front suspension steering / alignment trouble

[lightbulb8817]

I'm having some trouble with my front alignment or steering and I'm hoping for some feedback. Sorry for the long post but I want to try and provide enough background on all the steps I've tried to rectify the problem.

The steering wheel has a tendency go left for some reason I cannot figure out. When i crank the steering wheel all the wall left, it stays there, however, when I crank the wheel all the way right, the steering wheel has a tendency to move left on its own, almost as if there's a spring bringing it back for about 1 full turn. This is happening on some home made slide plates as the car is stationary. When the car is traveling, it takes a bit of effort to keep the top of the steering wheel at the top and car traveling straight.

My front suspension has the following parts that I installed recently. Before these new parts, the car was down for about 2 years as I was going thru other upgrades and I didn't measure the previous alignment settings. The old parts I replaced were factory parts that appeared to be fairly old and worn (rubber bushings, etc.).

Here are the details of my car and the front suspension parts
-1975 911s
-22 mm Sanders hollow torsion bars
-Rebel Racing front solid a-arm bushings with self aligning washers (torqued when car is at ride height)
-Rebel Racing bump steer kit (reusing 930 front steering that the previous owner had installed)
-Rebel / Tarrett top camber plates
-Factory under body 20 mm sway bar with new bushings
-New Rennline lower ball joint, factory offset
-New front Koni sport / adjustable shocks
-Factory length lower a-arms with no obvious damage/bends (but i'm no expert)
-Factory Koni strut assembly with no obvious damage/ends (again, no expert or other struts to compare against)

In attempt to fix the issue, I've tried the following

-home string alignment, getting the front toe to <1/16" toe in (I haven't had it professionally aligned yet after installing the new parts)
-camber using Fastrax gauge to 1.5-1.7 deg
-caster to 6.0-6.7 range
-about equal number of threads showing on both tie rod ends

After my home alignment didn't seem to fix the issue, I did some trial and error as follow:
-set the bump steer kit so the tie rod is almost level with the ground / a-arm (I noticed the left side tie rod is tilting outward/downward much more noticeably than the right side based on a small bubble level i squeezed in the tight space)
-continuing off the last bullet, i moved the washers/spacers on the bump steer kit on the left side tie rod to level it as closely as possible with the ground / a-arm. Maybe some improvement, but hard to say.
-I've tried pushing the top camber plate the complete opposite direction (forward/outwards) one side at a time to see how it reacts with minimal camber and lowest caster basically. No noticeable improvement.
-I've tried changing with the height of the car, going from about 25 to 26 inches fender height (running 225/45/17 front tires)
-I've checked the number of exposed threads on the tie rods from each side and they are within 1 count different. I went as far as turning one side to show ~3 threads less and the other side to show 3 threads more to try to "compensate" for the off center steering wheel but no improvement.
-Steering rack appears to be centered. turning the rack from center to either the left or right direction hits the steering rack stop around 1.6 turns (consistent with the 3.1 total lock to lock turns)
-When I rebuilt the suspension, I replaced my old steering rack with a newer but used steering rack that appeared to be in good condition. It moved freely without a noticeable tendency to travel in either direction. There were no apparent problems with it so I did not think to test it very carefully however.
-When the car is in the air on jacks (full droop), the steering wheel doesn't seem to have the left turning tendency. It happens mostly when the car is on the ground at ride height.
-At full droop, the bottom angle of the lower a-arm appears to be about 3 degrees different. At ride height, the bottom angle appears to be <1 degree different (but hard to measure accurately at ride height)

Some ideas for the next steps:
-Remove bump steer kit and go back to factory 930 tie rod ends (if i can find where i put them). Perhaps the bump steer kit is meant for cars much lower than mine?
-Continuing off the last idea, I'm thinking about setting the ride height extremely low (24-24.5-inches) to see how it reacts
-Perhaps the solid bushings is revealing problems with a misalignment in the body or the spindle/strut assembly?
-Swap top camber plate front the left to right side and vice versa. I may have them backwards, although i read it works in either orientation.
-Swap torsion bars from left to right to rule this out
-If no other ideas, I think I may strip the entire front suspension and put it back together piece by piece very carefully again

Here are some photos from my rebuild process for background info. Thank you in advance for any feedback.

[tperazzo]

Could it be that your corner balance is way off?

[fanaudical]

Any work done on the rear? 4 wheel thrust alignment on these is important for straight tracking...

[DRACO A5OG]

+1 above two posts.

[DanielDudley]

I recently did the suspension on my non 911, and it was remarkable how much better it was after I had it set up by a pro. I don't know who sets up 911s in your area, but there are several go to guys in my neck of the woods.

If you do the corner balance, they could just check that and do a full alignment. All I can tell you is that it is worth every penny to get it set up right. FWIW, it seems like 911s are more sensitive to corner balance than any other car I have experience with. This may be due to the fact that it is so easy to get the torsion bars off, or maybe because they are so light in the front. In any case, once you get it right, it is smooth sailing.

Do any or all of the rest of your suspension work, then get it set up once.

[T77911S]

you might consider corner balance then take it to a shop have it aligned. the reason I say go somewhere else is the price and unless the corner balnce guy has a good machine, (not sting align) I would find a shop with a good machine.

had my 930 done, no balance, about $70. latest alignment machine, an old guy that had been around for 30+yrs.
the machine was so sensitive it could tell when I leaned on it.

ask the alignment guy.

you don't need a Porsche shop to do an alignment. that machine had very tight tolerances for the results, in the end the alignment is what it is no matter who does it.
I went to a "Porsche" shop. the wanted like 500+, tried to tell me how complicated the suspension is.
I watched the old guy, he new what he was doing.

[eimkeith]

Originally Posted by tperazzo

Could it be that your corner balance is way off?

This.


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[lightbulb8817]

Thanks for all the feedback! the rear suspension was rebuilt as well. the toe/camber looks to be set pretty close however I know the rear height needs to re-adjusted to about 1" lower (it sits about 0.5" fender height higher than front which is the OPPOSITE of where the rear height should be), which will trigger re-adjusting of the toe/camber again. i was trying to solve 1 issue at a time and i didn't realize the rear alignment or corner balance would have such an impact on front steering issues, although it makes sense.

The car feels very light. i couldn't adjust the height screw in the front enough to get the car lower than 24.5" (not enough weight to depress the 22 mm torsion bars i think). When I tried setting height to <24.5" for fun, there was a gap between the top of the screw and the cross bar housing, even with re-indexing the torsion bar. The car being a '75 mid year, fiberglass bumper, and barebones interior should be towards the lighter end of the spectrum.

is there a chance someone local has scales that i can borrow to do a corner balance? i'm in south orange county, ca.

i'd like to get this alignment dialed in as best as i can at home. perhaps i might surprise myself and get it to where the alignment should be. if not, i will definitely bring it to a pro to get this fixed. i can see why they charge so much though because of the hours/labor involved to remove the rear spring plate and re-index the torsion bar...

[Knockdown]

Originally Posted by lightbulb8817

When I tried setting height to <24.5" for fun, there was a gap between the top of the screw and the cross bar housing, even with re-indexing the torsion bar.

Does that mean your control arm is binding?

[lightbulb8817]

Originally Posted by Knockdown

Does that mean your control arm is binding?

that is a possibility.

when i installed the solid bushings, i checked to see that the arm fell freely from the 3 to 6 o clock position per the installation instructions. it did, so i don't think the control arm is binding. When the fender height is <24.5" or so, the arm moves closer to the 2 o clock position so there is some potential it's binding there in that range of movement. I did re-torque the bushings and self aligning washers after the remaining suspension parts were installed and the car was at ride height though

it wouldn't hurt to rule this out and loosen the solid bushing mount bolts as i try the <24.5" ride height so i'll give this a shot too.

i noticed the a-arm is pretty sensitive to how "freely" it falls from 3 o clock to 6 o clock position, depending on minor position changes of the self aligning washers during installation.

when i couldn't get the ride height lower than ~24.5", my rational was that there was not enough weight on the front end but i could be wrong.

[T77911S]

if the car wont go any lower you are probably at the limit of adjustment.

[Mahler9th]

I don't think your methodology is quite right. Best to align all four corners based on a level platform and a square string set up. It is really hard to "quickly" align a trailing arm 911. In my car, I have pivot boxes and 935 spring plates, and it is still time consuming. I need ~1/16" of toe out up front and ~1/32" of toe out in the rear, and the string set up is critical (these numbers are per side).

What method of string alignment did you use? Did you square up the car (all four corners)? When I do mine, I use the front spindles (remove the dust caps-- maybe overkill) and the flat faces of the rear stub axles to ensure a square string box.

The SmartStrings product instructions are a great help as is the Puhn book, How to Make Your Car Handle. There is a connection between those two.

In addition to my own alignment (with a custom-car-mounted string set up and a SmartCamber tool) I also do my own corner balancing. I found a set of barely used Longacres on Craigslist for 1/2 price, and I bought a set of roll-offs on Ebay for about $500. Those make ensuring a level platform easy.

[356graham]

Originally Posted by lightbulb8817

i was trying to solve 1 issue at a time and i didn't realize the rear alignment or corner balance would have such an impact on front steering issues, although it makes sense.

I had same issue as you - car pulling to one side though alignment seemed correct. Thought I could simply adjust the front and fix the issue. Nope. Rear was so screwed up that it was impossible to make any progress on the front.

Re-adjusted the rear torsion bars so that the spring plates were at identical angles (some PO had set them WAY off). After that, adjustments in front actually helped.

I did get two bathroom scales to measure (approximately) the front left-to-right corner weight difference and was shocked by how far they were off and how little weight is on the front of the car. A little difference side to side made a huge difference because there is so little weight altogether on the front.

[Trackrash]

Agree, it does sound like the corner balance is way off. With solid bushings this will be noticed.

IMO you should put adjustable sway bars on both the front and rear. That is the only way to remove any preload from the suspension corner to corner.

If you want to try to solve this yourself:

Make sure your strut inserts are tight, struts are not bent, (are they gusseted? Raised spindles?), and wheel bearings are tight. Are the tops of the struts even in the mounts and is the camber even from side to side?

Find a PERFECTLY flat surface. Even 1/8" difference side to side will throw off your measurements.

Re- set your rear torsions ie, ride height, with the sway bar disconnected, so both torsion arms measure EXACTLY the same angle unloaded.

Reset the front ride height and use the tripod method to adjust corner balance, with the sways disconnected.

Re-connect the sways with adjustable drop links.

Check and re-set your bump steer. (this could be a new thread).

Re-check your alignment.

[lightbulb8817]

thanks for all the feedback. tonight, i tried adjusting the rear ride height. before this adjustment, i "leveled" my concrete garage floor by stacking linoleum tiles to achieve <0.10 degrees slope between the surfaces where the tire meets the floor. the longitudinal direction had about 1 degree slope prior to leveling, much more than i would have guessed.

after leveling the floor, i started by lowering the rear left ride height from 25" to 24". This seemed to have a substantial influence on how the steering wheel turns left! it seemed like the problem was 80-90% fixed with this "first" attempt.

i proceeded to adjust the right rear ride height to match the left rear, however, this brought the problem back.

the positive side is that it appears my problem is primarily due to corner balance/ride height several posts as indicated. thanks again for the feedback and saving me from tearing down my front suspension completely. i would not have thought corner balance has such a substantial influence.

i'm looking up costs for scales. it appears they run about $600-$800 at least. i could get it professionally corner balanced, aligned, and bump steer dialed in for this cost though. will have to sleep on this to figure out which direction to go. i usually prefer to buy the tools and learn how to do it myself (provided i think i can get achieve an end result that is close to professionally done).

my front sway bar isn't adjustable but i do have tarrett/rebel adjustable rear sway bars that i have yet to install (need to grind off old mounting brackets and install new/upgraded brackets). i can unbolt / loosen the front factory sway bar brackets to make sure it's not tugging on the front a-arms in order to remove/minimize this variable from the equation.

[smadsen]

Did you center the steering rack (centering the steering wheel doesn't count) & clamp it down before you set the front toe? Also, I like the Euro ride height with no bump steer kit for the street. While a lot of guy like to run their cars as low, it is possible to be too low regards suspension travel.

[lightbulb8817]

i will have to go back and restore some of the alignment settings that i altered thru the trial-and-error process, including centering the steering rack, centering the steering wheel, approximately equal number of exposed tie rod threads, front toe, front camber, front caster, etc.

the car will be 90% street car, canyon carver, eventually some autox. it's a '75 with steel wide body conversion by the previous owner and a 3.6L swap i'm still dialing in.

any thoughts on these alignment settings that i'm shooting for?

front
toe in (total): <1/16 inches
camber: 1.5 degrees
caster: 6.5 degrees (how much can the left and ride side differ by? this is a harder setting to measure)
fender height: 25.0" (trying to not damage my bumper more than i already have)

rear:
toe in (total): <1/16 inches total
camber: 2.0 degrees ?
fender height: 24.0" (ignoring changes from corner balance that still needs to happen)
rake: shooting for 0.5 to 1.0 degrees rake (nose down)

i still need to purchase or borrow scales to dial in the ride height / corner balance as well before wasting my time trying to achieve these alignment settings.

[T77911S]

if you are measuring to the fender that is the WRONG way to do it.
you measure ride from the center of the wheel to the center of the T bars.
the fenders will NOT be level. also notice that on the rear one wheel will be closer to the fender than the other.