Suspension setup / alignment issues
10-25-2004, 08:57 PM
#16
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The tire store mechanic and myself figured it out after we took apart the bolt and eccentric washers and put some anti-seize in the area. Now the alignments changes are swift and easy. Versus a race shop telling me that I could not run more the -1degree camber because the toe setting was stuck and something must be wrong.
Any other suggestions on alignment - since it sounds like you have been there done that - would be helpful.
You mentioned that the corner weighting would be off if the alignment was previously off - by how much would you see it changing?
Any other suggestions on alignment - since it sounds like you have been there done that - would be helpful.
You mentioned that the corner weighting would be off if the alignment was previously off - by how much would you see it changing?
10-25-2004, 10:03 PM
#17
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The small changes in toe required to put the car to factory specs are not going to change the corner weights enough to matter. If you significantly change the camber you have to significantly change the toe. As long as the changes are made (almost)evenly on each side, the corner weights won't change.
I always do the alignment and corner weights simultaneously. If you install a suspension and do not attempt to eyeball or preset the alignment eccentrics, when you put the car on the scales you often find the weights off by 5%(which is a huge amount). Just doing a rough alignment usually gets things back under 1%.
If you made only small changes it is unlikely that the weights changed much. On the other hand, you may be assuming that the weights were correct to begin with. Everybody seems to be finding that the factory alignment is terrible, which tells me that the cars were not aligned at all. From this I must assume that the corner weights were not set either.
Chris Cervelli
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I always do the alignment and corner weights simultaneously. If you install a suspension and do not attempt to eyeball or preset the alignment eccentrics, when you put the car on the scales you often find the weights off by 5%(which is a huge amount). Just doing a rough alignment usually gets things back under 1%.
If you made only small changes it is unlikely that the weights changed much. On the other hand, you may be assuming that the weights were correct to begin with. Everybody seems to be finding that the factory alignment is terrible, which tells me that the cars were not aligned at all. From this I must assume that the corner weights were not set either.
Chris Cervelli
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10-26-2004, 01:33 PM
#18
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Both my eccentric bolts were seized up on my cup car, but they were the ones used for the rear camber. I ended up replacing both of them since one was also stripped.
GT or Chris can you explain how the eccentric bolt moves, even if they are tight. I had my camber move ½ of a degree at the track and the eccentric bolt was tight. After I replaced the bolt it did not happened again.
Chris I use the smart strings to align my car and I have been able to get it pretty accurate. I have checked the settings several races later and they were still the same. I do the alignment on scales so I can check and adjust the corner weight, camber and toe at the same time. Always in that order.
GT or Chris can you explain how the eccentric bolt moves, even if they are tight. I had my camber move ½ of a degree at the track and the eccentric bolt was tight. After I replaced the bolt it did not happened again.
Chris I use the smart strings to align my car and I have been able to get it pretty accurate. I have checked the settings several races later and they were still the same. I do the alignment on scales so I can check and adjust the corner weight, camber and toe at the same time. Always in that order.
10-26-2004, 07:08 PM
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Bill--
The whole problem with the eccentric bolts is that while both ends of the bolt have eccentrics, there is nothing for the eccentric on the nut end of the bolt to push against. When you turn the bolt to adjust, it tends to bind in the slot on an angle. If you tighten down the bound up bolt, it may be in a position where the eccentric does not touch against the subframe. When you hit a big bump or a curb, the adjustment can then move a little.
This is all really annoying since this NEVER happens on a 993, since all that stuff is properly designed and built.
Also, when you turn these eccentrics you are trying to lift the weight of the car (at least in one direction). That really helps the tendency to bind up.
The string alignments are ok. Just ok. It IS arguable however whether the extra precision available with a real alignment is noticable to the normal driver. The speed and repeatability are the big advantage.
Phil--
I got mine thru Steve D @ ultimategarage.com. I don't know the current status of Beissbarth in the US currently. My machine is the ML4000. It has probably been replaced by something better by now. I have had it four years.
It was about $18000 and well worth it.
Chris Cervelli
Premier Motorsports
The whole problem with the eccentric bolts is that while both ends of the bolt have eccentrics, there is nothing for the eccentric on the nut end of the bolt to push against. When you turn the bolt to adjust, it tends to bind in the slot on an angle. If you tighten down the bound up bolt, it may be in a position where the eccentric does not touch against the subframe. When you hit a big bump or a curb, the adjustment can then move a little.
This is all really annoying since this NEVER happens on a 993, since all that stuff is properly designed and built.
Also, when you turn these eccentrics you are trying to lift the weight of the car (at least in one direction). That really helps the tendency to bind up.
The string alignments are ok. Just ok. It IS arguable however whether the extra precision available with a real alignment is noticable to the normal driver. The speed and repeatability are the big advantage.
Phil--
I got mine thru Steve D @ ultimategarage.com. I don't know the current status of Beissbarth in the US currently. My machine is the ML4000. It has probably been replaced by something better by now. I have had it four years.
It was about $18000 and well worth it.
Chris Cervelli
Premier Motorsports
10-26-2004, 07:55 PM
#21
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It is my understanding that the Porsche specified torque tightening spec is 90nm. Could maybe the stock bolt, which would be hard to replicate, with the stock eccentric washers, be replaced and tightened more without stripping the bolt and not ruining the aluminum frame/suspension? How do you get the bolt to hold without maybe putting something on the surface to stop it from moving? I notice the difference when it moves, and it is also dangerous not knowing when it has moved or not until you start driving at the limit?
The machine that I used for the alignment also recognized the toe setting while elevated. This allowed for the major toe adjustment, and camber adjustment, to be made while in the air, and the fine tuning while under weight.
The machine that I used for the alignment also recognized the toe setting while elevated. This allowed for the major toe adjustment, and camber adjustment, to be made while in the air, and the fine tuning while under weight.
10-26-2004, 08:03 PM
#22
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I think the torque spec is much higher than 90 Nm. I use 88 ft lbs for these. Since it is impossible to get a torque wrench in there, I do it by feel.
To properly tighten, you hold the bolt head with a 19mm wrench and turn the 18mm nut. If it is straight and torqued to spec or more, it is not going to move.
Chris Cervelli
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To properly tighten, you hold the bolt head with a 19mm wrench and turn the 18mm nut. If it is straight and torqued to spec or more, it is not going to move.
Chris Cervelli
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10-27-2004, 06:19 PM
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Thanks Chris that is a good tip on the eccentric. I will double check that they are straight from now on. And I agree the sting method is a major pain, but since I work on my car only and align it a few times a year it as a great cost benefit for me. If I had to do it anymore than that I would shoot myself.
