Ground clearance. Where is it measured to? Grand vitara XL7

Started by Anthony755, July 01, 2017, 10:06:07 PM

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Anthony755

Hi all

I'm considering lifting my 2004 stock JA 627 type 2 XL7,  and am trying to establish what amount of sag the car has from sitting 14 years on perhaps original Springs, struts and shocks.

I see the owners manual states the 2.7litre cars had 194mm of ground clearance new. If they were telling the truth,   rofl what were they measuring?   My car has a new 235/60R16 spare. Correcting for measured tread wear, my rear diff at the standard tyre pressure of 26 psi is 176/177 mm from the concrete.  The RHS chassis rail between the doors is 216mm off the concrete. Front transverse exhaust under bell housing 180/181mm. Join between two catalytic converter/mufflers =184mm. Front of rear cat con /muffler =184mm. And the lowest part of the vehicle after the rear diff, is the front of the front catalytic converter/muffler under the passenger front seat.  That finds itself at a corrected 179 mm off the concrete.   

I'd guess Suzuki pumped the Tyres up to perhaps over the max recommended pressure for the rears of 36psi before finding a ground clearance figure for the owners manual.

Is anyone able to shed any light on all this?

Would be interesting to get an idea of existing suspension sag so I can weigh up likely lift gains versus cost, but I'll leave it here for now.

Cheers

Anthony

GP

look at it a different way
your objective is to see if the springs are sagged
The ground clearance is what it is.. so...
Your owners manual will state how tall the car is at a certain spot along the roofline. This is a known number, provided by Suzuki so we use it.
So take that number in the owner's manual, (make sure your car is empty of stuff first) and measure the height of your car at the same spot and you got the overall height difference give or take what's in the petrol tank.
Let's say that there is a difference - the only other question to ask is what's the other variable to the height apart from springs and that's tyre size, if the tyre height is non standard, so...
Then, you look up the overall diameter of the standard wheel, divide by two and there's the radius, which is what's used.
If you're already running standard sized tyres there should be minimal difference (as you stated) allowing for tread depth and slight difference between brands so don't worry about it if there's a difference of a few mm
If the tyre is non standard lets say it's a taller tyre, and the difference in radius is 15mm more than standard.. subtract 15mm from the overall height difference and you have a figure, which can only be related to the springs themselves in which case the number will be
1. same as stock
2. lower, or,
3. higher (because you are not 100% sure if the springs are genuine XL7 or not)

Because the distance from the roof to the bottom of the chassis rails is always a constant number then the ground clearance is what you get after the other measurements are done (because the ground clearance number will vary too much depending on where that's measured from so.. it is what it is after the other 2 more reliable measurements and sums are done

cheers


Anthony755

Very elegant, i like it.

Just took a quick look, then stumbled at the first hurdle  :'(.

Total height (with roof rails) stated as 1740mm
Total height (without roof rails) stated as 1685mm

PS, these are stated to be the same as the 3 and 5 door GV numbers

BUT Actual measured difference between the two heights on the car, (highest point of roof rail to corresponding point on roof top) is 30mm (not 55mm) . I think the people in the manuals department weren't too bothered about real numbers.

Anyhoo I'll use what we have and see what I come up with.

Thanks  .applaud.