[NHFocus]

So I was recently asked by a buddy to design a harness bar for his car. (VR6 GTI. He has the rear seats out permanently, wants to slowly progress it into a track car. The design is intended to increase chassis stiffness a bit, and allow him to use harnesses on autox days). I am an engineering student, so it's definitely not going to be a random fab-as-you-go design.

I figured I would start up a thread to show the project as it progresses from sketches, to solidworks renderings, structural analysis', and final design/build stage.

Heres the general idea:

Keep in mind that was a 45 minute sketch (and I can't draw for ****), and I haven't had a chance to get any actual measurements yet. Once I have those I can do some analysis on the design to make sure it's capable of withstanding catastrophic forces with him strapped in, and modify the design a bit.

If you don't have anything nice to say, go away

 

[jholso]

::Subscribed::

Looks good. arty:

Deff a better drawing than I can do, guess thats why I am a computer programer eh?

Should be sweet, you gonna make it at school to?

 

[jholso]

O ha I like how that was my first post on fj weird

 

[Graffix@Rawfocusmedia]

no measurements yet? tell the kid to get on it :what: :lol:

 

[NHFocus]

.... I've tried, that Graffix kid is too ****ing lazy.

 

[thefrohn1]

O ha I like how that was my first post on fj weird

welcome to fj haha

look forward to progress on this project :thumbup:

 

[Graffix@Rawfocusmedia]

 

[sleeperlove]

Harness bars do NOT increase safety. If anything they decrease it.

If the seat back does not break in the event of a rollover crash, the harness is going to hold the occupant in a nice upright position to get their spine crushed.

 

[svtf02red]

Mk3 or Mk4? If the guy is going to go transition over to full track car, he may just want to go full cage instead of wasting time & money (not that your time & design is a waste) on something that's going to get replaced with a cage. Just a thought :dunno:

Here's a mk3 cage:

Another mk3:

The Autopower setups are pretty nice, too. Here's a good article on the install of one on a mk4:

http://www.eurotuner.com/techarticles/eurp_0706_project_silverstone/index.html

Looks like you're off to a good start. What's the middle support for? It seems that a 4-point would be plenty for a harness bar.

 

[Graffix@Rawfocusmedia]

Harness bars do NOT increase safety. If anything they decrease it.

If the seat back does not break in the event of a rollover crash, the harness is going to hold the occupant in a nice upright position to get their spine crushed.

what would the harness bar have to do with the seat back not breaking? Unless of course I am reading this wrong

Mk3 or Mk4? If the guy is going to go transition over to full track car, he may just want to go full cage instead of wasting time & money (not that your time & design is a waste) on something that's going to get replaced with a cage. Just a thought :dunno:

Here's a mk3 cage:

Another mk3:

The Autopower setups are pretty nice, too. Here's a good article on the install of one on a mk4:

http://www.eurotuner.com/techarticles/eurp_0706_project_silverstone/index.html

Looks like you're off to a good start. What's the middle support for? It seems that a 4-point would be plenty for a harness bar.

I have a mk4. And its not going to be a full blown track car, just for autocross and such. I can also have this bar built for 50 dollars or so not 500+ with an autopower cage, Which are show cages :screwy: We decided to go this route for the reasons justin listed and secondly because if it IS successful we can market this bar since no one makes them for the mk4 platform. I've actually been confronted by some mkv guys that were interested in getting one designed if this one works :rock:

I should have some pics of my interior up tomorrow...I hope...but so far ive been lazy :lol:

 

[polarisman14]

^^Yeah...The Focus ones sold pretty well, I have one and I love it. If you roll over in your car and you don't have a full cage, you're pretty much done...Harness bar or not. Might as well have something holding you in your seat so you can maintain control of the car better in the first place.

 

[Graffix@Rawfocusmedia]

^^Yeah...The Focus ones sold pretty well, I have one and I love it. If you roll over in your car and you don't have a full cage, you're pretty much done...Harness bar or not. Might as well have something holding you in your seat so you can maintain control of the car better in the first place.

rolled a car once pretty sure im ****ed next time

 

[sleeperlove]

what would the harness bar have to do with the seat back not breaking? Unless of course I am reading this wrong


I have a mk4. And its not going to be a full blown track car, just for autocross and such. I can also have this bar built for 50 dollars or so not 500+ with an autopower cage, Which are show cages :screwy: We decided to go this route for the reasons justin listed and secondly because if it IS successful we can market this bar since no one makes them for the mk4 platform. I've actually been confronted by some mkv guys that were interested in getting one designed if this one works :rock:

I should have some pics of my interior up tomorrow...I hope...but so far ive been lazy :lol:

It has nothing to do with the seatback breaking, what I mean is that with just a harness bar in the event of a rollover you are going to be held upright in the seat (unless it breaks) and be in a perfect position to have your spine crushed. If its only used for autocross it will be fine, but any track driving it is doing nothing to improve your safety, and if anything is decreasing it.

^^Yeah...The Focus ones sold pretty well, I have one and I love it. If you roll over in your car and you don't have a full cage, you're pretty much done...Harness bar or not. Might as well have something holding you in your seat so you can maintain control of the car better in the first place.

No.
In a rollover if you have a roll bar you have something supporting the roof from coming crashing down on you.
You can get a $40 CG lock that holds you in place just fine and then you are not pinned upright if a roll over happens.

Safety gear in regards to track driving does not work in pieces, you do it right (roll bar/cage, seat, harness) or you don't do it at all.

 

[Graffix@Rawfocusmedia]

It has nothing to do with the seatback breaking, what I mean is that with just a harness bar in the event of a rollover you are going to be held upright in the seat (unless it breaks) and be in a perfect position to have your spine crushed. If its only used for autocross it will be fine, but any track driving it is doing nothing to improve your safety, and if anything is decreasing it.

ya its just autocross and such...but wht i think what matt meant was that if you rollover w/o a roll bar you're pretty screwed anyway. I was lucky in my case.

 

[sleeperlove]

ya its just autocross and such...but wht i think what matt meant was that if you rollover w/o a roll bar you're pretty screwed anyway. I was lucky in my case.

Well if you are using stock belts in a rollover you have a much better chance since if the roof crushes all the way down your body can be pushed out of the way since the stock 3 points allow for upper body movement.

 

[Graffix@Rawfocusmedia]

Well if you are using stock belts in a rollover you have a much better chance since if the roof crushes all the way down your body can be pushed out of the way since the stock 3 points allow for upper body movement.

good point

 

[NHFocus]

I'm not entirely sure how this ended up as a harness debate, but tbh it can stop now. No one said he's taking the stock belts out, (I'm not sure if he is or not...kind of pointless to do so), so the harnesses could be used strictly for autocrossing and such. The design is going to be so that he can USE harnesses at his discretion, and the bar is going to be built to withstand significant force in the event of a head on collision. Chassis stiffness is another area that will be incorporated into the design.

 

[sleeperlove]

I chimed in with the harness debate because you claimed in the first post that it will increase safety, which it will not.

 

[NHFocus]

In the event of a rollover, no. A head on collision it'll prevent you from breaking your collarbone due to all the force being applied to one side of your body. I know a number of people with permanent spine damage from head on collisions because their bodies twisted so abruptly. But for the sake of getting this back on topic, I'll remove that statement, just for you.

Moving on... Hope to get some measurements from him soon or get down there myself to take some, so that this can start progressing.

 

[sleeperlove]

In the event of a rollover, no. A head on collision it'll prevent you from breaking your collarbone due to all the force being applied to one side of your body. I know a number of people with permanent spine damage from head on collisions because their bodies twisted so abruptly. But for the sake of getting this back on topic, I'll remove that statement, just for you.

Moving on... Hope to get some measurements from him soon or get down there myself to take some, so that this can start progressing.

And holding the torso in place during a head on collision is going to greatly increase the risk of cervical spinal injuries. Unless your friend is going to wear a helmet and Hans device at all times.

I am sure you will make a great, well fitting, and strong product, just don't try to do it/ market it it under the false pretense of increasing safety.