beetle and aero

[buildabiggerboxer]

Guys, i have to say i'm with farmers view, its castor thats needed before BIG aero, i have no aero ( that you can see anyway) because its weight and drag, and i go well over the ton and into turns at 85/90 mph in top gear without a problem (other than soiled underwear), but i do run 9 degs front castor and have another thinned down shim for a bit more at some tracks. the clincher for me is the many quick drag cars that pull 140 plus, ive even seen 175mph terminals, on 11, 10, even 9 sec runs done without any wings, a lot of these are beam cars, not all, but most, i see Rob says he's got squirelly on lift off, that will be the rear toeing out on lift off rather than aero.
I also think the reason the supers are higher at the front is explained by its huge trunk, it can carry a lot of weight in there, the standards are not set like that because you cant load them as much.
i Ran my standard 'nose up' one time, it helps me when i load it onto the trailer higher at the front, and i drop it down for the racing, one time i got late on the road and had to run it nose up for practice, not good, i dropped it down before the proper race for an instant improvement in front bite. the stop watch is the tool to use, but i do have some other subtle ideas on my car, i use the engine bay to channel air OVER the motor and out of the deck lid via wide louvres into the low pressure area at the rear, i'm wasser boxer powered, so the engine bay is more open for this, does it work?
well It doesn't hurt to lighten the deck lid so i cant lose, and i vent the front fender pressure out thro' slats and have guide vanes to turn the air away from the under tank inner wing area into these slats. Just my view on a complex subject, but always remember KIS KIS, and also remember, making special parts only keeps you in the workshop and not on the track, and then you have to make spare special parts, i do have spares tho'... spark plugs that is
best regards. BBB

[Bruce2]

, i see Rob says he's got squirelly on lift off, that will be the rear toeing out on lift off rather than aero.

That's exactly what I thought when I read that. What he saw is what happens to swing axle cars, not IRS. There's gotta be some wheel alignment trickery happening to him.

[4agedub]

9 degs front castor

Danm!!! That's a lot of caster. I'm sure you do get a load of camber when turning the wheel. Would you mind posting some more pictures of your car?

[judge]

The rear end of my car is a bit different to how most have there rear ends set up. I run 2 degrees two out at the rear to help low speed turn in, this makes it very hard work when the speed get s over 60mph, I use the wing to help keep the rear end going in a straight line. Notice the big side plates on the rear wing.

[buildabiggerboxer]

9 degs front castor

Danm!!! That's a lot of caster. I'm sure you do get a load of camber when turning the wheel. Would you mind posting some more pictures of your car?

we are getting a wee bit off topic, but i 'spose mechanical grip is difficult to separate from aero loadings without potentiometers and data logging, its no use saying " it feels better ", that only comes from the biggest variable of all, the driver.
Yes, the b/j front need plenty of caster, it has no camber recovery in roll, altho this, for reasons i dont know, is engineered out on F1 cars and the BTTC cars, and others most likely, why else would they run all that camber when they have huge wide tyres? , it must be at the braking/stopping power limits, so its not a prerequisite to go quick, and the b/j beam is proving an effective system in it own right, its only miss understood by non thinkers, it even comes with anti dive from the factory, but you will have to work that one out like i had to. 4agedub, you are right with the camber gain with added steering angle, i run 2 shims plus my own ones for about another 1/2 shim, front arb is 22mm, no understeer point reached yet, so it will be stiffer yet next season. Pics i'm slow on as i'm always in the car, i only get what others take, i'll see what i can find, best regards BBB.

[4agedub]

Sorry another off topic...
buildabiggerboxer are you running a ball joint front end of mcphersion? If ball joint, how did you get that kind of caster? I'm running dual caster shims on my link pin but, but only get around 4' caster. Next step looks like cutting the chassis to get more.

Caster works!!! You can then run minimum camber to help with straight line braking and as soon as you start turning in, you get good camber. Right now I'm running 2,8' camber on my race bug. It turns really well, but the straight line braking was affected.

[4agedub]

Pic to show camber from front on our two race bugs

#1 car with 2.8' camber

Historic_Saloon_Cars_ABCDE_30_07_2011_031.JPG

#2 car with 2' camber

Historic_Saloon_Cars_ABCDE_30_07_2011_049.JPG

[4agedub]

Ok, back to aero. I found these on the Jeffreys VW website.
I wonder what difference the front bumper will make with some gurney tabs, has anyone used any of their bumpers?

[judge]

i have run the dive plans on the front of my race car, they seemed to have cleaned up the air flow along the side of the car. in the wet i have noticed less mud splater along the sides of the car. the airflow on the lower ones of my car have pulled the rivets from the top edge so there must be quite a bit of airflow over them, what that airflow is doing i dont know lol

[Piledriver]

Sorry another off topic...
buildabiggerboxer are you running a ball joint front end of mcphersion? If ball joint, how did you get that kind of caster? I'm running dual caster shims on my link pin but, but only get around 4' caster. Next step looks like cutting the chassis to get more.

Caster works!!! You can then run minimum camber to help with straight line braking and as soon as you start turning in, you get good camber. Right now I'm running 2,8' camber on my race bug. It turns really well, but the straight line braking was affected.

Are you folks with 9 degrees of caster running power steering ?

I can visualize the increased camber when turning, but it must take a lot of steering effort to park.
(or not?)

[4agedub]

More caster does make the steering heavier... but running a steering rack normally helps.

[buildabiggerboxer]

Pile, Its heavy, but 6 yrs of kart racing have given me good upper body endurance altho' i'm a lightweight at 9 st, mines running a s/box still, i never run a steering damper, it does not need it. but I have moved to a NASCAR seating position for more leverage which helps me cope a lot better, i dont find it hard after karting, i did 2 hrs stints at Lemans 24 hrs 3 years running, that WAS tiring!! i also run 3 degs camber which eases the static loadings back a bit. 4agedub, you must be measuring the castor wrongly, they have 3 degs from stock, some a bit more, measure it level as they can lose caster on the ground with the rake. im also very heavy on the front wheel loadings which helps my braking, i have a radiator and coolant pipework, the coolant itself and header tank, d/sump tank@ 2gals of oil, oil coolers and battery all up front, all loading the axle, and i sit well forward too, but i do get a bit sweaty and smelly after a days sport. I have a pic somewhere of a customer car i preperad 12 years ago with 3 degs camber that you can see plainly, ill have a look see for it.......
No sign of it yet, it may be filed at the 'shop, but heres one of the beam and adjustable ARB

[VW&MGman]

How are you guys getting that much camber up front?

[FJCamper]

Gentlemen,

We ran our road race 1970 Ghia (ball joint front end) at 120mph+ on our 1600 engine straight and true, no extra caster shims, with front camber at 1.5 degrees negative. 19mm front sway bar.

When we installed a Puma adjustable front axle, automatic 2-inch drop, it took a single set of caster shims to compensate.

Caster is what separates the autocrossers from the road racers. AutoX cars need less caster to be unstable enough to be tossed around. Road racers or drag racers need lots of caster to go straight. We used our 1970 car for both for a few years, in the beginning just running stock caster. Driving AutoX with heavy caster was really different.

BuildaBiggerBoxer mentioned that the ball joint front end had anti-dive. Technically this is not true (at least by modern multi-link suspension standards) as the leverage of the front trailing arms makes dive worse, but stiffer front coilovers and/or torsion bars, and shocks helps a lot. The "modern" (1970's onward) suspension experts & literature flatly state that the VW suspension (IRS or swing-axle rear, ball joint front) has no anti-dive or anti-squat other than spring resistance. Old apples and new oranges.

Stiffening up the suspension overall is good. Remember what Colin Chapman said: "Any suspension -- no matter how poorly designed -- can be made to work reasonably well if you just stop it from moving."

For the record, our VW front suspension is a 1930's design, and we sorted out our Ghia so that the absence of modern anti-dive was moot. There is another saying to paraphrase here: "What model car you start with is far less important than how you engineer and develop it."


FJC

[buildabiggerboxer]

Hi FJC, your observations are always welcome, and all others for that matter, what i found with the t/beam cars, was that as they were lowered to the point where the t/arm sloped upwards relative to the road surface, it comes into an anti dive state, as you say, not in the angled pivot way of a wish bone, but the angle of attack to the road alters to the same effect. I sussed it when i put lowered road cars in for their annual ministry checks, they faied on 'no suspension travel', i took the shocks of and tried that etc etc, usal things, binding checks etc, found no seized bearings etc, so headaches for a good while, i had another 'tester' place that got them through' ok , but after a few more failures, i tried raising one up again and the travel returned, got the pass certificate and lowered it back again, its noticable how hard it is to move the suspension in the lowered, upward slope of the arms state, i was swinging around under there like a chimp.. . VWMG man, i bend the arms, easy, i did the same to link pin beams aons ago,tho thats more of a twist, no one could work it out
at the time.
FJ i now run drop spindles, mainly so i can attack the kerbs harder, without the short shocks it rides so much smoother as the angle of the front arms is more favourable,. Best regards BBB