Captain_Slow

This morning I cleaned and PB Blasted the adjusters, then marked them with a Sharpie, making it easy to rotate the adjusters one complete turn.

Put the C-spanner on the adjuster nut and was surprised how easily the right side turned. With each eighth of a turn of the adjuster the spring would twist with it - then release and twisting back to a natural position.

The left side required more effort. The spring twisted with each turn, but didn't return to natural position with every partial turn. I could sense that tension was stored in the spring, extending it very slightly. I tried rotating the adjuster left and right several times, to release the tension, before leaving it at exactly one turn higher. The spring returned a little, but seemed like some tension remained.

I drove the car about 25 miles, including going over every speed bump in the grocery store parking lot, a rail road crossing, fast turns, and mildly rough roads. I was hoping both springs would settle at close to the same level (they were level before I turned the adjusters).

Left side is still higher than the right.
1. Should I lube the spring perches with some WD-40 and just drive it for awhile to allow the springs to find their natural position?

2. Is it normal for left and right to need different amounts of adjustment?

3. Has one turn on the rear affected the front? (I don't notice any difference in height or handling.).

I'll make new measurements to points described in he WSM after a bit more driving.


I did sense a few immediate improvements: The back end handles better. Cars behind me now appear in the middle of the rear hatch glass when viewed in the mirror (not partially blocked by the high center taillight). And best off all...the rear tire noise is gone. The car came with rear tires worn badly on the inside, and made a fluttering sound (to much camber was wearing the tread blocks on the inside). When I replaced the tires (about 250 miles ago) the noise continued (at this point I knew I had to adjust the ride height). Now all four tires are silent. (Hankook Ventus S1 Noble 2, high performance all-season, on 18 inch Panamera 5-spoke wheels. Very quiet tires).

Chalkboss

I will follow this with interest, as I need to check my ride height. Note that if the ride height changes this will change wheel alignment angles. Just don't want you to wear out those nice tires prematurely.
That is interesting about the noise going away.

fraggle

Spraying everything down with wd40 wouldn't hurt.

Captain_Slow

Haven't applied WD40 yet, but did take it for another drive. Afterward the high side (left) has come down a few mm. Right side has stayed constant. Noted that when I'm sitting on the driver's door sill the left rear drops until both sides are level. I think Taylor Chapman (AutoWerks in Sterling, VA) told me that he puts bags of sand in the driver seat when doing alignments (I think the manual says to do it). Just makes me wonder if spring rates are a bit higher on the left side.

As for tire wear, the plan is to do an alignment at Chris's get together on July 26. He told me to adjust...drive...adjust....drive...etc. until I get it where I want it, before the gathering.

I've had a few setbacks with the brakes and fans. Having an easy time with the adjusters was just what I needed - a small victory

RKD in OKC

Unless the springs are progressive the spring rate should be fairly constant throughout the travel.

Ride heights do effect the geometry/alignment. When corner balancing a car, you assume the spring rate is the same on all four corners and balance weights on each wheel with the driver's weight in the driver's seat. So, by that logic you should do an alignment the same way.

It takes time and lots of bumps to settle the 928 suspension. When the local dealership mechanic does a 928 alignment and has to lift the car to do anything with the suspension, he does the prescribed strap pull down on the suspension, AND drives the car on bumpy roads for 30 minutes to make sure it is settled before re-checking alignment.

UpFixenDerPorsche

Hi Captain_Slow.

A couple of thoughts for height adjustment:

-ever tried to get all four legs on a table 'just right' so it doesn't wobble? Every time U remove a smidgin from one leg the table wobbles on another. Same with the 928. U can't adjust one corner without affecting the others.

- was driving me nuts one day so I stopped and thunk for a moment

... if I lift one end with a jack in the middle between the wheels, I'll be able adjust ride height of each side at the other end as theres no interaction with, say, the front wheels as they're off the ground and the car is able to rock to either side as the rear heights are adjusted. Then repeat for the other end and you'll have each corner height exact.

I use a length of timber that extends under the lower ball joints at the front so the front can be jacked without the suspension drooping. Only needs to be lifted and inch or so.

Apart from cleaning the gunk out of the adjuster threads the longest part of the job is moving the plank end to end.

When U get exact ride heights the corner balance (weight of each corner) will be even side to side.

Porsche specify that the side to side and front to back weight differences must be less than 10kg. Helps with surefootedness.

To cater for a heavy driver (I'm 240 lbs), before I begin I first measure the drop in body height at F & R driver's side guards when I sit in the car, and then later adjust that into the driver's ride height. My wheel aligner lets me sit in the car whle he 'aligns'.

Key aspects of this method are it's preciseness, avoids suspension drooping, and doesn't take hours and hours.


HTH

.

ammonman

The WSM calls for the left/right heights on each axle to be within 10mm of each other with no more than two turns difference in the position of the adjusters. As long as you are within the specified height range for the axle and are within the limits above you will be fine. This should put the corner balance within the prescribed limits.

Mike

RKD in OKC

Corner balancing is not done by the vertical height of any suspension point. That gets you in the ballpark.

Corner balancing is done by the weight on each wheel, and really has to be done by driving the car onto a scale for each wheel, i.e. 4 scales without lifting it to set it on the scales. Adjusting the height adjusts the weight on each wheel with respect to the other wheels like your four legged table example. It is done with the weight of the driver in the driver's seat and 1/2 tank of gas.

Takes time to do it right. And when done the car may not actually look or measure level.

As a note: Because the car takes time to settle, depending on your driving style, it may actually be better to balance the car for it's dynamic or "as driven" state. Example: if the rear starts riding high or getting light in the rear because braking is lifting the rear more than acceleration is settling it, the car would handle better if the rear is set a little low once settled. A few good hard stops and the car is balanced again. That's been my experience. The amount to offset would be dependent on how hard you are braking versus accelerating. The same could be said for left to right balance based on the number and force in turns if you want to get really precise.

It's all about setup.

Captain_Slow

Thanks to all who responded. Very helpful. Seems I have it set within spec and just fine for regular street driving. In a week or two I'll measure at the points under the car and see if all four corners are within the WSM specs.

dr bob

FWIW, if you are making the adjustments with the car lifted and the springs relatively unloded, you can just grab the spring and twist it one way and the other until the ends sit all the way in their recesses correctly. Grab, shake, look, until it drops in.