Rear kick up pictures pros and cons

[barnbikes]

I am new at this and would like input on the pictures I took at a car show couple weeks ago.

Now I realize that most guys don't like to rag on other peoples work but I think it is a learning experience to see what what other people like/ hate and why they think that way.

Is stacking frame rails better or worse then angle cutting and butting the ends?

 

[RPM]

Just my opinion but I like the angle cut and butt weld a lot better. I just think it makes for nicer neater job.

 

[mikesplumbing]

I'll take a stab at this

Doing a simple structural analysis on both methods will reveal the method used by most people ( mitered joints ) is much stronger than it needs to be. However, it's the hand that holds the welder that makes the joint strong, not the construction method.

Looking at your photos that's a real mess to look at and does nothing structurally. Again simple stress analysis reveals this quite easily.

Here is another take also. Something known as eccentric loading is something else to consider, a welded assembly can sometimes look like it's reinforced very well but in fact it can cause problems by shifting stress in to areas where stress shouldnt be concentrated. When looking at structures like this the formulas for calculating which joints are better you also need to understand "beam theory", "bending moments", "compressive, tensile, and shear stress etc". I suppose "moments of inertia" should be looked at also.

Do you feel like doing that?:rock: Me either!! LOL

In the end the mitered joints are proven not just mathematically but by years of personal experience by just about everybody on this forum. The past can usually be the best teacher but everything depends on how well you can weld. If you have a sub-standard weld it doesn't matter how pretty or ugly the joints are, it's gonna fail.

If welding is something you don't feel comfy with do some practice and take it to a good welder and have him cut the joint and inspect it. You can also do a destructive test. Either way, you gotta be sure the joints are welded right. Another option is to have someone else weld it for you. Hope this helps.

Mike

 

[mikesplumbing]

I see your in MN, I'm actually from MN but now live in Wisconsin. If you want help welding, cut the pieces and come on over, i'd be happy to weld up the frame over a few beers or something.

Mike

 

[donsrods]

The one you pictured probably is strong enough but it is a lot more complicated than it needs to be, and not attractive IMO. There is a fine line between not attractive and pretty and you need to study a lot of other peoples cars to decide which is which. I think you will find most good builders frames are extremely straightforward and simple, yet are much stronger than they probably need to be.

I also like angled cuts, and sometimes put a small plate over the inside of the frame in the joined section just to add a bit more peace of mind, and weld all around the circumference.


Don

 

[mikesplumbing]

That's a good idea Don.......What's cool is you don't even see it.

Mike

 

[GAB]

I've used this method several times and kind of like the idea of it. By having the weld in two planes, it seems to me that if you had a problem with a weld cracking, it would have a stopping place rather than continuing around the whole joint. That's just a guess on my part though.

More work to layout and cut.

 

[GAB]

Don't think that there are any rules that says you have to use the same size tube from front to back on the side rails.

This one uses 1-1/2 x 4 for the main section, 1-1/2 x 3 for the kickup and 1-1/2 x 2 for the rear porch section.

I'd let the bottom inch of the frame hang down below the body and get a little more room for mounting things of the inside of the rail. The smaller tube on the rear should give a little more space in a very limited space area. Just an idea.

 

[barnbikes]

I think I will go pick up 2 - 10' pine 2x4s this weekend rip them down to 1.5"x3" and start playing.

 

[donsrods]

Here is a little thing we have started doing that lets us get a little more penetration on that joint. We first make up a couple of "backers" out of something like 1/8 x 1 flat stock which we cut into sort of an arrowhead shape. (That shape allows the two pieces to butt up and clear it) We drill a couple of holes in the edge of one of the frame sections so we can rosette weld the backers temporarily in place. Then we slide the two frame sections together and weld it all up. The backers keep you from burning through when you are laying in a hot weld.

Here are a couple of pictures that might help explain the process:

Here are the arrowhead shaped pieces.....

Ready to rosette weld them into place.........

Welding through the holes completed.........

Both sides rosette welded temporarily in place....

Goes together like so...............

Leave a slight gap for good penetration........

Laid out to show what the finished kickup will look like.......

And after clamping the pieces down and welding them up it ends up something like this..

 

[eafree]

Donsrods

I bet tht really helps keep everything in alignment alot better, plus its alot like a internal gusset. I will have to try that on the next car I build.

Eric

 

[mikesplumbing]

Great work Don, I bet that does a good job of keeping both pieces in the same plane.

Mike

 

[mikesplumbing]

eafree, looks like we posted that at the same time. LOL I'm gonna use Dons method when I build my frame, thanks for the tip. What size holes did you drill?

Mike

 

[eafree]

Mike, they look like 1/4 in. holes to me, but will have to see what Donsrods has to say. Have you gathered all the info you needed to get started? I wish I had found this forum before I started my project.
Eric

 

[mikesplumbing]

I got quite a bit, and EVERYTHING I learned, I learned on this forum. These guys really know there stuff. Looking at your avatar it shows how have a real nice project going. It's getting cold now in Wisconsin so I think my son and I will start on the motor first. Were going to use a Ford 300 inline 6. There is a body manufacture here in the state I plan on visiting very soon and will take some picture for the forum. It's been fun and in just a couple of weeks have started to come up with a pretty good game plan. If I didn't have the folks here give me advice I would of welded up my frame and would of also had to cut and reweld it. This forum is great, and the folks are also!

Mike

 

[eafree]

Mike, your right I found this forum long after I started my project. I have learned alot and even had to go back and redo somethings.

Eric

 

[fluidfloyd]

GAB; Don't think that there are any rules that says you have to use the same size tube from front to back on the side rails.

This one uses 1-1/2 x 4 for the main section, 1-1/2 x 3 for the kickup and 1-1/2 x 2 for the rear porch section.

I'd let the bottom inch of the frame hang down below the body and get a little more room for mounting things of the inside of the rail. The smaller tube on the rear should give a little more space in a very limited space area. Just an idea.

GAB,

I prefer your method as to stepping the tubes so they in effect interlock. This puts welds both in tension and shear in two directions. I also prefer using a tall main rail tube and as you, 4" is just right. Then you can taper it from the firewall to the front cross member at it looks really good. Just my thinking on the subject.

George

 

[fluidfloyd]

donsrods;

I also like angled cuts, and sometimes put a small plate over the inside of the frame in the joined section just to add a bit more peace of mind, and weld all around the circumference.

Don

Don,

Your method of putting doubler plates inside the frame rails is really a good idea for everyone to think about. This helps those that are not really welders per say and it insures those that are welders by trade. Not only does it insure 100% penetration and allow you to grind off the weld seam but it also takes the welds out of tension and puts them into a shearing load. Something everyone should give serious thought to. Thanks for the pictures.

George

 

[Youngster]

Some random thoughts on the previous postings.

Don's backing strip is a great idea especially for those of you who are 'hobby' welders. A couple things to watch for are make very sure the inside of the tube is deburred as well as the backers. Don uses 3/16" wall tube and you can really crank some heat into this type of joint. I would advise a bit of a bevel also and less gap to increase the penitration. A good rule of thumb is not more than 1 1/2 times the dia of the wire you're using. Depending on what type of welding you are doing, MIG or TIG, you will want to drill the holes different sizes. If you're tigging then a 1/4" hole will be good. If you're migging them, you need to go to a larger hole. The filler will build up too fast to give good penitration around a small hole.

When i weld my kicks, I clamp the pieces down to my table with a length of angle on the top and then weld the beveled top and bottom seams. After they cool to the touch I remove the angles and weld the side on top. Again when it cools to the touch, unclamp them, turn them over and space them up off the table and clamp them again. Finish weld them and let them cool before unclamping. Sounds like the long way around the barn I know but you want the rails to be as perfect as you can get them. Everything you do from here on depends on the bare frame being straight and square.

Sorry about the length of this post .. lots of info here.

Ron

 

[railroad]

I am really impressed with your method of making a strong joint, but when I started reading the thread, I just knew it would have rosette welds on both sides of the joint.
I am sure it does not need them for strength, it seems I just want to do more than is needed. Fantastic work !!

railroad