Air dam on a Baja?

[PhillipM]

I extended the floor skid pans forward on my rail so there's about 1ft sticking forward of the front bulkhead and putting some downward pressure on the front - it still lifts almost completely around 110-120 though with the big mudguards.



Front weight is a waste of time, plot aerodynamic lift/drag vs speed - even if you put a couple of tyres hung right up front it'll only push the speed you lift the front up by 3-5mph or so - the curse of lift being a square of the speed.

Try to have the suspension set up to be nose down on the highway slightly too - that huge flat underfloor is a hell of a lifting device otherwise.

[DHale_510]

Have you thought about alignment?
Tracking is all about caster and toe. Positive caster and negative camber add high speed stability [tracking stability], and toe in does too.
Typically high speed caster over 4' is good, stock VW caster is about 2' and any rake [big rear tires] will reduce that, often to zero. Lots of caster steers heavy, but on a 1000# buggy there is no heavy. You can measure your caster with a hardware store magnetic protractor on your front beam, You can add caster with a 11/4" shim under the lower clamps, we used to just use old engine center main bearings. They are about 2' and usually need the longer bolts. 2" of chassis rake is pretty close to 2' of caster [measure the chassis rake on the lower chassis, the door sill on a sedan]. This also gives you a nicely stable offroad steering feel.
Any toe out, front or rear will make things pretty busy at speed. Especially rear toe out will feel unstable. Toe in of about 1/8" front and 1/16" rear is stock, you may like double those numbers on a buggy going faster than a 40 hp sedan....
Alignment adjustments are pretty easy easily reversed, and won't drag on the ground or get caught in the trees....
Dennis

[DesertSasquatchXploration]

Yes agree suggested an alignment as well. What has me laughing the statement 280Z cars lift at 75MPH (I Know the feeling). It that was true they would be worse then a Corvair with the weight removed. :lol: I have a feeling the OP has a fleet of poorly alignment cars clueless of how screwed up every car really is.

[DurocShark]

Got a pic of your z?

Here's the one I had before I moved states:

_________________
No boom today. Boom tomorrow. There's always a boom tomorrow.

[Dan_Lockwood]

I bought a brand new '76 280Z 2+2 back in '76. It was a very fast car and handled very well.

I had a long stretch of wide open road near where I used to live and hit, indicated, 136 mph without any lifting or unusual lifting at all, just say'n...

Dan

[DesertSasquatchXploration]

Sooo.... Have you tried a good alignment and reinstalling the spare tire (like they came from the factory) Or... are you going to keep making excuses and do nothing. You asked for help we cant do the work for you.

[DurocShark]

Asked for an air dam. Not this nonsense.

It's the Samba. Dunno what I expected.
_________________
No boom today. Boom tomorrow. There's always a boom tomorrow.

[Wulfthang]

The problem with speed caused lift, is that it's exponential. The further up the front end goes, the more lift you have. Once it starts to lift, it'll usually continue right up and over even if you chop the throttle.

I race R/C boats. My current one is a 48 inch inboard tunnel hull. It's running in the 80's (mph). Because it's a tunnel hull, it rides on a cushion of air. If it's tuned for max speed going downwind, it'll fly up and over heading upwind because it's to light on the water.

I fixed that by adding Canards on the nose that changes angles depending on the throttle setting. It also has an "aw crap" switch on my transmitter to cause the Canards to jump to full down in case it starts to fly over. It's successful about half of the time.

If everything else is in good shape on your car, I would look into lifting the rear or dropping the front while you do the hiway driving. An air dam would block air from going under it but it would kill your ground clearance.

[DurocShark]

Thanks, I'm not worried about ground clearance any more. Since my back surgery in December, offroading is no longer on the table.
_________________
No boom today. Boom tomorrow. There's always a boom tomorrow.

[oprn]

Wheel alignment has little or nothing to do with front end lift. Period!

The real issue here is that the center of aerodynamic pressure has been changed on the car by chopping off the front and putting the Baja kit on. It has been raised a substantial amount. Due to the shape there is a lot more air being forced under the car than before so naturally it will lift sooner. We put these kits on to force the rocks, logs and buck brush to go UNDER the car right? Well sir the air does too!

Now I will say that the comments about putting more weight on the front are not so far off the mark. There is a definite relationship between the center of gravity and center of pressure of a vehicle. The loss of the Beetle front end sheet metal and spare tire weight is part and parcel of this problem. Putting the engine up front would change the picture completely...

Could a big old spoiler be built to correct all that? I think it could but how big and what would it look like? Not like a Baja I suspect. In all reality, in order to be effective it would in the end look very similar in profile... from a distance... much like the original Beetle. The change needs to be quite large to offset the Baja kit.

The Baja mod was intended to change a higher speed street car into a low speed off road car with zero consideration to the effects of high speed aerodynamics. Now you would like to reverse that. All that is the long answer to my "Wrong tool for the job" comment. Sorry!

Go ahead and build something and keep us in the loop. By now I think you have realized that you will be pioneering the field.
_________________
Our cars get old, we get old but driving an old VW never gets old!

[DurocShark]

Not reverse it, just mitigate it some.

Yes, I get your point about wrong car for the task. But I like this thing, so here we are.

I'm just going to join the dbags who drop 70k on a fully overlanded 4Runner and never go off the pavement.
_________________
No boom today. Boom tomorrow. There's always a boom tomorrow.

[oprn]

When I was young and foolish (I am now officially old and foolish) I was in love with Beetles and owned several of them the last being a '71 Super Beetle. I had dreams of turning it into a real genuine sports car - imagine, a Beetle that would run with the best of the big dollar cars! The SB was the apex of VW's efforts and had some real potential in my mind and I worked to that end for a number of years. Then life, family, home ownership and job pressures intervened and my dream project died.

Fast forward to 6 years ago when I saw for sale and purchased my first 944. This car has virtually the same suspension layout and heritage as the Beetle but with better brakes, plenty of power, a more aerodynamic body and drove like a dream. In short I quickly realized it was the car I had always dreamed my Super Beetle could be. And.. it is completely bone stock, 100% all day long, every day dependable!

But I do get where you are coming from because my only regret about the car is that it is NOT a Beetle!
_________________
Our cars get old, we get old but driving an old VW never gets old!

[ORANGECRUSHer]

This thread is a good example of why the offroad section is dead
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-cut/turned front beam-AEM wideband-Auber CHT

[Schepp]

Why is there still discussion on this pointless topic?

[oprn]

All subjects are pointless in someone's eyes. Others sit back, think and learn. The OP is thinking, not a bad thing.
_________________
Our cars get old, we get old but driving an old VW never gets old!

[Dinggoo]

What about adding a diffuser or smaller diffusers underneath to break up the airflow and create a less stream line affect, which would in turn make the body less of a airfoil design. small fins installed at an angle might help.