hacker-pschorr

I've driven 928's with the max pressure on the sidewall (usually 50psi) for short distances. Usually going from my shop to another garage while the car is in "storage". The ride is jarring (even with 16" wheels) and the handling is, odd, but I never really paid that much attention since I knew it was going to be off.

I cannot imagine 60+psi in the rear.

Petza914

That's crazy pressure. I run 32 psi at all 4 corners with my 18x8 and 18x10 wheels with 235 & 275 tires.

Babado

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The shop said high pressure originally sets the bead and it's easier to move car around the shop, makes sense, tire pressure reset was forgotten since I showed up earlier than expected to pick up.

hacker-pschorr

That happens a lot and yes you set the bead at a higher pressure. No fault there other than forgetting to lower them before the customer picks them up. Every shop has done this more than once.

tv

this kid does a pretty good job on some key points for noobs - he loves the handling and taking corners, nice looking early car

gbgastowers

Triple digits fun in NC results in possible jail and maybe car impounded. Not worth it for me any more. I grew up in southwest Oklahoma plains where you can see for miles and low population. That was a dream for high speed. If you went off the road there you usually just went into flat farmland

SwayBar

Several months ago I bought 4 Koni Classics, set them to full-soft - and they are fantastic!

They are firm but not harsh - they feel perfect for a Sport/GT car on the street, and are half the price of the Boge Sports.

Adamant1971

I always thought my 87 drove well. I recently purchased another 87 with 15k miles and wow what a difference. Obviously my old 87 needs a full suspension R&R, I did the shocks back in 2014, but it clearly needs more.

Babado

I'm reporting back, the car drives completely different with 36f,36r, took my normal ride home, left and right sweepers posted 55 mph at 80 mph and she felt good, I'm going to have a local Rennsport shop look at the suspension and give me their opinion.
Adamant, 15k vs how many miles on your old 87? I do think the suspension can feel better, I know it's 37 years old rubber wears as do the shocks.

Speedtoys

I should head over the hill sometime in the next month or so...lets get together.

Entire suspension right now, is OE and <2yrs old.

Adamant1971

My old 87 has 240k km.s on it. Shocks were done at 185k back in 2014. I would have to look at the records but I think the upper A-arms were replaced in the late 90's. For sure she needs all new rubber bits.

Babado

I go in for registration 8/18, let me know when you'll be around I'll be legally driving it by then.

Speedtoys

I have PCA concours that date..we'll setup something soon after that.

GregBBRD

All of the following assumes that a car is set to a "reasonable ride height"...the front not being lower than 155mm.
Once the car gets much below that height, the car is riding on or very close to the bump stops and the "stock" suspension pieces need some "help", in order to get the shock away from the bump stop. (We've got "ultra high performance" pieces which allow the cars to be set to below 100mm.)
By 145mm, the choice of shocks is somewhat moot, as the bump stop becomes the primary shock absorber, in compression. (Unless stock pieces are modified.)
Rebound is still a factor, but the force of the "rebound" needs to include the force that the bump stop exerts. (So if the shocks are very soft, they not only will not be able to control the unsprung weight but probably can't even keep up with the bump stop.)

Unfortunately, there are many 928's sitting way too low, ruining the handling of these cars.
"Good looks" and "good handling/good ride quality" are very often an oxymoron in a stock 928....

The other thing to be aware of is that I'm "discarding" shock dyno results from shocks that are extreme "outliers"....shocks which I consider to be bad, right out of the box. (Not an issue in higher quality shocks.)


"Compression" in a Koni and a stock Boge (now F&S) are very close to being the same. Note that no amount of "adjusting" the Koni will change the compression numbers, unless the shocks have externally adjustable compression (expensive to have done.)

"Rebound" in a Koni at full soft is very close to the numbers of a stock Boge (F&S) at .5in/sec.
The force numbers stay very close to each other, up to about 2.5in/sec.
By 5.0in/sec, the stock Boge has about 75 pounds more force than a Koni at full soft.
By 9.0in/sec, the stock Boge still has about 300 pounds more force than a Koni at full soft.

What does that mean?
In normal driving conditions and in steady state corners (no bumps), a Koni at full soft and a stock Boge are very much the same.
However, at higher shock travel speeds, the Koni, at full soft starts to lag behind the stock Boge. The Koni, set to this stiffness, will be loosing the ability to control the unsprung weight.
At the upper limits of shock travel speeds, the Koni will no longer be able to control the weight of the unsprung weight. The bump stops, in the car, will be the controlling factor.

In short, someone buying shocks would generally be better buying the stock "off the shelf" Boge/F&S shock versus buying a Koni set and setting it at full soft.
However, the issue with stock Boge/F&S shocks has been consistency. The shocks we have tested were like "fingerprints"....no two the same.
These shocks probably need to be dynoed and then return/discard/sell on the internet the "lame ones".

As I mentioned before, Konis also tend to be a little "fingerprinty", especially in the lower "force numbers" once the shock are adjusted towards the stiffer side.
(Not very handy to have two front shocks off by 100 pounds of force at slower piston speeds....it's like having one shock which works and one which is completely worn out.)

Bilstein and Boge Sports usually have much better consistency, which is why we tend to use these brands.

Schocki

When I updated my GTS to Bilstein shocks and replaced worn parts in the suspension, the effect is very noticeable.
​​​​​​Car sits on factory springs but is set to the minimum factory height when delivered in 1992 (not the minimum permissible height of a sagged suspension).

I do my own suspension setup with self-fabricated laser tools, tangent calculation and turn tables for the wheels. Suspension height was adjusted with a full tank and my weight in the driver's seat.
Takes a couple of tries to get it right, but it's certainly worth it. After the height is correct and has settled, it's time to get the suspension angles into spec.
After all the work is done correctly, the car drives like a GT.

Most 928 sit way too low and people don't like the looks of a properly setup stock suspension. They have no idea what they're missing.

Another factor are tires. Yes, even in Germany you can drive any brand of tire. They just need to have the correct speed rating and load index. IMHO, the only way on how to get the correct driving experience is to go with Porsche recommended "N" specification tires. They are different, especially the tire side wall is a lot stronger with N tires.
When people ask me in the German forum about my tire choice: Michelin Pilot Sport N3. Great tire, with great grip and overall performance.