airkewl

I have read numerous discussions on this site (and others) about using the eccentric bolt to lower the rear end. So forgive me for reviving this yet again, but I want to make sure I have this right.

While all of the posters who know how to do this have been well intended, there still seems to be confusion (as evidenced by those asking for information) about just what result we are trying to achieve at the adjustment bolt. Most say that this will become obvious when you get in there and do it, but I can’t do that until the weekend, and have been racking my brains trying to get clear on what I am trying to accomplish, since I think this changes the way I approach it.

For consistency all of the comments I am making here relate to the drawing often referenced, which is on the passenger/right side of the car, and I am trying to lower the rear bumper of my 924S.

The first confusion seems to be on whether you are trying to make the short plate move up or down relative to the Trailing Blade. Sometimes the advice is let whole assembly hang and it will automatically drop to the lowest setting when the eccentric is loosened. I seems to me that can be very different on whether you have the shock and sway bar disconnected or not.

If you do have them disconnected, then the axle end will drop by gravity, and when you reach the limit of the torsion bar droop, then gravity continues. If you adjust the eccentric then, it will continue to fall. But this will set the axle at its lowest point relative to the torsion bar, and therefore at the highest bumper height. I realize that with all of the attachments and the preload gone, you can position it where ever you want. But I don’t think gravity should decide it.

However, if you don’t have the shock and sway bar removed, then the shock acts as a limit to the axle drop, and this limit is still within the torsion bar load range, so there is preload on the blade (down). If you simply let that preload come into effect, when you turn the eccentric, the short plate will go down at the rear edge, which is what we want I think.

There are numerous suggestions to mark the two plates and then monitor the change. I originally thought I wanted to mark the edge of the short plate at the trailing blade, but that would be the curved edge, and it seemed to me the change there could be very subtle. What I finally realized is I need to mark a straight line roughly horizontal across the two plates, and the best fixed point would be to draw it in a line from the forward adjusting bolt to the center of the rear axle, since that relationship (the trailing blade) won’t change. Then when we get the right motion on the eccentric, it should be to move the tail of the short blade down, making a sort of V in the line, or like this ---/ where the dashed line is the original line on the trailing blade, and the slash represents the original line on the short blade, and the gap being amount of adjustment we are able to achieve.

Please let me know if I have got this clear? Or if I have just further complicated this:-)

Thanks
Tony

MAGK944

To get a better understanding try thinking like this:

With the car on the ground that is your current rear ride height. If you remove the rear sway bar and dampers the car height isn't going to change one bit. So take those out of the equation.

Your aim is to loosen that eccentric bolt so that the result is the rear height is lowered.

Mark the spring plate as it currently sits, look at the eccentric bolt and figure out which way it has to move in its slot to "raise" the rear wheels. When you raise the wheels the rear height will lower.

The reason people say to mark the spring plate is so that if you mess things up you have a reference to set things right.

In reality you really cannot mess things up here, there is only about 3/4in height to be gained or lost.

Hope that helps.

airkewl

What you say makes sense, and confirms my thinking: you were much more concise.
Thanks
Tony

kens_74911s

It is my understanding the eccentric bolt is there to fine tune rear toe adjustment, not to mess with ride height . Shifting the torsion bar on its splines is probably more desireable since it leaves the eccentric to do its intended job.

Jfrahm

No, there is another eccentric for that. This diagram has rear camber and toe settings reversed but it shows the adjustments. Just remember that the locations are WRONG for those two settings.

http://www.924.org/techsection/techp...adjustrear.gif

You need a P221 tool to adjust rear toe and if you just drop the rear end like a dog pooping the other settings will need to be sorted out as well.

If your goal is to stance the car to impress boys at the Burger King parking lot then you might be happy with the results of dropping the rear all the way (until you need a few sets of tires or try to drive on the highway.) In that case how you turn the eccentric does not matter as it'll drop all the way when loose. The eccentric can be adjusted either way as it will turn 360 degrees and go through the full range.

If you are actually trying to set the ride height IMO you want to jam the rear spring plate or you have to fight the torsion bar to adjust the ride height. You can jam it with a piece of square stock before you jack up the car (or jack up the arm to load the torsion bar, jam the spring plate, then lower the arm.)
I use a piece of square stock for this about the size of a big screwdriver shaft. It needs to be square to fit and lock the spring plate. Stab it in under the plate so the narrow edge of the spring plate presses it into the torsion bar carrier. You are trying to jam it so the torsion bar holds the square stock in place when the A arm drops.

You also need the P221 tool to set toe so if you are actually setting up the rear alignment buy one or make one before attempting, or if you go to a shop make sure they have one or there is no way they will get this right. If the rear alignment is messed up the car may tramline and be a handful in the corners.
I made one out of an old 15mm socket I ground down to have one "tooth" I also use a bicycle wrench on the ride height eccentric, it's not realistic to set this without a 36mm wrench. With the spring plate jammed it's easy to adjust.

-Joel.

Jfrahm

BTW I do not think it prevents the suspension setting going to full low when loosened if the shocks are disconnected, I think the trailing arm hits the torsion bar carrier and then the spring plate slices down all the way. Here is a pic I found of the area, you can see the light spots where in this case the ride height was raised by dropping the trailing arm relative to the spring plate. If the two spring plate bolts were loosened that plate would rotate down and cover up the lighter colored area on the trailing arm.

http://www.944spec.org/car_build/gen.../inst10_11.jpg

In this photo you see, from left to right, the hole for the rear toe adjustment tool, the camber eccentric (nut side) the ride height eccentric (nut side) and the nut on the bolt that locks up the ride height. The 36mm head is on the other side of the middle bolt.

-Joel.

Van

The real reason of the rear eccentric bolts on the slip plates - the ones you're referring to for ride hight - are really there to be used for corner balancing the car, since there are no "threaded shock bodies" (with the exception of the Turbo S).

As a secondary use, there are people who use that for lowering the rear of the car about a half inch (but it may mess up your corner balancing).

For alignments, the control arm - either steel or aluminum - bolts up to the torsion bar plate with 3 bolts. The middle bolt is the eccentric to adjust camber. On cars with a rear sway bar, the bolt for the sway bar drop-link is this camber eccentric bolt.

The "special tool", P221, is an eccentric to adjust the toe. While there are two separate adjustments for camber and toe, it takes fiddling with both of them to get your desired results. E.g. when you adjust toe, the camber will change... and when you adjust camber, the toe will change. So you make little adjustments until both are just right.