So as the thread title states I would like to know when these warrant replacement. They're what Porsche calls upper concave washers 92834304708.

I personally haven't seen what a failed one looks like as the ones on my 928s feel soft and not dry rotted, but that could still mean they're perished in other ways.

What is the current consensus on replacing these considering the current price of over $350 each?

 

They'll cost more when you cant get them any more.

 

Study what the upper mount/mounts do, carefully. (You won't find any information...just look at the pieces and think about function.)

Note that when it functions as designed, the spring moves, initially, at a different rate than the shock. They did this to reduce the NVH of the high frequency bumps (since digressive valve shocks did not exist.)

When these parts get hard, all of this is gone.

New or old, handling is not greatly affected, but the ride quality is greatly impacted.

However, in order of priority, the lower contol arms come first. Shock selection comes next (if you are using Konis, forget the upper rubber mount...nothing really matters.) The bump stops and ride height is of paramount importance. And when everything else is done and pieces are properly selected, new upper mounts versus old upper mounts makes a radical difference....front and rear.

 

Well, I guess that answers that.

I'm replacing all the rubber in the suspension already so I may as well throw these in there too. They're getting paired with Porsche original Bilstein dampers so they should work wonderfully in the S4 update for my 81.

Time to add more parts to the order list....

 

Time for Gregs shock kit!

 

The digressive valving of the Bilsteins allows the upper spring mounts to absorb most of the high frequency movements.

You will not be disappointed.

 

We've had a MAJOR SHIFT in our thinking about the pieces I develop to improve 928's.

Due to people stealing my ideas and copying our products, most of our new pieces will only be available on our own client's vehicles and will not be available to the general public.

Think of it like Singer's headlights...the only possible way to get a pair is to buy a car.

Everyone here, knows who to thank!

 

^^ Could we still get semi vague updates on what you offer? IE upgraded cam cover baffles, custom shock and spring sets, custom air/oil separator for S3s etc. We don't need the exact details

 

I keep talking about updating our website...and end up looking at our backlog of work and the people waiting to get into the shop for work.

My son and I work 60-80 hours a week, as it is. Only recently has my wife insisted that we take off one day out of the seven day week...so that just forces us to work later into the evening.

Obviously, not a bunch of spare time, as it is....and we are afraid to add more work into the equation, until we can find more help.

Qualified 928 people are few and far between. It has always been that way, but it has gotten worse with time.

Personally, I spend an extraordinary amount of time doing developmental work...because thinking and developing are my real passion. Making profit from the developed pieces is not even a consideration or a requirement....that's not the goal.

However, the goal is definitely to develop and make these pieces, for people to steal the intellectual property and copy it!

For instance, I've spent the entire last six weeks doing developmental work for a larger displacement (5.8 liter) two valve Euro based engine. Almost zero of those hours will ever be billed....it's more for my own satisfaction.

The main goal to build something very unique for a client. (425-450hp, and pass California emission standards, is the goal. 375hp is pretty simple. Beyond that requires a bunch of effort.)

Obviously, this throws a wrench into the backlog of engine building and spare time (I built all the engines and transmissions), but most of the people waiting understand.

They are waiting for something special, also!

 

How can I be your Client overseas?
l´m not satisfied with the ride quality of my car. More power is also good. The dilemma in such a small area like the 928 Community is That 90% of the owners here in Germany have the mantra originality and clean it to death .
Passionate drivers have very low chance to find a Shop with the right Knowledge.
My Shop tells me everytime the new billstein has a harsh Ride quality and prefer Konis but I know he doesńt change the Upper Spring mounts.

My feeling is my car has so much unexplored improvements under the surface.

 

^^ That would be a nice goal with my engine once I get it to you. But that'll be hard with just standard Euro S cams, S2 are a lot harder to find and I can get the S ones new.

Plus I'm going to guess a fair bit of that power will be in the top end, which is worthless to me. It'll be interesting to see how it performs if you post a dyno graph in the future.

I'll just assume they'll go with S4 injection since it just works and doesn't need all of the obscene tuning an aftermarket system does.

 

I don't know who thought the Bilsteins were harsh, they were great in my 81 even with 18 inch wheels on terrible in comparison California roads (we repave them every 20+ years if we're lucky unlike Germany's 5).

The best thing you can do right now is to replace all the rubber in the suspension as it has all aged well past its best by date.

Luckily it's all available from either Porsche or through the aftermarket like 928 International's rebuilt A arms and new Weissach links.

 

The interesting thing about the upper spring mounts is that Porsche never changed them, as the cars got heavier, the tires got wider, the spring rates changed, and as they installed different brands/types of shocks.
One size/stiffness fits all.
We've done a boat load of R&D in this area, alone.

The difference between a Koni and a Bilstein with digressive valving is like the difference between a grape and a cantaloupe.
However, the design of the upper spring mount and the shock mount (on a 928) separates the spring from the shock a certain amount.....when the spring mount isn't rock hard.
And the suspension on a 928 was certainly not designed around a digressive valved shock.

The "issue" with a Koni is the adjustability.,,,or the difficulty of adjusting them in a 928 application.
They are very sensitive and tiny changes makes a world of difference.
On the 951 M030 cars, 1/8 of a turn completely changes the way the car drives...very sensitive.

Of course, there's a whole "group" of 928 "experts" who think that a 928 needs to be super stiff to handle correctly and just "crank" up the stiffness on the Koni shocks.
They are confused and think that 928's are Formula One cars.
As Glenn Yee is famous for saying...don't even waste your time talking to these idiots,
just drive around the inside, when you get a chance.

 

Thx a lot Greg,
if I dig in this area I will contact you because I‘m too stupid to understand the Solution for the understeering Safety Thing. First I Need 2 S3 Oil Control baffles from you for my engines and a bunch of the improved gaskets .
After Inspektion of my S2 engine I saw leaking cam towers .

 

The solution that is the most cost effective is either stiffening the rear sway bar with special drop links or getting a smaller front sway bar from an early 928 of the 78-79 variety.

After that comes wider front tires ( just wider rears will induce understeer).

These two should make the car handle much better without sacrificing comfort like stiffer shocks would.

Easiest thing to memorize is stiffen up the rear if you want more oversteer, stiffen up the front if you want more understeer. Find a balance of the 2 that you like and roll with it!