Help me design my suspension - I have a REALLY rough road!

[tadink]

HI all -

Here's a bit of a challenge - the road leading up to my house in Napa is exceedingly rough - acknowledged as the 'worst road in Napa' year in, year out. It is 8.5 miles of rough asphalt, harsh transitions, potholes, etc. Bottom line - it is thrashing my 89 Slant Nose Cab to pieces!!

The car is built on a 76 frame - and I'm planning on adding some strengthening to shore up the torsional rigidity, and adding a strut tower brace and roll bar to help. The current plan is to run some cross bracing under the floors....working with a local fabricator but open to ideas.

The suspension is the real challenge - the stock or sport suspension is simply too harsh for this road, and yet I'd like to have the ability to dial it in for smoother roads and AX once off the hill.

Current suspension needs a refresh - I've already done new Boge front inserts and Bilstein rear shocks (the suspension is all 1989 era kit). All stock at this point.....but worn out bushings all around.....so new A-arm bushings, sway bar bushings in the front, turbo tie rods too.....and new / refreshed spring plates and bushings, rear sway bar bushings, etc. I've already done the engine mounts and trans mounts (made a huge difference!!).

What are my options here? Adjustable coilovers (like Fox) that would allow me to soften or stiffen on the fly?

I can (sorta) "live with it" once I get the bits all refreshed, as I have with my 914 AX project, but I hate to think that I'm actually harming the car and shaking it to bits going up and down the road.

Options? Suggestions?

Thanks guys -

td

[gtc]

Chassis stiffening, like what is commonly done to the longitudinals in a 914, would go a long ways towards improving the ride. (There is an old thread here where someone did this to a 911)
Then have the shocks revalved with digressive valving.
New rubber suspension bushings should make a difference as well.

[chrisbruck]

Dumb question.... can you lobby to have the county fix the road or is it a private drive?

[Chuck.H]

Dropping your tire pressure might help - raise it again if you're planning longer drives to save the tires and get better mileage.

You could also consider getting 16" rims and taller tires with softer sidewalls.

Chuck.H
'89 TurboLookTarga, 392k miles

[tadink]

Originally Posted by chrisbruck

Dumb question.... can you lobby to have the county fix the road or is it a private drive?

Not a dumb question at all - we've all been doing that for years but there only a few homes / vineyards up here and it is on the bottom of the county's 'to do list' - LOL

MY tax dollars are apparently at work somewhere else!!

Keep the ideas coming - can someone explain in more detail the 're-valving the shocks' comment???

16's with 50 series sidewalls might help a bit - with the inflation management idea mentioned as well. hmmmm, but I LIKE my speedlines!!

Would coil-overs with progressive springs help at all?

thanks for your thoughts!!

td

[Trackrash]

We feel your pain here in Sonoma county as well...

Unfortunately the best thing to do would be to raise the car, rally style. More wheel travel will really help.

However that isn't the best solution if you want to AX.

I have externally adjustable shocks (Konis) on my car. I run them full soft for normal driving. When I get to an AX it only takes a minute to adjust them to my optimal track settings. This helps quite a bit.

You may also want to consider softer or adjustable sway bars. Stiff sway bars will contribute to a harsh ride.

BTW, Redwood's first AX is this Saturday!

[J0hnny]

Koni makes shocks designed for this, FSD's

The thing is that they don't make them for old 911's, but probably using the body's and attaching them to the 911 upright might work, they would have to be custom, I used those in a saab 9-3 that used to have rock hard suspension, and it did improve driving over potholes while keeping a firm ride.

[tadink]

"You may also want to consider softer or adjustable sway bars. Stiff sway bars will contribute to a harsh ride."

ahhh, that is an interesting thought - my stock sway bars are pre-loaded and may NOT help with the harshness.....hmmmm

good thinking....

td

[winders]

You can't get there from where you are......

[RSTarga]

elephant rubber bushings. Stock torsion bars, stock roll bars euro ride height or higher.
Springs won't help.

[tista]

Garage at bottom of road. Old jeep for the road. Car remains as it should. Carry on.

[tadink]

Originally Posted by tista

Garage at bottom of road. Old jeep for the road. Car remains as it should. Carry on.

ugh, my thoughts exactly!!!

I'm hoping for some compromise - and a rally tribute, slant nose cab with a roll cage may be the 'only' option? sigh.....

keep the creative juices flowing men!! (and women!!)

td

[tadink]

Originally Posted by J0hnny

Koni makes shocks designed for this, FSD's

The thing is that they don't make them for old 911's, but probably using the body's and attaching them to the 911 upright might work, they would have to be custom, I used those in a saab 9-3 that used to have rock hard suspension, and it did improve driving over potholes while keeping a firm ride.

Doing a bit more research and this popped up on the local CL - Bilstein PSS9 Coilovers with a bunch of adjustment settings. This set is for a 2002 Turbo, but I'm wondering if a very adjustable set like this might help soften the ride on the hills, and then tighten it down for AX?? Bilstein PSS9 Coil Over Kit 2002 Porsche 911 Turbo AWD

also looking at adjustable sway bars to take out some harshness as suggested....

Thx guys -

td

[J0hnny]

Originally Posted by tadink

Doing a bit more research and this popped up on the local CL - Bilstein PSS9 Coilovers with a bunch of adjustment settings. This set is for a 2002 Turbo, but I'm wondering if a very adjustable set like this might help soften the ride on the hills, and then tighten it down for AX?? Bilstein PSS9 Coil Over Kit 2002 Porsche 911 Turbo AWD

also looking at adjustable sway bars to take out some harshness as suggested....

Thx guys -

td

It is a different damping mechanism, in those Bilstein's you adjust the settings and that is what you have, what feels good for that road will likely affect handling in a good one.

On the FSD's Koni did a two setting that changes cording to the input, it "softens" itself when you go over a bump.

It is not as good as a self adjusting electrohydraulic system, but it is better than nothing, btw, I do not work for Koni nor am I associated with them in any way, just sharing what worked for me.

This shocks are kind of popular with the R53 mini cooper guys, since their suspension is ungodly harsh.

http://www.koni-na.com/fsd-frequency-selective-damping.cfm

[island911]

I had a similar problem with my SC and Seattle nasty road. I bought a Cayenne with active suspension. :-/

Winders is pretty much spot on You can't get there from where you are......

Springs shown are trying to give some non-linear response, and will, but not much range. And certainly, you will not be adjusting on the fly (that's where you need active suspension - which I don't believe exists for these 911s)

Definitely start with new rubber suspension bushings. Likely, the T-bars are bumping against metal. Considering that was once a 77, I would guess that the T-bars are bigger than OE.(someone had mod-fever bad)