Time to replace 30 year old suspension - little help please?
 

After spending many hours over many weeks reading through most every thread I could find on suspension upgrades/refreshes/replacements, I feel I'm now ready to do the hardest part and get out from behind the computer and turn the first fastener. However, I wanted to run my list of suspension components by the collective wisdom of this group to see if I've made the right decision for the intended use of the car. Plus, as you will see, I still have some questions (big surprise).

First a little about the car - it is a '77 911S Targa which I have owned for the last 22 of its 30 years, and used as a pleasure/DE car. It currently has 102K miles on it. About two years after the purchase (1987), the motor was dropped (at about 82K miles) and completely rebuilt down to the polished crank. I went with 2.7 RS Piston/Cylinders, Webers, cams, SSI's and a bunch of other goodies, including everything to make the Mag case as bullet-proof as possible at the time. The motor has been perfect ever since - not even a drop of oil leaks to this day - kudos to Steinels Autowerks in Ohio (I have long since moved to TX).

A few years ago I noticed that the rear suspension was making some noise and as I suspected, the spring plate bushings were shot. This was no surprise as the all original suspension was now nearly 30 years old. I pretty much stopped driving the car and started looking into what I would need to replace the bushings. Around the same time I also purchased an M3 for my daily driver. After driving the M3 for a while, and only driving the 911 to take it for its annual inspections, I noticed that the 911 did not handle nearly as well as the M3, and was much softer. It was then that I decided that I would replace more than just the spring plate bushings, when the timing was right to start the project.

Well, the time is now. Since I don't drive the car that much anyway (at least not recently) I can afford to have the project take several months if necessary. For me this will probably be the case because I'm a bit of a clean freak and on occasion I concour the car. So the urge to clean "while I'm in there" will be hard to resist. I have a feeling that every part and fastener I take off will either be repainted, replated or replaced before going back on.

Once complete, I plan to use the car for occasional street and DE again (and concours). I don’t mind a firm suspension (in fact I prefer it), as long as it is not too harsh (my wife may complain). Oh, and the only suspension related type work I’ve done to the car to date is put on 6 & 7x16 Fuchs (it has Carrera flares). So, given that, and based on the countless threads I’ve read, this is the list of suspension components I came up with:

Torsion Bars (hollow): 21/27 or 22/28?
Shocks: Need help here. The car has original Koni’s
Sway Bars: 22/21 (OEM from 86+ Carrera?)
ER P-B Ctrl Arm bearings
ER Low Friction Ctrl Arm mounts
Rennline Truss-Mount 3-point Strut Brace
Monoball upper strut bushing? (w/camber plate?)
Turbo Tie Rods
Ball Joints
Bump-steer Steering rack spacers (needed for euro height)?
Spring Plate Bushings (ER P-B, or WEVO SPS?)
Monoball Trailing Arm bushing
Wheels: 6 & 8x16 or 7 & 8x16 Fuchs (probably wait on this)

Some misc notes – the front has the aluminum S calipers (< unsprung weight), and the complete A/C was removed from the car some time ago. Plus the engine intake/exhaust mods lightened things up a bit as well.

So the questions I have are:
- Which torsion bar combo given a slightly lighter than stock weight for a ‘77 & some DE?
- Since the car came equipped with the optional Koni’s (adjustable), and since they supposedly have a lifetime warranty, should I just try to increase the dampening? These are the older type which require the strut to be unbolted from the top to adjust. I would prefer the newer style. Should I just assume these are shot (at 102K miles) and replace them? If so, do I go with Koni’s again or Bilsteins?
- If I use a 3 point strut brace, will my Targa top still fit in the trunk? I measured it and it looks close. One posting I found here says it will fit. I never put the top on the car (since I never drive it in the rain), but occasionally I take it with me for insurance. I can always place it unfolded behind the front seats.
- If I use a truss mounted strut brace, does this prevent me from using the style of upper strut monoball that includes a camber plate?
- Should I expect the existing rubber upper strut bushings to be in need of replacement at their age? If so, I would go ahead with monoballs there. If not, they may be a little harder to justify.
- And what is the advantage of going with the strut monoball that has the camber plate? Is it just to allow for more camber adjustment?
- If I just drop the height to euro-spec, do I still need to raise the rack for bump-steer. I wouldn’t think so (it seems like it should be in its natural setting at that height).
- The Spring Plate bushings are the big dilemma for me. I like the WEVO SPS, but I don’t know if I really need the adjustable spring plate. I don’t see myself adjusting the ride height all that much once it is dialed in. It would certainly be nice for setting the initial height and for corner balancing, but after that I’m not sure if I would touch it. Plus the recent thread on the two plates separating (with any adjustable SP) makes me wonder if I’m not better off with the ER P-B bushing (which I like just as well) and my OEM adjustable spring plate (much less $ as well). I plan to do the front half of the car first while I agonize over this decision (with help from some of you I hope).
- I mentioned that I will probably wait on the 8x16 Fuchs as they are hard to come by these days, and when you can find them, they are not cheap (I should have bought them when they were "only" $400 per wheel years ago).

So there it is. Sorry for the long post. I will probably start taking the front suspension parts off soon so that I can get the control arms power coated while I’m figuring which parts to buy.

Thanks,
Frank

Frank, I can't offer any knowledgeable advice but I will be watching this thread with interest since I have a '76 coupe in similar condition.

I hope you will keep updating this thread with blow by blow desriptions and photos. I am also a bit of a clean freak. I won't be doing any concours competitions but I'll be interested in hearing/seeing what you do to make your suspension and undercarriage look sharp.

I'm subscribing

I say do it. Use the biggest torsion bars you can find!

I am no expert but I do remember that you do not necessarily want the largest torsion bars you can find. There is a limit to how stiff you want the car. Too stiff and the tires will lose contact with the road surface easily on rough surfaces....certainly not a good thing.
Give someone like Elephant Racing or TRE a buzz. They have forgotten more about setting up a car than most will ever know.

I used 22/28 torsion bars on my 74 Carrera and really liked it's behavior on the track, did not find it objectionable for road driving as well. Like everything else you have chosen.

Re: Time to replace 30 year old suspension - little help please?
 

Tbars - Given your concerns about the wifes comfort, I would suggest 21/27. This will make a big difference in control and body sway, but still be pretty comfortable.

You could go with adjustable sway bars, and tighten them up for your DE days, then run them softer for the street.

And your adjustable konis can also be tuned somewhat for DE/Street settings.

You can also achieve big differences in DE/street comfort with differing wheels and tires for each. More sidewall will make a big improvement in street comfort.

Using the above, you go quickly go from fairly comfy street ride to DE-ready just by swapping the wheels, tightening the shocks, tightening the sways.

Shocks - Original 30 Year old konis I would replace. I believe the originals were hydraulic, the new ones are gas-charged. And the new ones have the external ajustment on the fronts. This will make it easy to go from street to DE, as above.

Strut brace - With the Elephant triangulated you can stow the top. I assume the Rennline is the same.

Camber plates - again with Elephant brace, you can use camber plates. I can't answer for the Rennline.

Strut top bushing - generally this bushing holds up pretty well, better than most of the original bushings. Give yours a visual inspection.

Camber plates 2 - Correct. The advantage to a replacement camber plate vs a monoball cartridge is the additional negative camber range. That's all.

Bump steer - This is a long discussion by itself. Short story, I recommend using a bump steer kit at Euro height.

Spring plates - Your car has factory adjustable spring plates. While the factory eccentric-bolt type adjustment has a bit less range-of-adjustment than the screw-type Wevo, it does work well. For a set-and-forget rear setup, I don't see this as a factor. As you know I have a horse in this race, ymmv.

I would also replace the wheel bearings, and of course get a corner balance and good performance alignment. Not a quicky tire-store alignment, spend the money and get it done right. :)

Dan,

I will definitely be taking pictures as I go and posting back progress. I'm not sure how much more I could add to the already excellent threads by other members on this topic, but if some will find it helpful, I can certainly post my experiences (good and bad) along the way, along with any insight I may discover.

Frank

Frank,

I would suggst you do what I did, find a good Porsche Tuner (for me it was Steve Weiner and Jeff Gamroth) and spend some quality time with them to figure out what you need. You may be surprised at the suggestions.

Chuck,

Thank you so much for chiming in here - I feel honored.

I may have over-emphasized the concern of my wife's approval. She hasn't even been in the car for about 5 years, but there's always that chance that she may want to do a winery tour with the local PCA club one of these years :). So if I were to remove that as part of the criteria, would 22/28 for t-bars be reasonable? Also, I noticed on your site that the recommendation for Street Track 1 & 2 is 21/28 & 22/29 - i.e. a 7mm difference F/R rather than the 6mm I often see quoted here. Is that directed towards applications in cars heavier than mine (Magnesium motor & transmission?).

So it sounds like I should definitely replace the shocks as well. The reason as I was asking about the Bilsteins is because they seem to be mentioned most often here. I'm not sure if that is simply due to more people not having the Koni style strut. I do like having the adjustable option of the Koni's if they are considered comparable to the Bilsteins.

Thanks again for advice,
Frank

Yes the targa top will fit.

I recently had my suspension redone. By far the most dramatic change to my car;

Fikse FM10's (17")
Brembo GTP's w/ 23 mm master cylinder
Elephant Racing Monoballs (rear) and Elephant polybronze bushings
Turbo tie rods
22/28 Torsion bars
Rennline triangulated strut brace
Koni adjustable shocks front and back
Smart Racing sway bars
Alignment and corner balance.

http://forums.pelicanparts.com/showthread.php?s=&threadid=211879&highlight=suspen sion

http://forums.pelicanparts.com/showthread.php?s=&threadid=214333&highlight=suspen sion

Moses,

Thanks for the validation that the top will fit.

The suspension components on your car are a very close match to my list, so a thumbs-up would give me a vote of confidence.

I took a look at the two threads you listed (very nice car, btw), and it made me remember one thing about the choice of wheels. After the suspension work, the next on the list (probably a year after recovering from the suspension) will be the brakes. Sticking with 16" wheels will certainly limit any brake upgrades that I can make. It seems 17" would give me more options for rotor/caliper sizes. Up until now my braking setup has been adequate, but then again, I'm not that good of a driver.

So, if I'm planning on a brake upgrade at some point, should I even bother trying to locate a set of 8x16 Fuchs, or just start looking for a set of 17's (I do like the Fikses) and run with the 6 & 7's for now? What widths are your FM10's?

I recently went through mine and am very happy with it.

New wheel bearings, Bilstein sport/hd struts, 21/27 sanders bars, elephant bushings, turbo tie-rods (yrs ago) later carrera or turbo sway bars (can't remember size)

At any rate, I see your in TX. If your in Houston or nearby you can check out my set up and see how you like it.

Frank, I went with th 21/27 setup with Bilstein Sports on my 79SC. It's a perfect setup for mainly street driving with some track time. I would not just put the largest torsion bars on. Remember, that the stiffness is related to the diameter of the bars to the fourth power, so a small increase in diameter will cause a significant increase in stiffness. Also, you can adjust the oversteer/understeer of the car by changing the ratio of front to rear from the stock setup. That is, by allowing more weight to shift to the front wheels, (e.g. select a torsion bar pair that gives more stiffness percent wise to the rear rather than the front over stock values), you could induce more oversteer if this is what you want; or vice versa.

The attached Pelican link explains the relationship between stiffness and the diameter of the torsion bars. What you will notice is that the 21/27 setup gives approximately the same increase in stiffness front and rear, 56% and 57%, thus maintaining the stock ratios. I think this is one reason many go with this setup; stiffer suspension with similar oversteer/understeer characteristics to the stock setup.

http://www.pelicanparts.com/techarticles/911_torsion_bars/911_torsion_bars.htm

Frank

Bilsteins are an excellent choice. However not available for your koni struts. So unless you are prepared to buy new struts, not an option.

The tbar sizes you find on my web site are not recomendations, they are just starting points. My recomendations for individual cars depend on a variety of factors including weight, engine, wing, how used, driver sensitivity etc.

do a search -- IIRC, Koni will rebuild your shocks for a very nominal fee - pretty sure it's been posted on

The suspension is wonderful, you'll love it. In a few months we'll be offering cast Fuchs replicas for under $1000/set. Stay tuned.

jmz,

Thanks for the offer. I'm in Austin, but I do get over to Houston occasionally (Woodlands area). If I'm over that way any time soon I'll certainly let you know.

Frank

Ok, so Koni's it is. Chuck, thanks for clearing up the Bilstein question. One decision out of the way.

So now I'm trying to figure out which Koni's to order. I figured this couldn't be too hard - riiiight? Now I've got more questions:

- I would like the Koni's that are externally adjustable (knob at top). Even Koni's website is not clear about this. Are both the red and yellow (sport) shocks ext adjustable? Some indicate that only the Sport is, and others say both are. Perhaps this is moot because I plan to go with the Sports anyway.

Front shocks:
- I would like to go with the Sport model. It's rather clear that the Sport shock (8641-1039S) is only available for Boge struts. However, some threads I've read here, as well as Koni's site (http://www.koni-na.com/display.cfm?mt_id=1&mak_id=37&my_year=1977&mod_id= 1&submit=Continue)
say the Sport insert can be with the Koni strut if a different Gland Nut is used ("8641 1039Sport front can be used with OE Koni struts if gland nut 73.25.01.011.1 is ordered as well.") So, I called our host and they do not sell the gland nut. I also searched Paragon's site and couldn't find it. Can I order the nut from Koni directly? Is this the route that most people take with Koni struts, or do they stick with the Red inserts (86-1942)?

Rear Shocks:
- Koni's site lists two different rear Sport shocks available for my car: 30-1214S and 8210-1159S. Most sites that sell Koni's seem to offer the first part number only. The second part is much more expensive (on Koni's site). Does anyone know what is different about this second part number?

And what about the oil in the strut housing - some posts say leave it, some say replace it, some say dump it. It seems that if it is present in my strut, and that since I'm replacing it with another Koni, that I should leave it for cooling purposes.

thanks again for all the help.
Frank

I wanted to let people know that I started a separate thread on the Koni shocks question (hopefully this is not a breach of etiquette).

http://forums.pelicanparts.com/porsche-911-technical-forum/325343-koni-sports-77-911s.html

Frank