Hi all,

I am building a new garage and just realized that the slope of the garage approach could possibly be an issue. I currently have stock suspension in my C4S but plan on the M033 ride height in the near future.

Standard approach is 6' with a 1" per foot slope. So, 6" rise overall.
The approach is off of a public back lane (alley) and there will be no step.

I know this is hard to determine without measurements and numbers but any input is welcome.

I am going to create a sketch. Does anybody know min underside clearance with M033 ride height?

 

Never mind.....

I'm sure I will have more than 1.7" of clearance. Shouldn't be an issue.

 

Arh you beat me to it...

A geometry exercise! When you say no step, nothing? Usually where your approach meets the garage footing there is a step, usually 1-2"?

I think you will be ok but it will be tight. Just a rough calc, (and if its tight I would do an exact calc,) but say your car is 5" off the ground at the nose. You go in about 30" before your tires hit and start raising you nose. On a slope of 1" per 1' at 30" "in" your approach will have raised up 2.5" towards your car leaving you about 2.5" Pretty close, but it looks doable if you go slow. And that's dead in, if you can come in at an angle it will help.

Obviously you can't do anything with the alley, but if you can moved the garage back a few feet, that would probably help? Or not an option either?

 

FWIW If you have never had a garage with a slope before, a Porsche will find the exit by itself when left out of gear....

Ask me how I know

 

You are probably correct in saying that there will be a small step at the base of the approach.

I might go with a 4" vertical rise on the approach instead of 6". It can only help.

Thanks

 

I have no idea how to answer your question but I'm very impressed with your "sketch". You must have slept at a Holiday Inn Express last night!

 

 

Lol,

I was (am?) a mechanical designer for years - aerospace & manufacturing.

I always keep a 3D CAD package on my desktop for important issues like this

 

Does anybody else see the glaring error here?

 

Few unknown's....tire compression, etc.

Feel free to mention any errors. I whipped the sketch up quick.

Tire diameter was incorrect, but it doesn't change the 1.7" min clearance required.

 

Well, for one, the diagram is based on an 18" diameter wheel but with an overall diameter with tire of 22.064". Which is 2.73" less than the 24.8" diameter of the 285/30-18 tire. Therefore, which means that there would be approx 1.365" of addl clearance.

Disclaimer: I don't remember very much about geometry and certainly am not an engineer. So, I may have misread the diagram entirely!

 

I think the wheelbase is 89.4 inches.



Andreas

 

How nerdy is it that only thought at the sketch was, "oh, looks like he uses Inventor." CAD designer here as well...

 

I have a civil engineering company and most of the custom homes we do grading for I generally think an exotic will park in the garage. The owner is always happy to hear that I will try to make it driveable even on a steep slope. With that said I would try to get that slope to be less than 8%. 6/72 is 8.33% 4/72 is 5.56%. Your picture falls within driveability for Los Angeles, but I think they still factor some old Cadillac from the 70's for clearance.

When I was low on my 993 I don't remember having clearance issues on any normal driveway, and I would think that going into the garage is much less steep than a driveway.

Any chance you make the the transition longer than 72"?

 

When I built my house, our garage was lower than the street and we had a significant hump from the street to the drive since the driveway needed a hump to keep storm runoff away. When I checked it for exotic approach, I found that low sports cars were not the issue, the long wheelbase 70s Cadillac however would scrape.