Torsion bars and bushing swap (and...while I'm in there?)
 

I have an '84 M491 that is race-car light and race-car stiff (2500#, 23/30). I decided to go all the way back to stock with the torsion bars and shocks so that I have a long-term baseline from which to judge, should I ever want to make changes to the suspension again. My only other comparison is my bone-stock '87 coupe, which drives like a dream on the worn roads where I live.

In addition, I believe the car has polybronze bushings that make a fair bit of weird noise, and seem like overkill for a car that won't be tracked until they ban human drivers on public roads. I eyeballed them pretty hard in search of grease zerks, but found nothing. Research on the matter of bushing replacement has begun to make my head spin—OEM? Elephant Rubber? Sphericals? That brand that starts with an N that I forget??

I plan to have a shop swap out the torsion bars and shocks for a stock set of 930 bits that I have already procured, and I'd like to have all my parts ready ready when I hand the car over. What other bits are worth doing while the front and rear suspension is apart? This will likely cost me a grand in labor, so I don't want to skimp on a $50 wear item. The car currently handles phenomenally when the road is like glass.

With the ER polybronze rear bushings the zirks are forward of the spring plate cover so they can be easy to overlook. Chuck recommends greasing them every 3k miles.

I did my rear suspension myself earlier this year. Polybronze bushings, adjustable spring plates and 28mm t-bars. My Bilsteins were basically shot. For about the same price as new (less actually), I had Chuck at ER re-valve them on a digressive curve. I was worried about stiffer being a harsher ride but it rides so much better now. I think the Bilsteins had more to do with it than anything else so maybe it is worth thinking about the shocks than worrying about changing the rear bushings or torsion bars. There are also bushings for the trailing arms. I would just go with rubber. A few people told me that if you go with the monoball bushings there it really contributes to ride harshness.

I am picking up my car this week from a local shop. First time I've let anyone else work on the car since I first got it. They are putting on all the front suspension parts I've been acquiring because I'm going on a road trip in a couple of weeks and I don't have the time between now and then to do it myself. Up front I chose the ER spherical control arm bushings (yea... probably way overkill in retrospect), the strut top rubber bushings, 21mm t-bars and new ball joints. Again, sent the front struts to Chuck @ ER to re-valve on a digressive curve. He is also raising the spindles 25mm because I'm lowering the car. Since the geometry is changed I'm replacing the tie rods with turbo tie rods that have an adjustable bump steer end.

Good time to replace the sway bar bushings. They are cheap.

You're probably thinking about Neatrix. I think that's the name.

My 1973.5 with 160,000 miles has a mostly stock suspension. A few upgrades were done a few years ago. I drive on the street for fun and autocross 5-8 times a year.

My suspension has turbo torsion bars from and rear with 19 mm adjustable sway bars at both ends. I replaced my rear spring plates bushes with neatrix parts. All other bushes are stock and original. For the street I use 16x6 Fuchs with 205/55-16 BFG g-force sport as tires and auto cross on 15x6 cookie cutters with Toyo RR 205/50-15 tires. I had Rothsport lower/corner balance/align the car and apply his "secret sauce". Car rides and handles great.

One data point for your consideration.

This is a good read...

http://forums.pelicanparts.com/porsche-911-technical-forum/726309-78-sc-elephant-racing-suspension-rebuild.html