Trying to decide on a suspension setup for my SC Targa

[david05111]

Hey Gents-

Next project on my car (80 SC) is to go over the suspension. The car sat for over 25 years and most of the rubber, while it may still look ok visually, is probably shot. The same goes for the shock inserts; they seem ok, but I'm sure they're basically worn out.

So I've been looking at a complete overhaul. Bushings everywhere, new spring plates if that becomes necessary or advisable, new shocks/strut inserts, turbo tie rods, etc. But while I have a general understanding of what some common setups are having read a few forum threads on the subject, I still could use some advice.

I'm aware that there will be some performance limitations, being that it's a Targa. And I'm honestly not really focused on track performance. I don't really see my self ever taking this car to the track, and probably never an autocross. I'd like it to be a tight little canyon carver to some extent, but at the same time I still want the ride to be compliant and comfortable for some grand touring. I'd like to be able to take the car on a multi-week road trip over a a thousand miles and be comfortable doing it; I don't want to be beat up if I'm in the car for 6 hours a day if it were to come to that. I want that sort of grand touring comfort, while being able to tackle some mountain passes if they present themselves.

So with that in mind, here are a few questions.

1) My inclination is to either stick with with OE rubber replacement bushings or go to something *slightly* firmer. I think something like bronze bushings from elephant racing is a popular choice, but I'm really not sure what to go with on that front. I'm not sure if you do some more aggressive/harder bushings in some locations and the OE in others. The same goes for a lot of the other suspension components, such as ball joints.

2) As I understand it, Bilstein or Koni shocks are recommended. My car did not have the optional Bilsteins from the factory. From what I've read, it's recommended to go with something like a set of Bilstein HDs up front and Bilstein Sports in the back (and the same idea for the Koni offerings).

I'm really not sure where to go on this one. I know basically nothing about "valving" either. I'm just used to going online, buying a set of shock replacements for my other cars, and throwing them on the car when they arrive. I've never run into a position where the valving in them has to be adjusted, so I'm out of my element.

So I'm not sure if I'm better off with the Bilsteins or the Konis, and I'm not really sure what role valving plays in the whole process.

3) I'm not really sure what to do about the torsion bars. I'm not sure whether to stick with stock, or to go to something a bit thicker. A common setup seems to be to go to a 22mm up front and a 28 in the back, but I'm not sure if this is advisable with what my goals are or not. I'm not sure how aggressive that sort of setup really is, or what it does to the ride comfort/compliance.


I did my best to read up on this stuff without creating a new thread, but almost every thread I found was geared toward a coupe. I know that the Targa isn't going to perform like one of those, and I don't really strive for it to do so. I know that the chassis itself isn't really rigid, especially with the top removed. I could just use some advice on where to go with this. I think I read that people suggested calling Elephant Racing and having a discussion, and I may do that, but I'd like to start here and see where it goes.

Thanks

[fanaudical]

Be careful - It's easy to go overboard and put together a setup that is great on smooth roads (or the track) but no fun for everyday driving.

I've got a light '75 Targa and rebuilt the suspension a few years ago. I went with sport rubber, slightly larger torsion bars, raised the front spindles, turbo tie rods, added adjustable spring plates, and Vons Level 1 shocks. It drives and handles great - but it's a bit stiff. Almost too stiff for a long, comfortable drive on crappy roads on some days. There are days that I think I should have just done the following:

- Sport rubber bushings
- Turbo tie rods
- Adjustable spring plates (not a standard option on a '75 but I think those are standard on an SC)
- New stock-size torsion bars
- Kept the adjustable Koni's and set 'em a big soft

Porsche did a pretty good job with the stock suspension setup...

[Otter74]

I’ve got an SC Targa that the previous owner rebuilt completely in the 15 years that he owned the car. I have stock torsion bars with a lowered (a fair bit) ride height, Bilstein HD (front) and Sport (rear), ER polybronze bushings and monoballs on the rear banana arms (upper front bushings are stock), stock a/r bars and the usual Turbo tie rods. Stock front strut housings. I’d say my car fits the description of what you want pretty well. I read what you wrote and think, “yep.” Myt car is loads of fun in the twisties, rides acceptably on crappy roads (I live in Chicago), and is perfectly comfortable on long trips (I’ve done as long as 16-hour days in the car). If I were doing it myself I’d probably put sport rubber bushings in instead of the polybronze and monoballs. I’m happy with it as it is so I’m not about to go change it, but I don’t think it’s necessary. If you pick one thing to spend more money on, I’d do it on good shocks.

[jwolfe]

I agree in the sentiment of not going overboard all at once. I for one like to gradually add things so I can clearly identify the difference it makes. Change 4 major components at once and you might not exactly know what’s causing a ride you are happy/unhappy with. Upgrading struts is an easy one, either brand you recommended works well. I chose Koni for the easy adjustability. I agree something in the 21/27 22/28 TB range is probably a safe bet.

[SkunkWorks]

Think you'll be pretty happy by keeping it simple.

Fresh rubber bushings throughout, adjustable Konis, and turbo tie rods. Save your money.

[rwest]

Rubber bushings for sure- don’t even think about anything else for a street car.

Turbo tie rods would be a good upgrade as well.

Don’t slam it to the ground either, nothing fun about having to creep up and down all the curb cuts and steep driveways that are everywhere.

Just refreshing all the bushings will make the car so much better than you have now. You might even want to do the engine and transmission mounts as well in factory style.

[cmpski]

As usual I go a different path. My car is SWB, not a SC or Carrera. I took almost all the rubber out of my suspension and it's much smoother than before. I let springs spring, be it t bars or coil, and shocks shock. I don't want deflecting rubber. At one time I bought what folks said where the best sport rubber spring plate bushings on the market. They smashed flat in two years. So I went with Rebel Racing non grease bushings F&R. Smooth as silk. Switched to coil overs during the supply issue years. So neither Elephant or Rebel had everything, so I bought parts from both. Then I replaced my a-arms with Rebel front bushings with Elephant's GT3 type front suspension. All this stuff works on cars to 1989. This thing handles amazing but is smooth enough that I've driven from Colorado to California and back 3 or 4 times and I'm in my 70's.
I primarily drive the car in canyons and mountain passes here in Colorado.

[david05111]

Thanks for the replies, all. I'll try and give a more thorough response to each when I get back on in a few hours.

I did want to note that I understand the idea of not doing too much all at once, but at the same time, I also recognize that certain things have to get done and are going to expose the obvious opportunity to do the others.

For instance, the spring plate bushings likely need replacement. Doing so is going to expose the torsion bars. I'd rather not have to take all that apart again to swap out the torsion bars in a stage-2 suspension overhaul. "While I'm in there" it makes sense to consider swapping them out. Same goes for the front torsion bars since the front suspension needs to come out and apart to replace all the bushings.

Since the car is going to need an alignment and a corner balance no matter what I do (and I'm going to lower it to euro spec), I don't really want to have to do that more than once.

So really, it's sort of a "well, I wouldn't mind going basic, except basic is still disassembling most of everything else, will offer easy opportunity to swap more complicated parts, and no matter what it's going to need extra services". That's the only reason I just didn't swap the bushings and move onto another part of the car.

[silverlock]

On my ‘78 SC (no A/C, no heater blower) that sees very spirited backroads + some AX/track:

* Koni Sport shocks/inserts: externally adjustable. Compliant shocks make a big difference.
* Sway-a-Way T-bars from ER. 21F, 26R. LOTS of opinions here. Go search Bill Verburg’s posts on this forum for lots of insights. I would run 21/27 if I had more weight in the rear.
* ER HD bushings for trailing arms & spring plates.
* About to upgrade to RSR’s spherical bushings for the A-arms
* Eibach 24/25 sway bars.
* Turbo tie rods (big fan, some folks dislike)
* RSR adjustable bump steer kit going on soon.

Rides great. NYC freeways not the smoothest at the best of times, and not all backroads are either. Car had to be communicative & adjustable. I don’t mind a slightly firm ride but I put a lot of miles on this car getting to/from events (let alone at them!) and rock hard just isn’t fun.

PeteKz will probably chime in with some good advice too.

[Marko888]

David,

Your plans for the car are quite close to how I use my ‘87: Sport touring, wife friendly.
It sounds like you want a sweet car…not a track car.

My favourite suggestion these days is to remind folks that there are a lot of companies with a lot of stuff to sell… but many of us don’t really need much of the stuff!

1) My suggestion is to replace all of the bushings, with rubber, maintaining OEM NVH. Choose sport hardness on the rear spring plates. I have the easy-adjust spring plates, which make fine tuning ride height much easier for DIY.

2) I found Bilstein HD‘s all around to provide enough control for a sport touring car.

3) I’d suggest inspecting the original torsion bars and sticking with them if they are in good condition. If you have to replace them, increase the rear torsion bar diameter by 1 mm from stock, which will make the car feel a bit more sporting by reducing squat under acceleration and slightly reducing tendency to understeer. Keep the front stock 19 mm for ride quality, and retaining ability for easy weight transfer forward under braking at street speeds. My second car is on 22/28mm torsion bars (bought it this way) and it makes sense IMHO as a 50/50 street/track car, but feels overly stiff for pure street use on imperfect roads.

Enjoy the journey!

[nickelplated5s]

Read PeteKZ's sig line. His setup is pretty much what you described looking for. I did the front first. Ordered rear stuff yesterday. Von2's but for a SWB options are limited, mines stiffer than you would want. For yourself Koni Sport is my 2c.

[Schulisco]

There were some discussions on that.

My advice: Stay away with a cab/targa from Bilstein Sporty Road!! Too stiff! There's Bilstein series replacement you can use, this is the original sporty ride M474.

https://forums.pelicanparts.com/porsche-911-technical-forum/1171586-cabriolet-carrera-structural-integrity.html#post12377282

https://forums.pelicanparts.com/porsche-911-technical-forum/1111488-bilstein-shock-question.html

Thomas

[Bill Verburg]

Originally Posted by david05111

Hey Gents-

Next project on my car (80 SC) is to go over the suspension. The car sat for over 25 years and most of the rubber, while it may still look ok visually, is probably shot. The same goes for the shock inserts; they seem ok, but I'm sure they're basically worn out.

So I've been looking at a complete overhaul. Bushings everywhere, new spring plates if that becomes necessary or advisable, new shocks/strut inserts, turbo tie rods, etc. But while I have a general understanding of what some common setups are having read a few forum threads on the subject, I still could use some advice.

I'm aware that there will be some performance limitations, being that it's a Targa. And I'm honestly not really focused on track performance. I don't really see my self ever taking this car to the track, and probably never an autocross. I'd like it to be a tight little canyon carver to some extent, but at the same time I still want the ride to be compliant and comfortable for some grand touring. I'd like to be able to take the car on a multi-week road trip over a a thousand miles and be comfortable doing it; I don't want to be beat up if I'm in the car for 6 hours a day if it were to come to that. I want that sort of grand touring comfort, while being able to tackle some mountain passes if they present themselves.

So with that in mind, here are a few questions.

1) My inclination is to either stick with with OE rubber replacement bushings or go to something *slightly* firmer. I think something like bronze bushings from elephant racing is a popular choice, but I'm really not sure what to go with on that front. I'm not sure if you do some more aggressive/harder bushings in some locations and the OE in others. The same goes for a lot of the other suspension components, such as ball joints.

2) As I understand it, Bilstein or Koni shocks are recommended. My car did not have the optional Bilsteins from the factory. From what I've read, it's recommended to go with something like a set of Bilstein HDs up front and Bilstein Sports in the back (and the same idea for the Koni offerings).

I'm really not sure where to go on this one. I know basically nothing about "valving" either. I'm just used to going online, buying a set of shock replacements for my other cars, and throwing them on the car when they arrive. I've never run into a position where the valving in them has to be adjusted, so I'm out of my element.

So I'm not sure if I'm better off with the Bilsteins or the Konis, and I'm not really sure what role valving plays in the whole process.

3) I'm not really sure what to do about the torsion bars. I'm not sure whether to stick with stock, or to go to something a bit thicker. A common setup seems to be to go to a 22mm up front and a 28 in the back, but I'm not sure if this is advisable with what my goals are or not. I'm not sure how aggressive that sort of setup really is, or what it does to the ride comfort/compliance.


I did my best to read up on this stuff without creating a new thread, but almost every thread I found was geared toward a coupe. I know that the Targa isn't going to perform like one of those, and I don't really strive for it to do so. I know that the chassis itself isn't really rigid, especially with the top removed. I could just use some advice on where to go with this. I think I read that people suggested calling Elephant Racing and having a discussion, and I may do that, but I'd like to start here and see where it goes.

Thanks

It mostly depends on what you want from the car
certainly stick w/ all rubber bushes, go to stiffer sport rubber for a little bit sportier ride
people upgrade t-bars mostly to stabilize and minimize camber changes during roll conditions, if this isn't an issue then others want less under steer so just go w/a bit bigger t-bar in back, factory used up to 18.8 front and 26 in back on some race cars , then added coils f/r to and/or bigger t-bars for more control.

w/ stock wheels and tires roll is less of an issue than w/ upgraded items

twin tube shocks are associated w/ cushier ride w/ a commensurate loss of at the edge performance, Koni adjustable are on example of these, Bilstein inverted mono-tubes area step up performance wise but a step down comfort wise especially w/ the stock linear valving, there are other options like Ohlins and KYB that offer various +/- attributes.

roll can also be reduced w/ bigger sways, the 22/21 versions from an '86 are popular or aftermarkets like Eibach

That being siad while a targa has less torsional chassis stiffness than a coup targas do respond well to all the upgrades that can be used on a coup

[PeteKz]

David: If you have read through the other similar threads, you have certainly seen Bill V's comments, and probably mine. You have described what you want as a "sporty street car." That's what I have.

Here's the most important question: How much d'ya wanna spend? You can easily lose $6,000 if you want the latest and greatest (Vons or KW multi-adjustable shocks and struts with raised spindles, etc.). Or you can spend a lot less than half that and have a real nice street car.

Another question: How many miles on the car? If it sat for 25 years, the suspension may not be as worn as you think. How much have you driven it since getting it back on the road?

Ditto Silverlock and others on keeping the suspension compliant, and jwolfe about making changes one at a time. Yes, there are some things you want to do at the same time "while you're in there," but most of the changes you can make independently.

Look at my signature line to see what I have. One thing I wouldn't do again is the RSR solid bushings--I'd stay with rubber suspension bushings for a street car. The solid or poly bushings DO increase noise and harshness in the cabin, unless you live in some dream world where all the roads are smooth! They are also a PITA to install. Turbo tierods: Meh. If your old tierods are not loose, leave them in for now. Easy to change later.

Answer the budget question and we'll go from there.

[nickelplated5s]

was waiting for Pete.

[PeteKz]

I'm slow.

[Bill Verburg]

Originally Posted by PeteKz

David: If you have read through the other similar threads, you have certainly seen Bill V's comments, and probably mine. You have described what you want as a "sporty street car." That's what I have.

Here's the most important question: How much d'ya wanna spend? You can easily lose $6,000 if you want the latest and greatest (Vons or KW multi-adjustable shocks and struts with raised spindles, etc.). Or you can spend a lot less than half that and have a real nice street car.

Another question: How many miles on the car? If it sat for 25 years, the suspension may not be as worn as you think. How much have you driven it since getting it back on the road?

Ditto Silverlock and others on keeping the suspension compliant, and jwolfe about making changes one at a time. Yes, there are some things you want to do at the same time "while you're in there," but most of the changes you can make independently.

Look at my signature line to see what I have. One thing I wouldn't do again is the RSR solid bushings--I'd stay with rubber suspension bushings for a street car. The solid or poly bushings DO increase noise and harshness in the cabin, unless you live in some dream world where all the roads are smooth! They are also a PITA to install. Turbo tierods: Meh. If your old tierods are not loose, leave them in for now. Easy to change later.

Answer the budget question and we'll go from there.

rubber needs to be exercised regularly to maintain it's properties, unexercised rubber deteriorates far more rapidly than exercised

[avr924]

1986 I believe is the one year of larger factory sway bars, if you can find a set they bolt right in

21/27 torsion bars
Bilstein HD (several years ago you could send your cores in to have rebuilt at a reasonable cost)
Replace all bushings, ball joints, wheel bearings, etc.
Polybronze are nice, I would go with rubber in hindsight for street
Turbo tie rods
Set to euro height and get aligned and balanced- you can do yourself and get very close with ride height, much lower isn’t fun on street and actually seems to handle worse below Euro height IMO
Tires if needed- old hard tires aren’t safe and effect ride quality

Then drive and maybe a DE event or auto x to learn the car. This setup is solid, anything more gets diminishing returns very quickly.

[unclebilly]

Seriously - don’t ruin your road car like I did to my 77.

It has:

23mm front torsion bars, 30mm rear torsion bars, weltmeister sway bars, raised spindles in bilstiens, front strut brace, and a race alignment.

The car is incredible on the track.

The car punishes me every time I drive it on the street.

For what you want, put in a set of adjustable sway bars and maybe update your shocks / struts. Be careful though - an aggressive setup on the rear sway bar makes these cars way more prone to stepping out. In our endurance racer, we didn’t run a rear sway bar for this reason.

[david05111]

Originally Posted by PeteKz

David: If you have read through the other similar threads, you have certainly seen Bill V's comments, and probably mine. You have described what you want as a "sporty street car." That's what I have.

Here's the most important question: How much d'ya wanna spend? You can easily lose $6,000 if you want the latest and greatest (Vons or KW multi-adjustable shocks and struts with raised spindles, etc.). Or you can spend a lot less than half that and have a real nice street car.

Another question: How many miles on the car? If it sat for 25 years, the suspension may not be as worn as you think. How much have you driven it since getting it back on the road?

Ditto Silverlock and others on keeping the suspension compliant, and jwolfe about making changes one at a time. Yes, there are some things you want to do at the same time "while you're in there," but most of the changes you can make independently.

Look at my signature line to see what I have. One thing I wouldn't do again is the RSR solid bushings--I'd stay with rubber suspension bushings for a street car. The solid or poly bushings DO increase noise and harshness in the cabin, unless you live in some dream world where all the roads are smooth! They are also a PITA to install. Turbo tierods: Meh. If your old tierods are not loose, leave them in for now. Easy to change later.

Answer the budget question and we'll go from there.

$6000 doesn't really bother me, but I'd obviously like to save some money where I can on it. Generally speaking, I'd like it to be turn-key for under $5000, including the corner balance and alignment, lowering, etc. Obviously me doing or not doing the work myself -- or parts of it -- will make a difference on how much I could do in terms of actual parts. The big ticket items seem to be the shocks and spring plates, with torsion bars not too far behind. So if I did stick to stock bars, that would help the budget.

I don't need the best and newest innovations/equipment. Just imagine, for instance, I shipped the car to Europe and wanted to tackle a 1000 mile road trip, covering highway to Alpine passes like Stelvio and Furka along the way. I want it to be comfortable on the trip, but I want the car to be safe and capable on those passes. And those roads aren't glass. Same idea in the US; the roads aren't going to be perfect, so building the car as though they will be isn't what I'm going for. That's kind of the goal, ultimately.

The car has about 60k on it, maybe a bit more. The odometer stopped on it at some point, but the records I have on it date to around the time it was parked. It was parked from around 1995 until 2024, when I got it out of storage and had a lot of work done to it. The shop did some work underneath on it (new CVs, etc.) but didn't otherwise touch the suspension. It's my suspicion that all the rubber on the car is original, and that even the shocks are original. They're not showing visible signs of leaking, and they seem to dampen ok, but I'm sure they're not 100%. They are, after all, 45 years old.

Regarding the tie rods, the steering feels pretty tight. There is sort of a squeaking noise that comes through the steering rack that I haven't been poked around to look for yet. I replaced the steering bushing at the steering wheel itself, so that's not it. Not sure if it has anything to do with the tie rods, but I'll inspect those when I come to actually working on the car. As you said, they're an easy thing to add.

Regarding the bushings, yeah I wasn't really planning on going with anything but rubber. It really comes down to whether there's a better option than OE at this point that still is compliant and quiet, but a better performing compound.

My real concern was something like the torsion bars. I can't see myself getting a year down the line, regretting I hadn't tried something different, and having to take that whole spring plate assembly and everything apart on the rear, and the whole front assembly again, and then have it aligned and corner balanced again. I think that whatever I do, leaving it stock or replacing, I don't really want to mess with it again for 10 years. So leaving them stock is fine (I'm sure the bars are in good shape), but I didn't know if going to thicker bars was an obvious thing to do at this point.