Well, I am looking at operation within design parameters. These are not intended to touch down at any sort of speed. It is for crawling up steep driveways without scraping stuff. Sounds like a good design to me.

The key is just making sure it does not touch down in other areas of driving. So stiffer torsion bars.

I really liked the JMPRO ones I tested. But my car is pretty low, and I did get contact with the road in extreme compression (fast driving through a dip or elevation change in the driving surface). It would have worked if they'd been shorter, but that illustrates the problem of designing something like this what will work with an assortment of 911s with different ride heights and spring rates.

Philistine!!!!!!!!!!!!
 

I know I'm messing with the minds of the purists, and apologise for being such a philistine. If all goes well, such a mod will never have to be be used.
But there is apparent interest, judging by the # of views. So, with apologies to Tennyson:

Hoots to the left;
Hoots to the right,
Onward he came.
Was the Pelican dismay'd?
Not tho' the Pelican knew
He had possibly blunder'd:
His not to make reply,
His not to reason why,
His but to do and die:
Into the valley of Death
Rode the philistine.

If this doesn't work, and I am still alive, I'll be the first to say so.............:D

I think the wheel idea is dumb. Just what you need, 2" less ground clearance. And when the wheels catch on the edge of a ditch, something really ugly is likely to happen.
Perhaps a Subaru would be a better transportation choice?

Milt, are you suggesting a skid-plate such as used on Rally Cars and Off-Road trucks?

Rally Armor FAQs
http://www.rallyarmor.com/store/imag...ate_unbolt.jpg
http://www.rallyarmor.com/store/imag..._mud_flaps.jpg

"Panzer Plate" heavy duty aluminum skid plate kit for 1998-2010 New Beetles
Panzer Plate heavy duty aluminum skid plate kit for 19982010 New Beetles by www.dieselgeek.com
http://www.dieselgeek.com/catalog/BottomView.JPG
Lexus Gx470 Skid Plate View Photo 4
http://image.fourwheeler.com/f/90935...plate_view.jpg
Bottom plates for racers and people looking to save gas by smoothing out the airflow under the car are common enough.

dumb is as dumb does
 

JH,
I know. There's just no excuse!!!!
I've driven all around your part of the country, and if memory serves, you've got relatively smooth roads, except when the earthquakes hit.
The fix I'm adding will use up less ground clearance than these,
and are about .5 " less than the original tiedown before they're all bent out of shape. (see earlier pic).
I've tried the Spoiler Protection Skid Plates and they offer good protection for most applications. I'm just taking it the next step.
Not to worry, all will be well.
Just remember my credo: I have more ass than you have teeth....................:D
On the other hand, if you happen to hear a loud explosion east of you, it might be NC exploding cause I PO'd the Porsche gods.

OK, Just throwing this out there...

What about small air bags to lift the front of your car?

So you get to your drive way. Hit a switch and they raise about 40mm or 50 mm so you can drive in without scraping your car.
I've seen modified struts advertised for the later water cooled 911s. They have a small air bag between the spring and the perch.

I'm not sure how you would set them up on our cars. Maybe between the body and suspension arm? It would have to be small to fit.

well, sheeeeeeeeeeeeeeee it!
 

Peter,
sounds like a good idea for predictible type transitions. In this case, the driveway is not an issue. On occasion, these cars bottom out. All you have to do is look at your tiedowns on the front a-arm covers. Betcha their bent. what this does is provide a rolling transition across an obstacle that would have bent the tiedown. The ride height of the resulting gizmo is actually~.5" higher than the original tiedown.

............on the other hand..............

How hard can it be? I mean, what could possibly go wrong? I can do better'n that! Reactive armour!!!!!!!!!!!

Each panel measures about 250 x 150 x 70 mm and has four bolt holes, one at each corner, to attach one brick to each corner. Located centrally on the edge of each brick is a pair of mounting pins enabling it to be attached to the tank's main armour. Attach to front of a-arms. Bottom out and BOOM!!! Your car is gently lifted right over those pesky bumps!!!!

http://forums.pelicanparts.com/uploa...1313861868.jpg

this just keeps getting better & better................ass check: yep, still there:D

I wasn't planning on having the skid plate shear off and expose the rubber mount. The rubber is to lessen the impact and the plate is to provide something to protect the rubber. The hockey puck is s good idea. A half moon mounted vertically would be a good design.

A steel roller is going to be prone to damage and the impact will be the same as hitting the tow hooks and/or condenser bar. We all know that's pretty harsh.

How much are hockey pucks?

The ideal sacrificial material should be:

cheap
quiet
long lasting (relatively)

Sherwood

You are making a hovercraft lift fan with bow skirt seem like an attractive alternate.

karlo | – Kit Speed — Build It –
http://www.landrovermonmouth.com/ass...Hovercraft.jpg

progress report
 

OK, I've removed the front a-arm covers, and completed the welding and drilling.

weld, with angle set to make the wheels ride about level
http://forums.pelicanparts.com/uploa...1313886594.jpg

front shot showing angle set to compensate for angular installation
http://forums.pelicanparts.com/uploa...1313886648.jpg
back shot weld job. Could have made it a lot neater, by spending the time grinding and filling.
http://forums.pelicanparts.com/uploa...1313886691.jpg
etching primer front
http://forums.pelicanparts.com/uploa...1313886732.jpg
etching primer back
http://forums.pelicanparts.com/uploa...1313886770.jpg
black paint corrosion control
http://forums.pelicanparts.com/uploa...1313886804.jpg

I'm beat, and my electrolytes are dangerously low--time to replenish them with spiritus fermenti.
Will install tomorrow. Pics and test drive to follow.

Well that's something and it looks like it will do the job. Cred to you for having a go.
Your set-up would have to be better than nothing at all.

Just a thought. It may be better to have the wheels mounted in such a way so that if they hit something "hard" they would break off rather than bend the pan.
Your design is fine... You could carefully cut away some material to weaken them a bit. (50%)

It's just a suggestion, do what you want. It's your car... Good luck with your design.

installation
 

Got up this AM and had traditional southern breakfast of fricasseed frog lips and grits with redeye gravy, and washed it down with some fresh 'shine!. Yummy..

The A-arm cover re-installs as before:
http://forums.pelicanparts.com/uploa...1313945976.jpg

Access hole to front bolt position. Center the hole as best as you can--I could have done better--drill at an angle to match installation angle of bolt:
http://forums.pelicanparts.com/uploa...1313946037.jpg

Make sure the 17mm socket you will use will fit into access hole.

• I had originally planned to use a hex-head, but couldn't find one in the whole frickin town, so I went to plan B.
• If you can find something with a smaller head size, then your access hole can be correspondingly
  smaller--more strength....

http://forums.pelicanparts.com/uploa...1313946096.jpg


The front A/C condenser protective bar had done it's job, and suffered as a result. I suggest that you eyeball fit the bar before trying to re-assemble, as it may be bent from taking bumps. This one was bent, and I had not dry-fitted before re-assy. It came to rest about 1.5" below where it was to be attached, and the bolt would not align to pull it tight.
http://forums.pelicanparts.com/uploa...1313946219.jpg

I used a jack and spacer to position the condenser protective bar, then mounted the bracket.
http://forums.pelicanparts.com/uploa...1313946281.jpg

Mounted bracket, showing angle correction so that wheels are parallel to ground. Remember that the bolts align at an angle for proper fit. Suggest using a screwdriver to get mental picture of angle before screwing in bolts.
http://forums.pelicanparts.com/uploa...1313946350.jpg

Mounted wheel. Note color. I used it to provide contrast, corrosion control, and to add a certain je ne sais quoi...................besides, it was the only color I had in the shop.
http://forums.pelicanparts.com/uploa...1313946409.jpg

I used lots of grease and tightened the lock nut till it squeezed the wheel , then backed off till the wheel turned. Also added extra washers as spacers.
http://forums.pelicanparts.com/uploa...1313946462.jpg

There has been lots of discussion and expressions of concern about the wheel compounding the problem if you scrape the bottom of your porsche, and they are valid concerns.
But, if you compare the ground clearence of the installed wheel to:

• the ground clearence of the tiedown
• to the tie down with the aftermarket scrape plates installed

this installation allows:

• at or more ground clearance than the tie downs
• over .5" more clearance than the aftermarket scrape plates

http://forums.pelicanparts.com/uploa...1313774910.jpg
The proof is out there, waiting to be discovered in the real world ...........
Next...go thrash the living buggers out of the wee beastie and field test the design.:D

Watch the axel nuts . They have a habit of coming loose when used in the way you have it. That is why I used pins for axels instead of bolts. Also for ease of changing the wheels if necessory.
Jerry

JMPRO,
Thanks, I'll keep an eye on the nuts.
I might just swap out anyway to be on safe side.
JD

Very nice John. We can hopefully try them out this weekend.

Now you need to mount a video camera down there so we can see them in action.:cool:

Nice work.

I think if I ever revisit this topic I'll be installing a HDPE sheet like the ecomodders do to increase gas mileage. Problem then will be the attachment points and how large, and where to stop the sheet. I'm thinking the cross over cover hiding the fuel pump as the back end. Attaching to the underside of the chin spoiler for the front would be idea, but would not be secure enough on impact and would cause spoiler damage.

Covering the whole bottom is always an option, right?
http://forums.pelicanparts.com/porsche-911-technical-forum/294153-poor-mans-aero-wingin-7.html
http://forums.pelicanparts.com/uploa...1154096927.jpg

Good PDF on underbodies:
http://sports.racer.net/docs/aero/rva2002_gr02_underbody.pdf

http://forums.pelicanparts.com/porsche-911-technical-forum/182467-poor-mans-ground-effects-i-need-some-input-4.html
http://forums.pelicanparts.com/uploa...1095510399.jpg

Duk, where/when to meet?
Kach, if you do something like that, would there be any way to measure before and after to see if it significantly reduced drag?
JD

The stuff they sell on the EcoModder website to estimate fuel mileage is for 1996 cars and newer. So, I'm out of luck there.

EcoModder Store: Get Stuff, Support EcoModder - EcoModder.com

I can get 26 mpg mostly highway with the top on and doing 70 mph. However the commute I did a couple of years ago to get that figure is not likely to be part of my life again.

I'd have to do a couple of fill ups and controlled runs before and after such a modification to get a good idea. Would be far from perfect though.

I have to imagine that a lot of track guys already have done something similar (not just Jack Olsen). They might know already what to expect. I suspect they use the lightest materials (thin sheet aluminum), and maybe not the heavier HDPE.

NOTE: the 26 mpg was with sticky but low height 50 series summer tires. I now run higher profile 60 series all-season tire, sitting over 3/4" higher. Between the harder tire compound and increased amount of air getting under the car, it should be the same 26 mpg, but I'm not sure.