Minimal operational clearance: Cross-member to ground?
 

Hey guys, I have been thinking about cars where the lower frame rails are running 4" - 5" off the ground, the front cross member will be the first point of contact for road hazards. What is a safe running clearance for the cross member to ground? I'm thinking coil-overs with 2.5" compression & 2.5" rebound will be a firm, but street able solution. That would be 1.5" clearance on compression. What are your thoughts?

Bumping up....

Just wondering if anyone else had this concern when designing their suspension.

Don't quote me, but I have read a couple places that about ~5" is a reasonably good minimum ground clearance for street. This would be 5" from the lowest point on the car. I'm sure many people will have different #s.

How LOW....
 

I say as low as possible and still be able to slide a jack under the cross-member:unibrow:

Ive been running just about 4" of crossmember clearance on my vette (Front splitter is only 3" :eek: ). You just have to be aware of road hazards and how you go over them if you do encounter one. Never had any problems yet... Knock on wood

I need to measure mine again but if I have 4" I'd say that's being generous. I have to use a low profile jack to get under mine.

Speed bumps and things like that aren't a problem with the crossmember. That's because the crossmember is pretty much aligned with the wheel track. Uneven roads with a high crown are definitely a problem, and the other issue is that if your crossmember is that low, the rest of your car is probably pretty low also. And, what about your oil pan. I just changed to a different oil pan to gain about 1/2" clearance as my previous pan got pretty beat up at the rear edge last year. My header flanges (Dougs headers, so they're about as good as you can get for fitment) are the lowest point, and I'm using 3" oval exhaust to help out.

Thanks guys for all the great suggestions on other concerns.

1. jacking the car
2. oil pan clearance
3. header / exhaust routing
4. crowned roads

I'm looking to avoid this donk look (22s shown, I will run 20s):

http://gallery.me.com/jbanko/100327/...uarter/web.jpg

The bigger concern I have is even if I run Speedtech upper and lower a-arms + dropped AFX spindles, I will get have some steep a-arm angles & possible ball joint bind if I can not raise the upper & lower a-arm mounting points to try to make the a-arm parallel to the ground.

This pic shows the cross member touching the ground w/ airbags deflated on another car and steep a-arm angles.

http://www.motivational.net/Chevelle...alibuframe.jpg

X2 ...

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The bigger concern I have is even if I run Speedtech upper and lower a-arms + dropped AFX spindles, I will get have some steep a-arm angles & possible ball joint bind if I can not raise the upper & lower a-arm mounting points to try to make the a-arm parallel to the ground.

This pic shows the cross member touching the ground w/ airbags deflated on another car and steep a-arm angles.

http://www.motivational.net/Chevelle...alibuframe.jpg[/QUOTE]

that looks as low as possible??????

http://i1235.photobucket.com/albums/...a/DSC_0793.jpg

This car has exactly what you are asking about, with QA1 GMP kit. and 550 lb springs. as well as the complete rear kit.
here it has 18 and 20's

.0005:unibrow: