Another way to lower the back of an F1

OK, I'll do the listening now. What basic principals am I missing? I need to know, this is cool stuff!

How does your design take the basic principal of frame flex into account? Those cross-braces seem to add rigidity....to members attached to a flexible frame. Shouldn't all 4 points remain independent, so they can move when the frame flexes? Otherwise, something will give.....the bolts, or the frame....I think. No?

 

I love everything you've done to this truck so far except for this. I think they get the best and most practical stance from reverse eyes in the front with stock springs in the back and slightly shorter tires in the front. That's only my 2 cents though, and it won't get you far these days.

 

Voodoo Twin, I only see the word "HACK" listed in your profile. Seeing as how you must have typed that in when you filled the profile out can we just assume you know better than anyone here when it comes to your qualifications. That being the case might I suggest you stop wasting Ryan's space and refrain from further posting on this thread? Feel free to show us some of your superior engineering/fabrication examples but until then GIVE IT A REST.

Frank

 

Clever, and very cool.. Love this truck (and those calipers).

[We stopped in the other day, but it looked like you had family over so we didn't want to invade.. So if anyone saw some unsavory types eyeballing the F1 - no worries .]

Have good one man!

 

i think I might understand voodo's concern, which is also mine.
Instead of the load now being on the SIDE of the frame, in the C channel area as it was designed. now the load is on the TOP of the frame, that area would be more prone to failure, but adding a plate to compete the BOX of the frame in that general area would help to stiffen that top area of the frame.

Not sure if that was his concern really, but thats the only part that scares me.

 

yeah i too thought partial boxing plates along the inside of the chassis rails would be good but pretty complicated with the original Xmembers there and quite prob wouldn't gain much....plus partial boxing plates can generate there own issues.

 

There was a FNG asking just the other day how to drop his F1 on the cheap. Hope he sees this.

I think a lot of guys hesitate to post pics of their projects or work here just to avoid having to explain themselves to those who criticize stuff they obviously don't understand.

Solid, simple tech. Thanks Kevin.

 

Truck looks great.....let's be clear that there is NO disputing that sweet, sweet fact!


I'm not an engineer, but from what I've understood* about old truck chassis' is ....

They were designed to flex & move around, then rebound to their built position.All of the components attached to them were designed with this in mind.

Anything that you do to TAKE OUT flex at some point, will add stress to the other 'still-flexing' parts, in the form of metal fatigue/cracking,
Often at joints to crossmembers or bolt/rivet holes.
This is why we see failures next to a partial boxing plate, not at the boxing plate.

As long as your design allows you (and future owners who might hold you liable) to inspect for signs of this stress, It's all good!

*All knowledge garnered or offered was gleaned from the internet, and should be taken as such.

 

Kevin, unless your gona be carting lots of heavy stuff with your truck and/or traversing rough terrain and/or travel tight winding mountain roads on a regular basis ....theres absolutely no issue with your set up .

After lots and lots of road miles its poss you maaaay get a couple fatigue cracks...but i'd bet not on the upper flanges of the rails..lookin forward to seeing how you remount your deck.I may do mine in similar fashion to how you've done yours.
PB

 

clever way to static drop any veichle, i did something similar on a way diffrent car, but same principle.
I have also an article on an early car craft that describes something similar.
Rising the mountin point of suspension is kinda liek drop spindles, maintains geometry while lowering susbtantially.
Loveit.

 

Nice job on the drawing Kevin, I like that! To your question: the frame rails will flex due to irregularities in the road surface, they will not remain parallel to each other (that crossmember only exists at the front hangers, not at the rear where most of the frame flex will occur). The welded assemblies are rigid, so when the rails go out of parallel due to frame flex, a bending force will be placed into that top flange much like my tin example.

Back to the primary concern though, the original suspension attached to the vertical web of the C frame, which is quite strong and resists bending and shock forces much more so than the small horizontal flange that you are now attached to. That would be my primary concern, which is why I recommended that you somehow tie the angle iron into the vertical web. If one of those flanges cracks (60 year old metal, which you found corrosion on?), someone is in for one heck of a rough landing.

And thank you for allowing me to continue in a mature adult discussion.

 

I read his concern completely different than he or you illustrated. I was thinking about a vertical plate that ties the vertical web to the new piece that you added above the frame to prevent those two seperating.

Not questioning your design it looks really strong I just enjoy good discussion about these types of things and learn from them.

 

Yes, that is what I was recommending. Tying the new angle iron to the vertical face of the Ford frame. And I would remove the tube that ties each side together, to prevent the "lever action" when the frame flexes. Let the frame flex all it wants.

 

"And you're singling out this top flange like it's hanging out in the breeze bearing the entire weight of my truck. It isn't."

So, if the weight of the back half of the truck isn't on the top flange where is it?
My point, your design has the truck suspended off from the top flange of the frame, maybe 2 inches wide at the top of the C, it was designed to hold the weight from the vertical part of the C about 5-6 inches thick and in the middle of the C.

Why not finish boxing the frame, or as suggested, maybe add a plate onto the vertical part of the frame to SHARE the load along more than the top flange of the frame?

Maybe your top of frame mount will be fine, but when its OBVIOUS that youre suspending the truck from a much smaller piece of the frame than it was designed to be attached to why not add in some help?

Open your blinders and see what we are trying to say.

 

I understand how it works perfectly. When the frame flexes, the 2 rails change planes (go out of parallel) the most at the far rear. So the deflection is greatest at the rear hangers. Yes the top flange of your frame IS suspending the entire rear weight of your truck. If we can't get past these basic facts, then you are right, there is no point in continuing to discuss this because that's where this all begins. No hard feelings at all.

Good luck on your home sale.

VDT

 

Q: did you grind the heads of the rivets on the top flanges down flush where you put your new angle brackets ?... to allow them to sit right down on the rail..

 

w/ all this flexing goin on im surprised you managed to drill parallel, and straight, holes...

 

great post Kevin.
Did you ever tell how much clearance you had between the axle and frame???
Have you had any problems bottoming out??
I am ready to fix my frame and I was thinking to have 3" of clearance between the axle and frame.(leaf springs)
Opinions?

 

Gotta prove you are right,right???


Thanks sounds like 3" will be enough.

 

I am going to C notch or step notch, I am not sure yet.
I already cut my pieces for the step notch But I like the cleanness of a c notch.
The PO cut the f1 frame right at the kick up and fabbed a 7 foot high step notch to run big ugly tires.
I have to do it all over again but better.
I am running leaf springs.

 

The old compass trick for layout. Thanks kevin
Picture is worth thousand words

 

Kevin when doing the notch be cAreful of flexing lol. Awesome truck

 

Kevin, i live ft. scott and have seen your truck several times in the city, Just have to say amazing!!! I am going to do this to 51 over labor day weekend maybe, cant decide if i want a 5 inch chop top or lower the truck, regardless i am going to steel your idea, as for flexing about about all those A frames that got boxed and flex taken away from them back in the day. I am not concerned about it. if something breaks then you fix it thats why they are projects and daily drivers.

 

there are several pix on the hamb (kevin's included) of lowered trucks.

i can't show you the back of a chopped cab, but my avitar shows what a 5" chop looks like from the front.