The Eibachs that were designed specifically for the 928 as I am aware are a similar length as the stock springs whether exactly the same not sure- they are a progressive rate spring that divides opinion- personally I think they work very well and were developed in conjunction with Eibach by Mr Kim Crumb who has a most impressive 928 CV. What you need are the adjustable perches that were not a stock item on earlier models and it may be possible to get an extended range version but then your regs may impact such. There is also the hypercoil spring option- just a question of how eagle eyed your scrutineers are and of course your integrity as a competitor- I am all for pushing competition rules legally.

 

Well, OE is roughly 13.75" long, and 2.5" inner diameter.

The stiffest oe spring is maybe 230 front 175 rear...so..shop for that ID and length.

I'd look for UP to 650 front, 300 rear..no lower than 575 275 depending what you've taken out.

And you're going to need way more shock to deal with that too, not sure the OE fitment options here, Carl can likely help there.

 

I measure now under sump and sway bar mounts 5" …. ( only driven the car a few meters after changing wheels… so can be even less after more miles )
so i need the car sure 1" higher and stiffer…. but also not to much : i know from my local (prof) rally shop ( BMW ) that to stiff isn't good for car handling.
Pity, i can't compare it , those are MacPherson struts , so the spring acts as almost in center wheel. A 928 has them more inboard , so a leverage , they must already be stiffer by design to have the same results.

 

A street spring on a HEAVY car on rally roads...will never be acceptable.

Good luck.

 

Exactly!

 

From memory they are 25% stiffer.

 

i have to found a compromise…. oem look , higher ride height and stiffer … let's not forget "off roads" are normaly only small sections , sometimes none. And we can be careful on those , and gain average time back on the following better paved ones. In the end is not "rally" for speed , for that i have my other build…. but not street legal. Only allowed in rally events.

perhaps a explanation :

rally cars have a special "book" from rally authority inspection and must pass tech inspection every 6 months … example : to check that the brakes work ,OK, but they get disapproved because they are not oem. One gets a "red" document , only allowed for official rallies. NOT street legal.
regularity cars must pass tech inspection as a daily , to get the "green" document , so street legal. And here they are severe , a "oldtimer" , historic car must be OEM ! no changes allowed except some small things…. sure not suspension,steering,brakes,engine etc....also "stupid" demands : strut brace not allowed, tires only up to 1 grade wider, hood pins not allowed ( hinges and slot must be oem ) .

Of course a strut brace is no big deal to remove it for inspection…. shocks&springs is a bit more work…..

 

There are stiffer stock springs available, fits some koni internally adjustable with those springs and perches maxxed out height wise and your should be good to go. Not many 928's actually sit at the factory proscribed ride height but when they do they look as though they are on stilts- that is the look you are going for by the sound of it- plenty of daylight between the top of the tyres and the lower side of the fender [25 inch rolling radius wheels]. When set per factory settings there is about 3 inches of daylight and looks more like a rally car out of the factory!

You can live with 25% stiffer springs no problem- just a pain at slow speeds like over speed bumps etc then they knock your fillings out!

 

And I handed you that on a platter.

Yet here we are still wondering what to do.

 

Ya...street speeds...etc..add some real energy to what you want the springs to do..and he's still going to eventually split the block in two.

He needs to _arrest_ and manage vehicle weight.

 

Would a 1/2 spacer ring between the body and upper shock mount sneak by? You will need longer bolts but i think it accomplishes some of what you need.

Also S4 springs are a better choice. When I upgraged my S2 with a complete S4 suspensions it was clear the springs were stiffer and I recall the spring wire was a bit thicker. Stands to reason as S4 got a bit heavier.

 

Barry, I have a stupid question, but does your car have the suspension height adjusters? From memory early cars didn't have height-adjustable suspension, in which case sourcing the later 928 OEM suspension setup that lets you adjust the height upwards would be a good start.

 

Hilton , adjusters only in the rear , fronts are fix.
Iscamerica, no spacers … not allowed for tech inspection… as sure no wheel spacers ! Offset ( ET ) must be right....
Speedtoys, i think mine are bigger than 2.5" diameter … yes, those in Carl's set on the rally car , which are common in rally cars and available here in all rates.
Will check this evening .

 

Google ‘928 Expedition’, this guy has the setup your looking for.

 

The Eibach springs, at least the 928-specific set that 928 International sold, are shorter than stock. I had the adjusters up all the way up in front just trying to maintain 170mm height, the bottom of the factory warranty-acceptable range.

Barry, in the US, there were "competition package" cars that had some mods, including some springs and Boge sport dampers. I wonder if you could sneak in a set of adjustable perches on those shocks, as they were fitted that way on those certain cars.. After that, having coil springs made to spec is not impractical, assuming that there isn't a factory option from another make that could be cut to fit.