In an indirect answer to your question, Bentley Section 44 in discussing alignment shows correction to caster for vehicles NOT level as measured at the sliding door. Thus they acknowledge some front-to-rear angle may be acceptable if compensated for, but infer the vehicle should be level.
What makes absolute hieght difficult is that the Vanagons typically had 3 different height options. Most Vanagons came into the US as GL's and therefore had a 'lowered' suspension. Standard Westies (based on the non-GL kombi chassis) had a 'standard' suspension, and Syncro's had a raised suspension. What then occurs is in aftersales replacements, mismatched shocks & springs may be introduced. Worst, documentation from VW was poor and the parts manuals did not always differentiate the options.
Short of removing the springs & shocks to determine what you've really got and what was supposed to be there -- as well as checking for condition -- there isn't any easy answer and I don't have any specs that might help. In real world, the rear shocks tend to go first, so that's where I would start to look. (It's also the easiest.) And just because you have Boge's doesn't mean you have the RIGHT Boge's. Boge makes shocks for thousands of applications including all the VW configurations -- bus, truck, military, etc. See the "Shocks . . ." topic in the Front Suspension forum.
Since VW didn't match the color coding of springs to any published data, this might be a good time to take your dealer's parts manager to lunch. If springs are the issue, you might have to ask him to order all 3 and then pick the one that fits, returning the other. Guideline #8!
I'll again mention as posted elsewhere on the site, the most common source of different hieghts is someone putting in the wrong shocks at one end or the other.
Interesting discussion about springs. Sometime back, having observed the afore mentioned leaning condition on my 87 Camper, I replaced all the shocks, checked the tires for wear & inflation and took the van in for an alignment, requesting care being given to look for signs of excessive wear in suspension components. Everything checked fine and only minor adjustments were needed so I came to same conclusion many have about worn springs. I went to a friend on mine at the local VW dealer and ordered new rear springs only. He ordered what he said were correct for the camper GL. The new springs had 2 blue paint marks on each of them. Total cost, $365.50. Installation, about 30 minutes per side. Jack up, secure on stands & remove wheels. Support lower control arm with floor jack, remove top shock bolt & lower floor jack. The springs are now loose & can be pryed out. I wish I had bought new spring pads but old ones were still solid. Proceed to position bottom pad on control arm & top pad on spring, insert spring into top retainer first then pry up slightly to position bottom. Be sure the ends of the coils are positioned to the stop point in the pads. Jack up control arm till shock hole lines up & insert and tighten bolt. Ride feels less mushy & van appear to be level. Measurements from ground to wheel opening are approx. the same so am holding off on frt spring swap.
We've recently purchased a 1992 Eurovan MT and want to tow a tent trailer but not sure what we need to do (if anything) to make this work. So the question is - do we need to beef up suspension? Is there anything else we should know before we attempt this caravan style of travel.
Any information/help, greatly appreciated
tsmith5041: Did you get the correct factory springs? There are a bunch out there that fit but weren't for the Westy. See the Westy parts fiche at a dealer.
kcongra: Towing is very tightly limited for many reasons. Follow the guidelines in your owner's manual! Beefing up the suspension is not required as it will handle the limited towing VW allows. See the "Towing . . ." topic in ACCESSORIES.