Are SWB & LWB Ball Joints Interchangeable?

[mshaver51]

Learned Friends,

I just read an article which discussed the front suspension foibles of the SWB cars, and the "pig iron" ballast that was installed in '68s. The article said that the pig iron was installed to improve the handling and distribute the weight better, but that the real problem was the ball joints. It recommended that the later (LWB) ball joints solved the handling problem. The article suggested installing the '69-'80+ front suspension to correct the handling problems. (I have a '68, and i have the pig iron inserts.)

So here are the questions I pose to the scholars ...

Is it possible (or advisable) to simply install the LWB ball joints into the original '68 front suspension assembly (and leave the remainder of the front suspension assembly original)?

Would it be better for the car to simply install an entire LWB front suspension? (Obviously, this is not original, so I'm insterested in value implications, as well.)

Would it hurt the value of a restored '68 to leave out the pig iron inserts?

Thank you, in advance, to those with knowledge to share.

mike shaver

[304065]

Mike,

The SWB and LWB ball joints are completely incompatible. The LWB mount with screw threads and a big nut into the control arm. The SWB are contained on the end of a forged stalk which slides into the lower control arm and is secured by a pair of M12x45 bolts with castle nuts and cotter pins that also capture the shackle for the lower end of the ARB link.

What handling deficiency are you seeking to correct? Let's start from there. Barring any rule restrictions, the race solution is to mount a complete front suspension from a Carrera, and take advantage of decambered LWB ball joints and camber compensating upper monoballs (like a WEVO Camberking). Big brakes, you need a 23mm MC and the parts are a LOT cheaper. (The SWB ball joints are about $200 each).

Yes, leaving out the weights diminishes originality. 68s are sought after because they are original, not because they are light.

Save EVERYTHING.

[mshaver51]

This is why I love this community! This is exactly the sort of information I needed and wanted!

Given your advice on the ball joints, would I be correct in concluding that the only way to get the newer-designed ball joints would be to install and entire LWB front suspension? I'm assuming that, if a Carrera suspension bolts on, then a '69-'70 suspension should bolt on, as well. If this conclusion is correct, then it looks like my two best choices would be an entire '69-'70 front suspension, or simply remain original (with $200 ball joints).

I'm restoring a '68 SWT. Almost everything used in the restoration has been NOS, at least so far. I've never driven a SWB, so I am only reacting to the handling shortcomings that I read about. To be honest, though, the pig iron weights don't really seem "Porsche" to me. They are too low tech and seem like a badly designed band-aid. Plus, i don't want to think about one of them coming unglued and tearing the floor pan out of my car.

I'm not planning on taking my '68 swt to the track. I just want it to be fun and safe to drive. I'm not a street racer, but it's fun to get out on some Indiana back roads and drive quickly, without being stupid. So, for that usage, what's the best alternative?

I believe the suspension that is in the car to be original. Are you suggesting that the best alternative is simply to ignore the handling/suspension shortcomings and stay totally original?

Thank you, and other opinions are welcomed, too, if anyone else has a thought.

[tomkirkcis]

I took the ballast out of the bumper and put them on the shelf. It is very easy to reinstall them in the future. It is a SWT. Unless you want to do a sport purpose hot rod out of your targa, or want to auto x or track your car, keep the suspension original . Remember the tires that were available in 68. New avons in 175/70 cure a lot of the complaints writen about these cars in 1968.

[chris_seven]

The real question is handling versus originality.

I have had the opinion for a long while that the bumper weights fitted to some SWB cars are a complete waste of time and only add weight and increase polar moments of inertia, neither of which are particulalry desirable in my view.

As regard the SWB suspension being 'poor' I can't say that I would agree.

The issue is to set the car correctly to make it turn in and this is relatively easy to achieve with careful adjustment and decent tyres.

If the SWB has any handling issue it is more likely to the the flexibility in the bearing housings on the rear trailing arms causing rear toe steer.

There are two ways to resolve this problem.

The most extreme is to shorten some 1969/72 spec steel arms so that the fit the SWB car and add the RSR style strengthening. This is quite involved but has a very positive influence on handling. It also allows latervented discs to be fitted and give larger rear wheel bearings.

We fitted a pair of these arms to one of our cars and took it to a Trackday at Brands Hatch where we also fitted a set of Avon Slicks just as a try out.

The car has an RSR style strut brace and a 6 point Bolt-In Roll Cage.

The Turn-In and cornering capability was incredible to the point that the body deflection cracked the windscreen.

.

We now need to add more stiffness to the entire front end.

The other would be to modify the original SWB Trailing Arms and this is a project we will try to do this Autumn.

If you want originality then you will just have to leave it alone but even then the handling is nothing like as bad as the rumours make out.

[savaden]

Probably the easiest thing to do with the most effect is to simply replace the top front strut mounts with monoballs. That gets rid of the double donut rubber bushings and will greatly improve the directional stability. The next thing would be to replace the rear spring plate bushings if they are worn. After that things get more expensive.

SV

[304065]

This is why I love this community! This is exactly the sort of information I needed and wanted!

Given your advice on the ball joints, would I be correct in concluding that the only way to get the newer-designed ball joints would be to install and entire LWB front suspension? I'm assuming that, if a Carrera suspension bolts on, then a '69-'70 suspension should bolt on, as well. If this conclusion is correct, then it looks like my two best choices would be an entire '69-'70 front suspension, or simply remain original (with $200 ball joints).

I'm restoring a '68 SWT. Almost everything used in the restoration has been NOS, at least so far. I've never driven a SWB, so I am only reacting to the handling shortcomings that I read about. To be honest, though, the pig iron weights don't really seem "Porsche" to me. They are too low tech and seem like a badly designed band-aid. Plus, i don't want to think about one of them coming unglued and tearing the floor pan out of my car.

I'm not planning on taking my '68 swt to the track. I just want it to be fun and safe to drive. I'm not a street racer, but it's fun to get out on some Indiana back roads and drive quickly, without being stupid. So, for that usage, what's the best alternative?

I believe the suspension that is in the car to be original. Are you suggesting that the best alternative is simply to ignore the handling/suspension shortcomings and stay totally original?

Thank you, and other opinions are welcomed, too, if anyone else has a thought.

The weights actually help. Look, more weight up front makes the car easier to drive for anyone below the level of a professional. My 71E race car has the battery relocated to the smuggler's box to allow use of a fuel cell, and the car handles a lot better just after a fuel stop than at the end of the race. We aren't allowed cockpit adjustable ARB's, however.

If you install them correctly they won't come loose. We glued the weights back in '065's bumper with urethane windshield adhesive. It would take a sledgehammer to get them loose. Make sure the contact surfaces are properly prepared. I replaced every suspension part with a new one ($,$$$) and will align the car to "modern" settings.

I'm with Tom, it's a soft window targa, after all. Not quite as much body flex as a piece of linguine but close to it. This isn't a slight, it's simply an engineering reality-- the car will never have the torsional flex capabilities of a coupe, or even a more modern economy car. Hell, a modern Subaru probably is several orders of magnitude better.

Also remember the historical context of the bumper weights-- at that time, Ralph Nader was doing his thing- and the target of his invective was the Corvair, a six-cylinder, rear-engine car deemed to be "unsafe at any speed." Even despite FRE 407 (the lawyers here will know what I mean) the Factory was concerned about the handling-- hence the dual batteries in the LWB cars. Really now, the LWB had at most 9,8 to 1 compression, it's just not so hard to start that it needs two batteries-- this was the Factory surreptitiously increasing polar moment. Ever seen the battery in a 911SC? It would make a nice boat anchor. This stuff didn't get really addressed until the 964, and even today, with all the electronic interventions, you still have probably 85% of the weight of the engine aft of the rear axle.

Which means what, from a practical perspective? It means that for street driving, you keep the car below the limit of adhesion. This isn't very hard to do given the necessity of defensive driving in a world full of SUV drivers texting with one hand, working a hairbrush with the other and eating a sandwich as they hurtle towards destiny at fifteen over the limit.

On the rare occasions where you can take the car on the track, it means taking a nice late apex and keeping your right foot planted most of the time. It's counterintuitive at first-- when you begin to feel the rear end coming around, to step on the gas and open the front radius by steering away from the apex, but eventually you get the hang of it. Some skidpad time would help and would be a great deal of fun besides. Modern cars are set up to understeer at the limit to reinforce the tendency to lift off when you've overcooked it, or even worse, hit the brakes. It takes a while to unlearn this.

The tradeoff to our unconventional configuration is that the act of pushing the throttle down in the corners is also what makes a 911 fast. Porsche has won more races than anyone, period. The other part of it is superior braking performance.

[hoffman912]

they are not interchangable and are crazy expensive. I am kind of pissed right now.. i just redid my entire suspension and i think the roads of new hampshire on the north east mountain melee destroyed my new ball joints. f**king frost heaves.

[ix0ifan]

Surely increasing the Polar Moment of the front end of the car will increase the tendancy to understeer?

[304065]

Surely increasing the Polar Moment of the front end of the car will increase the tendancy to understeer?

Polar moment affects the car's resistance to rotation around the vertical axis-- both starting to rotate and stopping. Whether it understeers or oversteers is a function of coefficient of friction and corner weight and the resulting slip angle-- before it starts to move. To me, and I'm willing to be educated on this, the two are not directly related. High polar moment will definitely affect your ability to react to understeer or oversteer, but it doesn't on its own cause it.