Suicide Front End.. Now I know what they meant

more pics , how many miles on the build?

 

was that car on ebay earlier this year? How many miles before it broke?

pleeeeeeeeeeease more pics and closeups too. Looks kinda similar to my car.

 

Definitely looks a little small but it's hard to tell from that pic for sure. What it looks like is it's loose! That bolt shouldn't be sticking out like that... More pics needed, stat!

 

Close up pics of both sides would be helpful.

 

I got the car on ebay about a year ago.. not too many miles on it before it broke, and NO freeway miles. The perch bolt snapped clean off.. and the bolt looked really thin in diameter. I need to look for more upclose pics to see... but it was definitely too small of a diameter to be driven, I should have changed it when I got it. Definitely attached to the bones. and not too sure how well the weld was.....

Gotta get home and get more pics loaded up.. Im still at work

 

I hope you're not the victim of :

"Let's throw a bunch of this **** together real quick and sell it on eBay..."

 

I just love all the speculation and conclusions founded on two photos that don't illustrate any detail at all.

Designs like this must take into account a mul***ude of forces like sheer, tensile and torsional stress. Only a mechanical engineer has the capacity to say what is best with any certainty. The rest of us can only guess at what might be better than something else. How about opening your minds to learn instead of jumping out front with hasty opinions?

Any one that thinks they KNOW what happened here is a fool. Anyone wondering what happened here without jumping to a conclusion on so little information can be confident in their own judgment.

Eddie,
I hope you'll respond to Kevin's questions and provide some additional photos. Don't be concerned about any that would p*** judgment. You have an opportunity to share what you find out and we all appreciate it.

I will reserve my opinion until I know more.
It doesn't matter what it was welded with, but how well it was welded. It doesn't matter what country made the materials, but rather if there was an unseen flaw before, or unknown damage after, construction.

All you experts with your conjecture need to get over yourselves.

 

Scotty...well said!!
Clark

 

Well here we go.. I could only find a few pics from when I got it.. Now I really wish I had taken more of the "before" stuff. But what I can remember off memory was.... The tube was welded to the bone... the perch was screwed through the bone and a cap was welded over the nut. there was about a quarter inch gap between the tube and the perch, and now that I think about it... my spring was at maximum with no bounce. Must have been stretched as far as it could go.




I know they dont show much.. but maybe that will help.

her is a pic of the broken perch and the one that survived

 

one more if it on the flatbed




and what we did to fix it

 

Speedway T bucket type perches. with them welded solid, you simply tore the bolt off at the end of the cut threads like Bruce L stated. If they would have been bolted through the bone in a bung and allowed to pivot ever so slightly it prob would have been fine. Your suspension simply "worked" on the threaded part til it let go.

 

SHEARED off right at the shoulder portion... totally as expected!! I've been waiting to see this EXACT picture for while. Hard to tell if it was pure sheer or if there was some torsional "twist" fracturing there from your picture, but I suspect a little of both in this case. The base threaded portion was WAAAAY too small in diameter (obviously) the location of step/shoulder was really the worst part of it though. You are very lucky!

I would rather see people mount their perches solid like Paul shows in the tech section and mount the crossmember at the correct angle to provide minimum binding. The spring will allow some twist.

Another similar way to yours was to actually weld a thru-tube into the bone transversely through the tallest face and then bush it so the perch is allowed to rotate. Again though... those spring perches are not really designed to be loaded like that and still could potentially fail if the pure bulk of the perch doesn't support the side loading.

I don't think people should be discouraged from mounting their spring to the bones AS LONG AS IT'S DONE CORRECTLY WITH GOOD WELDING PRACTICES. Also, some bones will NOT take the side stresses of this type spring loaded. Some are thicker walled than others.

Maybe someone can dig up Pauls spring shackle mounts as well as some good examples of the "pivoting" type using spring perches.

Scotty rules! Well stated man!

 

Are those perches really supposed to be left "loose"? If the bolt is not tight ( properly tight ) the constant movement will lead to a breakage every time, given enough miles.

 

well said scooter!

 

I agree with everything except this bit. Bad welding is not the main problem with most of the failures presented on the hamb. **** design, and most often ridiculously undersized parts are to blame. The welds that are shown to have failed, in most cases have failed due to inappropriate placement, and improper materials selection.

I'm not directly having a go at you , scooter. But it seems that whenever there is a failure, its soon followed by a chorus of people crying about MIG welders.

 

Thanks Eddie. I'll put my .02 in now. It appears to be a tensile failure, likely from your spring being too short, as you stated above. I think you'd do well to seek out the tech Kevin mentions. You really want the suspension to bottom out with extra length still available in the spring and shackles. The angle of the shackels through the suspension travel is very important.
I applaud you for sharing. Too many people play down any issues on their car. Thanks to you, we all learned a bit.

 

But a lot of the time failure can be from the welding skills or the lack there of... seriously we've all seen the bubble gum displays on other threads, which is not the case for this car but you have to agree it's probably split 50/50 for **** design and bad welding. At least I think it is.

 

I fully agree and that's what I was trying to get at with the "done correctly" part.

 

Ductile steel doesn't fail all at once. The crack started some time ago, and worked its way through the bolt. The failure could have happened on any bump, it just happened to be this bump.

The original design was built and had enough strength, but did not account for the fatigue loading. Putting those perches in a bending load (shear loading is not a failure mode in this case) on the treaded portion was a **** design and was going to fail sooner of later. The valley of the threads magnified the bending stress and began crack propagation. If that bolt was an inch in diameter, it still would have failed, and actually wouldn't have lasted much longer.

Welding them on will work for now, however, you are leaving a place for crack initiation in the middle of the welded area. Given enough time, this setup will also fail, but this might be far past the life of the rest of the car, but we don't have enough information to know. I'd like to see a better perch stuck all the way though a hole drilled in the bone and bolted or welded in. Don't give cracks a place to start and they won't start.
David

 

Seems in this case it could be a combination of things, proably not welding but quality, parts selection (as Scotty-B mentioned) and sizing of the components to boot.

 

Another well put answer!

Great things have come out of this thread!

 

I use forged perches, and a thickwall tube with a taper to match the top of the perch put right through the bone and tig welded in, then you ***mble the front end and with car at ride height, Torque the perchpin nuts, to set the angle correctly without preloading the spring.no way would I leave it loose,'bushed' or not. any angle change is almost immeasurable, and will be absorbed in the spring pack.
I started reading this thread with trepidation about my methods..but seeing the tiny and poorly designed perch pin that failed, im no longer worried about my stuff.
Oh and im glad your ok..

 

Thanks for all the input guys! Time to do some research and get it done right.

 

fukn eddie...
glad your ok now after lookin at the pics!
raise that friggin steering box and engine and make a real scrub line!
TP
now thats material for a new Luck of the Draw song!!

 

Had the same thing happen....Discussed a lot in this thread

http://www.jalopyjournal.com/forum/showthread.php?t=124309

 

The perch should have been installed tightly against the tube,
so the bolt is loaded in tension,and the shoulder distributes
the bending loads.Stronger,and will last longer that way.

The spring was too short,so you had no suspension travel.
All the suspension loads were concentrated on the bolts.
The weakest link.Sooner or later,they had to break.

Shackles should be at 45 degrees.

Any binding will break parts,sooner or later.

 

Aaah, finally a voice of reason in an ocean of stupidity....