911 Suspension Refresh - What do I need to know?

[VaSteve]

After driving the Targa some 300 miles yesterday, I'm thinking it's time for a suspension upgrade. Seems a little boingy on the highway. After doing the 944, I'm amazed at how well it handles, just by restoring to "mostly" stock.

Since the Targa is going to be mostly street (maybe an AX or something) I think I will just got back to the stock set up with little upgrades. I already have Bilsteins so I plan to replace with Bilsteins. I figure I can do all of the bushings and whatnot as well. So I have a few questions for the trailblazers here:

- If I revalve my Bilsteins, can they put them back to stock? I have also heard that if you replace Bilsteins, the ride height is raised because the shocks are quite stiff when new. True? I guess I could lower it at the same time.
- I plan to do all of the rubber spring plate and torsion bar bushings. Am I missing any? I understand that the spring plates are easy (I have seen it done) but I have heard that the fronts require some vulcanization or some other laborious effort. True? Is this beyond the scope of a home garage install? Is it something I can take the compoents somewhere and have it done and just reassemble?
- I understand that by design, there is something you really just can't swap out... rear trailing arm bushings, maybe? Is that true?
- What other considerations (and parts) am I missing? I'm trying to build a list to price this adventure.

[randywebb]

this is an ugly, greasy, but rewarding project

check the Perfo. Parts catalog for a diagram of all the rubber bushings.

the front ones are hard to do - can send to SRP and let them do it

consider the original rubber or Neatrix vs. the Elph. Racing option vs. the Wevo needle bearing option in the rear.
- Gamroth told pwd72s to use the rubber on his '72 street car - he posted on this

there are many threads on what to do but I haven't seen a comprehensive compilation. You could make one & everyone on the entire bbs will send you a beer...
This is pretty much the ultimate model for a How-to thread:
Pelican rcecale, Randy’s classic thread.
”Reconstructing Constant Velocity (CV) Joints”
Don't let any lack of being a jet mechanic for the USMC stop you.
- There is an outstanding one also on the suspension.

I'm sure that Bilstein can put your shocks back to stock - what are they at now?

[ianc]

Steve,

I would rethink the 'stock' thing. If you're going to go to all the trouble of ripping everything out and renewing, you may as well make everything a bit tighter and stiffer. Randy is right in that this is an ugly greasy project.

I went the ER Polybronze route, and it was fairly straightforward, although labor-intensive. The results justified it though. The biggest single improvement I saw and felt was stiffening up the rear torsion bars. Even more than new Bilsteins.

To do the job right, count on:

1) ball joints
2) turbo tie rods
3) bump steer kit, if this is an issue
4) all bushings
5) torsion bars, F & R
6) Bilsteins
7) corner balance and alignment

ianc

[Gordo2]

Originally posted by randywebb
there are many threads on what to do but I haven't seen a comprehensive compilation. You could make one & everyone on the entire bbs will send you a beer...

I'm considering suspension refresh myself, with an offer like that I might beat your to it...

Another question in relation to your project (hope you don't mind me tagging on, you may already know):

-What parts can you remove/replace without having to get an alignment, or if easier what suspension parts if removed/replaced necessitate a post assembly alignment?

Good luck, Gordo

[randywebb]

the shocks - maybe the ball joints - not sure re the latter
otherwise align...

For a street car, be conservative about putting stiffer torsion bars on - you may not need new ones.

It will not hurt to inspect them carefully for signs of corrosion or stress cracking - at that time you can also inspect the inside of the torsion tube for any rust. It might be a good idea to paint it and then spray grease on top of the paint.
One might make up a radial spray head to be pulled & pushed thru the tube to do this with...

[randywebb]

I think the biggest decision that has to be made is the rear suspension. You have a choice of:
1. replace stock rubber/Neatrix - this is cheapest -- see the pwd72s comment above &
http://forums.pelicanparts.com/porsche-911-technical-forum/212391-why-no-rubber-front-bushings-post1827698.html#post1827698

2. change to the Chuck Moreland's Elephant Racing items. IIRC, these need to be greased peridically but provide xlnt. performance while still giving a good ride

3. change to the Wevo items. Here is a quote from an acknowledged expert (I don't know if he wants to be anonymous or not so he will be for now):

The Wevo Springplates do not require any on-going maintenance since they use sealed ball and roller bearings.

These are intended for track & race cars, but they do offer a VERY supple ride thats better than OEM rubber and even smoother than Chuck's poly-bronze ones.

- they are noisier than the stock rubber mounts; this may bother some

Whether they are an advantage or not really depends on the rest of the suspension upgrades and how the car is to be used & driven.

---------------
So, it appears that the N has been decoupled form the NVH triad.

[randywebb]

A saved quote from CM --
Options for the trailing arm link, in order of decreasing goodness
are:
[no Wevo product existed at the time he wrote this]
- Monoballs
- Factory rubber
- Polyurethane (delran, etc)

Trailing arm links need to move on multiple axis, hence Polybronze is not a suitable solution. That is why I make monoballs for this application. That is also why polyurethane ranks at the bottom of the list and isn't recommended.

Monoballs move freely in all required axis, as does rubber. Benefit of monoball is that it doesn't compress and therefor maintains alignment under load. Polyurethane binds.

Polybronze is available for spring plates and control arms. These are pivots points and require significant movent on one axis only. They work very well on pure street applications. Their low friction properties yield a very smooth ride, quiet too.

Monoballs don't relay much vibration. This is true of front and rear monoballs.

Somehow monoballs have this rep and it simply isn't true. I believe it's because most cars with monoballs also have stiff shocks, stiff springs, low profile tires, and [spit on the ground] polyurethane bushings. Surprise; they ride harsh.

The problem isn't the monoballs. Their contribution to harshness is tiny compared than all those other listed mods.

Keep in mind you already have a monoball in your car, it's called a ball joint. That one doesn't make the ride harsh
either.
__________________
Chuck Moreland - Elephant Racing

[randywebb]

saved quote from Tyson when he worked at TRE on the Elph. items:

Tyson Schmidt:

IMO, yes [they have the same comfort level as stock]. If I put them in your car and didn't tell you, I seriously doubt that you'd complain about noise-vibration-harshness. But I bet you'd notice the tighter feeling handling.

[randywebb]

old post from Wil re getting more neutral handling:

I might suggest a "slightly" different approach. I once published an "equivalent" spring rate vs. torsion bar size chart ( look at Rennlist technical area) and it became apparent that 21/27 is the often-quoted upgrade for lighter cars and 22/28 for later heavier cars. This, however, increases the stock TB rate by about an equal amount
fr/rr...and will maintain the dialed-in low speed understeering characterisitcs of our cars that Porsche used to avoid law suits.
A set up that provides a tad-less basic understeer is 21/28... or 22/29 ( some people go even more aggressive at 21/29 or 22/30), which helps set the basic car balance more toward neutral... most people like this. Of course, you can always fine-tune with anti-roll bars, but it's better to set the basic set-up with TB's first.
- Wil Ferch

__________________
- Whether this makes for "too much" oversteer at greater speeds or steering angles I don't know.

[svandamme]

i'm planning this as well
but i'll be doing it in stages
first the front , then the backend

currently in the front parts gathering stage
Turbo TieRods, SC Calipers, pads ,Rotors, bushings and whatnot

i want to mostly build things up outside the car
then when i'm ready , do a quick in-out

had to much down time the last years , so now i want to condense projects as much as possible

[ianc]

Stijn,

I thought you were getting rid of the old girl?

ianc

[svandamme]

Originally posted by ianc
Stijn,

I thought you were getting rid of the old girl?

ianc

no serious candidates

had only one person come and see it
who gave me grief over missing rough coating in the engine bay
which was supposed to be from repairs
and insited that the body was bent , due to door gaps beeing a bit on the large side

in the end , it went on ebay , but came 2 grand short of my absolute bottom price(which would allready have been a bad price for me personally )


either way , i said it was unfinished , but it wasn't a rustbucket with 20 K of work on the to-do list
in fact, many issues have been fixed since
it got it's road legal certification last wednesday
body panels and doors have been redone , great improvement
little bit more for the 4mm will work just fine

[TWork]

I'm about halfway through the front suspension rebuild on my T. I've pretty much got everything off and R&R'd. I just have to put on tie rods and everythings ready to go back together. I have to say that the job isn't nearly as bad as I anticipated based upon what I'd read in my searches in anticipation of the work. My particular rebuild includes Chucks polybronze bushings, turbo tie rods, new Koni strut inserts. I think the most difficult part of the project was breaking loose the ball joint. I think the key is to just have patience, don't be afraid to walk away and come back later. Beyond that, have a heat source, lots of PB Blaster and BFH. Good luck!

[VaSteve]

Originally posted by Noah
You should only replace what's worn. Polybronze bushings are an absolutely unnecessary expense for a street car, on top of the fact that the factory bushings are likely not sufficiently worn to need replacing, except for the spring plate bushings. You can tell if those are worn visually by looking to see if the torsion bar is eccentric in the spring plate cover. Check your sway bar bushings as well; those tend to wear.

Last time I looked at the rear sway bar bushings, I could see a little light between the rubber and bar so that's a given. I figure if doing the shocks and it changes the reide height I might as well lower it a tad, and thus need to do the spring plate bushings. What might *not* be worn after 23 years and 111K miles? The car has never been aligned in it's life, the tar hasn't been cracked at all.

Polybronze are probably more than I need unless it's easier/cheaper than redoing it with "stock-like" items. Competition or track set up, isn't a priority for this car. Think nice sunny day driver.

[randywebb]

"the factory bushings are likely not sufficiently worn to need replacing"

- Bad information. It is not wear alone, or distortion alone that causes problems. The rubber hardens with age no matter HOW MANY MILES on the car. After 2 or 3 decades it is highly likely that you will see a serious improvement from new rubber -- or from another of the options I noted above.

The same poster commented that the polybronze (Elph.) items were a waste on a street car. This is debateable. And it depends on your pocketbook and how much you value various dynamics that come from the suspension.

IF possible, you should drive a newly refreshed rubber suspension, a polybronze setup, and the Wevo option -- all back to back over the same roads on comparable cars. I doubt that anyone can make such a comparison. It would be a perfect thing for a PCA group, Rgruppe faction, or Excellence magazine test.

[ianc]

The same poster commented that the polybronze (Elph.) items were a waste on a street car.

Yes, I saw this as well and didn't agree with it. PB will give you better handling over the stock pieces no matter what you do. It just depends on how you drive the car. If you granny it around town, you might not notice it, but if you drive aggressively, you probably will.

Steve, if you're going to have everything apart, I'd seriously think about torsion bars. Try to drive a car with thicker bars than stock and see what you think. It's well worth it IMHO, and my car is 99% street-driven like yours...

ianc

[ianc]

Bubble Schmubble.

You have your opinion, I have mine.

Unless you can actually prove what you say, I guess that's all they'll be right? You want to be careful of stating your opinion as though it's fact however.

ianc

[randywebb]

Ha! I agree with you both.

And this: "Beware of the placebo effect." is esp. important.

BTW - I don't wear a lab coat and we amke fun of those who do... binoculars, backpack & field datalogger instead of a microscope (tho I have been known to use one in secret).

FWIW, I went with factory rubber BUT that was all there was back then. I'm thinking about the Wevo item and will post if I ever scrabble up the $$ for one. But first, I am going to put SMALLER torsion bars on my car - hollow ones.

[rfuerst911sc]

I did my 83SC coupe recently with: 22mm/30mm solid torsion bars,Elephant Racing polybronze bushings rear and poly graphite front bushings,22mm front 21mm rear Carrera sway bars,Bilstein Sport rear H.D. front shocks,turbo tie rod ends,balljoints,lowered and corner balanced...............phew! The handling is amazing and the ride is still very good but firm. If you have time on your side you can pick up used items like Carrera sway bars fairly cheap, I collected parts for about 8-10 months and then brought everything to my mechanic . I also had a 4 wheel alignment done I'm hoping the suspension is good for another 25 years.

[Shaun @ Tru6]

In my experience, the single best (as measured by $/feel) upgrade to a Targa is to put a front strut brace in. Putting one in my 84 changed the car dramatically for the better. much more stable, predictable, "pointable."

As I did a full R&R on the suspension in nearly one move, I can't say what each individual component did, but when I upgraded to:

22/29s matched with Bilstein Sports F/R
Elephant Racing Bearings F/R
Turbo tierods
ball joints
lower to just below euro height
corner balance

the car was transformed into feeling modern and comfortable, even on day trips to NY, yet truly track-worthy. Getting into friend's cars with factory components felt like getting into a Chevette.

The most important factor to consider in upgrading your suspension is understanding that it's a symphony of parts and all need to work together, not against each other, tires and wheels included, to be pleased with the end result.