antlee928

Hi, OK current ride heights are:

Front Left= 142mm
Front Right=145mm
Rear Left=160mm
Rear Right=163mm

As measured at last alignment in February 2015.

My issue is that the fronts won't adjust and do not have time to resolve (removal of dampers to "unlock" seized adjusters. Rear adjust ok.

So, given this situation what recommendations from the list for an appropriate rear ride height given the front (currently non-adjustable) ride height.

Driving with current set up (seat of the pants) seems to have the following effects:
1. Feels nose heavy under braking i.e. feels like more weight shift than should be expected;
2. Corner turn in from Apex out feels understeery requiring more steer on exit;
3. Power steering feels heavier and more loaded (new PS rack installed about 12-18 months ago).

Looking forward to some practical ride height suggestions for rear. Car is not tracked but does enjoy some fasy road exercise :-)

Thanks in Advance

UpFixenDerPorsche

Hey Ant. A few questions:

- is this just a recent thing, or has it been around for a while?

- what is 'nose heavy' under braking? The 928 does not like 'trail braking' - ie braking while turning deep into a corner (becomes light in the rear). Given the 50/50 weight balance it's far better to brake hard to a specific turn-in point on the ground, then accelerate from there, producing a rearward weight shift (balancing the car on the throttle), as this will allow the front tyres to deal with cornering forces only, and make the rear toe correct outwards as per Weissach axle design, to lessen understeer.

- power steeing feeling "more loaded": is the PS belt tension correct? Less tension = slippage = lower PS pressure.

Having said all that, what are your wheel alignment numbers? Toe and camber, front and rear. These can be set to spec, irrespective of the ride height, so you can discount ride height as being a factor for the moment.

Then there's ... ahem ... ... koff koff ... tyre pressures ...

Cheers Ant.

Trust this helps.

Upfixen.

dr bob

I'd leave it where it is and sort the whole thing as one as soon as the time is available. I shared a guesstimate formula on a recent similar thread, suggesting that it takes at least 6mm or more of downward rear suspension adjustment to get the bottom rear of my front spoiler to move up 1mm. You don't have any space at either end, unfortunately. Drive carefully!

Hilton

Given you don't have time to fix the fronts, just leave it as-is.

Lowering the rear isn't going to fix your issues with steering feel etc - they're caused by the change in geometry due to the very low front height (you're almost 4cm too low in front).

Sounds like your best bet is to gather up the parts (including some used working adjusters), and book some time to swap shocks and clean up the suspension.

Captain_Slow

Nice explanation...
My car is 151+/-1mm in front. 165 rear driver side, and 163 rear passenger side. When I sit in it, an eyeball check at the wheel arches becomes equal on both sides...so maybe higher on the driver side is actually a good thing to compensate for the weight of the driver. Some days I think I'll get it aligned as it is...others I think I will remove the shocks and deal with the seized adjusters in front. I know the latter is what I should do. I'd like the front to come up to 165 to match the rear.

FredR

Your situation is rather 928 typical. A well set up 928 that lies within factory specs understeers by design and if the front end drops it simply exacerbates this condition with more weight on the front wheels.

If you are not prepared to rectify this defect then all I can suggest is that you fit a set of Carl's bash plates and hope that you do not hit a severe pot hole in the mean time as your alternator and a/c compressor are now in a target rich environment.

I would think it will be way cheaper to pay someone to rectify your problem now than to fix the pothole damage that could also wreck your entire motor. In simple terms you have a loaded gun and the odds are not in your favour [I would politely suggest].

Needless to say if and when the ride height is corrected you will need to realign the car.

I was somewhat surprised to read Upfixen's opinion that the 928 does not trail brake- I was under the impression it does that rather well, especially if you have a 33bar bias valve fitted. It would be interesting to hear from our track stars in the US what their perception of that concept is.

antlee928

Many thanks. Judging from all responses it appears best to attend to the front ride height sooner than later. The car was "set up" this way when I bought it and so far (fingers crossed) I have not had any issues with bottoming out and doing damage to the oil pan.

Thanks again

Cheers Tony

antlee928

Hi Hilton, well as you can see from the other posts that this is the best course of action. Although my priority at the moment is TB and WP. Thinking of giving this a crack myself (given that the 928 is not a daily driver). Also considering Porkens Tensioner versus the factory standard tensioner system.

Thanks again and thanks to all who replied.

Cheers Tony

FredR

Tony,

I would recommend the bash plates even if the car was 3 feet off the ground [slight exaggeration]! As I understand the problem is not so much the oil pan but the lugs that the accessories hang from that are cast into the block. The force transmitted can and quite often does crack the casing and makes $30 or whatever look ridiculously cheap. Carl had a special recently on these- not sure if it is still available.

The problem with this sort of issue is that it is not a problem until it is. Then you wish it wasn't!

Pulling the front units is not that difficult and the parts to resolve are cheapo bucks. Get a few of the boys round to give you a hand. The nearest I have to that kind of assistance is 500 km away in Dubai and I presume you do not live at Roswell or where the first nuke was detonated.

Rgds

Fred