Injuneer

When you first asked the question in the PM I looked at the shop manual and saw what you posted above. What I was curious about, and what I would ask the dealer tech would be the purpose of the "window" in tool J39931. Does that allow them to observe the voids, or just the depth?

I agree that it's best to stay away from most shops - they appear to be horribly incompetent in many cases. No substitute for doing it yourself, and from your post I can see that you are very thorough in researching the procedures.

However, once you get screwed over by one of them, I understand the desire to even up the score and make them do it right.... I've beat a couple shops and vendors into submission in my many decades of playing with these toys. At some poinit though it's probably a good idea to back off and start over.

As I mentioned in my PM, the Energy Suspension polyurethane front upper and lower control arm bushings are good replacements, in particular because they use a totally revised design for the rear/vertical lower control arm bushing, to eliminate the "bind" that the voids in the stock bushings appear to be designed to minimize. Might be worth looking into those. I did mine 14 years ago, using a torch, hammering the "can" for the rear/vertical bushing out of the rusty arm (required for the ES hemispherical 2-piece bushing), and pressing stuff back together with a big C-clamp. Messy, but satisfying

sbca96

What pains me the most is about 6 months ago I had to dump a 67K mile parts
car (1994 Firebird Formula) bought for the drive line used in a EFI swap into my
wifes 1978 Camaro. I have done all the design work myself on this install, and
needed the room in the backyard due to idiot neighbors. The parts car left with
the front suspension intact and was crushed before I could get back over. This
has sucked since I needed a hub assembly about 2 weeks later. Buying unknown
used parts for these cars these days isnt so wonderful, the newest example will
be over a decade old. The rear bushings are a known problem and therefore we
can assume will need replacement in 70% of the used arms found.

Replacing the bushings seemed the best way to solve the problem.

I do all the work I can do myself, I just could not safely position the arm into my
press with good feeling about the outcome. If have to have ONE done, I might
as well have them all done - that was the train of thought.

I considered aftermarket, but this particular car has a buttload of Hotchkis on
it and that makes it ride VERY harsh. I felt by going Poly would add to this and
make the car unbearable on our daily 110 mile commute.

BTW, here is the LT1 swap into 1978 Camaro thread : California legal!

'94 Firebird LT1 into '78 Camaro project back on - NastyZ28.com

Tom

sbca96

Just back from the Dealership. They do not have the tool, nor do they have a
source to get the tool from. GM has no technical documents that show what
the proper orientation of the bushing is. This was a dead end. They said that
they would mark the arm and simply line up the voids pressing the bushing into
the arm to the depth measured before. This is what I told the shop to do, as
the service writer ignored my input and shrugged it off with "we do these all of
the time".

I guess I need to call Moog on Monday. This sucks since I have quite a few of
projects being held up by my now unavailable garage.

Tom

sbca96

I called Moog, the tech put me on hold immediately and I waited for about 12
minutes before he came back to tell me he searched the GM Service Manual
and didnt find any information about the orientation of the bushing. I told him
I could have saved him the trouble had I known that was where he was going
to look since I already did that.

He went on to say that it must not matter (contradicting what the quote I got
off another forum saying a Moog tech said inboard/outboard) since it didnt say:
but I explained the Manual says to use certain tools that no doubt fixture the
orientation within an allowable tolerance for error (couple degrees).

I KNOW there is a document somewhere, and I KNOW it matters, I just do not
have any idea how to get to that level of GM. I do this kind of stuff for a living
so I know they wouldnt just randomly put voids in a bushing.

This my friends is ridiculous.

Tom

multicar

I went with the full contact(1LE) bushings all around. Here's a pic:

sbca96

I have read about those, apparently they cause binding and wear out fast due
to the lack of the reliefs. Considering the original bushings lasted 230k, I think
its not the bushing design that is the problem - but the lack of info to install.

Do you have a better picture of the entire arm showing the voids?

I have a friend whose sister works at the Corvette plant, I figured it was worth
a shot so I drew a quick sketch for her to forward to engineering/doc control.



Tom

multicar

Hmmm, I haven't heard that they would wear quicker. WhenI replaced mine at ~60k, the slotted rubber, as evidenced in the pics, had already started to split. I have heard of the poly bushings binding, and limiting travel somewhat, but not the rubber ones to the same extent. IMHO, poly is great for straight line performance vehicles and also vehicles with higher profile tires to absorb some of the jolts. I noticed a significant improvement in the cornering dept. with my setup. Anyway here's another pic:

sbca96

Doug,

Are these old pics? Is there a high resolution version of this you can email
to me, and do you still have both lowers laying around that you could take
a couple pics of both (maybe even marking where the voids start and stop
on the control arm)?

sbca96 at aol.com

I figure if I can get enough OEM examples together I can get an average on
the orientation and use that to reposition mine. I just want to match what
the Factory did.

Update :

I got a reply back on my sketch from an assembly tech at the Corvette plant
but he only sent me the Service Manual pages I already have. I called him
at the plant and explained the situation and he said he just didnt know where
he could get access to documentation. As he mentioned the platform has
been out of production for well over a decade now. He said he would check
around and see if anyone knew where to look.

Tom

multicar

Yes, and yes...those pics are from the mid '06 when they were swapped in and out. I also have the original LCAs and will try and get some recent pics of them.

sbca96

That would be awesome. I hope to reposition the bushings this weekend, so
sooner the better if possible. The wife is getting annoyed at the car sitting.


Tom

multicar

Here's a link to latest photo taken tonight...My other site is having issues with the downloads; hopefully you'll be able to see it at this link:
z28-frt-LCAs_zps2c18bb1c.jpg Photo by multicar1 | Photobucket

sbca96

Thanks ... this makes me feel that I didnt totally screw it up by rotating. Looks
as if they are pretty close to inline with the front bushing. One of them I recall
was inline, the other was angled off about 5 degrees. I figured there is a slight
tolerance allowance .. I ASSUME that ideal is inline with the front bushing. That
is how I installed them ... dead on straight with the front bushing. They flex up
and down as they should .. no binding or odd noises.

I have everything back together and greased ... just have to put on the tires.

I took pictures of how I orientated them, will post when I get them off the cam.

Tom

sbca96

As promised here are some pictures. I had a long piece of aluminum to use as a
kinda straight edge to show the path of the axis as I see it, also shown as a dash
line in my sketch.

Here are three pictures getting closer each shot.







This puts the voids on each side of the axis, I figured this was a safe bet on
how I think the part was designed.

Second point I wanted to show is this, the service writer who failed to write
down what I told him to avoid most of what went wrong claimed that had I
bought "quality bushings" the depth would be controled by a "Step". I tried to
explain to him that installing the bushing to a measured depth was part of the
design of the control arm, but he kept on with "crap bushings". I went home
and found the one bushing I pressed out and it had no step. I brought it back
to him to show that even OEM was this way, his response? "AC Delco is crap!"
I asked him what a quality bushing was, he said, "Moog". We all know that is
tough to argue with, so I backed down. Interestingly enough, the bushing he
had to replace could only be got that day as a Moog kit.

So here is a "Quality Bushing" (Moog) vs a "Crap bushing" (Master Pro):







The catch is ... not going to tell you which is which .. any guesses? You also
might notice : neither has a "step". Hummm.

Tom

sbca96

For the record the Moog is on the right. Funny, the Master Pro has a thicker
wall than the Moog - other than that they seem identical.

Tom

Ricardo

Great thread, Tom.
I am completely re-doing my front control arms (upper and lower) right now with moog bushings. I am also replacing the ball joints and found your thread very usefull.
I have an extra set of control arms that I am keeping as a reference for the installation depth dimensions.

Did you finally press the bushings in by yourself or did the shop install them?
I have already removed the old ones and am getting ready for the installation of the new ones.
Just trying to figure what is the best tool to use to press the new ones in.