Settle an arguement....Is this front end safe?

Bingo, the way the spring mounts to the chassis worries me. That and spring function, one can see that the spring does not touch the frame when it is sitting there (Apart from the mount) but how about in motion? If that spring bottoms out then you risk sheering the ends off.
Without question this would NEVER pass for registration in Australia!

Though it looks oddly good!

Doc.

 

The spring mount looks like the weak point in the setup.........

 

i would have thought if you went over a decent size bump in the road the x-member underneath the spring is going to come up and hit the spring - what happens then?? break the spring at the ends? will it lift the whole front end of the road? also the top shock mounts are in single shear, I always prefer them in double shear.

 

Marty McF..... obviously we're not going to change the fact that the machine is already built. However,the point of discussing a build like this is to stimulate people's thinking processes. Whether some of us agree or disagree with the way it's built is largely irrelevant. If it means someone can think things through and come up with a new concept that IS safe, based on the results of these discussions, then surely that is a satisfactory result. As a bonus, it may help new guys to see what can and what cant be done.

 

I think that spring mount is a bad design and, based on that, inherently unsafe. I don't even like the idea of having a rear axle mounted over the rear spring. At least in that case, heavy u-bolts are wrapped around that axle and they are bolted thru a mount that is below the spring.

In this case, there are too many weak links in the design and it is a big accident just waiting to happen. Always design systems so that inevitable failure will not result in catastrophic consequences.

 

Pretty much the same as whats on my car.
I'm not planning on running this set up as the front end is too low like this. I also think the U-bolts on mine would be safer.





Norton

 

It's only as strong as the weakest bolt holding it together. The way it is suspended the frame is going to want to "Dip" under braking. I see bad things happening on a road that has a patterned concrete. Ever ride down the hiway and have that haywagon bounce feeling? A few of those and your frame is liable to try and scrape. Also this whole thing is relying on the shear strength of 6 bolts. I wouldn't ride in it accept maybe around a parking lot.

 

a suicide frontend is never as save as non suicide ,thats the reason its called suicide ,i would not trust the bones

 

Bingo! If a component failure occurs, there is loss of steering as the frame glides (hopefully) along the pavement.

 

very unique..I dig the look.
would like to see it when the car is complete to see how it all goes togeather.
Im not going to comment on safety or how it was built..I think I would have to see it up close and personal for me to judge that.
not to mention see how it was all modified to work togeather than i would have more knowledge of the craftsmanship that went into the design.

other than that,,looks kick ass

 

If you even have to ask the question. You know that it being safe is questionable. Of course it is not safe but who cares its cool OldWolf

 

Rather than repeat the comments from above, I'll just add my vote to the unsafe group.

 

Spring on top of the crossmember safe?,,,NO! HRP

 

I believe this is a safe, as well as, unique design. Perhaps we are all so used to seeing the front spring mounted underneath the cross member, or a little farther forward, that when we see a design like this we are all cautiously suspect. As far as increased weight on the spring, yeah, but that spring can handle it, I am sure the welds are good, look how well done this car is. The builder has compensated for the increased weight by installing a split wish bone instead of hair-pins, which I believe is stronger, even though the primary indication for neither is to bare weight, they are none the less still burdened with it.. The bones and leafs will not fail, and I am sure the welds are top notch. You do not build a car of this quality if you cannot weld. I'm just spending my two pennies for what it is worth, which is about a half a penny.

 

Hunh... I've seen plenty of crappy welds that had real nice paint over them. Don't be fooled. Just because someone can polish and make something shiny does not make it quality.

I have doubts about the front end, but without better pics I can't say anything more than has already been said...

 

Lots of opinions and conjecture, facts are few and far between.

Design analysis: as long as the spring and the hardware attaching it to the wishbones is guaranteed never to fail it would be safe. Knowing the integrity record of the common leaf spring, it should live a long and happy life. However, if the spring is bound, shackles or perches are compromised, it's a lawn dart.


Suicide front ends are inherently dangerous as there is nothing to catch the falling frame in the event that the spring should fail. At speed that would mean a loss of control. Without control, you better have a lot of luck on your side.

 

The thing I wonder about is the spring slapping against the frame when it rebounds. Not that it is a safety factor but it will be noisey, I bet. Sorry if this has already been posted, I read a page or 2 and went on.

 

I think that if failure occured it would be where the shackle bracket is welded to the wishbone. This would probiably take a long time to happen, but the leverage at that point will create a crack right in front of the weld.

 

My thoughts exactly, Root. Assuming everything else is well executed and the correct grade 8 hardware is used, I'd run it.

 

To answer alot of questions on here....

This is what the welds look like under that nice paint..

 

There are very few people here who have mentioned the wishbones. Everyone seems fixated on the spring mount on the cross member.
Wishbones are NOT designed to carry the weight of the vehicle, they're designed to control the axle. The spring carries the weight of the vehicle, and is attached to the axle. The bones are there just to keep the axle from deflecting front/back.

How thick is the steel on those wishbones? All the weight of the front end of that vehicle is concentrated on a 1-inch wide area of the wishbones, which are probably how thick? The same thickness as a driveshaft? Maybe a little thicker? And the wishbones have now been made a leverage point as well--everything ahead of the spring mount (on the bones) is ahead of the fulcrum, while everything behind the leaf spring is on the other side of the fulcrum.

Those bones are going to fail long before the spring mount on the chassis.

Let's look at another vehicle, just for the sake of discussion: the rear trailing arm suspension on '60-'72 Chevy trucks. They have a coil spring immediately ahead of the rear end housing, so it's nearly the reverse of this set up. Those trailing arms are made of two pieces of stamped C-channel welded together. That's considerably stronger than wishbones, and the fulcrum point is much closer to the axle.

I think that car and the other shown in the thread are piss-poor designs.
-Brad

 

Those welds look pretty darn good boys. I would say now, as I suggested earlier, this rod is more than just a paint job. Although we have not seen every bracket and shackle, I think we have seen enough to know this kid has turned a wrench or two in his day. Car looks good, chassis boxed, the kid can weld... I say more power to him.

Just spending my two pennies, which are worth about a half of penny.

 

I don't think it's an issue as to how well any of this is welded as engineering wise it's a bad design. The spring sitting on top of the crossmember is a weak design. It can be done in a manner that is strong enough but a flat plate or ears welded to the top of the crossmember is not correct. At a minimum there should be gussets welded to the portions that overhang the crossmember to lend strength to that area. The force of the spring pushing up wards will have a tendency to bend that area up wards. There is nothing wrong with grade 8 bolts and a flat plate on top vs U Bolts. In fact it has been done on trucks from OEM manufacturers before. U bolts are more cost effective for them and quicker on the line to install. The other issue is there appears to be very little clearance for rebound travel which will not only ride like crap but put a huge load on the leaf spring that irt was never intended to have.
The bones by design were never intended to carry the load of the front end. I know others here have done this with some success but the reality is it's not a good design, especially if starting with Ford bones that weren't designed to carry the load.
As a side note, the breather location on the valve covers is going to spew oil everywhere! And anyone that is near this thing when it's running is going to HATE the crap that the headers are going to spray everywhere.
Also if it ever hits anything those motor mounts are gonna fold like a bad poker hand