Finally lowered, but rear is different on each side

N

Neilster

Guest
I finally got around to lowering the 98LSC on Sunday. I really like the way it looks, crouching there ready to pounce.

Curious thing though. The left/right rear heights aren't the same for some reason. There is only one rear sensor. hmmmmm. Could it be because instead of backing it up on ramps, I jacked up the drivers rear side and made the mod that way? Much easier access with the wheel off. Of course I had the air ride switch off when I jacked it up.

I am thinking that over time, maybe a week or so, it'll level out on its own. I am also assuming that the heights were the same before I started. I don't think I measured each side before I started. (Doh! Add that step to the procedure).

One last thing. I am measuring from the apex of the wheel well on the body to the bottom of the rim.

Any thoughts?
 
RE: Finally lowered, but rear is different on each side

I'd suggest checking the height at several different parking locations - it doesn't sound like you're at a level place. Think about your car as though it were a flat piece of wood. If the front is level side to side, the only way the rear wouldn't be level side to side is if you actually warp the board, and while the Mark VIII unibody can warp a little, you shouldn't get too much difference...

John
http://mark8.org/users/johnaec/Mark_VIII_s.jpg
'97 Mark VIII LSC
'96 T-Bird 4.6L
 
RE: Finally lowered, but rear is different on each side

Ah ha.. One other piece of information I failed to provide. The front is off a bit as well. From your explanation, if I make sure the front is level, the rear will take car of itself.

Perspective is everything...

Thank you for your explanation.
 
RE: Finally lowered, but rear is different on each side

mine was doing the same for a while. i either stopped noticing or it fixed itself.
 
RE: Finally lowered, but rear is different on each side

It can still be deceiving even if the fronts are equal. For instance, you could have an *almost* level parking place, but imagine that the left front and right rear corners of the parking place were only 3/8" lower than the average rest of the parking place. It would be almost impossible to notice the corners of the parking space being perceptibly any lower, but with the way the Mark VIII suspension works, such a place would make it *look* like one side of the rear was 3/4" higher than the other when the fronts were level!!

John
http://mark8.org/users/johnaec/Mark_VIII_s.jpg
'97 Mark VIII LSC
'96 T-Bird 4.6L
 
RE: Finally lowered, but rear is different on each side

I had the same thing going on, sensor lowered but the ass was uneven.
It actually looked WORSE on level ground. Come to find out the driver's side adjusting bolt on the sensor loosened and it made the driver's side lower. The difference was about 3/8's of an inch on each front side.
That seemed to equate to a more drastic (maybe 5/8's) height difference in the back. Of course with the pass. rear higher.
After carefully adjusting and measuring the front to perfect proportions the rear sits nice.
No matter what I did though the driver's rear is 1/8 lower,but you can't even notice that, it was 5/8's and that looked bad.
 
RE: Finally lowered, but rear is different on each side

Well darned if I didn't have the same thing happen to me this past weekend!

I lowered my rear a couple weeks ago, and got so busy cleaning + polishing my wheels that I didn't have time to do the front. It looks like a sagging old K-car now... ;)

Anyway, this past weekend I parked on some uneven ground at a friend's place, and when I get in to leave, I notice the pass. rear is slammed - top of the wheel is in the well. I'm thinking the compressor's dead and/or I have a sudden bad leak in that bag. Greaaaat. After I fired the car up and put it back on level ground, it raises the pass side rear, but still close to an inch lower. It's been 3 days now and maybe a dozen raise/lower cycles and the one side is still lower than the other...

I haven't touched the front sensors, and the car's been on lots of level ground... (cement pad in garage) Thing still won't sit properly though. I thought about jacking the whole back end up to cause both rear bags to vent completely and then refill once I put it down again. (on level ground) This sound crazy?

I won't be touching the car for the next 3 days so I've shut off the air ride s/w to see what happens when it sits. (verify no leaks)

Thanks,
 
RE: Finally lowered, but rear is different on each side

Usually when this happens. The opposite sides will be off (ie: the front right will be lower than the front left and the rear left will be lower than the rear right) This is caused my the fronts not being perfectly equal. I had the same issue with my car when it was sensor lowered.
 
RE: Finally lowered, but rear is different on each side

Here's a theory that has been discussed in the past which I recall happened to at least a couple members.
If you park on severe unlevel ground it forces one rear bag to compress more and the other bag usually is extended beyond normal. This creates a pressure differential between the bags. When the car vents to parked height more air (volume) will escape from the bag that is compressed due to the pressure differential making it even lower on the side that was low (more compressed) to begin with. Since the air line feeding each bag is common, one would think this problem would fix itself on the basis that the pressure should equalize when both bag solenoids are open to a common line with the car on level ground but doens't always seem to immediately. I've had a minor uneven condition which eventually fixed itself after about 1-2 weeks. Depending on how extreme the difference is, sometimes you're better off to deflate both rear bags with car on a level surface and start over. If there is still variation after defalting both bags and refilling, there could be something causing excess drag in the suspension movement, perhaps a malfunctioning solenoid, or kinked line, all of which I would consider uncommon problems.

This wouldn't explain why Neilsters car changed just by sensor lowering. Could be that the problem was there before. Its easier to tell height variation side to side as the gap is reduced between the tire and wheel lip plus you are staring at it a lot more too after sensor lowering.
 
RE: Finally lowered, but rear is different on each side

Here's a bit of a follow up. As pointed out earlier, the fronts must be dead even. Initially on mine were not. The front has since been corrected. However, the rear is still a little uneven by about .25".

Based upon your explanation, it may be because I altered the adjustment process a little. Instead of adjusting the rear by putting it up on a ramp, I jacked up the driver's side rear, removed the wheel and accessed the sensor from there. That may have caused the imbalance. (Even though the air suspension switch was off).

Gee, if I'd just followed the instructions...Doh!

In any case, I think that over time it'll even out. If not, the next step would be to completely deflate the rear and see if both sides re-inflate evenly... I guess I'll just give it some more time and see what happens.
 
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