Tired '78 SC - What Suspension Work to Do First?

[RV Flyer]

My '78 SC Targa has 145k on the odometer, and I've owned it since 1985. The car is stock except for turbo tie rods and bump steer kit, and had new Bilsteins all around at about 90,000 miles.

Over the last 6-8 years I've not driven it much, and the last 2-3 years it has gotten essentially zero use, just parked in the garage. Although the car overall is still (I think) pretty solid, wear and tear on various systems have resulted in it not being so much fun to drive.

Now, the goal is to get the car to where it IS fun to drive again, and I've decided that the first area to work on is the tires/suspension/brakes. The tires on it are 1990 vintage Goodyear Eagles, and my guess is that these are flat spotted, because there is a pretty good shake to the car at moderate speeds (30-50 mph), which smooths out somewhat at 55 or better. And, the car has been sitting on the tires, essentially immobile, for years, so I am assuming that between age of the tires and the long-term sitting, the tires are probably ready for replacement. The vibration/shake that is present does not strike me as being from halfshafts or CV joints; it seems to have a larger amplitude, and feels as though there is a lot of mass moving around to cause the condition.

What about suspension bushings? The car has the original bushings all around, and my thought is that perhaps it makes sense to just replace all these as the first step; then, test drive and see how things are; then, put new tires on if there are still signs of tire flat spot/imbalance (which I suspect there will be).

The last item (for now) on suspension/brakes is a rather "dead" feeling brake pedal. Pads and rotors are OK, and the power brake booster passes the test outlined in the Pelican Parts technical column. The master cylinder is original to the car, as far as I know. The pedal feels firm, at first, but then has a spongy feeling travel for about 1/2 inch or so before feeling firm again. Overall stopping power is simply not there - it feels more like a bad booster than a bad master cylinder, based on my experience, but I'm wondering if a new master cylinder would be a good idea regardless.

Any recommendations on (1) whether the tires could possibly still be OK, (2) whether to do the bushings all around, and if so which ones to use, and (3) the brake issue would be much appreciated. I would like to keep ride comfort a priority, as it is an open car and not driven that hard, plus our roads out here (and my aging body) make a smooth ride something really desirable.

Sorry for the lengthy post - the last 10 years have been spent building my RV-6 and getting that into the air, plus raising twin daughters, so the old 911 was on the back burner for a while and has lots of issues to be addressed. But I'm ready to get her spruced up and back in good form, so TIA for your suggestions.

[Jim Smolka]

Welcome to the board.

Lots of information here.

Suspension. One can spend a little one can spend a lot. Any chance of track time? Bushing are OK, or even bearings, but they are $$

Yes, replace the tires, bleed the brakes, see what you have then. If you need a MC, then consider the 930 MC. Firmer brake feel.

[javadog]

I'd change the tires first. The old ones are WAY too old. Install new valve stems when the tires are changed. This should make a big difference.

Check the booster to see if it will hold vacuum. If it's bad and you replace it, there are different sizes available. The turbos had a different one, as Jim pointed out, (and it changed in size in the '80's) and the smaller the booster, the higher the pedal effort. It depends on what you want, as to which one you pick.

How often did you change your brake fluid in the last 20 years? If it's not at least every two years, I'd suggest rebuilding the calipers, changing the master cylinder and changing the rubber lines. At the very least, I'd look at the calipers. I suspect the pistons may not be moving freely. You may also want to check the bushings in your pedal cluster.

I'd consider the suspension bushings only if they are worn to the point where you are nearing metal-to-metal contact with the parts that move, or if you have squeaks. I personally don't like the available choices in bushings (for a street car) compared to the factory originals (which I think are getting scarce, if not NLA.) I'd probably consider poly bronze for my next set, if I had to change them.

Tha last thing I'd do, after all of the above is sorted out, is a full alignment with corner balancing.

Good luck,
JR

[Joe Bob]

If not a PCA member....Talk to one in your area and find a good alignment shop that isn't a NASCAR joint. Consider joining PCA if they have an active club that isn't too full of "whine and cheese idjuts".....

Most alignment shops do tires as well. You can also order online at Tire Rack, have them shipped to the shop and they can bust down the tires and do the install.

A good P-car oriented shop will throw the car on the rack, evaluate tie rods, bushings, check alignment, balance etc and make recommendations.

[RV Flyer]

Thanks for the advice, everyone - there really are not a lot of squeaks or other indicators of the bushings being bad, so I think I'll start with new tires, a check of the brake booster to confirm it holds vacuum, and then a full brake bleeding. The brake fluid was not changed regularly and so Javadog may be right on the need for additional brake system work.

Are the 930 brake booster and master cylinder a straight swap, i.e, no re-fab of brake lines, switches, etc.? And can you mix and match a 930 booster with a 911 master cyl, or vice versa? The parts list at the Pelican site doesn't give any guidance on that. I'm not too concerned about pedal effort, so much as I would like firm brakes that feel like they are really getting the job done.

[jdowty3]

I'd say start with the brake first as stopping a 911 is pretty critical to yours and others health. Rebuild the calipers with new piston seals, add Speedbleeders, new rubber brake lines, and flush the system with new brake fluid.
Then decide if your going to do the suspension bushings. New tires and an alignment when the brakes and suspension are done.

[mede8er]

You don't mention any track implications, so I'd stay with a stock suspension set up....it was fun to drive when it arrived from the factory....

Tires and brakes...then run it awhile....it will tell you what it needs in the handling department......

While its up in the air try to get a peek at your sway bar bushings also......

[javadog]

I don't know if you want a 930 master cylinder, as they have a larger bore to suit the greater caliper piston volume of the turbo brakes. The bore sizes are 20.64mm and 23.81mm, so you're looking at about a third more area in the bore of the turbo master cylinder, which would change your pedal effort a lot. I've never tried it, so I can't comment on how it feels. Maybe Jim can chime in here, if he's tried it.

The SC used a 7" brake booster and the Turbo used an 8". The bigger the booster, the greater the reduction in the force needed on the brake pedal for a given amount of braking. In 1984, the Carrera got the booster from the turbo. In 1985, they changed the booster on the turbo to one that reduces the pedal effort. It's still listed as an 8", so I have no idea what the difference was. I have installed one on an earlier 3.3 turbo and it reduced the effort a fair bit. If you want a harder pedal or greater effort, I think you should stay with the SC booster, if it works.

I'll go out on a limb here and bet that your problem lies mainly with the calipers or a corroded master cylinder. I think if you address that part of the system, you'll be fine.

There may also be aftermarket master cylinders on the market, that are sized in between the SC and the turbo units. I've never looked. Bill Verburg, one of the moderators on this board, seems to have done a lot of thinking about brake swaps on these cars, so maybe he knows of some other alternatives.

JR

[RV Flyer]

Well, it seems hard to go wrong with making sure that the brakes are up to snuff, whatever else may need doing. So I've ordered up a master cylinder, caliper rebuild kits, rubber hoses, and ATE Super Blue from Pelican and will tackle that first.

If my wife REALLY knew how much it is going to cost to "just get the old 911 into decent driving shape..." she probably would not be so supportive. I mean, there are the SSI exchangers, sport muffler, tires, new or recovered seats, etc. still to come . . .

[javadog]

Naw, you're just looking out for her safety and comfort, should she wish to accompany you on a nice Sunday drive, or two. It's really a sacrifice on your part, I think, what with all the work you're getting ready to tackle. She should be grateful for your dedication and hard work.

Have fun,
JR

PS; Let us know how it turns out.

[jdowty3]

We NEED pictures!!!! Don't you know we're image junkie.
Definately of the car, maybe the wife too, it's up to you.

[Jim Smolka]

The 930 MC bolts up fine, no mods needed. The 930 MC was installed in the 3.6 SC since the front brakes have been upgrade to 4 piston calipers. The 930 MC is a good upgrade if one plans to spend a fair amount of time at the track or changes to 4 piston calipers. Just my $0.015 worth

[RV Flyer]

Finished up the brake work this weekend; all 4 calipers rebuilt, plus new master cylinder and flex hoses. Observations:

1. The front calipers each had one REALLY stuck piston, and one only slightly sticky. Compressed air was enough to get the latter out, but had to put the caliper back onto the car and use the brake pedal to put enough pressure on the system to get the really stuck ones out. The rears were each a little sticky, but air was enough to get them out. I think most of my braking was coming from the rears, with the fronts not helping much, and the pad wear on the rears (a lot) compared to the fronts (not much) also suggested this.

2. All the pistons had some amount of rusty buildup near the pad end, and a few of them had some light pitting/corrosion near the pad end - this was not far enough back on the piston to contact the sealing ring in the bore, as far as I could tell, and cleaned up OK with some scotchbrite.

3. Caliper bores had some sticky residue, no pitting but there were different surface finish areas that looked like slight scuffing had taken place, or something similar. Getting the new seals and dust boots in was straightforward.

4. Master cylinder replacement went very easily as per the tech article our host has at the Tech Info Center. I just cut the gravity feed lines from the reservoir to the MC itself, thereby avoiding the need to undo the ventilation control cable end , which runs between the hoses and would be a B**ch to hook back up. Found the correct brake hose (silicone w/sheathing) at the local VW shop for replacement; expensive but worth renewing these while everything is apart, and you only need about 8 inches of it.

5. All flexible brake lines were replaced; old ones looked pretty crusty on the outside but when cut open they did not appear to be too swollen.

6. Speedbleeders and a vaccuum bleeder helped a lot in getting everything bled and a reasonably firm pedal. It feels like there is still a little air in there somewhere, but from other threads on this I gather that is not uncommon and a re-bleed after driving for a week or so may help. Braking action is much better now, even with a less than perfect pedal feel.

Time to go put some miles on the car now - and get some decent weather here in the Seattle area for a pic of the car for this forum......

John

[Tim Hancock]

As a fellow homebuilder, I am ashamed to hear you did not figure a way to retrofit double piston Cleveland brakes picked up at the Oshkosh Fly-mart and that you did not use MIL 5606 hydraulic fluid!

How about a picture of the RV (along with a pic of the SC just to stay on topic)

Did you put a 360 in it?

[RV Flyer]

Tim, it has a new O-360-A1A and Hartzell blended airfoil prop; a slow build kit that I started on early 1995 and first flight was 9/04 - took a long time to build, what with kids, law practice, etc. taking priority.

Pix below are from my first long XC in it last spring to Phoenix; one on ramp at Chandler right after I arrived (6:15 total flight time from Seattle, man I was ready for a beer), and one on the ramp at Sedona with daugher Grace (and stuffed friend) who flew up there with me for the day.

Still deciding on paint options and saving the $$ for same.

Will post a pic of the SC once I get a couple decent ones.

Interestingly, when people ask what the RV is like, I tell them to think of an early 911 with wings on it - snug, fast (relatively) and sporty flying for 2 plus modest luggage

[Tim Hancock]

Nice! It is going to be hard to put it down for paint now that is up and flying!

I am about 7 yrs into a scratch built "One Design". I have been too busy the last couple of years to finish it for basically the same reasons you listed.



B4 I got married, I pretty much "scratch" built this Minimax in 1 1/2 yrs. Worked nearly every evening and weekend on it including Christmas day! Those were the days! Nowadays family cars (two teen daughters) have been consuming most of my free time!

[RV Flyer]

Thats a clean looking MiniMax, Tim. Are you flying that, or something else, while the One Design is under construction?

John

[Tim Hancock]

I still fly the Max on occasion (especially int the winter on skis), but most of my flying lately is in the Pacer pictured next to the Max. I just do not get out for fun much lately. Oshkosh plus a few local fly-ins and family trips amount to 30- 40 hrs a year on the Pacer the last couple of years.

I need to install an oil cooler and address an oil leak on my 911, then hopefully build an addition to my hangar (need more car/mower etc parking) this spring and early summer. Hopefully around Oshkosh time I will start back in on the airplane project as long as I do not get too many sidejob airplane repairs coming in. I picked up an IO 360 C1C complete with Bendix fuel injection that I have torn down, now I need to send parts out for overhaul. Too many projects, not enough time (or money for that matter)! I need to wean myself away from this forum as this whole 911 thing wiped out all of last years free time!

[RV Flyer]

UPDATE: The brakes are feeling pretty good as the pads get mated up to the rotors. Modulation is easy, with pedal travel and pressure both feeling better.

More improvement came a few days ago by way of some Yokohama Avid V4Ss, in the factory 205/55 VR16 and 222/50 VR16 sizes for the Fuchs that came on the car. MUCH improved ride, less noise, easier steering, and decent all-weather grip. These tires are pretty cheap (~$85-90 from Tire Rack) and have given good performance on my 1.8T Beetle, and get pretty good reviews from the Tire Rack customers. So, for an old Targa that doesn't get driven all that hard, or all that much, I figured these Yokohamas would be a good compromise. If nothing else, they were guaranteed to be better than 15 year old Goodyear Eagles, which had gotten rock hard by now.

Now I gotta start saving some $$ for all the other things that want attention ..... interior, exhaust, etc......

John

[PorscheGuy79]

Originally posted by Tim Hancock
I still fly the Max on occasion (especially int the winter on skis), but most of my flying lately is in the Pacer pictured next to the Max. I just do not get out for fun much lately. Oshkosh plus a few local fly-ins and family trips amount to 30- 40 hrs a year on the Pacer the last couple of years.

Tim, just happen to notice this but if you are ever in need of someone to grab a beer at Oshkosh with let me know. My dad is ultralight pilot/recent Porsche nut as well and im the car nut. We live close enough to Oshkosh and go up every year.