View Full Version : Exhaust ground clearance

09-06-05, 09:05 PM
Hi Guy's,

In expert opinion...what is the MINIMUM ground clearance needed for underslung exhaust...especially the rear boxes......trying to set my system up at the moment without too much joy....cheers...steve

09-06-05, 10:46 PM
Not sure about the expert opinion bit but I can tell you that my system has a clearance of only 60mm at the lowest points, the boxes are fitted with skid plates that have leading edges on them, they scrape quite frequently but are still in place.

p.s. you soon memorise where all the speed bumps are!

10-06-05, 01:58 AM
Steve. Had underslungs on Dax De Dion which has slightly less than naff all room underneath. My most vulnerable point was just rear of the front wheels wher the pipe came down and bent back towards the rear, hence, front wheels coming down speedbump leavingthem very exposed. They were approximately 2 3/4 inches fromthe ground...

The rear boxes (well, kind of an oval cylinder thing just slightly wider than the 2 1/2 inch pipe..) were cleverly placed between the rear wheels. Good Ol DB.. They took a little hammering at the bottom of a hill where they'd ground out.. I think the distance was about the same..

Never had skid plates, and the system never fell off..

David Large
10-06-05, 06:30 AM
I used to have a very low exhaust system which would scrape the road quite often. That is ok; but tice i pulled half the system off on the channel tunnel trains. Putting it all back on on the platform is not so much fun......but possible. I raised the rear ride height a bit, re aligned the system and so far so good. It doesn't catch the road now but next Thursday is the tunnel test!
I will measure the min. clearance this weekend

10-06-05, 09:03 AM
Thanks Guy's....I think i have been a bit OTT with the size of the rear boxes......but even so it looks like i have about 75mm max clearance ( but not too keen on the look of the car from the rear due to the boxes being so low down!!)....looks like i may have to scrap them and have smaller ones made!!!


Grease Monkey
10-06-05, 01:13 PM
Road humps should be under 100mm, so if you're running anything under this you may be in trouble..



10-06-05, 03:52 PM
I suspect that there are too many variables here to give an absolute figure - where on the car the lowest point is, (i.e. within or outside of the wheelbase), the softness/travel of your suspension, and so on.
On my old Sumo, the downpipes and a section just in front of the rear axle were ground to a half moon shape. On the Crendon, the exhaust never grounds, despite being underslung, as it is not the lowest point anywhere along it's length.

Good old trial and error is probably the only way you will discover what works on your car, but from memory, the RAM is one of those chassis' where sidepipes might be the better way to go.


10-06-05, 04:10 PM
Talk to Simon Finlay!! :thumb:

He knows all about Exhaust Ground Clearance !! :D :D :-( :-(

or rather what clearance NOT to have!! :rolleyes:

30-06-05, 10:39 PM
Minimum workable clearance on a public road is 4" firm. Anything less and your in trouble. If you are going to race the car and want maximum performance side pipes are the only way.



30-06-05, 11:51 PM
I have underslung pipes on my RAM and they never hit, the lowest points are the bodywork under the oil cooler and the sump.

01-07-05, 12:46 AM
i have approx 4.5" clearance.....

What have I done wrong!???!??!??

01-07-05, 09:59 AM
i have approx 4.5" clearance.....

What have I done wrong!???!??!??

You have accidentally built a jeep replica. :thumb:

Go back and read the build manual again! :D

Grease Monkey
01-07-05, 11:06 AM
i have approx 4.5" clearance.....

What have I done wrong!???!??!??

Take the Land Rover wheels off!

01-07-05, 10:33 PM
Maybe it should be 6 bricks per corner instead of 8??