MK IV tubular spaceframe drawing

[H.J.Bayer]

Hi,
I would like to build a MK IV by myself.
My plan is to buy the body parts from Gregg.
I have now constructed a frame,i found some drawings in the forum.
I changed these so that the frame fits into a MK IV.
Since I don't have any body parts yet, everything is still very unprecise.
But as a concept it should be enough at the moment.

I am not a frame designer so I would be very happy for any constructive feedback.

(Sorry for my bad english)

 

[Randy V]

How close to original do you want your car to be?

 

[H.J.Bayer]

Hi Randy,
I will try to make it look as original as possible.
But unfortunately this won't be possible in many places, because I don't have an original template.
I miss all measurements. I have only the pictures from the forum and my Exoto models.
Also my budget is not endless.
The frame should look somewhat original after the covering with aluminum sheets. Original aluminium honeycomb panels are not an option for me.
I would like to use a Craft 408/410 B Crate Engine or similar with Audi transmission.
Since such a car cannot be registered in Germany, I want to use it only on trackdays.
I will probably have to construct the suspension myself.
Here in my hometown Ingolstadt I know people I can hopefully ask for the right geometry.
But my biggest problem is that I don't have the right measurements.
The body on my pictures is from the internet. You even need a clearance from Ford to use it. But I don't think that the measurements are right....
All this is not easy

 

[Randy V]

Rather than trying to reinvent the wheel - I would suggest adopting Suspension geometry and components from a very successful car such as C5 Corvette.
Ditch the transverse springs and use coil-over shocks. Lower control arms should be parallel to the ground at ride height. You’ll find that even Formula1 and Indy cars have used that tenet..
Doing this gives you a number of items that would otherwise be difficult to source - PLUS - You’re taking advantage of suspension designs that cost millions to create.
Food for thought anyway...

 

[Paul Hendrickx]

Hi, Ingolstadt..... in this treat you find some basic measurements concerning gt40 mk iv

GT 40 specs

Hello, After several contacts with a FORD archivist, I was able to obtain some documents from the 60s about the different GT 40s. I made a summary but would like the experts to confirm it, or tell me about possible errors. I have a particular question about the MK I John Wyer P/1075 which won...

www.gt40s.com

greetings Paul... ex Audi technical trainer

 

[H.J.Bayer]

Rather than trying to reinvent the wheel - I would suggest adopting Suspension geometry and components from a very successful car such as C5 Corvette. .....

that sounds like a very good idea.
I looked at the parts on the net, it looks very good.
At the moment I'm trying to find CAD files of the suspension parts.
I have found some, unfortunately not complete.
Somewhere in the forum I read that the wheel carrier does not fit at 15" rims. That would be a problem

 

[H.J.Bayer]

Hi, Ingolstadt..... in this treat you find some basic measurements concerning gt40 mk iv
...
greetings Paul... ex Audi technical trainer

Thanks for the Link it was very helpful for me.
Do you miss the Bavarian beer in the "Biergarten"

 

[H.J.Bayer]

After some considerations I now plan with the suspension of the Audi R8.
It has a very modern design and is very easy to get for me.
I like that the wishbone mounts are parallel to the driving-direction and everything can be mounted very easily.
The only problem is that the wheel hub is so big. It doesn't fit into a 15" rim.
Maybe I will push the wishbones further together and design a new hub.
What do you mean?

 

[Mark Winton]

Hi,
I would like to build a MK IV by myself.
My plan is to buy the body parts from Gregg.
I have now constructed a frame,i found some drawings in the forum.
I changed these so that the frame fits into a MK IV.
Since I don't have any body parts yet, everything is still very unprecise.
But as a concept it should be enough at the moment.

I am not a frame designer so I would be very happy for any constructive feedback.

(Sorry for my bad english)

Hello H.J. Bayer ... Nice CAD work. I am doing the same except a Mark 1. ie. CAD model for tube steel scratch build. I am interested in some of your overall key dimensions for compatibility with say Tornado or similar Fiber-Glass Body panels. - Could you publish some dimensional data drawings ? ... Thanks.
Structurally, the tube steel spaceframes are quite strong; however, they are not particularly torsionally stiff. Its only a problem depending on what you want to use the car for - track work would benefit from a stiffer chassis, road driving not a problem.
I consider some of the ubiquitous suspension (A-arm) pivot attachments to the chassis are less than structurally ideal - they would be vulnerable to fatigue. They do not appear in your CAD model - so I won't know your design.

 

[Mark Winton]

Hi,
I would like to build a MK IV by myself.
My plan is to buy the body parts from Gregg.
I have now constructed a frame,i found some drawings in the forum.
I changed these so that the frame fits into a MK IV.
Since I don't have any body parts yet, everything is still very unprecise.
But as a concept it should be enough at the moment.

I am not a frame designer so I would be very happy for any constructive feedback.

(Sorry for my bad english)

H.J. Bayer : - I suggest that for the detail circled, that the transverse member be continuous and the larger longitudinal tube notch around the transverse tube. This is because: - [1] The transverse member participates in the load path from engine members (longitudinals) to the rest of the spaceframe chassis. Being discontinuous in the middle is not god practice for a such a member. [2] It reacts onto the web of the longitudinal, which loads it in bending. It would likely crack in time. [3] Decreases the number of welds - it will be hard to keep straight and flat - weld shrinkage won't help either !

 

[Howard Jones]

IMHO that is not a complete drawing. Maybe it is a partial from some more complete drawing made before adding the rest of the tubing elements. There are no triangulated elements across the box sections for example. Otherwise I would not hang the roll bar down tubes out in space like that sitting on a unsupported horizontal element. They should feed the load straight down to the bottom tube with the upper tube attached to the side of the vertical roll bar tube. There is no bracing attached to the roll bar system. It will fold up like a mouse trap.

Good start though.

 

[Jac Mac]

Why not just get the body parts from Gregg & then make a jig up to hold those in place while you make alloy templates of chassis from those at necessary points and weld up the alloy mono, then rivet gussets in the corners and over the edges like the original honeycomb. make it look like the original, albeit a welded alloy tub.

 

[H.J.Bayer]

Hello together
Thank you very much for your comments, that really helps me a lot!
I have now constructed the first of your improvements.
I understand the whole thing at the moment only as a concept.
Only when I have the parts from Cregg can I consider the real dimensions.
Please continue commenting so that the whole thing becomes reasonable.
It should be a vehicle for the race track, so it has to be safe and stiff.


@mark
I changed the traverse.
I can make the CAD drawings available to the forum,
if that's what you want.

@Howard
i hope you can help me to place the triangulated elements correctly.

@jac mac
I hope that everything looks original after dressing up with metal sheets.
But I can't start without the parts from Cregg.

Thank you so much for helping me!

Translated with www.DeepL.com/Translator

 

[H.J.Bayer]

here still the first try to bring the Audi R8 axle into the model.
But without the exact dimensions of the rims, I can't determine the fixing points.
I will use this one:

https://vintagewheelsus.com/index.php?main_page=index&cPath=15_14

or does someone know something better?

 

[Howard Jones]

HJ, here is a link to a video about chassis design in particular. The same commentator has a complete series on race car construction. I recommend watching them. This series and the video I have linked to is far more qualified than I am in this subject. I hesitate to design a chassis for use by anyone other than myself because of my lack of profession qualification. However I can see where you would benefit from some guidance in space frame chassis design and I would in the most positive of ways encourage you to spend some time studying the subject.

Your rollover hoop is a good start however it lacks (as a example of adding triangulations) the diagonal brace from the upper top corner to the lower opposite corner. This simple change in design increases the strength of the roll over hoop immensely.

Here is a good book on the subject of race car design that I recommend :

Chassis Engineering: Chassis Design, Building & Tuning for High Performance Handling: Adams, Herb: 0075478010554: Amazon.com: Books

Chassis Engineering: Chassis Design, Building & Tuning for High Performance Handling [Adams, Herb] on Amazon.com. *FREE* shipping on qualifying offers. Chassis Engineering: Chassis Design, Building & Tuning for High Performance Handling

www.amazon.com

And a link specifically about triangulation:

Car Chassis Basics, How-To & Design Tips ~ FREE!

FREE Tutorial on How Car Chassis/Frame Work PLUS Tips on How to Design and Build Tube, Space Frame and Monocoque Chassis! BEST Materials ** CHECK IT OUT **

www.buildyourownracecar.com

Google is your friend.

 

[H.J.Bayer]

I had time this week and have continued in CAD.
"Triangles are the engineer's best friend"

The front suspension of the Audi R8 would fit very well.
But unfortunately the rear suspension doesn't fit.

The 15" rims don't pass over the wheel hub.
I don't have an idea right now.

Comments are always welcome

 

[Jac Mac]

I had time this week and have continued in CAD.
"Triangles are the engineer's best friend"

The front suspension of the Audi R8 would fit very well.
But unfortunately the rear suspension doesn't fit.

The 15" rims don't pass over the wheel hub.
I don't have an idea right now.

Comments are always welcome

That is an easy fix, simply get a wheel manufacturer to make the wheels with 15" outer bead dia and say 20'' inboard bead dia, and make tires with same bead diameters, that way you get the benefits of 'original ' appearance form outside and enough clearance to run large diameter braking systems. BTW I sent this suggestion to several tire manufacturers years ago and got no interest, If your successful I would appreciate some financial reward for my efforts!! There must be market for this idea. Think about how easy it would be to fit tires and the current problem of kerb damage would virtually disappear with the higher outer sidewall.

 

[Randy V]

Very funny Jac!
—
You may want to consider going with aftermarket rotors and hats - then machining your own caliper mounts. Given the rest of your project’s complexity, this should be a walk in the park!

 

[Jac Mac]

Was not joking Randy.

 

[H.J.Bayer]

Better design? Now for 17" rims