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rear poly bushings on outboard end of CA


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OK, bad news...

 

I finally got all my little parts together, bolts, spacers, etc and went out to the garage. I figured the thing to do first is to verify that I welded everything on straight, since I didn't weld the outer tube and tube ends with a jig.

 

One control arm moves through its range of motion very easily. The other does not. So I F'ed up the control arm.

 

Possible solutions:

 

1. Cut the tube off of the control arm, buy more threaded tube ends, weld them in properly.

 

Sounds like a pain in the ass to me, and I honestly do not know how to make a jig to make sure that they're all squared up when it is done.

 

2. Use G Machine bushings and ditch the monoball inner idea.

 

I haven't tried this yet, but I'm betting that I can slap in my old G Machine bushings and if I rotated them around the right way the angle of the strut would be fixed and that would alleviate the bind. I REALLY wanted to use the monoball inners.

 

3. Use oversize rod ends like Terry did and then make offset spacers to fix the misalignment.

 

Again, big PITA, not sure how to get the spacers machined offset like that.

 

4. Set the monoball holders in such a way that they adjust out the bind, just like I would do with the G Machine bushings.

 

I'm a little frustrated, a little pissed off, and I'm about to just say F it and use the GMachine stuff instead. Due to a number of factors I haven't been able to do much in the last few months, now I'm starting to feel the time crunch with my move starting to loom on the horizon. Probably moving in April or May...

 

Anyone have any good ideas?

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3. Use oversize rod ends like Terry did and then make offset spacers to fix the misalignment.

 

Again, big PITA, not sure how to get the spacers machined offset like that.

 

Jon,

 

If this is what I think it is, it may not be that big of a deal. PM me a sketch or picture and I'll see what I can come up with.

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I made the following jig prior to cutting the lower CA. This insures that the axis of both inner and outer bushings are parallel in both vertical and the horizontal planes

 

standard.jpg

 

My experience has been that the lower CA can be made to flex more than I ever expected (I won't go into how I discovered this), and feel that as long as the rod ends are spaced EXACTLY the correct distance, that there should not be any substantial binding due to a "twist" in the CA. I did find that if the spacing between the rod ends was off by even a few thousanths, that the rod ends (balls) would start to bind once the nuts on each end are torqued down. To alleviate this problem, I am using arbor (shaft) shims to take up the slack of when I positioned the rod ends too far apart. Visually, and during mock up, the distance seemed perfect, but I found out that the "047" thick seals for the Heim joints were in actuality .049" thick. I used one on each side so that is .004" difference, which will show up if one is using precision parts such as rod ends, etc. Rubber bushing can compensate for this, but not rod ends.

Long story short, It all is going in as originally planed, but it just took a little bit of shimming and close attention to detail in getting it all to fit correctly and not preload the Heim joints, and that is the primary concern.

 

Once I started putting all of this together, I had to ask myself, "are these kits for rod end CAs assembled to these required close tolerances, and if not, are any of the customers noticing the potential for early failure if not?" I can only assume that there is no deviation between the length of the pin bosses from one strut to the other. If there is, than 'look out".

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That looks pretty easy Terry. Wish I had asked first before cutting.

 

I think I have to rule out the eccentric spacers to fix, because apparently you can't buy rod ends with a 5/8" shank and a 3/4" hole. So I have another idea courtesy of Cary, which might work. The idea is to cut the control arm right through the rectangular tube, bolt it into the car to align the rod ends, then weld the tube back together. I think this might be a good option because it would be fairly easy to do and I don't think the end of the control arm is particularly stout.

 

If that works out, my next concern is that if I continue with the inner monoballs, how can I make sure that the inner pivots are parralel to the outers, other than by grinding the frame, tacking the monoball holders, and pushing the suspension through its travel? In my mind I'm thinking that it is the holders that must be parallel to the outers, otherwise the strut will travel fore or aft when the suspension is compressed.

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I'm assuming you are asking the last question based on the requirement that you grind the saddle larger so that the monoball housing will fit up for a weld?

If so, I'd try this:

Tack one housing (front or rear, it won't matter) into place, tack it so that it could be removed if things get out of hand on the following. After you've tacked one housing in place, insert a long, straight rod (3/4" in diameter for your case) through this monoball assembly (thru through the bearing) and through the second free monoball assembly. Now, place the free monoball assembly up into position in the other saddle (you may need a second person to help you with this part). Next, using line-of-sight, align your viewpoint so that this bar, and the other side mounted control arm inner mounting tube are aligned. If both control arms have been removed, then place a straight bar up against the saddles of the other side, and then compare the two bars. Any difference in angle should visually become readily apparent (one end of the rod will be higher or lower than the other end as compared to the CA tube that is fully mounted). I'm not under the car, and not sure this could be viewed in the way described (the bars may be hidden from sight being too high up in the chassis), but I'd give it a try. This way you will at least know that the newly welded housings will be parallel to the other side, which should also be parallel to both outer arm spindles. Any misalignment on the horizontal plane can be adjusted with the rod ends. Lastly (and I don't know if any laser level offers this feature as mine does not) you could simply mount a laser level onto the bottom of the opposite side CA inner mounting tube so that the laser points to the long rod in the monoball assemblies in such a way as to provide a very close measure of whether it is parallel or not. Obviously the angles will not be perfect with this option, but it should be very close.

 

I know this line-of-sight is not a scientific remedy, but one that serves me well, and in fact was the way I checked for parallel mounting on my first arm, which did work when installed) prior to fabrication of the jig for the other side control arm. I hope this makes sense, and should take out any factors in how the car is sitting, and where the suspension is sitting.

standard.jpg

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My car is on a rotisserie, and I think the strut assy and the control arm weigh enough to hold the suspension in a position where I could line of sight it. I did some real quick investigation just laying the bearing holder in the saddle, and it looks as though the saddle needs quite a bit of grinding. Also in the front this is going to mean that the diff mount will probably need to be ground out as well in order to fit everything together. I think the front needs to be done first, and the rear needs to match the front. I'm not so concerned with side to side getting the roll center exactly the same as I am about getting it right front to back. Similar to the outer bearings, if the inner bearings aren't level front to rear, then the control arm will sweep to the front or rear when the suspension compresses, and again you're looking at either twisting the control arm or putting a hell of a lot of side load on the strut shaft.

 

I'm also starting to wonder if I can get away with welding in the diff crossmember. This should make it stronger and prevent any shifting, and I have the Simon DeGroot style front diff mount. I'm just not sure how hard it would be to pull the diff if I couldn't get the crossmember out. I'll have to take a closer look at that issue.

 

Thanks for the help. I think I at least have a renewed interest in making this work. I was pretty pissed off about the whole thing yesterday.

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Sounds good. I lit a fire under my machinist's a$$ yesterday on getting my bearing retainers turned (he's been putting me off for a couple of weeks). Hopefully he'll have them turned by next week so that I can work with them while on vacation. Maybe next year a lathe will show up at the garage and I can take care of business on my own time line.

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I did a little playing around today, and I think I've got this misalignment of the outer bearings thing handled. All I had to do was change around the shims on the bottom. What's more is I figured out that both sides were equally wrong, and in the same direction. So what that tells me is that my assembly job wasn't as bad as I had feared.

 

What I did was to unbolt the top of the struts and look and see where the strut sat in the monoballs. Both were pressing against the leading edge of the monoball. So I changed the shims around to move the strut back. Now they are both centered in the monoball holes. Then I compressed the suspension with a ratcheting tie down strap (that's about the point where I wished I didn't have gas charged shocks) and both L and R sides stayed pretty well centered in the holes. Maybe moved .015 to one side or the other. That kind of side load is pretty acceptable I think.

 

I was surprised, because the one side felt so bound up. I think it is just the polyurethane. I pulled the strut out swung it around and checked for binding in the rod ends on the outside, and it was pretty apparent that there wasn't any (strut would swing back and forth like a pendulum at least twice if you pushed on it). So I think I have the outside done to my satisfaction. Despite my earlier hesitation, this gives me a little more confidence in doing the inners.

 

Some pics:

 

Improper shim on bottom:

DSCN1447001.jpg

 

Proper shim on bottom:

DSCN1453001.jpg

 

Strut shaft offset to one side with incorrect bottom shims (doesn't look as bad as it really was):

DSCN1451001.jpg

 

Strut shaft with correct shims:

DSCN1459001.jpg

 

Strut shaft compressed with correct shims (see the movement?):

DSCN1452.jpg

 

The reason why the last two are upside down from each other is because I was spinning the car on the rotisserie to check preload on the rod ends and to change the shims around.

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Lessons learned:

1. Poly bushings suck.

2. If you're going to do this yourself, bolt the strut in tight, THEN you should be able to put the strut through the monoball.

 

I think what I did wrong was I had the strut hanging from the monoball, then I stuck the bolt through and tried to adjust the shims to fit. I was surprised that the shims were so heavy on the rear, and I couldn't figure out why it wanted to be so far forward. When I redid it there is still more shim to the rear, but at least the strut comes straight thru the top.

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Need opinions. It has become clear that hogging out the straps on the rear bushings is going to be iffy. It's hard to do, and they'll be pretty thin when they're done.

 

I'm thinking since the bearing holders will be welded to the upper part, does the strap on the bottom really need to be there? I'm starting to think it doesnt and if that is true it would save me a lot of hassle.

 

Likewise in the front I'm thinking that what the diff crossmember is really goint to be doing after this is done is taking the lifting load from the nose of the diff and putting that into the chassis. It won't be locating the front bearing holders, since they will also be welded to the chassis. So I am tempted to just hog the crossmember out so that it doesn't touch the bearing holders at all, rather than trying to get a precision fit. Still also considering welding the crossmember in. I think the way my car is set up I could pull the diff by disconnecting the front mount on top and then the studs that go through the mustache bar, push the diff forward then tilt it back and drop it out.

 

Thoughts on any of this anyone?

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If you have the uprights in back, could you not weld the bearing housing to the uprights themselves (and then perhaps a tube welded between the housings if room allows)?

All of what you said sounds possible with a caveat. I would investigate any gusseting to areas that are spot-welded or seam-welded to ensure the housing does not flex and break. You will no longer have rubber in these positions absorbing initial impacts acceleration and braking. With a "solid" mounting system such as we are striving for, the stresses must be distributed throughout a larger area that simply 1/2 of a saddle. The main concern I have in this area is that the forces will be sent to the center of the housing assembly, not above it where it would be more equally distributed. Thus, the area where the two OEM saddle pieces usually join must (IMHO) be well gusseted to prevent any tear-out. I think something like a 8" X 2" X 1/8" steel strap welded to the bottom of the housing (at the mid-point of the strap) and then bent upwards on each side, and then welded on the ends to the body would one option or thought.

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I guess the other option is to make a new strap from 1/8" steel. I don't want to weld the bearing holders to the uprights because I still want to use the toe adjuster.

 

I'm thinking in the front I could just cut the crossmember off so that it uses the two bolts on the insides of the bearing holders, then weld a similar strap on the front to reinforce it. Box in the end of the crossmember, and it would be done. I'll have a look tomorrow and post some pics.

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The diff X-member braces the back of the tunnel... the trans X-member braces the middle of the tunnel... the firewall braces the front of the tunnel...

 

I was just looking at that area... with some 2"x2" box... you could make a new rear floor frame from side to side... and incorporate the monoball housings into it...

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More progress. This is really starting to come together! :D

 

I used a die grinder and hogged out the upper part of the bushing clamp in the rear. Then I cut the center out of the bottom, and hogged it out to fit the bearing holder.

 

DSCN1485.jpg

DSCN1484.jpg

DSCN1480.jpg

 

Then I hogged out the frame part on the top, and did likewise on the diff crossmember:

 

DSCN1481.jpg

 

Bolted everything up and checked to make sure it was all moving smoothly:

DSCN1482.jpg

DSCN1483.jpg

 

All looked and felt good as it went through the suspension travel. Nothing left to do but check the strut and make sure it was moving straight. Heres the results from the driver's side.

 

Not quite perfect when fully extended but the nut goes on really easily:

DSCN1478.jpg

DSCN1479.jpg

 

Heres the toe adjuster. I painted this thing a few months back and due to all the modifications with the swaybar and now the control arms, it already needs new paint. I haven't even driven the car yet! oh well, just one more thing to do...

DSCN1486.jpg

 

Fully compressed (it just doesn't get any better than this!):

DSCN1473.jpg

DSCN1474.jpg

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I'm starting to think that I could get away with not welding in the bearing holders at all, and just use the bushing clamps to secure the bearing holders.

 

Or, I could weld the bearing holders to either the frame on top or the bearing holders and the crossmember on bottom.

 

I'm still thinking welding to the frame is the better decision for strength, and that way if I did pull the diff I wouldn't have to disconnect the control arms.

 

I'm off to dig in on the left side front bearing holder. if anyone has any advice on welding or not or which parts to weld to what, post away...

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