How can I repair (weld) a unibody rusted near rear stab-bars?

[sad-lumina-owner]

The brackets holding the straight bars for the rear wheels look solid, but rusty.

However, the 'frame pieces' which extend from the rear bumper all the way to the rear seats have rusted out around the connection there, which seems to me to have weakend the unibody.

(I picture 3 fat men getting in the back seat, and the car folding or something).

How can I, or why can't I, weld some u-beams or I-beams or L-beams or something to rejoin / strengthen the front and rear portions of these frame-pieces?

Would a bodyshop actually replace the whole piece? or cut out a quarterbody, or what?

[Scrapper]

i would go to salvage yard and get the whole the rear body. but you can weld like you said but it would have to be a thick rod or what ever you going to weld.

[bobss396]

Do you have any pictures to show us? That would be a big help. But do be advised that some states require body shops to have an inspection done on structural repairs.

In some cases, you could wind up with a title for your car that lists it as a salvaged vehicle. All depending on how extensive the repair is and whether or not the shop has to report it to their DMV office.

Bob

[MagicRat]

The problem with rusty unit bodies is often the rust damage is not limited to the pieces you can see. Often, there are internal bracing panels which become weak or rusty/holes that you cannot get to or repair. So welding what you can see may not help and it may be time to replace the car.

Also, ( I presume this is the Lumina) the mounts for the front sub frame rust as well. If they get too rusty and weak, the sub frame shifts and your steering seizes up. How do these look?

[sad-lumina-owner]

Originally Posted by bobss396

Do you have any pictures to show us? That would be a big help.

Okay I'm going to give it a shot here...

But do be advised that some states require body shops to have an inspection done on structural repairs.

In some cases, you could wind up with a title for your car that lists it as a salvaged vehicle. All depending on how extensive the repair is and whether or not the shop has to report it to their DMV office.

Bob

This doesn't apply since I don't live in the USA.

Okay here goes:

REAR PASSENGER SIDE, LOOKING BACKWARD AT REAR TIRE FROM UNDERNEATH:

I originally painted the underside with old motor oil on the advice of a friend. That didn't last long, so I then painted the underside (with Black rustpaint, and here with John Deer Green rustpaint $6/can).

In order to assess the damage better, I had knocked off and out all loose rust and metal with a hammer.

I wanted to see if the stabilizer-bar was really in danger of falling off on the highway. The bracket holding it is in fact solid, even though heavily rusted. Its got plenty of strength left. You may note that one flange of the bracket welded to the unibody is bent, probably from falling off a jack or hitting a curb at some point in its history. I have not attempted to straighten that.



There are two severe holes, one on the flat horizontal part of the frame-piece, and one on the side. The side-hole originally held the bracket for the exhaust, now moved further down by me. The combination vibration/heat? and original welding (repaired?) may have contributed to the side-rot.

On the horizontal surface, there was a bracket for the brake cable and ABS line, now being held by a nylon tie-lock. That also may have helped to start off the rusting here.



A closer look at the horizontal surface of the frame-piece, with really two holes (or one large one) crossing the stab-bar bracket.

Design issue: the unplugged round hole (without any undercoating or paint inside) probably contributed also to the rusting of this frame-piece inside and out. Those bastards.

More pics to follow.

[sad-lumina-owner]

A closer look at the side of the frame-piece, and unattached exhaust hanger:



most of the underside of the unibody only suffers from surface rust, in places serious but limited. The rustpaint seems to do a good job here of keeping oxygen and salt-water away from this corrodable surface.

I know the damage is significant here, but I am hoping to weld heavy plate on the side and bottom, (perhaps an L - bar) to restore the strength of this stretch of frame. At either end, the frame-piece is solid and strong, although having surface rust (now painted).

[sad-lumina-owner]

A closer look at the Stab-bar bracket:



Although rusted, it is solidly welded to the unibody, interestingly, deep inside the frame and probably to the unibody itself. This is probably a good design decision, since the rusting of the frame-piece has had no effect on the strength of the stab-bar attachment.

It looks as though rust will eventually however destroy this bracket too, and its seat, unless immediate steps are taken to stop the rust, and seal off the area from air, water, and salt.

[sad-lumina-owner]

Closeup on side of frame-piece:



I think rust can be halted at the unibody join, but perhaps some of the side of the frame-piece will have to be cut out. I picture a heavy plate welded along this edge vertically, giving rigidity and strength to the unibody/frame here, where it has been weakened.

[sad-lumina-owner]

Another angle (from passenger side) showing extent of rust/damage on inner sides of holes:


Note the bolt which held the original brake-cable bracket is still rusted in place (not visible in previous shots). The layered rust looks ominous, but the bracket is solid against a sledge hammer.

Peeking inside the hole from another angle (under the car):



Here you can see the worst (thinnest) part of the frame-piece.



Re-focussing on the deepest parts, showing the rust in the upper unibody panel.

[sad-lumina-owner]

Originally Posted by MagicRat

...
Also, ( I presume this is the Lumina) the mounts for the front sub frame rust as well. If they get too rusty and weak, the sub frame shifts and your steering seizes up. How do these look?

In contrast to the rear, the front frame-pieces seem to be great, and match the general condition of the underside (little or no rust, except surface rust in welding spots etc.):

[bobss396]

Great pix of a bad situation. Well, this is not something to fix yourself at home.

The options are, find a shop that will stabilize what you have or get one to do a cut-out-and-repair job.

Any legit registed auto repair shop will want to do it right or not at all since they assume liability once they touch it. Your best bet is to find a shop that specializes in rust-out repairs, they're out there, hopefully close to you.

Bob

[jonathanwang]

The damage of the rusty is more then you can see .Of course the rusty will weak the intensity of the bracket.When there rusted it is hard to weld it .Is the bracket a welding bracket or a casting bracket .If it is a casting bracket it hard to weld ,and the weld result is not so goog as you image.If it a welding bracket it is till hard to repaie it ,the rusty and the paint will influence it.Maybe you can consider about changing the bracket or replace the car. As you show in the picture ,the front frame-piece is till great.But l think it hard to replace the part of the frame,maybe you can change the frame as a whole.

[MagicRat]

Great pictures.
I have had several cars in the past that have rusted out in a similar manner. As mentioned above, it's pretty much assured that there is further rust and weakening inside the structure.

Given used Luminas are very inexpensive these days, it may be reasonable to find a good used rust-free car to replace this one and keep this one for parts.

If these rust holes were in the floor, I would just weld in patch panels. However, they are at a vital location. If a control arms broke loose due to rust you could very easily get into a severe accident, so IMO the car is not worth the risk to fix.

Finally, the police in Ontario (local or OPP) make a habit of spot-checking older cars for road worthiness (it has happened to several of my friends). They would pull your plates and force you to fix this (or you scrap the car) if they saw this damage.

[sad-lumina-owner]

Originally Posted by MagicRat

Great pictures.
I have had several cars in the past that have rusted out in a similar manner. As mentioned above, it's pretty much assured that there is further rust and weakening inside the structure.

Given used Luminas are very inexpensive these days, it may be reasonable to find a good used rust-free car to replace this one and keep this one for parts.

If these rust holes were in the floor, I would just weld in patch panels. However, they are at a vital location. If a control arms broke loose due to rust you could very easily get into a severe accident, so IMO the car is not worth the risk to fix.

Finally, the police in Ontario (local or OPP) make a habit of spot-checking older cars for road worthiness (it has happened to several of my friends). They would pull your plates and force you to fix this (or you scrap the car) if they saw this damage.

First, me and my car are in Quebec, but thanks for the heads up. The Quebec Police are less interested in the mechanical condition of cars.

Fact is, the stab-bars/control arms aren't coming off anytime soon. I have been bashing them with a sledge hammer to check their solidity. There is still a lot of steel there right now, and this is partly by good design.

The bracket and its weld-mount are independant of this rusted frame-piece entirely. They only protrude through a slot in it.

In any case the rust has been halted for now by rasping down and painting.

Obviously I want to fix this as rapidly as possible (ASAP), and I'm not going to drive the car like this except to the store and back at 10 mph.

My plan is to consult a reputable bodywork/restorer in town immediately, and explain my financial situation. My only concern is safety, not looks or resale value, not even certification, since I don't intend to sell after investing over $3,000 in parts and labour in this car so far this year.

The motor is in great shape, the brakes are all new, the tie-rod ends are done, etc. etc. etc. This is the only (future) problem involving any safety issues. The car looks like new otherwise.

Yes I'd like to get another Lumina to use for parts (including body parts if needed), but that is not a pressing issue. It may be problematic finding a NON-rusted Lumina in Canada. Every Lumina I've seen was rusted badly all over the place (i.e. /97 and older).

Anyway, I'm picking up heavy steel plate now, and I'm making patterns to cut. I am taking this on as an educational project. I can't afford expensive repairs, but I CAN afford to pick up a new trade, namely welding, and buy new tools (a welder unit).

I can pick up steel just about anywhere. Junk yards in these parts have drop-offs for free recycle, and on sundays people just use the bins as a 'swap meet'. Steel is easy and free.

The only expense I see here is my time. Every fifth house here there's a guy with a set of mechanic tools and a welding unit. I just need to make more friends.