Questions From the Underside

[Paul W]

Hi people,

Over the next couple of weeks I'll be upgrading my suspension and restoring the floor pan of my car. Before getting into it I thought I’d canvass the collective wisdom of the board on a few points.

Firstly, my wrench has advised me to go from no sway bars to 15mm on the front and 18mm on the back. He has also suggested “re-valving” my Koni shocks, what ever this means. What I want to achieve is good cornering without completely compromising road ride. Does this sound like the right path to take?

I am also about to strip the floor pan (almost no rust) and inner guards and treat with POR15. I notice several bolts are showing some corrosion and was thinking about replacing these with s.steel. I remember from my school days sacrificial corrosion was an issue when mixing different metal types, is this something to be careful of?

Regards,


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Paul
911T'69

[Jens Wendorff]

Sounds like a good project.
For suspension questions, I am no expert.

Concerning bolts:
Stainless Stell bolts may corrode in conjunction with Aluminum. That is to be remembered dealing with suspension/gearbox/engine parts. Mostly can be avoided by using enough anti-seize (copper paste).
S.Steel bolts have another drawback: Their strength capability is MUCH LESS than conventionel steel bolts. (Unless you use special aircraft quality which cost a fortune).
This means that S.Steel bolts should be avoided for any safety critical parts (esp. for fastening parts of suspension, seat belts, seats etc.). Be aware that the spec torques applied on some S.Steel bolts will lead to unusual high stresses and thus may lead to failure.

My advise: Use standard bolts (of the correct strength range, of course) as a standard. Use anti-seize on the threads and wax coating on the outer side to protect against corrosion.
Use S.Steel bolts on any uncritical application where much rust is expected (like heat exchangers, mufflers, etc.).

Just my $0.02 from exeprience

Jens

[rattlsnak]

If you're anything like the rest of us, take this advise, Dont bother with 15/18 sway bars, get the biggest ones you can (22's), because its just a matter of time before you'll want to upgrade anyway! This goes for any upgrade! You will spend more time and money upgrading upgrades ! Been there, done that, got the t-shirt, now I want the pants!!
Marc

[This message has been edited by rattlsnak (edited 05-28-2001).]

[ClayMcguill]

I concur wholeheartededly on the stainless steel bolts-they're great for non-loadbearing assemblies like body components and exhaust parts, but you don't want to be using them anywhere on the engine or suspension-they're just not strong enough. Most stainless are equivilent to SAE Grade 2-while automobile suspension hardware should be SAE grade 5, at the very least-(Grade 8 on off-road or race cars).

My '66 912 project is going back together with stainless body hardware and metric grade 10 suspension hardware-I'll never have to worry about rust or fatigue weakening any bolts.

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Clay McGuill '66 912, '97 Jeep Cherokee www.geocities.com/the912guy

[Paul W]

Thanks for the responses guys; the plan is now S/S body hardware and stock for suspension components.

Still interested on any thoughts on the proposed sway bar combination. I’m told the 22mm front and rear option does compromise ride, especially on the lighter early cars, which I’m keen to avoid. I plan on doing some DE events, and eventually our Targa Tasmania (tarmac road race), but 95% of driving will be road.

Regards,


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Paul
911T'69

[Jack Olsen]

If you get the adjustable 22mm bars, they'll be as stiff or as soft as you want. You can even remove the drop links altogether for no sway correction at all. I don't see the logic in lighter bars, unless weight is a huge concern. For an autocross you're going to want to set it up pretty tight.

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Jack Olsen
1973 911 T (3.6) sunroof coupe
jackolsen@mediaone.net