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So last week my front alignment was so bad that I wore the insides of the front tires down to the cords. On the rack the toe was -2.33 (toed out) so they installed the new tires and aligned the car, being careful not to unweight the suspension. They set it to factory specs and the car was essentially undriveable veering all over the road and taking off to the sides whenever the wheel was turned the slightest bit. We put it back on the rack and toed the front out about 0.25 and it was much better, but weaving under braking and still unstable and some noises from the front suspension.
Today, I took it out to make sure it was OK before heading off to SITM on Friday and it's just not good - same issues and noises from the front suspension. I can shake both front wheels and they make noise and have play in them. I jacked up one wheel and when I shake the wheels I can see the A-arms moving and I can spin the washers that are part of the A arms. When I built the car in 2014, the steering rack was rebuilt, new steel ball joints, and rebuilt A-arms were installed, and the car was stable before the alignment change, but I think it was masking the actual problem as I can't imagine there should be this kind of play in the suspension.
I don't know if I should tighten the nuts on the A-arms or if they're supposed to be this way when u weighted, but the real issue is that whatever I do is going to change the alignment so first I need to fix the issue then talk someone into aligning it for me with zero notice.
Attached are pics and here are videos of the spinnable washers on the A-arms and the wheel movement and sound (passenger side is worse than driver's side, but both do it).
Thanks and let me know. Do I need new rubber bushings or just to tighten the nuts on the A-arm assemblies and then redo the alignment or is there more wrong here (rack, tie rods, etc).
do the nuts have washer on them? they should.
Then tighten the nuts.
NOTE check every other bolt on the front suspension,
check the rear lower control arm clamps with the car on the ground before you jack it up.
get a helper and with the engine running and the car on the ground,
have the helper turn the wheel back and forth about an inch or so while you observe the rack bushings and the tie rods and the A arms
Both sides of the car are configured the same way and look like these 2 pics - one end has this shiny metal washer and the other end this thicker black one. As you can see from the videos, both will spin freely. How tight should they be and tightened to this # with the wheels on the ground or in the air?
3. Rubber bushings should always be torqued at neutral ride height. If your car is currently sitting at the "settled" suspension height, that's the best time to tighten them. In many cases this is rather difficult to do with certain car models. In those cases mechanics eyeball roughly where neutral is and tighten the bushings. Just trying to avoid bushing bind as the arm moves through the full range when in actual use.
4. The elephant in the room is weather or not the bushings have been damaged by being driven around loose like that. I honestly have no idea, just the first thought to cross my mind.
I'd say there's no risk at this point to tightening those nuts and seeing if it helps. It isn't like you are going to harm them by tightening the nuts. If the alignment seems to come back in and the car drives right - enjoy SITM and we will talk about replacing those rubber bushes with poly when you get back.
If you tighten them and it still drives poorly, then the rubber bushes have been badly damaged and you probably should not drive it to SITM until we get them replaced.
You want to snug them up to take the play out of them, but not tighten them tight-tight; they still have to be able to swing. Granted, they can be pretty darn tight and still swing.
I can imagine that the re-builder did not tighten the new bushings all the way when he assembled them, or that the nuts have slowly been walking backwards since they were installed to their current position.
Thanks everyone. Car is on the 4-post lift still on the tires and I'm going to get started first thing in the morning after reviewing the info Hacker linked to and the WSM tonight. Hoping the PORSCHE Indy I use in Greenville (about an hour away) can spare about an hour of rack time tomorrow (sent them a note tonight) or worst case is I'll drive it the 2 hours back to Atlanta tomorrow to the place I went last week.
In preparation for checking the torque values on everything tomorrow, I went through the 928 Chassis WSM Volume and captured the following torque values for the Front suspension components and put them into a Word document for easy reference, and so they can be reprinted once the sheet gets all dirty from garage use.
Thought it might be a handy reference for others so I've attached it here. In some cases I used terms I'm more familiar with to limit how often I had to go back to reference the diagrams in the Manual.
Once I get things tightened back up, what are you guys running for a good street alignment Front & Rear for Toe, Camber, Caster, etc since I'll need to have this redone and might as well use #s that have been proven to work well.
My Chilton Manual says:
Front Caster: 3-4 degrees with ideal being 3 degrees 30 minutes
Front Camber: -40 to -20 minutes with ideal being -30 minutes
Front Toe: 0 degrees
Rear Toe: 10 minutes +/- 5 minutes
Rear Camber: 40 minutes +/- 108 minutes (can that be right?) I'm thinking it means 40 minutes +/- 10 minutes and the 8 is a typo
These good or would you guys modify them slightly.
Quick update - went through and have tightened most of everything, which wasn't too bad, except in a couple of places. Obviously the upper control arm bushing caps were loose enough where I could spin the washers. Torqued them down to 62 ft.lbs. from the threads Hacker provided.
Worst was the Rear Lower Contol Arm Clamps, which I checked with it still sitting on the ground. The two bolts on the drivers side were finger tight and very far backed out. Considering they're supposed to be at 88 ft.lbs, that and the loose Upper Control Arm Bushing nuts was probably the source of the front suspension noise and the crazy Ivans that the car would do when turning and under harder braking. The Rear LCA Clamp Bolts on the Passenger side were probably at only 30 or 40 ft. lbs.
Getting ready to put the wheels back on and see where we are with regard to shakability & noises, then a neighborhood test drive and I hope a trip to an alignment shop this afternoon.
Wow. You may have solved a whole handful of suspension noises and driving anomalies by running around and setting all the suspension fasteners back to torque.
Wow. You may have solved a whole handful of suspension noises and driving anomalies by running around and setting all the suspension fasteners back to torque.
Yup, just did a test drive and the issues are gone - no more snap hook when starting to turn, no noises, and stays straight under heavy braking . Got a recommendation for an alignment shop about an hour away so the suspension will settle have a chance to settle prior to being aligned.
Carl, being short on time, I didn't check anything in the rear since you would have revisited all of those pieces during the Z06 trans install, right?
Thanks everyone - I'll now be able to see many of you this weekend again. Really didn't want to miss the 20th anniversary one !
Anyone have recommendations for alignment settings I should give to the shop this afternoon, or are the ones I posted earlier or whatever is in thier alignment computer what I should go with?
These are the ones I posted earlier
Front Caster: 3-4 degrees with ideal being 3 degrees 30 minutes
Front Camber: -40 to -20 minutes with ideal being -30 minutes
Front Toe: 0 degrees
Rear Toe: 10 minutes +/- 5 minutes
Rear Camber: 40 minutes +/- 108 minutes (can that be right?) I'm thinking it means 40 minutes +/- 10 minutes and the 8 is a typo
Good catch on the loose fasteners. The loose bolts on the UCA bushings will allow caster to change a lot, maybe to the point where caster would go negative under braking. The car would be a real handful at that point.
For street driving on modern tires:
Front caster is spec'd at 3º 30' with a +30' allowance. Depending on your wheel offsets and tires sizes, you might want to go to the end of that range at 4º. Most important is that both sides are exactly the same, and that may limit where your settings end up. On my later car, there's a narrow range between 3º 45' and 4º where I can get both sides the same.
Front camber is spec'd at -30' +/- 10'. Modern tires like a little more camber than what was available on the cars when originally sold. Try for -45'. Again, both sides need to be exactly the same.
Front toe is spec'd at -15' +/- 5' TOTAL toe. This spec is for cars at factory ride height (where the lower control arm is exactly level, center of rear lower bushings at exactly the same height as the lower balljoint pivot), where the toe change with suspension movement is minimal. For cars that are lowered either from sagging springs or adjustment, a little more toe-in may keep the front tires alive a bit longer. Go to the -20' limit if your car falls into the "lower than 170mm" category as most seem to. A little toe out "feels" better, as it offers sharper initial turn-in feel. But the inner ribs of the tires will quickly go away in normal street driving without a tiny amount of toe-in. The correct value will feel almost numb on center. For those like you who have rear- and mid-engine cars in the fleet, the contrast in apparent on-center "feel" will be most noticeable.
On your rear settings, that "8" is a typo. Go to -45' to -1º rear camber with modern tires if you want to take advantage of them. If you don't push the car hard much, stay with the factory settings. Again, getting both sides the same is critical.
05-31-2017, 10:03 PM
Need HELP if I'm going to make it to SITM
