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yeuporsch's Avatar
 
Join Date: Apr 2002
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problem with height adjustment

After a very long and tedious effort to renew the rear suspension, new ER monoball, update to factory adjustable spring plate, new bearings, new rear rotors, new rear welt sway bar, my height adjustment has gone out of wack.

The rear springplate was even from left to right with the angle finder. The car was previously hit in the right front. It seemed that it is about a half an inch lower on that side. If I adjust the front to be even, it increase the right rear height to 1/2 to 3/4 in more.

At this point, what is my option to correct this, should I have a frame shop try to correct this or should I compromise on the height adjustment. Or am I hosed?

So far I haven't gotten the car to the alignment shop until this is figure out. I drove it around up to 40 mph to settle the suspension, it seemed ok.

Any thought/comment ? Thanks in advance.

John
Old 09-07-2004, 08:55 AM
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Lets back up - do you have the home alignment book for 911s? IF not do a search, some one scanned it in.

Its hard when you change stuff out because you dont have a good starting point.

disconnect all of your sway bars.
Are the front T bars adjustment thingies at about the same place? if not remove and adjust (two minute job).

When you jack up the rear are both spring plates set to the center? Then is the angle the same? IF not pull one off to make it the same splines (roughly) on both sides.

Another thing I noticed is that the rear camber and toe adjustments will hang up and not pull tight. Leaving everything out of wack. Make sure all the plates are pulled together.

I also noticed that the toe and camber need to be kinda in the ball park to get your ride height close. So loosen those up and play with the adjustments - you can sort of eye ball them close.

Give us a little more detail before going to the frame shop. Might still be OK!!
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Old 09-07-2004, 09:18 AM
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Are you measuring to the fender or the center of the torsion bars? You need to use the torsion bars. Body work is too variable.

Are you on a truly level surface as determined by a water level? Some try to determine level using a carpenter's level and a long stick, this is not accurate enough. Some try to use their eyes , not a chance.

Do as above and you will have good measures that will enable further diagnosis.
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Old 09-07-2004, 09:35 AM
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i used a "smart level" for spring plate angle, its a level that will measure degrees, % of plumb/level, and inches per foot. i was able to use the will french/thom(widebody911) angle finder deal and the degrees were easy to find, and keep consistent.

did you subtract the angle of the car on jacks prior to setting spring plate angle? the smart level tool is like $50-60, and well worth it. i was speaking to another board memeber who used the recommended bubble angle finder and had a tought time. additionally i found that scribing the desired angle on the body about 1" above where the spring plate will rest allows you to get it very close prior to even putting you angle finder/compass deal on the plate. good luck.
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Old 09-07-2004, 09:47 AM
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John,
4 wheels makes setting ride height a little complicated, moreso because 911s are one of a few cars with the ability to adjust 4 wheel ride height. You've found that changing corner height on one end of the car affects the other end. Yep.

Even after getting all corners the way you want, you may still end up with an unbalanced chassis. A balanced chassis is one in which the side to side front-to-rear weight proportion is the same. An unbalanced chassis, even with the correct ride height, won't handle correctly and during braking, may cause a corner to lock up prematurely and loose directional stability.

Once you isolate each end of the car from the other, you can see what you've got. Think of a tripod. If you lift the rear end off the ground (midpoint between LR and RR wheels), you have now isolated the rear end from its affect on the front end. Any apparent difference in LF and RF corner heights are now solely attributed to that corner (don't forget to disconnect a sway bar drop link). Vice versa with the rear end.

Hope this clarifies a little,
Sherwood
Old 09-07-2004, 01:33 PM
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I know that I am pretty close after doing this over that past month. The rear spring plate angle is almost the same after jacking the rear up. I did check the front measuring the ground to the rear of the torsion bar. This project has taken 8 months, working on it around family and job time. I am very anxious to start driving it again.

I will try to do it as Sherwood recommended. I will check the floor to see if it is level. Well, it looks level to the eye.

Thanks,

John
Old 09-07-2004, 02:52 PM
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Are the spring plates both adjusted to the middle of their adjustment?
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Old 09-07-2004, 02:54 PM
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can you post a pic of the "smart level"??
Old 09-07-2004, 06:38 PM
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The Smart Level was developed for the building industry, thus you could find this in a prof. building supply store. It's a self-contained component with a digital display that fits into a builder's level. SR adapted it with their line of camber gauges.

Here are some:
http://www.professionalequipment.com/xq/ASP/Laser-Digital-Magnet-Levels/id.15/subID.252/qx/default.htm

Sherwood
Old 09-07-2004, 07:05 PM
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Thanks, Sherwood -- at $150 tho, I'll just admire it from a distance....
Old 09-07-2004, 10:00 PM
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Randy,
I'm with you. I opted for the Sears magnetic inclinometer at $10. I don't think there's a need to get down to the fractions of a degree when adjusting ride height.

Another nifty tool is a water level kit to level the playing area . I got mine from the same guys I picked up the Deco weight jacker tool, Speedway Motors.

Sherwood
Old 09-07-2004, 10:29 PM
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- That's what I got in anticipation of soon driving the car (being able to) and then doing this.

"level the playing area" - you mean to check the area the car is sitting on? I've always assumed that the garage slab is nearly level - but it is prob. slode a couple of degrees for runoff.
Old 09-07-2004, 10:41 PM
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My garage floor is nearly level, but there are some low/high spots. Thin flooring tiles under the wheel(s) gets things closer.

Sherwood
Old 09-07-2004, 10:46 PM
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Quote:
Originally posted by 911pcars
Randy,
I'm with you. I opted for the Sears magnetic inclinometer at $10.

Another nifty tool is a water level kit to level the playing area .
ditto, ditto

I check everything with 3/4 fuel tank, drivers weight in the seat, perfectly level floor, and ft wheels straight.

as per Elombard suggestion.. the scanned 911 alignment text is a home run
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Old 09-07-2004, 10:49 PM
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Quote:
Originally posted by Elombard

- do you have the home alignment book for 911s?

IF not do a search, some one scanned it in.


here is the link

Toe Adjust Techniquest
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Old 09-07-2004, 10:54 PM
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I used the magnetic inclinometer from Home Depot to get the angle. Why is it important to have the springplate bolts at the middle of their adjustment? Is this before or after the adjustment? I thought one would set at the middle to start and then do the fine adjustment to get both side even.

Had to work till midnight last nite. Will start at it again tonite. I am only trying to get the height adjusted properly so that I can get it to the alignment shop. I set the rear to maximum camber so that they don't hit the rear wheel well and that the side to side would be roughly even. I tried to set it to the mid camber but am unsure that they were the same on both side.


John
Old 09-08-2004, 09:52 AM
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Adjustable spring plates come from the factory with the adjustment fully to one side..alowing ONLY raising the car. This is meant to counter-act the possibility of spring sag over time. Most people are well advised to re-adjust the two halves of the spring plate to "mid" position when re-indexing bars...this allows fine tuning either up or down.

Wil
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Old 09-08-2004, 11:21 AM
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Sounds like you are OK. I was envisioning you set the angles and the two arms were at different adjustments to start and it might throw things off. Can you eye ball the camber and see if it is close? I forget what the manual says but I think camber dramatically affects the height??
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1994 Lotus Esprit S4 - interesting!
84 lime green back date (LWB 911R) SOLD
RSR look hot rod, based on 75' SOLD
73 911t 3.0SC Hot rod Gulf Blue - Sold.
Old 09-08-2004, 01:58 PM
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I'm still unclear on the water level as used on a floor... I guess you have to measure the ht. off the floor of each meniscus (?) I don't see how you could use it otherwise...??
Old 09-08-2004, 09:24 PM
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A water level kit has two identically graduated cylinders, each sitting on a base, and each one has a hose fitting at the bottom of the cylinder. A clear PVC hose connects the two (any length works). Position the cylinders where a tire will rest. Pour water into one cylinder (both will fill as water finds its own height). Add water until the water level is even with a graduation mark, then observe the other cylinder to see if the water level is at the same graduation mark. If the water level/graduation mark is the same in both cylinders, the two floor locations are at the same height. If not, adjust the height of the lower cylinder with shims (vinyl floor tiles). Repeat at the other two tire locations on the floor.

Carpenters use this same method. For example, if wall cabinets are to be installed, they can establish a horizontal line around the room, then measure from this reference point to install all wall cabinets at the same horizontal position, even if the floor is not quite level. Laser pointers have made this practice a little faster. Works with drop celings as well.

Hope this helps,
Sherwood
Old 09-09-2004, 01:08 AM
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