Took The Mule's suspension apart today. I surprised myself slightly by getting the spring out without unbolting anything but the top of the strut. I was *amazed* that after being installed close to 15 years, the spring perch still turned freely on the sleeve.
The 6 5/8" metal to metal travel limit checks out.
Full droop ride height:
19 5/8"
Metal to metal contact ride height:
12 1/4"
Bump stop *contact* ride height:
13 11/16"
ETA: "Metal-to-metal" means that the top of the strut body just touches the bottom "bell washer" that installs under the strut top bushing. The bell washer is there the retain the end of the strut approximately where it needs to be if the bushing comes apart. A really hard hit would both deflect and maybe tear the bushing as well as possibly flattening the bell washer, so this isn't he "structural contact" ride height that would do serious damage to the tub or the strut... that's maybe 1/4 - 3/8" more jounce travel that what I measured.
It's weird that the difference between the bump stop and metal-to-metal ride heights is 1 7/16", as the bump stop measures a smidge over 1 3/4". I may have compressed it *slightly* when positioning the suspension and could be off on the ride height a little bit, but I don't think those effects can turn 1 3/4 into 1 7/16.
ETA: I just realized that this discrepancy is there because the top of the bump stop fits into the bell of the bell washer, so the bell washer cuts down on the difference between metal-to-metal and touching the bump stop.
Full droop travel:
Metal-to-metal contact:
Gap to the outer fender lip:
Gap to the rear trim strip:
Gap to the front trim strip:
From the four photos above, rubbing on the front trim strip is probably the first contact point, but it can be mitigated by moving the wheel back in the wheel house a bit. An adjustable trailing arm could do this on an '88 and a custom fully adjustable control arm could do it on an early car.
2 7/8" from the tread surface to the rear fascia:
Can't really get a comparable measurement, but ~2" for the corresponding measurement to the quarter panel:
Inner lip clearance to everything in front of the axle--nothing is even close to the top of the tire:
Inner lip clearance to everything behind the axle--I can still get my finger between the top of the tire and the wheel well liner:
The toe link is danger close to the frame rail:
I bumped my spring rate up 200 ppi, shortened the springs by 2", lowered the car slightly to a 15 3/8" ride height... and the spring perch barely moved
The spring is seated directly against the strut top plate, so it won't be going up any more. If I build a fancier top mount with an axial load spherical bearing and a needle bearing set to let the spring squirm, the perch could come down another 1/2" easily. Shoot, I may have to go to 8" springs.
Also, flipping the strut top plates, or making new ones that put a spherical bearing strut top mount ABOVE the top of the strut tower could lower the metal-to-metal contact ride height by *maybe* as much as 2", but that really just means that the current metal-to-metal height becomes the new bump stop height. Still not bad, though. I haven't run the numbers yet to see if I can get 8" springs that will have enough travel from ~15" static ride height to hit the bump stops a meaningful distance before they coil bind.
If I could get the current metal-to-metal height to be the new bump stop height (unlikely that everything can package in the space available), then a 14 3/4" ride height, which is about what Steven's running, would still have 2.5" of compression travel before even touching the bump stop. With 550# springs, that's 1375 extra pounds on the outside tire in a corner... that's a LOT of cornering g's!
Currently, at 15 3/8", I'm only 1 11/16" off the bump stops.