Retaining rear suspension settings during mods?

[Vipergrün]

Hello all,

Gonna install 22/27mm torsion bars on my SC soon. I am curious if I can retain the rear camber and toe settings by putting reference marks on the heads of those adjusting bolts and the trailing arm assembly. Then, when I re-assemble it, I'd line up the marks and tighten. It works in my head, but I'm am not an alignment specialist


Thanks for yer input.

[surflvr911sc]

Dr. Brad, I am by no means an alignment expert either but here's my opinion.

I don't think you could actually keep the setting good enough for anything other than driving to the alignment shop. Changing torsion bars them selves, I would suspect that even if you could keep everything the same the corner balance would be off do to different spring rates and the loss of spring the old bars had. I have realized from my latest fiasco that any little adjustment really affects most everything else.

You may be able to get it close enough that it would drive fine and tires would even wear ok seeing as though it’s the rear not the front. I would bet though that if you drove it this way, and then had it aligned and c/b’d you would feel the difference.

Hmm, maybe I should have taken a little of my own advice sooner.

[pbs911]

Brad,
In agree with Ryan, and from my personal experiece (limited as it may be) I did exactly what you are describing. I drove the car for about five months after marking the adjustment nuts/bolts, lowering the car, and completing all the suspension bushing replacements until I could get the car CB/aligned. For normal street driving, I did not have any problem. The alignment will not be perfect, and the CB will be changed, but I think it is a compromise in costs. The best approach is to redo the entire suspension at one time and have 1 CB/Alignment. But that akes more time and more $$ up front.

[Vipergrün]

Thanks Doctors.....

Thinking of that scene in "Spies Like Us" when the doctors meet each other...."Doctor..Doctor..Doctor"

Anyway, thanks guys, this is exactly what I was looking for. Just wanted to do a sanity check before moving on. Can sway bars be added later w/o messing up the alignment?

[surflvr911sc]

Not sure on that one but my feeling is "no". I think that changing the sway bars will change the forces on the corners. Bigger sway bars, bigger forces applied the corners, not necessarily the same percentage as the old sway bars. Again, the settings before the change are set to the old components. Change the components, the spring rates change, old components are just that, "old", and the settings are again "off".

[john walker's workshop]

you can keep it fairly close by scribing a line along the edge of the spring plate onto the trailing arm. the eccentric adjusters are used to align the scribe lines on reassembly.

[surflvr911sc]

Originally posted by john walker's workshop
you can keep it fairly close by scribing a line along the edge of the spring plate onto the trailing arm. the eccentric adjusters are used to align the scribe lines on reassembly.

Finally an expert! I think the key word is "fairly close". JW you're not saying "good enough" are you? I interpret "fairly close" as still needing an alignment, true?

[Vipergrün]

Originally posted by john walker's workshop
you can keep it fairly close by scribing a line along the edge of the spring plate onto the trailing arm. the eccentric adjusters are used to align the scribe lines on reassembly.

Thanks JW. So, that will work for both *planes* of adjustment?
Should I set one before the other?

Well, Dr. Ryan, looks like I had better spend all my $$ now and do the alignement/corner balance once.

[lshimp18]

You can change sway bar sizes up or down as often as you'd like without affecting the chassis (wheel weights) settings. The sway bars should be unloaded (free) at ride height. That means when the car is at rest on a level surface the sway bars are not supposed to have any preload on them. Some racers set their cars up with the bars free with the driver. You can accomplish this by placing balast in the driver's seat representing your body weight. If you make chassis changes, ie: camber, caster, corner weights, height changes with the bars hooked up, you will chase the chassis settings all over the map. This is just some old racing experience talking.

Luke

[surflvr911sc]

Well, that makes sense. If the sway bars affected C/B at rest then racers would have to C/B everytime they adjusted them. I know they aren't doing that between sessions. Good call Luke.

[lshimp18]

You hit on another good subject. You can use your sway bars as a guide to adjusting your chassis back to the proper setting at a track by how much load is on the bars. A vehicle will settle when you are at a track. After the first run it is necessary to adjust your chassis to proper height. Keep in mind all of these measurements should be taken on a level surface. If you do not have a scale set-up that is able to be leveled, use the tech lane at the track or their scale area for taking your measurements. Sway bars are a sort of on-board ride height guage. The main thing is to be consistent on your measurements and location when performing the changes.

Luke

[TimT]

Dr Walker responds with sage advice...

you can keep it fairly close by scribing a line along the edge of the spring plate onto the trailing arm. the eccentric adjusters are used to align the scribe lines on reassembly.

Your sway bars have nothing to do with alignment.. as posted by others.

JW is describing "matchmarking" components "mark" the component, disassemble and reaplace parts in question, then reassemble with the "matchedmarks"

you deal with sway bar settings after your alignment and corner balance are dialed in

[lshimp18]

I fully agree that sway bars have nothing to do with the alignment/cb/chassis, unless you do not unhook them when performing any changes. If they are hooked up and under load, your chassis will be in a stance that is not free. So, when the car goes into a loaded position everything changes and it may not drive as you'd like it to.

Luke