Yet Another Boring Rgruppe Car – Part II, Suspension

[RWebb]

There is an inexorable trend (a fad?) to stuff the biggest torsion bars possible under one's car. But, I've driven "tight street" (22/27 torsion bars) and nearly stock 911's side by side to test them on some of our windy & bumpy roads nearby. I have a very twisty and very bumpy road near my house. It is narrow and goes up a hill leading out of town.

Neither car had metal joints (monoballs or purely metal Heims). I drove them back to back and it takes only about 7 minutes to get to that road from my house. This means I could drive a car on that road, then quickly check out the other car, without having to make comparisons to a distant memory. I found that the softer suspended car (my old '75S) was not only more comfy, it was also faster on this road. The Boxster S I used to have was much, much faster than either.

This '73 is the car that had the 22/27 combo. So, I am now going to go "backwards" on the front to a 21 mm bar.


Here is a map and some pics of my test track:

[RWebb]

[RWebb]

The nicest torsion bars I've seen are the hollow ones that are plugged and plated by Chuck M. (Elephant Racing). I think they are made by or for SRP.

[rfloz]

Originally Posted by RWebb

There is an inexorable trend (a fad?) to stuff the biggest torsion bars possible under one's car. But, I've driven "tight street" (22/27 torsion bars) and nearly stock 911's side by side to test them on some of our windy & bumpy roads nearby. I have a very twisty and very bumpy road near my house. It is narrow and goes up a hill leading out of town.

Neither car had metal joints (monoballs or purely metal Heims). I drove them back to back and it takes only about 7 minutes to get to that road from my house. This means I could drive a car on that road, then quickly check out the other car, without having to make comparisons to a distant memory. I found that the softer suspended car (my old '75S) was not only more comfy, it was also faster on this road. The Boxster S I used to have was much, much faster than either.

This '73 is the car that had the 22/27 combo. So, I am now going to go "backwards" on the front to a 21 mm bar.

Horses for courses - track or auto-cross, stiffer will generally be better; for the street, not so much. My (2550#) Carrera has 22/29 T-bars and they work very well for auto-cross, which is my priority. I also drive it on the street and bumpy roads are not its forte. For a street-biased car, less is better.

Aside from the variables you noted, shocks/struts matter, a lot.

BTW, a well-driven Boxster or Cayman can be a fearsomely quick auto-cross car. Of course, with 20+ years of development and a mid-engine, some might argue it damn well ought to be.

[sjf911]

I found that the stiffer suspension was just miserable around here with the poor roads and endless speed-bumps. I am in the process of converting back to 26mm/19mm from 28mm/21mm. I also found the Bilstein Sports to be intolerable for our streets so it is back to HD's.
It did have one benefit. My wife refused to drive it.
As to the goop on the front camber plate, it looks more like sound deadening material. I wonder if it is there to reduce noise and vibration from the front suspension.

[RWebb]

I wouldn't think so. Stock, the car's strut is mounted inthe rubber center of the camber plate. That will isolate NVH much much more than a layer of goop.

Bob - yup -- this is "mainly" a street rod. It is, of course, capable of venturing into a parking lot AutoX or onto a track....

[RWebb]

OK, I am not going to post pics (or text) that are duplicates of what is already out there...

This is a particularly well done thread on this operation and the rear suspension too:
Front suspension refreshening

And here is one pic showing the denouement:

[RWebb]

Various threads have discussed "stiction" -- the stationary friction or sticking encountered when two parts are at rest, as opposed to sliding friction.

I have an interllectual unerstandin' of the issue, having gone to an engineering school as an undergrad. But, I never had a real world "hurts my back" type FEEL for the nasty stiction of the polygraphite bushings until now:




It was simple to take the A-arms off (tho I have a nagging suspicion that it might be tricky to put them back on and get the ball joint shaft inserted correctly into the female strut.)

But just taking off the front & rear mounts was a real mother -- now I have felt stiction in my own hands (and back muscles).

The thing can be rotated with (at a guess) 100 ft-lbs. of torque once you get it going. But it must be 2x or 3x that to get it moving in the first place. And rotation with a pull was the only way to get the thing off of the arm.

[Chuck Moreland]

Originally Posted by RWebb

But just taking off the front & rear mounts was a real mother -- now I have felt stiction in my own hands (and back muscles).

The thing can be rotated with (at a guess) 100 ft-lbs. of torque once you get it going. But it must be 2x or 3x that to get it moving in the first place. And rotation with a pull was the only way to get the thing off of the arm.

And that is unloaded. Torque goes up when the corner weight is resting on the bushing! Or twice the corner weight as when loaded up in a hard turn!

In operation both bushings are twisting simultaneously, twice the torque!

That is why polygraphite bushings ride so harsh.

[RWebb]

"While in there," I pulled the upper port cover off the steering rack.

It looks fine to me. The grease was not at all caked or "clayey" and not too liquid either. I put a bit more grease in, put the pressure block and spring back and put the cover back on.





The pressure block looked fine too - I guess I should have used my fingernail to make sure there was no groove, but I didn't. [see: SC Steering Rack DIY Bearing Replace and look at post #39 by KTL and the pic on the first page]

[RWebb]

Ugh!




This rust could not be seen while the front A-arm mounts are installed. Something else to check over periodically I guess.

Another problem is the poor design of these things. The red ellipses show the 4 areas where the welded on reinforcement shell has gaps in it. These allow water intrusion deep into the area which fades into a crevice to either side. I cannot think of a better design to promote rust.

[kenikh]

Is this car gonna be ready late April?

I am in agreement on t-bars and hard joints. My car is going to 19/26 turbo bars, Elephant PB bushings and rubber everywhere else. Everyone also forgets about sway bars - they significantly affect ride quality, too.

[RWebb]

HA! May well take that long. Turns out Wurth self-etch primer needs 65 oF for application. I have some light bulbs under the car now, trying to warm it up.

I spent a day grind at the rust (got rust, undercoating & grunge all over my face & hair - washed that out ok then went drinkin' -- got to the restaurant and this Morrocan place had warm wet towels so I wiped my hands & face... turned the towel black. I had bits of undercoating & etc. all thru my beard....). Finally washed all of that out & then used rust reducer (aka, converter, aka neutralizer) on the remaining areas.

Next, will prime and then top coat with a satin black oil based enamel. I don't have any epoxy type paints and it seems crazy to buy a bunch of that stuff when I have half-pint of the XO-Rust stuff sitting there waiting for me to use it up.

Then, I'll have shot at undercoating in the cold...

Waiting for the Pelican parts shipment now...

Yeh - the sway bars will be addressed in phase 3....

[RWebb]

I appreciate the danger of While You're In There - itis, but I'm glad I decided to pull the pedal cluster....





As Zippy the Pinhead put it "YOW!"

[kenikh]

Originally Posted by RWebb

As Zippy the Pinhead put it "YOW!"

I've seen that before! Scrapte...scrape...

[RWebb]

my plan is to wire brush it - scrub it clean w/ soap & water

and then use a rust converter treatment

Kenikh & others: any thoughts on that?

I don't see the point is spending a lot of money for an epoxy paint like POR-15 for this application.

[kenikh]

I'd scrub/sand it down, then use a rust converting primer - it's only $10 a can. You let it sit overnight, then you can paint over it with POR-15, which is again, only about $10 in a spray can. $25 is cheap insurance against future mishaps.

[Carrerax]

Glad you found that! Take care of that now. I just had to replace that whole panel on mine (plus the whole floor, both door jams, all rockers..inner and outer, suspension pan, fenders and other assorted parts)

[RWebb]

who carries the spray cans of POR-15?

Autozone?

Knecht's?

Napa?

CarQuip?

that's what we have here...

[Carrerax]

I think you have to order it.