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Discussion Starter · #1 · (Edited)
Man, I have my hands full these days. 3 car projects going on in my spare time, more if you count other people's projects that I have my grubby hands in. But I digress...

Overview:

So, you have a great running c900 that you want to keep driving, but there is some nagging rust on the passenger's side control arm that is always on your mind.

It might look something like this

and you might not want to send it to the crusher just because it has a little rust...

You wonder, is it safe to be driving the car with rust around those mounting points? Probably not, but it depends on the severity of the rust, and often times you can't see the whole picture without removing the suspension components, and all the oily good around that area.

Is it expensive to have this issue fixed? In many cases yes, the shop I used to work for charged well over $1,000 to fix it. But if you pay to have it done you don't have to so much as lift a finger after driving the car to the shop. But bring your wallet.

Then there is an option to buy a product that I will not name for around $200

These have had good reviews from several people - moonracer/Marty Adams of Meyer Garage and Iowa City Saab tested one to its limits, and told me it held up very well.

Lastly there is the option of fabricating the cap/control arm mounting area yourself. This option has the potential to be the most affordable, yet it easily more time consuming than the other two options.

My goal:

I plan to try the third option myself. I will try to keep costs low, and (as long as the cost of the welder is not figured in) this should be a very affordable project. I estimate this will not cost me more than $25 to fix the rust. I will be trading time for money; it will take me a few days working after I get home from work to get it done.

Let's get started!

(I will update these first few steps with photos later, my camera was not working for me my first night of working on this)

The first step you need to take is to find a stable area to park the car, somewhere with solid ground to place jack stands on for safety.

With a stable floor jack lightly installed under a solid jacking point crack all 4 lug nuts loose. Next you will need to loosen the large hub nut that holds the axle shaft to the hub.

Turn steering all the way, full lock, to the right. Insert some sort of spacer between the upper control arm and the body to take the load off of the spring when the car is raised in the air. This makes removing the upper ball joint quite a bit easier. A photo of this can be seen in my second post below. I used some rectangular steel for my space (a cut piece of a roof rack load bar).

Jack up the car - as soon as possible place jack stands in two points to keep the car stable. I personally jacked the car at the front-rear balance point and lifted the entire passenger side in the air. I placed the jack stands on a frame rail in the front, and in the rear on the rear suspension mounting point.

Lower the weight of the car onto the jack stands and remove the front wheel.

The fun begins when removing the steering knuckle/hub and lower control arm.

This is the first goal: To pull it out as a unit and have it sitting off to the side.


You need to remove the following in roughly this order:
-Axle nut, already loosened before jacking the car up
-Tie Rod End, separate from steering knuckle, do not remove the TRE from the tie rod
-Lower shock nut, slide shock off of the mounting stud on the crtl arm.
-Upper ball joint, I usually remove the two bolts and slide it out of the upper control arm
-Remove the nuts holding the sway bar to the lower control arm, then pop the sway bar off the lower ctrl arm
-Disconnect the brake line front the front brake caliper
-Lastly, remove the 6 nuts that hold the base of the lower control arm to the body of the car

At this point you should be able to pivot the steering knuckle/hub away from the axle. You might have to give the end of the axle a pop with a hammer to pop it out of the hub. You will also be able to drop the control arm away from the body at this point. Be careful, with the hub attached its kinda heavy.
Note: sometimes you need to wiggle and pry to get the control arm off the the 6 studs that are attached to the body.
 

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I have the exact same issue.
watches thread intensely
:shock: :shock: :shock:

I plan on trying a similar approach on my c900, after i know you were successful with it :D

In the mean time, since my rust isn't horrible yet, i'm gonna shoot it with that magic stuff I see at NAPA that "turns rust into black primer" just to maintain the area so it doesn't deteriorate any further... that is once I swap out every damn wiring harness in the car :rolleyes: ... i hate fires!
 

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Discussion Starter · #4 · (Edited)
So now you should have a fairly empty wheel well. You might opt to remove the axle shaft to gain a little more working room in the wheel well. I recommend removing it, at this point it will take 2 more minutes to get it out of there. When its removed you have the chance to re-grease the tripod joint/inner driver cup which suffers from the heat of the downpipe that runs inches away from it.



And with the control arm out of the way you can inspect the area and see what you have gotten yourself into!

This is what I found:



















It's bad enough the the ctrl arm mount that's toward the rear had a hole around it where you could see up into the cavity between the sheets of metal



And needless to say, there is quite a bit of missing metal in there.

This is where I am right now. Next I will begin cutting some of the rusty metal out of there and making some cardboard templates that I will use to trace onto the metal that I will be welding into place.

I will not be cutting out the metal around the two mounting areas, but instead cleaning up the metal around them and capping over them in order to retain the correct suspension geometry. I don't want to even think about attempting to cutting those studs out and trying to fit them back in where they are supposed to be.

I will use some galvanized steel, probably 12-14 gauge, which is slightly thicker than what was originally there.
 

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definitely a nice write-up.

reminds me of that '86 that i left my GF drive home, the one that i took the transmission out of. i am rather surprised both front wheels did not splay (bottoms out), especially on the passenger side. there was about 1/4" of rust holding the front bushing bracket in place.

in comparison, you have a lot to work with. in comparison, i am glad that i have a southern california car... which will be inspected for underbody rust this weekend, just because i want that peace of mind.
 

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Dan and Steve of Road Tested Saab also use these in there shop to repair c900's as well here in Indy. Good product from the looks of it.
 

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Discussion Starter · #11 ·
Good to hear!

Mike, do you have any idea what gauge steel they use in the safe-t-cap?
 

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Excellent thread, I look forward to seeing your process and results. My wife's otherwise good '87 900 base has rust in the same area and I'd like to get it taken care of soon.
 

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Discussion Starter · #15 ·
Having cut apart a car where there was no rot in this area I was pretty suprised how thin the metal in that area is when its not rusty!

I will be happy to have a bit thicker metal there and I think I can get away with 12 gauge.
 

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Discussion Starter · #16 · (Edited)
So, I all but wrapped up my version of the safe-t-cap today!

After cleaning up the rotten area a bit I went inside and played with the an image I found on the internet that does not exist any more - don't try to find the image, because the owners of a place that makes a good product very similar to what I made will get pissed.





The size was not exactly right on, but close enough to get this car to the moon

I traced the template onto a 16ga sheet of steel and cut it out with my angle grinder - ALWAYS USE SAFETY GLASSES, GLOVES AND EAR PROTECTION! AND CAREFULLY SECURE THE SHEET OF METAL IN A STURDY VICE. AND BE CAREFUL!!!





My next step was to drill the holes that the mounting studs for the control arm pass through. I used the control arm for the template to be sure the holes would be in the exact spot.





Be sure there is enough clearance for the rear bushing housing in the cutout. I had to grind a little out from my initial cut.



Next, you need to bend the sheet in several places, again, I used a image of a product I found on the internet as a reference for where to bend. Since the image no longer exists, use photos of the piece I made, and look at the under side of the car to figue out where to make bends. These bends keep the metal stronger. Be sure you bend the tabs the correct direction for whichever side of the car you are working on (I bent them the wrong way first, and had to hammer them flat and re-bend them the other way).

The only difference between making a driver's side and passenger's side is which way these tabs are bent.





Once its bent, make sure you clean off as much paint, grime, and oil, and whatever else is on the metal the best you can. Its pretty much impossible to get the under sides of these cars free of all of the crap that's down there, but get as much bare metal as possible in preparation for the welding.

Then free up the subframe girdle/brace/thing and pry it down far enough to fit the new metal over the mounting studs.







Then snug the new metal up to the old rotten stuff by tightening up the nuts for the control arm. This keeps the new metal in place quite well.





 

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I'm glad to see my former $800 SPG is getting such attention. Have you transferred the title yet? :)

Don't you want to treat the rust on the metal you're not removing, even it's just to slow it down and prevent migration to the new metal? Even if not POR-15, just some regular "rust-prevention" paint might help out some.
 

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dude thats great! you should make up a .pdf or CAD file of that piece so the rest of us dont have to dick around with making it the right size...please? :lol:

looks like an easier fix than i initially thought it would be, especially if we have a template :wink: :lol:

Paul
 

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Discussion Starter · #20 · (Edited)
Alrighty children, onward!

Set up the welder, and start welding the seams. Be really careful because the car will start on fire a few times when you're welding. Be sure to have a fire extinguisher handy - I'm serious. And I ended up having a lot of oil/power steering fluid/gunk turn molten and drip down when welding, occasionally it would be on fire. Fun times.









Alright, well, as you can see above, the mounting point for the rear bushings was pretty much sitting there, not connected to anything. Had I followed the design of the palce that makes there to order I would not have had enough bracing for that area. I decided to weld a vertical plate in there to fix that issue.





The next step was to add metal to brace things up even more. You might ask, why did you cut out those areas in the bottom plate instead of just using a full piece of metal?

Well, because it would interfere with the control arm travel. Those spots need to be notched out as seen in the template that I made, from an image that no longer exists. Then you brace that little piece of protruding metal with some more metal that you piece together and weld in at angles, or hammer upward to make enough clearance for the control arm.





I made one piece straight, and welded it at an angle, the other piece I made curved. Then I braced it up with a bit of scrap metal.



Then I started boxing the rest of the area in with cut pieces of metal. I didn't really follow a template, just eyeballed it a bit. And bent, hammed and welded to fit.



I used some paper and cut it to make a little half-ass template for the next piece of metal to cut.



Then I cut more metal, and welded it in.







Then I ran out of wire for my welder and needed to eat something.

Today's work started at around 1:30pm with no template, and nothing cut out or welded to the car, and I wrapped it up at 5:50pm. Not bad for an afternoon's worth of work!

It's not pretty, but its a hell of a lot better than the rusty-ass nothingness that was there before, and it will be quite strong.
 
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