Someone had mentioned this thread: Mustang II Kit Failure, and that it was closed. Not sure why, I think it had something to do with inserting high-quality threads into the Knowledge Base a while back, and locking them upon doing so. Anyway, I've re-opened that thread.

I remember calling the manufacturer (Fatman Fabrications) about that incident, and receiving a very cagey response, related to the fact that there was a "bad batch of bolts" or some such. IIRC, the crux of the issue was not that there was a faulty bolt batch, but that the manufacturer had failed to implement a recall upon finding out, on the grounds that there were very "few" units on the road. Someone mentioned that if this were an OEM part, even such a small number of faulty units (and the fact that a failure could be life-threatening) would've prompted an immediate massive recall.

One option is to call the manufacturer, and point them to this discussion. No matter who or what caused the failure, they will likely want to see the discussion.

The entire "MII Suspension" issue would be an excellent topic for a wiki article.

I have photos somewhere of a after market Tube axle failure ... the welded end broke away from the tube ... causing the Model A to turn around on a bridge and self destruct. Any thing made by MAN .. can mess up.

I believe that ( like the 32 Ford ) proper maintenance and inspections would have prevented the Model A tube failure accident.

The main cause for this thread was to get folks to LOOK at their stuff ... and do preventive maintenance and select their parts according to the use and weight of the vehicle.

You do not need a Mack truck steering box on a T-Bucket and you would not want a aluminum Corvair box on a 2 and 1/2 ton vehicle.

Deuce ...

Here are my observations from the photos:

- While the topic of hydrogen embrittlement and chrome plating of suspension parts is an interesting topic worth its own thread, it does not appear that the suspension is chrome plated and therefore does not apply.
- I can see that what is still attached on the front right corner is the tie rod and upper control arm. It looks like the stabilizer bar is also still present.
- What is missing is the lower control arm, coilover spring and damper and the spindle.
- In particular, it can be noted that the lower control arm mount to the frame is visibly torn away from the frame.
- The body doesn't appear to have any roll-over damage.

From the position the car came to rest, it would appear that after the suspension failure, the front right corner must have Don Quixote'd the pavement which sent the back end up into the air landing the vehicle on its left side with the front end pointing in the direction from which the vehicle was travelling.

From the shape of the tear on the frame, it does not look like that was the initial failure point. It certainly suggests that there was enough strength in the lower control arm to support the forces necessary to tear the frame apart and initiate the flip.

The lower ball joint doesn't raise any red flags for me, but I have to say I would look at the coilover attachment to the lower control arm as a prime suspect. On the drivers side you can see the intact lower control arm, and I see a round tube welded to a round tube under tension. That says to me small contact area in non-ideal loading conditions.

Weld quality is key in this sort of construction, and I would be concerned about how much air gap is being bridged by weld and to what degree pre and post treating of the weld is being done.

I would speculate that fracture initiation probably would have occurred in an area that is pretty difficult to see, and there wouldn't be any obvious warning signs from the driver's seat-of-the pants.

Someone tell me if I am spending too much time on this thread....





If you look closely at the construction of the A arm mounting structure, you will see that it is a large tube, welded into fishmouth trimmed top of a prism shaped sheet steel box. The sheet steel used in those is usually a minimum of 3/16". The LCA throughbolt runs all the way through this tube.

There is a right angle created where the tube meets the box, and the tube and lower control arm are cantalevered out forward and behind the box. There is no reinforcement in that area other than a weld. IMO, this area is a "designed in" stress riser, with the strength of the weld not being being the only thing keeping a crack from starting. As I said before , a gusset there would be a great improvement.

All of the torque input from the LCA is concentrated at those points.

A small crack starting at the front intersection of the tube and box, and growing rearward until there just was not enough sheetmetal to support the strain, would result in the box being torn in that manner. The edges of the tear are rotated rearwards, the same direction that the majority of forces are directed when the car hits a bump or when the brakes are applied.


I would still say that a sharp impact, such as hitting a curb or other road hazard, caused a small crack to start, either in the weld itself, or at the weld edge.





I have yet to see that joint construction fail. That joint design is present in many thousands of control arms, four bar setups and panhard rods. The length of the weld is actually longer than the circumference of the tube, due to fishmouthing. And if that part of the arm failed, how did it take the rest of the lower mount with it?

Even most of the urethane bushed rod ends are a threaded stud, either resistance welded or electrically welded at a right angle to a tube. I don't see any of those breaking either.





I agree with you on the quality of the weld, but I would think there is no pre/post heat of that part done, as it is fairly thin mild steel, and a tig welded part. (All of the IFS units of that particular design I have seen and installed are TIG welded)
I would guess that the fit of the individual peices would be pretty good, most all of the production shops making those IFS units are using cad laser cutting equipment.

The welding may or may not be done by experienced welders, I know of one company who makes that design of IFS that is reputed to hire guys with no prior training, teach them to weld beads on the bench, , and set them free in the production room. I have looked a quite a few welds from production shops like those that appeared beautiful on the outside, but had minimal penetration.




The failed area on that crossmember is highly visible once you get down on eye level with it. You can not see it from the drivers seat.

Regular inspection would quite possibly prevented this.


Later, mikey

__________________
BE different....ACT normal.

No one is completely useless..They can always be used as a bad example

I have been following this with keen interest since I have been thinking a lot about this type of system and I certainly have had a few questions about some of the thinking behind the design. You just answered one question for me when you said "thin mild steel" is that all that is used in these things? From the very start of this thread I have been picturing poor welds as the possible cause and wondered about what kind of steel was used but I have not said anything since my experience with this set-up is so limited, interesting to say the least.

It's so hard to tell from the small pictures that we have but the section that is gone seams to be torn off with a significant torsional impact. I'm still guessing that something else failed causing the rest of the damage.

I have not seen anything built out of less than 3/16" CR plate steel..(that doesn't mean there aren't some out there built out of less)
Most of the aftermarket crossmembers are 3/16" wall or more as well..some use rectangular tube, some others are of fabricated construction.

The stock MII crossmembers are built out of sheetmetal about 1/8" thick, but use a strut rod to spread the stress on the crossmember out, and have some doubled thicknesses in high stress areas..


My reference to "fairly thin" was in relation to a part that would normally need preheating to build properly.

Later, mikey

__________________
BE different....ACT normal.

No one is completely useless..They can always be used as a bad example

If your brain is working like mine, it's like trying to solve a puzzle.

I would not think that the pictures given show a initial failure of the LCA mount to the crossmember. The way that the metal is twisted appears to suggest that the the LCA was yanked towards the rear of the vehicle. This could have happenned in a curb impact, which reportedly is not what happenned, and from the before picture I wouldn't think it'd be a pre-existing condition because you would have very obvious wheel alignment problems.

Only under braking would the LCA carry loads in a direction consistent with the tears in the cross-member. I don't buy that even the heaviest braking would be enough to create those kind of tears, and a fatigue crack would mean that a part of the joint was not subjected to the tearing forces.

A failure of the LCA mount on the crossmember would most likely have had to result from the load placed on it by the vehicle weight through the spring, the damage would have appeared as if the LCA was yanked downwards, not twisted. The resultant vehicle crash event would've involved the inboard end of the LCA going into the pavement, then pulling back, then the front of the frame would dive into the pavement.

In the LCA mount failure scenario, in order to end at the position pictured, the end of the frame would have initiated the rotation of the vehicle, in which case it would be bent in the opposite direction scene. The bending of the frame appears more consistent with being hit during the flip than with causing the flip.


In case I worded it poorly, my theory is that the end of the shock absorber broke free from the LCA and grabbed pavement. It would have stuck down between the front and rear members of the LCA, and the shock would have impacted the LCA as if it had been subjected to a curb strike.

I haven't really looked at so many LCA designed from the suspension kits, and it's hard to see how they're constructed from the images I've been able to find, but I don't like the look of the lower shock mount on that one. A flat steel tab on both sides of the tube would be better, or gusset the tubes. That joint if loaded under compression instead of tension would be better. Putting a notch in one tube improves the joint. I didn't see any of these on the LCA that wasn't torn off.

I also agree that we can't spend too much time on this subject until we find out what the cause really was. I only hope that we can get more info about this from the original sorce otherwise we are just speculating.

Mild steel will be common and the most economical option.

You'll find chromium-molybdenum (Chromoly) alloy steel is used by some. It's a higher strength steel alloy, and when engineered properly it can mean that you can use a thinner walled tube and get the same strength as a mild steel component. In this case, good build practices become more important since treating a weld joint wrong can mean that the joint won't be any better than if it had been made from mild steel, and you lose the benefits of chromoly yet pay the higher price.

You may also find some parts made from stainless steel. These will probably come with a price tag of $alot and if you want something shiny, it's probably the way to go. I'm sure there's a trick to welding stainless steel I haven't taken the time to learn, but in my opinion as someone with lots of time on a TIG welder for a hobbyist, it's a pain to weld good. I could be wrong, but my thought would be that I'd trust a stainless steel weldment over a mild steel weldment that had been chrome plated. I would expect that poorly welded stainless steel would be easier to detect visually than improperly post-treated chrome plated parts that could crack from hydrogen embrittlement.

Hey walt,

Just saw a picture of your pickup in a magazine at the newsatnd during lunch. Special addition called Hot rods or something put out by Drag Racer.

Niiiiice

WOW........Thanks for the tip. I'll have to see if I can find that.

Earlier in this thread, Mikey suggested that maybe it was time for some sort of inspection program. I can't believe that someone could built a vehicle from scratch or own an existing vehicle that they have failed to maintain and continue to operate it un-abated.
Where I am, all vehicles must go through a full mechanical inspection every six months. There are specialized testing stations in every community where this test is undertaken. The vehicle is raised on a four-post hoist and the entire under-body is meticulously inspected. Ball joints, bushes, steering arms, steering racks/box's, control arms, brake pads, exhaust systems, drive shafts, differentials, tire tread, rust, fuel tanks, engine and transmission mounts and all suspension components. After the car is lowered back down the inspection continues with lights, indicators, wipers, horn, seat belts, door latches, wheel bearings, seat mountings and then it is driven on to a series of rotating rollers where a computer tests the braking ability, front, back and emergency brake. If it passes all of this only then is it deemed roadworthy. The testing officer attaches a label to the inside top right corner of the windshield where it is easily visible. The label has an expiry date exactly six months from when your car was tested. If you drive your car with an expired label and are stopped by the police your car is ordered off the road or impounded. If for example you parked it in town and a parking officer noticed your label was expired then it would be wheel clamped. Because every vehicle in the country is involved in this, it is also a good means of picking up and identifying stolen cars, illegally modified cars, shoddy crash repairs, structural rust that has been illegally obscured with body filler and vehicles where the owners try to avoid buying registration.

DON'T EVEN SUGGEST ANY MORE GOVERNMENT INTERFERENCE IN OUR HOBBY. An isolated incident here and there does not warrant that.

Well, that sort of response is not what any responsible person wants to hear.
A car in a poor state of machicanal repair is no different to a drunk driver...neither should be on the road.
If I have my fmily in the car and I'm stopped at a red light, the last thing I need is some dick slamming into the rear of me because his brakes wore out months ago.