28mm torsion upgrade, ride height and "preload"

I just received my Sway-Away 28mm torsion bars for the rear of my 78SC, and plan to install them this weekend. I have already r&r'ed my stock tortion bars when I set ride height and installed Neatrix bushings a while back so I am familiar with the procedure. However, the instructions included with my new bars say their may be some problems with torsion bar preload. Has anyone experienced this "preload" and the associated problems with installation? If so what can I expect and how to go about installation with this added factor? Additionally, I plan to mark the angle of the swing arm before I r&r the swing plates. Will the 28mm upgrade change the angle of the swing plates or can I just set the spring plates on the new torsion bars at the same angle as the factory bars? Thanks in advance.
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Paul
78SC Targa

Paul...A number of club members have used Johnson's Alignment in Torrance CA. He will install the 22 and 28mm t bars, align and adjsust ride height as well as corner balance for $350....I plan on having it done soon. I just got my new Konis on and the t bars just showed up as well...

FWIW...I have been told that the rear t bar install is a real PITA and should be done at a shop that has an alignmement rack....

I will be looking on a Friday install date prior to the next San Diego autocross...1/6/01....maybe we can negotiate a group discount?



[This message has been edited by mikez (edited 12-29-2000).]

Paul,

I think you will want a more shallow declination angle with the heavier bars. I don't know what 'problem' with preload, other than difficulty in compressing the bars to get the cover back on (with the swing arm covering up the fourth hole at the lower right corner) ... could you be more specific about their 'warning'???

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Warren Hall
1973 911S Targa

could you be more specific about their 'warning'???

Warren, the warning states, "to reassemble, place the spring plate on the torsion bar at teh proper angle . . . " Is the proper angle the same angle I would have marked on the car body from the position of the swing plate before I began this procedure?

It continues, " Set the cap in place over the grommet and start the upper left hand bolt and the two right hand bolts. Thighen the three bolts just enough so the cap is snug, but not tightened down." "Now jack the end of the spring plate up until you can see the lower hole in the cover, and insert the fourth bolt. Continue raising the plate until it's just above the stop, and then clamp the spring plate top the casting. Tighten all four bolts."

"If you have a lot of pre-load on your torsion bars it may be hard to jack them up - the whole car may start to life up. In that event you have to take a piece of chain, 4' to 6' feet in length and wrap it through one of the holes oin the casting and around the floor jack (be sure the chain is behind the wheels so it can't slip off.) With the chain in place the car will no longer lift andthe spring plate will move up into place."

Now, the confusion comes from the swing plate covering up the 4th hole. I have never had this happen before in perforing this on VWs and the swing plate did not have to be jacked up to replace the swing plate on my SC the last time I R&Red them to replace the bushings. This makes me think that I am incorrectly replacing the swing plate because they must cover up the 4th bolt hole. Am I incorrect, or is it if the the "preload" conddition is present then the swing plate will cover the fourth bolt hole on the cover and in the past I have not had to deal with preload?

Thus, I presume I am to remover the swing plate cover, make sure the swing plate is down as far as it wants to go and then mark its position before removing it. Yes?

One final thing. Approximately much should I adjust the degree of angle on the swing plate to compensate for the added stiffness of the 28mm torsion bars? I presume the car will not "settle in" as much as it did with the factory torsion bars after the car is lowered to the ground and driven.

Paul,

It doesn't sound like you will have any problems, so just do the same thing you did when you installed the Neatrix bushings. Funny how legal remifications have increased the 'warnings' that go out with products! When I installed 26 mm Sway-A-Way bars 20 years ago, there wasn't anything in the box from them, except for a free decal! Same way with their adjustable spring plates!

As far as an angle ... I would guess at about 30 degrees, but that is a SWAG, so the usual disclaimers apply. Your settling will be less than with the factory bars after the new bushings, but I'm not sure how much less.

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Warren Hall
1973 911S Targa

Hey, I didn't get a free decal!!!
Thanks Warren, again.
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Paul
78SC Targa

I just installed 28mm bars in the back of my 89 and used 25 degrees with the car sitting level as the spring plate angle. They were adjustable, but the angle was correct. If you use the old angle, your car will sit too high due to the stiffer bar. Somehow, the mechanic I work with was able to use the factors of torsion bar size, ride height, car weight and years to come up with this angle. If all else fails, your may have to lower the car and then move up or down accordingly.

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