Chassis bracing
 

I started a new thread because the old one was originally about a tube chassis and now I am wondering about bracing a stock Vw chassis.

How much bracing do you feel is required to safely run a 240hp Subaru engine to a 915 Porsche transmission in a Karmann Ghia?

Anyone have any links to any volkswagen running a similar set up?

All help is greatly appreciated.

Thanks

A multipoint roll cage would be the ultimate even for a 60hp chassis! It very much depends on what you expect and how you are going to use it? A wibbly wobbly chassis is perfectly acceptable for a 240bhp engine in a KG if its only used to drive in an out of shows.
Give us a clue on what your aspirations are?

evilC

Sorry still a little new to the whole forum thing. I plan on building a daily driver that I could auto cross whenever. As stated above Subaru engine somewhere in the 240bhp range and a 915 transmission, I will be running full Porsche brakes. I am new to chassis designing and don't know for sure what would be safe and what wouldn't be. Wibbly wobbly is definitely what I am trying to stay away from. Thanks

I have seen some with kafer braces only and I wonder if that would be enough? I just feel that there would still be a bit of flexing in the chassis/ body. Does anyone wiht more knowledge about this than I do have any experience with it or could make a better guess than I could?

I assume that you are based in the States? since Autocross in the UK is competed on grassy field generally and not that much on tarmac. If it is Stateside Autocross it is akin to our Autosolo with perhaps bigger expanses that generate slightly higher speed.
As I now understand the backdrop i expect that you would not want a full multipoint roll cage that will be a pain in the derriere to clamber in and out of. I would suggest that a kafer cup brace is desireable with maybe links back to a crossed braced 6 point rollcage. You may also feel it necessary to take some support to the rear of the motor as it will experience excessive front /rear load reversals under accelleration and braking. Detachable door braces and fixed mid height horizontal braces with connection stiffeners will provide considerable torsional stiffness. What you are trying to acheive is a shell that will resist twisting. To that end it may also be worth bolting the cage to the body shell in an effort to bringing that into play as well. This is usually done at the pillars.

evilC

Alright I know this is a significant difference but how much bracing do you think would be needed for just a 2.2 Subaru maxing 150hp 150tq being driven as a daily driver and nothing else. No G force attempt in turns, just a car with some git up. I am realizing that it will be a lot longer before I can afford the build with the sti engine. I just had a little girl.

With that I would go with just a kafer cup brace in the rear and maybe some cross bracing in the front to stiffen the shell (I assume the KG is a ball joint front). I wouldn't put a cage in the cab unless you wanted the 'look' as they can be a pain in the rectum for day to day use.

evilC

Yeah I was trying to stay away from having a cage. Yes it is a ball joint beam. How to the chassis stiffeners perform. I believe they are the ones that bolt below the pan in the rear I cant think of where I saw them right now. I wanted to just get a tube chassis but money is an issue apparently :rolleyes:

Hi

I'm interested in this issue as well, if I fit a cage to my car my state laws will only allow my car to be a 2 seater, I want to keep this car practical and as useful as I can.

I took some ideas from the Beetle cabriolet.

Steve

PS The car with the nice paint is not mine, I just put them in to show what the finished product looks like.

http://www.clubvw.org.au/images/stiffening.jpg

http://www.clubvw.org.au/images/AB_stiff.2.jpg

http://www.clubvw.org.au/images/AB_stiff.3.jpg

This my car, I've run brace between the B pillars.

http://www.clubvw.org.au/images/P9060103.jpg

http://www.clubvw.org.au/images/P9060104.jpg

Hey Steve,

Where did you get those from? I've been wanting to do that in mine, but I can't find a source for them. I will just fab up my own version if I can't get them, but that would be a lot easier.

To add to the conversation, I'm adding these to my car down the road, but I don't know if they make ones for the KG.

Eyeball Engineering Pan Stiffeners

They have other "stiffening" stuff too

Jason

Volksdent,
Those where what I had in mind, however I would like to run both.

Hi

A local metal fabricator made the A & B pillar sections for me, I just took him some old body section bits which he used them to make templates.

I also looked into the Eyeball Engineering solution but the freight down to me would have been a killer.

Steve

Is the design his or is it a copy of an orginal part? I was thinking of something with a curve, but I'm not an engineer.

Jason

I wanted to use those pan stiffeners from eyeball engineering as wel but live in Belgium and shipping was to expensive. Solution: buy regular VW bug convertible pan stiffeners and weld those under the body.

steve, any chances on getting dimensions for those pillar sections, it would be greatly appreciated, i could make them myself, my job is useful at times :D