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Thread: B13 rear suspension re-assembly problem. Alignment all wrong. (Broadband only!)

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Posts: 41-50 of 97
2008-07-20 16:59:51
#41
My rant was inspired by what we call a Gobo head, in the film biz.

Here's a link so you can see the action of swivel. Just imagine the top part of the swivel head in the picture, would be machined to fit into the body, allowing movement up and down, bushed as a standard link end; however the bottom of the swivel chunk, would look similar to the picture, but just the lower half, with the link sliding through the chunk. The link would be off-centered (with a grade 8 bolt, not a grip handle), so the link may be adjusted:

http://www.adorama.com/catlite.tpl?op=large_image&sku=AED250.JPG

The sliding hole may be off-centered, so a solid aluminum link can slide through, with fat springs on either side, mounted to the blue aluminum, through this swivel head, to stabilize the link movement. It would help if the swivel head was ground flat on both sides, (instead of being round, as in the picture).

The springs will seat into the swivel, on the inner side and outer side of the head, possibly machined round for spring seats.

A street-able version wouldn't have springs, instead it would have pre-adjusted notches on the link ends. Maybe 5 levels of pre-cut camber, ground as notches into the link-ends. This system, even as a solid link, will lower the angle of the link, with adjustment to camber, but not flex-able as the spring loaded version. Again, this allows X-Y travel, without any reaction by the link, as in a spring loaded version.

On an adjustable version, with springs, the center bolt in the center of the swivel head, would have to bottom out, leaving the shims to flex, as a swivel.

The choice of materials used between the swivel head, are also "dealers choice", for thicker or thinner / slippery, less slippery- materials, which will react differently, giving you the option to tighten up the reaction time of the swivel / spring loading, as the chassis reacts within the flex-able machine limitations.

The outer link-ends with springs would be the hard stop, Just as the inside springs, mounted on the link ends, would stop the geometry from drooping the suspension, in concert with the struts. (The end of a sprung set-up, would need to be designed to take a hard hit, against the end of the link, so it doesn't break when it snaps back. Like a collet, with a replaceable compression pin, to act as a stop, or a lock-nut, threaded on the end of the link, so the outer spring tension is adjustable.

Maybe you want a bunch less spring on one side or the other. The swivel-head with inner and outer springs, is infinitely adjustable.

With pre-set rear wheel camber, when you slide the car hard against the link springs, the outside tire, in relation to the slide, would camber outward, until the outer tire settled flat to the ground, at max spring tension, (or at the stopping point of limited travel at the swivel). The lower swivel may reduce body roll, as it lowers the assembly to close to 90 degrees.

The opposite side, during a slide, would react against a shorter or harder spring, so camber deflection would be restricted, keeping the inside tire, during a slide, near pre-set camber, (or just slightly increased, at the most).

This system may require a racing torsion bar, instead of a standard rear stabilizer bar, and a ball joint at the strut tower, so everything can shift smoothly, under stress.
2008-07-21 17:00:42
#42
Moto, I appreciate what you're trying to do here but I worry you've gone off the deep end. Your design seems to allow the rear suspension to move left and right independently from the chassis. You seem to worry about lateral loads and shock with a spherical bearing but forget that there are rarely sudden lateral loads to a suspension. You mention "curbing" the car. This isn't something a suspension should have to deal with gracefully. If you've got play in the suspension from left to right, you've lost any sort of connection between the car and the road. You might as well be driving a body-on-frame pickup truck. Not to mention your solution is entirely over complicated. Also, it would seem the correct answer (a double wishbone suspension) would be easier/cheaper to design and fit than your Rube Golberg machine.
2008-07-22 01:08:31
#43
This is for my own reference.

Parallel Links
Front: 55121-50Y10
Rear: 55121-50Y00

No way of telling front from rear by inspection or measuring as far as anyone knows.


Radius arms (control links): 55110-50Y10

Only one part number, meaning both sides use the same part, so there's no way swapping them left for right will change anything.



I ordered all new parallel links and control links, all with stock rubber bushings. $$$ =[
Forgot to order new bushing for hub side of control link. Might leave it ES to save money and lessen the hassle of install. We'll see.
2008-07-22 01:57:49
#44
Originally Posted by BenFenner

Only one part number, meaning both sides use the same part, so there's no way swapping them left for right will change anything.


...but you can put them on 'backwards', don't ask me how I know. The bend is supposed to be in to the car, not out. If you put them in backwards everything else is messed up.
2008-07-22 04:08:02
#45
Yah Calum that possibility was brought up earlier in the thread. I've checked and they are on the correct way. Also there's no way my wheels/tires would fit if they were on the other way.
2008-07-22 07:16:08
#46
Hey Ben, sorry I lost track of this thread. Have a couple of thoughts to share;

Did you ever check my suggestion about the perch/top hat orientation? I just had a look at the old ones I pulled when I installed the AGX/GC combo, and realized that it is possible to have the orientation of the three bolts that fit into the strut tower correct, and still have the perches wrong! So, to review, when looking a the strut from the trunk/hatch area, the arrow points to the outside of the vehicle, and there may be on the upper perch (the one that interfaces directly with the underside surface of the strut tower) a L and R (for left and right as viewed from the rear of the car, facing toward the nose) to confirm orientation. Looking further at it, this may be a wild goose chase, as I also believe that having this reversed would actually cause massive positive camber, not negative camber as you describe, as the locating vertical axis of the hub would essentially be moved outward toward the fender.

You mentioned cutting out the old long bolts that link the parallel links to the hub. What else did you do to get them out? Any BFH action, air chisel, etc.?

I am going to just brainstorm this a little more, so bear with me; I am wondering how it's possible for a bushed pivot on two sides, to exert enough force to bend the shank of the bolt inside the two hub bores, when they would have a stabilizing influence on the torsional rigidity of those bolts (maybe I am envisioning that wrong, is that the failure mode you are describing, or was it the ends that passed through the parallel links, just the end bits that bent?). The only way I could see that working is if the bores were oversized, so as to allow slop within the interior space of the hub. We are talking LOTS of leverage to be able to accomplish that, or compression in the longitudinal plane of the bolt axis to instigate buckle and compromise. Hmmm... Maybe not; if the toe was REALLY out, it would have kicked the rear link out (or in) relative to the front link. As by nature of the parallel links, that would mean you would have opposing moments on the long hub/parallel bolt, thus setting the stage for and S-type bend to be initiated in the longitudinal axis of the bolt (so the deformation would look like a slight S-shape when viewed overhead; is that what happened?). If the durometer on the ES bushings is high enough, coupled with the stick of the Falkens, over the course of that drive you described, that could have done the damage. I'm also thinking about that link that was damaged by cutting, then repaired. What if that warped during the repair process? That could cause an asymmetry that would account for not being able to equalize the sides. Was the bolt damage worse on the side that the repaired parallel link was attached to? I'm also interested in the "crab walking" you described; remember, how a car drives (in this case, the differential of the long axis of the car vs. the path the car actually travels in over the road surface) due to the alignment, in a static sense (in other words, disregarding articulation of the suspension components), is merely a vector based resolution of what each corner of the car is doing in regards to tire slip angles.

I would LOVE to see a picture of the failed assembled components, with particular attention to the hub, the large bolt that runs through it, and looking at the parallel links both at the hub and body side.

Not to make light of your situation, but this is a very interesting problem indeed. I apologize if I'm covering concepts you already are well versed in; just trying to drag this one out into the light, and if I don't hit upon it, maybe my process will twig someone else. Also, feel free to correct any incorrect or unfounded suppositions.

Darrin
2008-07-23 03:46:24
#47
Let me start off by saying that I appreciate your attention to detail SkyShepherd, and I thank you for taking an interest in my situation and giving it your time. Thanks so much.

Originally Posted by SkyShepherd
Did you ever check my suggestion about the perch/top hat orientation?
This is #1 on my list. I have little time. If I'm going to drop the rear dampers to check this I need to do other things at the same time. I'll be checking this and reporting back for sure.

Originally Posted by SkyShepherd
I just had a look at the old ones I pulled when I installed the AGX/GC combo, and realized that it is possible to have the orientation of the three bolts that fit into the strut tower correct, and still have the perches wrong! So, to review, when looking a the strut from the trunk/hatch area, the arrow points to the outside of the vehicle, and there may be on the upper perch (the one that interfaces directly with the underside surface of the strut tower) a L and R (for left and right as viewed from the rear of the car, facing toward the nose) to confirm orientation. Looking further at it, this may be a wild goose chase, as I also believe that having this reversed would actually cause massive positive camber, not negative camber as you describe, as the locating vertical axis of the hub would essentially be moved outward toward the fender.
I'll just add this to the stack of reasons why I believe I got their orientation correct when installing. I'm still going to check though. Thanks for the idea and clarification.

Originally Posted by SkyShepherd
You mentioned cutting out the old long bolts that link the parallel links to the hub. What else did you do to get them out? Any BFH action, air chisel, etc.?
Before I resorted to cutting them out, there was some BFH action (went and bought an 8 lbs. sledge). I tried pounding out the long hub side bolts with some well placed blows (towards the front of the car) to the threaded end of the bolt with no luck. The bolts, the metal sleeve inside the bushing and the hub were all fused into one part at this point. I also tried applying 300+ ft./lbs. of torque to the bolt head trying to just snap the bolt (the bushing sleeve and hub acting as resistance) with no luck.

Funny you ask. :o

The side I did all this to isn't the side with the major problems though. =/


Originally Posted by SkyShepherd
I am going to just brainstorm this a little more, so bear with me; I am wondering how it's possible for a bushed pivot on two sides, to exert enough force to bend the shank of the bolt inside the two hub bores, when they would have a stabilizing influence on the torsional rigidity of those bolts (maybe I am envisioning that wrong, is that the failure mode you are describing, or was it the ends that passed through the parallel links, just the end bits that bent?).
Honestly I'm having a hard time remembering here. I believe the bend (there is just one) in the long bolt is centered 2/3rds of the way down the shaft. It's as if the head of the bolt going through the front parallel link bushing and then the first hole in the hub is sort of the base or anchored well and then the shaft goes through the open space to the second hub hole which acted as the fulcrum (if the bolt is the lever) and the force was applied by the rear parallel link causing the bolt to bend in this manner.


Originally Posted by SkyShepherd
The only way I could see that working is if the bores were oversized, so as to allow slop within the interior space of the hub.
There are two bores/holes in the hub with about 5 inches between them. The space between them is wide open and allows all sorts of slop. The bores/holes themselves seem to be a mm or two larger than the bolt passing through. otherwise I don't think I could have even re-inserted the bent bolts when I re-assembled.


Originally Posted by SkyShepherd
We are talking LOTS of leverage to be able to accomplish that, or compression in the longitudinal plane of the bolt axis to instigate buckle and compromise.
There's certainly a lot of force somewhere. These bolts didn't bend themselves and they are really stout.


Originally Posted by SkyShepherd
Hmmm... Maybe not; if the toe was REALLY out, it would have kicked the rear link out (or in) relative to the front link. As by nature of the parallel links, that would mean you would have opposing moments on the long hub/parallel bolt, thus setting the stage for and S-type bend to be initiated in the longitudinal axis of the bolt (so the deformation would look like a slight S-shape when viewed overhead; is that what happened?).
This is exactly what I think happened, except I didn't get an S shape. The alignment was so off that by trying to correct for it I had the toe adjustment bolts at their full, extreme setting which pulled the rear link inboard. The hub didn't like turning this way however (due to the front parallel link + radius arm?), and when the bolt bent in like it did, it would have relieved the stress induced by my meddling. *sigh* I don't know...


Originally Posted by SkyShepherd
If the durometer on the ES bushings is high enough, coupled with the stick of the Falkens, over the course of that drive you described, that could have done the damage.
This is what I'm thinking. Something happened for sure! =]


Originally Posted by SkyShepherd
I'm also thinking about that link that was damaged by cutting, then repaired. What if that warped during the repair process? That could cause an asymmetry that would account for not being able to equalize the sides.
The link didn't warp, but I'll tell you the bushing never quite fit right in that one end. When filing out the hole there could have been a bit more material than normal left causing the bushing to insert improperly, and skewed, which I know for a fact it did, just a tiny bit. More fuel to the flames...


Originally Posted by SkyShepherd
Was the bolt damage worse on the side that the repaired parallel link was attached to?
One of the bolts was bent much worse than the other, and one side is way off alignment more than the other. The side with the bolt that's bent worse and alignment's off more I believe is the side with the repaired parallel link, but don't quote me on that.


Originally Posted by SkyShepherd
I'm also interested in the "crab walking" you described; remember, how a car drives (in this case, the differential of the long axis of the car vs. the path the car actually travels in over the road surface) due to the alignment, in a static sense (in other words, disregarding articulation of the suspension components), is merely a vector based resolution of what each corner of the car is doing in regards to tire slip angles.
The rear passenger side tire faces almost straight ahead. The rear driver's side tire faces towards the passenger side of the car a pretty good amount. The net affect is the the rear tires are facing to the passenger's side a bit. To keep the car going straight, the front tires need to point in the same passenger's side direction. Something like this:

/------/
Front
|
|
Rear
/------|


You can see how it would go straight down the road, but the car's headlights point off to the right side of the road a bit. Yay!


Originally Posted by SkyShepherd
I would LOVE to see a picture of the failed assembled components, with particular attention to the hub, the large bolt that runs through it, and looking at the parallel links both at the hub and body side.
Sure thing. I'll take as many pics of as many parts in as many different configurations as I can think of.

Originally Posted by SkyShepherd
Not to make light of your situation, but this is a very interesting problem indeed. I apologize if I'm covering concepts you already are well versed in; just trying to drag this one out into the light, and if I don't hit upon it, maybe my process will twig someone else. Also, feel free to correct any incorrect or unfounded suppositions.
Thanks for all your help! You haven't hit on anything that's been covered before, and you've got a full grasp of what's going on here. No worries.

Thanks again!
2008-07-24 05:37:16
#48
ben sorry for the spam hope you get your problem fixed, its just, i've been looking around for a diagram or some sort of illustration to learn the parts names in the rear suspension, as some of you know english ain't my native language so i get messed up in the translation some times.... would it be too much to ask if anyone could post a pic and draw the names on it? i kindda feel stupid asking for this but i can't actually help much if i don't fully understand the names... or where could i find a fsm in english to start to get familiar!!!

anyways hope you solve your problem!!! some pics might help for that too!!!
2008-07-24 14:34:45
#49
Are the diagrams in this post not what you're looking for?
2008-07-24 17:12:38
#50
Originally Posted by BenFenner
Are the diagrams in this post not what you're looking for?


well they don't exactly picture all the suspension... besides im kindda stupid and really need pics ... but ok i promise i'll study it a little bit more since i'm starting to take mine off today
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