All Torque is slightly more sensitive as it has a lot of weight there, being a WBX.

[Typ3racing]

Now thats a cool thread here! (no updates?)

Ive been thinking a lot about those problems.

First thing to get the car more stable is lengthening the wheelbase for sure.
Almost unpossible with a beetle, but i will add about 50mm to notchback.

So far i never had any problems. My really heavy car always went straight like a arrow.

Even at 250km/h (not on the 1/4 mile, but on the german autobahn)

Is it the weight (1140kg incl. driver) or the better aerodynamics of a type 3 keeping a stable ride??

[Jon]

First thing to get the car more stable is lengthening the wheelbase for sure.
Almost impossible with a beetle, but i will add about 50mm to notchback.

Next best thing, narrow the rear axle track width. Not impossible to do, and has the exact same effect.
Check this out, a narrow To#¤ta Starlet with a narrow real axle, and rims that pushes the physical center of the slick even further in.
It looks quite undramatic for a 7.621 ET and the 7.555 looks even better... remember this is a super short car.

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

[Vwfreak53]

Holy mother. That last pass was more dramatic than I would've liked had I been driving! LOL

[Fiatdude]

Short Wheel Base cars are FUN



Even with the Abarth front steering mods to the Fiat you can see the toe out has increased during this wheelie -- but I never had any issues with it when I was going around corners or down the strip -- -- but this car had the A-arm geometry vs the beam geometry that is on VW

But maybe you can see that the seat has disappeared a little -- I has the stock seats in the stock floor rails at this point and they had just ripped away from the floor pan on this launch .. took me a couple of days to get all the upholstry out from between my cheeks -- lol

[richie]

I thought I would drag this back given the ET barriers that been broken this year. With the Hater maker going 7.70@186 at vegas last month with ease realistically can we now look to mid 7s being possible? and more & more cars running 8s and no crashes what has been discovered to make this possible?

cheers Richie

[Andy Sykes]

Out of the box thinking and making it happen

[dannyboy]

i think it was just a big tailwind 

[spanners]

Getting rid of bump steer is a matter of playing around with the placement of the inner rose joint. If you do, you get rid of it the same way for both sides.
The lengths of the steering rods does NOT affect bump steer on a trailing arm front suspension, so don't change them, and DO NOT fit a single rod from one spindle to the other!

The reason I say this because I'm seriously worried for the safety of the drivers of cars with the JCL conversion, as it WILL reproduce the bump steer (however minor) from one spindle to the other, thereby making the making the car steer.
I think all will agree that having toe in or out during suspension travel is minor problem compared with a car that actually turns the wheels the same way while you are racing. But when only one wheel is going thru a bump that's when the single bare is really going to bite you, since it then will produce the bump steer (you do not have independent suspension anymore). The reduction of bump steer you may or may not get with JCL set up comes from playing with placement of the rose joints... and NOT the length of the bars.

Stay safe.

This, ^^^^^ the best front end to get right, if you can't get a beam and 'box set up right, a rack and strut system will kill you,I've seen so many wrong moves from folk that should know better,  zero bump comes right out the factory door,  but understand how to set it up for zero bump, it's all down to the steering gear installed angle, it a delightful system with independent caster adjustments completely removed from geometry changes, rack and strut cars need re bump steering after castor adjustment, I regularly spank double wishbone equipped sports cars with my B/J car, they don't bother me, but I seem to worry them