ok, the control arms ARE funny....

[fiero308]

well, Don and I have decided that the lower control arms, for the 84-87's at least, ARE funny.  Funny weird, that is.  We looked at both my lower control arms last nite and the main pivot bolts - that the bushings go on- are NOT lined up; in fact I would guess they are 'unaligned' by a good 1/2" or more.  This means that the control arm, when moving up or down, is trying to rotate about two different centres at once.  Something has got to bind here.  I have never seen anything like it. I don't understand how this can work, much less work well.....  now I REALLY want to talk to someone with poly bushings!!!! to see if they have 'revisited' them to see what shape their suspension is in!?!?!
Don and I discussed mods and I am pretty sure I will go ahead with them. Very strange, especially when in all other respects this is a very good suspension design; essentially unequal length A-arms which VERY few other cars have.  (but is popular in formula one....)
Will take pix and keep records of what I do.
Any feedback from anyone who has installed poly bushings???  ANYone?
 

[34FieroGT]

Graeme,

   I have poly bushings installed at all four corners, but I didn't install them.  I had David Power from Power Automotive do the installation.  I used a spare set of front control arms from a parts car to minimize down-time and I don't recall the mounting points being out of alignment as yours are.  Unfortunately, I can't find the extra set of control arms at this time.  I have some parts in storage at my sister-in-law's, and I'll take a trip over tomorrow evening to look for them.

   As for the ride feel, I didn't notice much difference at all, but that could be because I had a set of Eibach lowering springs installed the year previous.  One thing that I did notice was that the car is much smoother on rough pavement.  I had a "clunking" noise when going over bumps disappear!

   I'll post a picture of the control arms once I find them.  HTH

tyler...

[fiero308]

decided to call a shop to see what they had to report. The Fiero Shop in Toronto confirmed that YES they are out of alignment but that is "just the way they are made" unquote.......  Said he has installed on 'lots' of cars which I expect he has.
Still shaking my head on that one but what can I say???
I AM pretty surprised that your car seems better on rough pavement; that seems to defy logic too, but I am starting to get used to that - LOL.  How much did you lower?  Special shocks too?  Are the springs a lot harder; do you know the spring rate?
Thx for the input and reply; if you get a chance, check out the other control arms and see.  If they are NOT misaligned let me know right away!!!! I will stop work!
 

PS; the top arms seem to be aligned ok; it is just the lowers.

[FieroDough]

if the "hinges" on the frame are miss aligned as well, then all is good.  

[fiero308]

welllllllllllllll, ...........
it isn't that simple.  If you look at them and do a little geometry, you will know what I am talking about.
THEN you will wonder too.
 

[FieroDough]

you have to think in 3d geometry, if axis x and axys y are the some as axis x1 and y1 and the oposite side, axis a and axis b are the same as axis a1 and b1, then you are ok.

I beleive the offset x and y axis on the a-arm and fram are to help prevent possible for and aft movement.

I wish I can draw a picture.. sec...


Maybe the pic helps. with those axis, the a-arm still moves freely, mind you the arm only has to move so much. it never goes all the way down or all the way up.

cheers!
Eric

[fiero308]

I'm not really sure what you are getting at but will try to describe it this way; see pic below; it shows the offset between the poly bushings reasonably well, so at least you can tell that the holes don't line up.

The lower bushing in the pic has the longest arm and so will be the 'master' centre of rotation, if you will. Since the entire control arm is a rigid assembly, it operates as a unit. Let's pretend/assume there is no planned or intentional distortion of the arm (by the designers). SO - when the control arm goes to move either up or down (end-to-end movement should be negated by the bushing ends, washers, nuts and bolts) it means that the ENTIRE arm is trying to move thru an arc defined by the radius of the long arm. This INCLUDES the rear bushing!  However, it is 'held' in place by the bolt of course, and thus I can only assume that something distorts somewhere.
IFF both bushings were aligned; ie on the SAME axis, then there is obviously no problem. But they are not, so they are trying to define two different centres of rotation every time the control arm moves.
The shorter arm will not act as a centre of rotation because it is effectively a 'support' that is 'mid-beam' - that is, the wheel is acting as a fixed point to one side and the longer control arm acts as a fixed point to the other side, so it is a 'stabilizer' at best, but still in conflict with the long arm.
Don't know if that spells out my concern any better but it is a try. Don?  Do you want to try?
Still a mystery to me what they were thinking of.  I will be doing a mod and taking measurements, pix and logging info just for the record.  And I hope to go autocrossing or at least do a pylon grand prix somewhere. Maybe that will be the proof in the pudding.........
I will see if I can do a pic in AutoCAD and post it to show the two radii of rotation (ie from the front). Have to get measurements....... that will follow.

[FieroDough]

I understand your point of view, and if the brackets were parallel to eachother, that would in fact be correct But the brakets have that same offset. The  "prooff of the pudding" would be to mount them without any spring ect and move the a-arm up and down. Looking for "different" resistance or binding. (resistance is somewhat normal because of the bushings, friction ect.. ).

I checked on the 85 GT in the garage, the a-arms do move freely and are not stressed by the brackets at all. Also keep in mind that the suspention on the fiero is not 100% vertical, it is at a slight angle (hence the reson the wheel seems to move forward or backwards when "bouncing" the suspention.

From my point of vew. Your a-arms are 100%, you did a great job od cleaning them up and painting them.  Grease the bushings with lithium grease like a mofo and you will be fine.

cheers!
Eric

[Boy-z]

Since there are so many axis/axes just take the damn axe and cut the damn thing off. maybe you should start with a hatchet first then a Quebec speed wrench.

[fiero308]

latest update:
after looking at them again (and again!) it would seem that the axes of rotation thru the two bushing holes actually intersect, rather than are parallel; that would allow somewhat 'freer' rotation (less binding) than if they were parallel (but not aligned) as was first assumed/imagined, but is still not ideal.  
I see that Chris West put in 'Bearings' rather than bushings; that would answer this problem so maybe he recognized it then.....
I am trying to come up with a suitable jig/system to make mods and thus be a self-imposed test case; will take pix and keep people posted.
Of course, this has become a much bigger project than simply installing poly bushings.......... like ALL of my projects; LOL!!!
 

[dguy]

If you still have the LCA's out of the car, could you take a quick moment and measure the "hinge" bolts for me?  Length & diameter are all I need--I don't really care what the thread is.

When I installed the poly bushings at the rear of the car, all four of the bolts which attached the control arms to the cradle were in questionable shape.

When I start on the front arms, I'd like to have the replacement bolts in my hands before I start, rather than playing the waiting game like I am now...

[fiero308]

i do still have them out, as I continue to prevaricate on how big a project to make out of them ..what's new..... ...  but my latest understanding - at least for poly bushings - if that is what you are doing??? - is that the poly bushing is supposed to 'slide' on the inner steel sleeve which means the bolt must be an interference fit inside that steel sleeve in order to lock the steel sleeve solid with the bolt, thus making the poly material slide around that sleeve.  Did I make that clear as mud??  Is that a run-on sentence, too?  SOOOOO, all that being said, and iff that is correct (think so) that makes the diameter of that bolt very important.  Someone on this board said that you can still get the bolts from GM, so that might be the best thing; when you go to a fastener house you might get a lower tensile strength steel, etc etc so it might be best to get the original.  That is what I am going to do.
AND besides, mine had to be cut out so the length is not really measurable and they are kinda rusted and corroded (into those same steel sleeves) so the diameter is a bit unsure too, IF a few thousandths of an inch are important here which I think they are..........   You should be able to measure your bushings and use that for a diam gauge and I think the bolts overall could be measured in place if you want to go to the fastener shop.
Good luck; are you doing the poly thing?
 

[dguy]

i do still have them out, as I continue to prevaricate on how big a project to make out of them ..what's new..... ...  but my latest understanding - at least for poly bushings - if that is what you are doing???

Yep.  I have to change the bushings on the RF wheel to eliminate a rubber-rot induced negative camber, and I decided to go the full distance and poly all four corners.

is that the poly bushing is supposed to 'slide' on the inner steel sleeve

That is my understanding as well.

which means the bolt must be an interference fit inside that steel sleeve in order to lock the steel sleeve solid with the bolt, thus making the poly material slide around that sleeve.

Ahh nuts...  I overlooked that part of it.  Come to think of it, the bolts that I removed look like they're slightly larger in diameter closer to the head, which I suspect would pinch against the inner sleeve when tightened.

Is that a run-on sentence, too?  SOOOOO, all that being said, and iff that is correct (think so) that makes the diameter of that bolt very important.  Someone on this board said that you can still get the bolts from GM, so that might be the best thing; when you go to a fastener house you might get a lower tensile strength steel, etc etc so it might be best to get the original.

I didn't overlook the strength part--the replacements I ordered were 10.9 grade.    But... I suspect that the replacements will not have that same "flare" near the head the the originals do, and fail to keep the sleeve from pivoting against the bolt.  Argh...  Assuming that the bolts arrive today, I'll be able to compare them to the originals when I get home this evening.  My suspision though, is that I'll have four nice heavy bolts going into my nut & bolt bucket, and waiting for GM to bring the proper parts in...

[dguy]

The supplier I was working with for the aftermarket 10.9 bolts didn't come through, and I managed to cancel the order without incident.

Spoke with the parts department at a GM dealer today, and the ones I need should come up overnight from Montreal.  

So that'll be the rear bushings taken care of after tomorrow evening...  then...  on to the front...

[fiero308]

Well, that is sort of a good thing, anyway.......
how did the rears go? did they give you an awful time or not too bad. I am not looking forward to them as they look so inaccessible.........
Good luck with the fronts; that is about all the help I can offer with them...
 
GP