@bkrantz very interesting read following your rear suspension set up.
remember doing that a couple of years ago.
not sure what springs you are running.
think they can make a difference to things.
og factory settings for the spring perch are suprisingly far up the shock absorber!
not that anyone should necessarily be seeking to do that.
but is an interesting base line and what you find is the car does sit suprisingly high in stock set up. not everyone's cup of tea.
i changed from the original boges to a bilstein set up as part of suspension rebuild.
we had the og rear boges with the perches in original position as reference.
non adjustable back in the day.
pretty sure i have softest springs. still using originals. a 74 1.8. could not find any paint dots but springs were coated in old original undercoat. but it has original front and rear sway bars so think spring set up would have been soft with the sway bars to compensate and to give a comfort tuned ride?
the spring perch on the rear was 180mm up from the bottom!
surprising distance.
once on the ground again dead set match for how it always was.
we worked away from that to level the front and once we had it level we went back to the factory manual and checked against their measurements.
found ourselves right at the limits of the 5 mm up or down they speced.
taking on board ian karr's comments about the original nose up attitude that USA market cars seemed to have been set to, i think the factory went to the upper +5mm of the front dimensions they give to get the nose up setting.
we found going to the -5mm seemed to be level front to back with rear spring perches as per original. ie 90mm - 5mm = 85mm we achieved 85mm on that A-B dimension.
its surprisingly high off the ground at around 190mm to the underside of the sill panel seam. but in fact thats the way it always was on mine, stock standard.
there is one more esoteric dimension hidden away in things. its in the glove box manual.
its the min clearance of car. 130mm. its to the u/s of the low pressure flaps at the front of the engine bay. we checked against that and found we matched that too with all our settings.
those factory dimensions in the manual work very easily and get the car level within their tolerances - but only if you have the reference dimension on the rear shocks for the lower spring perch and i'm guessing only if using the original factory springs.
if you want it lower i guess you work the perch down on the rear springs and keep setting it level. and use the upper value of A-B = 90+5 mm they give you on the front. that should be the way it works because A is fixed (your wheel c/l) but you keep making B smaller as you lower the car.
photos of car in 89 and 21. rear is the same its always been (but with way better shocks) and i have levelled the front. back then it had the nose up USA understeer stance.
a lot of people take their cars lower i realise. but this is what the factory benchline looks like merely for reference.
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