RS Look Suspension Refresh For The Track

[Ira Ramin]

After years of lurking on this board and occasionally posting, It's my turn to share. My 1970 911S RS look is almost ready to race again after more than five years of sitting in my garage. I restored it about 13 years ago and raced it with the POC for a couple years. The original restoration included an RS look conversion, paint, and an engine rebuild, along with some basic suspension upgrades.

With 21/27 torsion bars, and my very first prototype set of swaybars on it, I managed to do some respectable (for HP class) lap times at Willow springs, but never felt very comfortable turning in on turn 8. But then, who does. The back of the car took a long time to settle in, and felt like there was a lot flexing and some lifting during the transition. Not knowing the main cause for this, I decided to address every possibility during the refresh. At least that was my excuse for what lead to rebuilding and upgrading the complete suspension.

What could be flexing in the back that can be addressed? I started with aluminum trailing arms and larger torsion bars. Although street legal, this was a dedicated track car, so might as well go with 31’s. Can you see me on the top the edge of that slippery slope? What’s the point of changing the trailing arms and torsion bars, if I don’t set the rear up properly with monoballs and PolyBronze bushings. And don’t forget the rebuilt and revalved rear Bilstien shocks. Some replating of the factory adjustable spring plates, and new swaybar arms and bearing blocks finished up the back cosmetically. Below is the finished front suspension.



As you all know, the front and rear suspension need to match and complement each other. The front suspension received the same treatment with 23mm torsion bars, PolyBronze bushings, monoball offset camber plates, bump steer kit, and turbo tie rods. The strut spindles were raised 19mm, decambered, and gusseted. The front was also cosmetically finished off with new paint and new swaybar arms and bearing blocks. Here's how the front turned out.



More to come.

Ira

[Ira Ramin]

While sitting for the last 5 years, the metallic brake pads had corroded so badly that they were literally falling apart. Performance Friction Gold racing pads, turned rotors, and brake ducting from the front bumper should help provide some improved braking performance. The battery boxes needed to be removed to route the brake ducting, which will also improve airflow to the oil cooler and dropped a few pounds of weight.

This weekend we aligned and corner balanced the car in a friends garage. Now I completely understand why it costs $400, and up, for a shop to do it. After spending a day getting it close in my garage, we spent almost another day getting right. I’m sure that a real alignment rack would have helped a lot, but it would still be a big job. I have to say that the Elephant Racing rear camber adjuster more than payed for itself the first time I used it, and I highly recommend it to anyone doing an alignment. I believe our host carries them. We spent about 5 minutes dialing in the rear camber. It uses a 8mm screw to easily and accurately change the rear camber setting. Great invention Chuck!

The alignment came in as shown below. Caster was maxed out and made equal on both sides to prevent pulling to one side. Keep in mind that camber, ride height and toe changes will all effect each other, so several iterations were necessary. That’s part of the reason it all takes so long and costs so much. Corner balancing wasn’t too bad compared to the alignment task. The front suspension was originally set pretty close by supporting the rear at the center of the car. I then adjusted the front torsion bars to get the desired front ride height and make the car level from side to side. Use a suspension mounting point to check for level, not the fenders. Then, repeated the procedure for the rear suspension. I didn’t record the original corner balance readings, but it was so close that it only took about one turn on the right front torsion bar adjuster to get the weights within 3 lbs. of being perfect. With large torsion bars, adjusting the corner balance is actually very sensitive and I overshot several times before getting it right.

Here's the Alignment and corner weight numbers.

[Ira Ramin]

Running short on daylight, I did manage to get a short drive in to check it out on Sunday. With all the changes made to the car over the winter, I didn’t want to test it in the dark or go too far from home. First impressions were actually a little scary to me. I’m used to driving a Tundra and haven’t been in the 911 for more than 5 years, way too long. The car is so responsive and light feeling that it gives the impression of being unstable at first. The turbo tie rods give so much feedback that you can feel everything on the road. The suspension feels so tight that I could barely detect any travel. The car does feel like it starts to wander with irregularities in the road, but it only starts and doesn’t go for long. It may just be that I’m just not used to it yet with all the changes, but I plan to recheck the toe and all the hardware next weekend. I’m signed up for the POC short track event at California Speedway in a month. The biggest tasks are finished, but there’s still a lot little things to do before the event. I’ll report back on the results.

Ira

PS
Here’s a few more things that got added to the project over the winter, while I was at it. Recaro Nascar seat, oil change, trans fluid change, fix multiple oil leaks, new brake lines, some dent and scratch repair (including front bumper repaint), RS style door panels, painting the wheels red, new Odesy battery, replaced leaking fuel pressure regulator and lines, headers, front and rear wheel bearings, headlight covers, 935 style mirrors, I’m sure there’s more. Here’s the finished Product.

[Chuck Moreland]

Awesome job!

Since I've been monitored the progress of this car offline for about 4 years now I am anxious to see you back in action. I'll be POC cal speedway event too.

[Cory M]

That spreadsheet looks familar

Looking forward to sharing the pits with you at Cal Speedway Ira. It will be great to see you and your car back in action after the long hiatus.

By the way the Tarett swaybars on my 944 spec car are easy to adjust and work great!

[Jack Olsen]

I think you're ready for turn 8, now.

But keep in mind, that makes turn 9 come up a lot faster.

[Shawn 357]

Ira,
I glanced at this post and thought "that guy has Tarret Sway Bars, Cool!" then I noticed it was you posting. The car is looking good I can't wait to see it on the track.

Chuck,
After helping Ira adjust his alignment with your camber adjusters I bought some the same day!

[DW SD]

Ira,
Great work! Hope to bump into you soon.
Who did your shock re-valving?

Doug Wierenga

[Ira Ramin]

Thanks Guys. I’m really looking forward to being out there with you all. The corner balance spreadsheet gives a nice presentation of the setup. The car may be ready for turn 8, but after 5 years of not racing, I’ll be doing a bunch of short track events first. The race compound pads and added cooling should be useful going into 9. Thanks for the heads up Jack.

Doug, You should try to make it out there. It would be nice to meet up with you one day. Like you, I bought my shocks, struts, and torsion bars from a friend. His car was set up similar to mine. The shocks and struts were already modified and revalved by Steve Alarcon. I don’t know the valving he uses.

Ira

[Jeroen]

Hey Ira,
Sweet looking ride and good to see you getting back into action!

[earlyapex]

Ira, I'm glad you're back on the track.

Thanks for helping me with my suspension!