Crazy Fast Rear End

[CrazyFastFab]

Hello,

I have been pouring over the forum and come up with this design.  Yes, it auspicious looks just like DS's frame.  DS has been immensely helpful and gave me some dimensions.  I have ordered the front end from him so I figure that is taken care of.  I am a big fan of design review so I was hoping you guys could look over drawings.  I am hoping you guys can provide two points of criticism one safety and two constructablity.

Thanks in advance,

[Yummi]

Wanted to get some jpegs up for ease of use of others.   

About the only thing I would suggest is get rid of the red shocks.  Proven fact red shocks do not work as well as blue ones. 

The smart ones will chime in soon.  For now you are stuck with the smart ass one.

[CrazyFastFab]

 The red ones look like they are welded to the A Arm, still working on the drawing.  Ya, but I already have the Sway Aways.

[dsrace]

sure is a nice looking chassis and design if I do say so myself!!

[dsrace]

I do pre-fer blue shocks myself too which are now black btw!!   

[trans man]

sure is a nice looking chassis and design if I do say so myself!!

[Carlriddle]

Black/blue thru. Looks long but could be angle?  Drag slicks?  What kinda power

[CrazyFastFab]

The frame is 144" nose to tail.  I have a '08 Hayabusa and Jeffco to make it go.  I need to get rims, tires and axles to start the building.

There is a really good chance the rail is going to be red as well guess I am stuck in a rut.

[CrazyFastFab]

What type of tubing are you guys using?  Yes I know DOM is the good stuff but the price here is one foot of DOM is the same as 20 ft tubing with a seam.  I guess I know the answer but was hoping not to spend that much on steel.

[dsrace]

if your going erw use 1026 ( this is what I bought a truck load of way back when ) grade if they have it there in .095 wall other wise if all they have is standard 1010 i would go  .125 wall. 

[fabr]

I'm going tp suggest using a true A arm on top with a single heim . Makes adjusting/aligning a whole lot easier and is plenty strong IMO.

[Engineer]

Looks good! 


What drawing program are you using?

What is the wheelbase?

Is it going to be a 4 seater?  I ask because you have two cross bars in the drivers compartment.  The rear bar to the rear wheels seems adequate room for the motor and chain so I am not sure what is going between the two bars unless it is a very small back seat.

A straight side view would be very helpful.

The diagonals on your sides really should land in the corners not in the middle of tube spans.  So in the drivers compartment you leave the bar up to the A-pillar the same so that it is easier to get in, but the bar below the mid bar of the car I would angle back at the bottom so that it hits the corner of the bottom tube and the upright tube.  The angle change will be hidden if you put panels on it anyway.

Same goes for the rear diagonal.  It should meet where the lower frame rail bends up.   You want to make the diagonals into triangles with the main tubes.  If they form a four corned box then it can "parallelogram" the whole thing with each of the tubes flexing a little but when it is a triangle the tubes don't want to flex, they would have to stretch or compress and that is how they are strongest.

Also with A-arm suspension in the rear if you lay the shocks very far forward you will get a negative progressive action at the bottom of the stroke.  (the further the shocks compress the more they will lay down because the A-arm is traveling straight up.)  It might help to do the cad work on the stroke length of shocks you have vs the wheel travel you want to establish how high the top shock mounts will need to be, and how far out on the arms they will be attached.

[CrazyFastFab]

 Thanks  for the input.

That is out of BendTech took about two hours to complete the entire frame.  I started my career as a Drafter in AutoCAD and I wouldn't want to go back to it for frames anyway.  I still like it for the flat pieces.  I have the BendTech Sheet metal module but haven't played with it much.  Best best thing about Bend Tech is it gives you the bend instructions for the bender, really nice.

Good point on the tubes going to the corners I think I just got a little crazy drawing and stopped thinking.  The frame is 144" long.  I didn't post the dimensioned drawing out of respect for DS as it is really copy of his frame, when it is done I will send the base files to him.  I am travelling when I get back to the house at the end of the week I can post the a drawing that shows all three views.

It is a two seater it is just the angle you are seeing a cross member in the back side of the frame that looks like a second bar across the frame.  It is really nice to have 3D model to spin around on the screen.

[Carlriddle]

So you got the good CAD drawing from DS.    If I had gone with the standard 2 seater I'd just let him build me a frame.  Less headache and possible cheaper.  Shoot he not doing anything, yest he was running down batteries on the remote. 

Looking good BTW.

[dsrace]

carl!!!!  only after mowing till dark  and no he didn't get greasy finger prints covered prints like you did lol lol  just measurements    he had so much already just from looking at pics it seemed pointless to send them when all he needed was a couple key measurments and he bought a front end kit.

engineer draw some lines of what you are talking about.

crazy fab can't wait to see them