Can you post some pics of the dash / front hoop area with the body off?Originally Posted by CharlesVsWorld
If you redo the front hoop to go above the dash & then remove some of the lower dash, that should gain you a lot of room. That is how most FVs are. The existing configuration is giving up a TON of leg space for you. Just make sure it fits under the body.
~Matt Clark| RTJ-02 FV #92 | My YouTube Onboard Videos (helmet cam)
Regarding roll bar replacement - make sure you have a very qualified person design this as adding height changes the force on the frame that occurs when you get upside down, and those forces will come from all directions...
Ok going to find someone who knows about these things to check my thoughts.
But here is one version that fits under the bodywork, frees up more knee room and retains much of the original chassis. Main roll-over bar is also extended.
That is more like other cars, so that should be ok.
All the tweaks (rollbars, seat, etc) in combination should get you a surprising amount of room, but it will be tight no matter what.
~Matt Clark
The forward roll bar braces can help or hinder shoulder clearance depending upon the angle. Some test fitting may be beneficial. Some upper frame rail triangulation and gussets may be useful with forward mounting.
I still do not think the front hoop is tall enough. You need to mock up the existing chassis with you in the car to validate your proposal.
I do not think you should have bracing over your knees. Your knees should be up in this area. Forget with the original body work over your legs. It is giving up to much space a big driver needs.
A tight fitting car is not really what you need as a new driver to this class and with probably not the best handling car. You need to be able to comfortably flail your arms and hands.
Brian
Agree on all of this. The GCR has specifics about gussets.
Not mentioned before, but the forward main hoop braces will have 1/2" padding on them.
Brian
At least ...
Steve, FV80
Racing since '73 - FV since '77
AND.. there is no requirement that the braces be absolutely STRAIGHT. They can be 'curved as needed' .. and you can 'bump up' the dia if the curve need is too great ... and gussets can help A LOT in that regard.
Steve
Steve, FV80
Racing since '73 - FV since '77
My bold of Brian's comment. I don't see how you would possibly fit with the bracing as shown.
All the FIA roll bar padding I've seen is 3/4"-1" thick.
There's alot to consider while you're in pre-design...glad you're taking time to plan for safety as well as anxious to get out for the fun.
Glenn
SFI I see is also 3/4 minimum (I didn't look up the rule itself).
http://www.rollbarpadding.com
I admit I haven't read all the posts, but did scan most of them, and something I haven't seen suggested is to move your headrest back, behind the main hoop; how far will be limited by the carb - I think.... This will give some additional room, though maybe not enough to solve your helmet clearance problem. The comment(s) about adding a higher front roll hoop are good suggestions especially since it will give your legs more room and will improve the ease with which you can extract yourself from the car, though it will likely also require a change to the body work. Lowering the floorpan is a bad idea in my opinion unless you have a steel frame to support it, because when, not if, you go off-track, the lowest part of the car is what will contact the track, rocks, etc. Also, I have successfully used 1/2" thick ethafoam for my seat pad and have not had any soreness issues; certainly thicker would be better, so perhaps you can get by with less.
Something else worth mentioning - not shown in the photos you posted, is pedal position and pedal travel - both need to be taken into consideration for you feet placement which then directly relate to seating position and then helmet height. The suggestion(s) about checking out other cars is excellent so you can what others have done to deal with these challenges.
Good luck.
-Jim
Really enjoying all the bike-shedding discussion and contributions about the best way to go about this. I showed the plans to Ron Chuck and he suggested moving the lateral support bar up and adding more gussets and was generally supportive of the changes.
Here is a modification in line with the suggestions of taller front roll bar. Only problem is it makes the bodywork completely unworkable - no way to pass that bar through the top. At a guess I would I have to chop it in half and have more fasteners in the middle? Would end up looking a bit "complicated".
Last edited by CharlesVsWorld; 04.25.25 at 11:36 AM.
If you think the comments being provided for YOUR benefit are "bike-shedding", then perhaps you really aren't interested in the input from existing racers of the car/class you are interested in joining. From what I have read, most of the comments are valid and useful and take time to type, which you apparently don't seem to appreciate.
-Jim
Perhaps I misspoke - usage of the term bike shedding used to denote the back-and-forth over details, no discounting of information implied.
Very much appreciative of everyone's contributions, interest in my project and experience. Can't think of a more positive/supportive group to converse with.
Just a thought, regarding fitment of the cowl...
Perhaps sliding it forward until the front hoop & braces are inside...trimming the front until it fits to the nose...then extending the rear with new glass to meet the tail.
Of course I'm simplifying and going on ALOT of assumptions based on the little I see here.
I had to do what I just described on a vee of my own for the very same reasons - fitting around a taller front hoop.
Glenn
Your images of potential changes are very nice, however they may not represent how you will really fit . Consider removing the steering support area, main hoop forward bracing while temporarily leaving the hoop. Work out changes with some cheap tubing (emt conduit) until you are most comfortable. Reconsider bends in the main bracing and low rearward bracing to the removable element.
Have fun and go racing
Ooh yea, I get it. Definitely a better idea than chopping it in half, thanks.
Yes! Another great idea. A trip to the homeless despot is in my near future...
Bike Shedding
Bike shedding is an interesting term. Is this something you learn in engineering school?
I learned something today!
Brian
Don’t forget some pre made bends if you don’t have a bender
Yes we tend to throw it around at work (software engineering) at times of collaborative brainstorming. I hadn't considered the diminutive nature of the term until I read @sabre1fv 's post so fair play to him, I'll suck it back up.
Ok this mock up with insulation tubing is looking like a viable concept, gives much more knee room and will work with minimal modifications to the bodywork:
Support tubes will fit underneath as well. Will mock those up next. Also got the motor assembled and ready to test minus the rocker assemblies
With much machination and conversion from metric to king appendages I present a close to final design:
Arranged in the following manner:
Should produce the desired clearances and free up room inside the cockpit while fitting mostly under the bodywork. Comments/suggestions/improvements?
Last edited by CharlesVsWorld; 05.09.25 at 12:10 PM.
Threads not dead! Just been waiting on an order of DOM tube which happily arrived today - got plenty of welding to do on the weekend:
Also designed an enclosure for the fuel cell area and finalized the safety cage structure, went up to 1" front support tubes:
Very excited to receive some parts made using sendcutsend. They fit perfectly! Just slapped on there for now but v happy with the fit around the fuel cell.
The welding for the new chassis pieces went pretty well apart from a few places that have porosity. It's really odd, it feels like lack of shielding when it welds but the gas flow is constant and every other weld has worked nicely. Best I can think of right now is some contaminated material in the frame of the car, maybe some thin cracks that oil or something has worked into.
I've ground out the porosity a few times but it bubbles up the same each time. Next attempt will be to pre-heat until it's red-hot to try and burn out any impurities before welding again.
Charles,
I've been following your thread with interest, but this picture from the side indicates TO ME, that you have not allowed NEARLY enough distance between the front hoop and the 'back of the driver' over the fuel cell. This is the first 'perspective' picture I have noticed, but I'm almost positive that you will NOT have enough room behind the front hoop to put your steering wheel, dash, shifter, and BODY between that hoop and the cell. If you haven't mocked that up.. you should do so and be SURE before you get too deep in this.
Good luck,
Steve, FV80
Steve, FV80
Racing since '73 - FV since '77
Positioning the driver in a FV
I would suggest that you remove the fuel cell and the steering system so that your seating position is defined by the front axle beam and the fire wall .
Because of the suspension geometry of the FV suspension system. the CG position is super critical. You want to get the driver as low as possible. The handling improvement from a low driver seating position can not be over emphasized.
In the early 1970's Ed Zink designed a FV the had the driver's seating position so that the top of his helmet was even with the top of the fan housing. The idea here was to have the smallest front area possible. The side effect, which was just as important, was to get the driver's center of gravity down in the car. Yes the forward visibility took a bit of getting use too. The designed resulted in 4 FV national championships.
Recently, I have helped restore the Z12 that George Fizel won back to back national championships. The main hoop on this car is only 36 inches tall from the bottom of the car. And the seating position is very comfortable. The cell has to be designed so that the drivers shoulders are against the fire wall. The top of the firewall bulkhead, under the roll bar, is about 14 inches from the floor pan.
The dash bulkhead is 31.5 inches forward of the roll bar bulkhead, inside dimensions.
One thing that allows the low seating position is the fuel cell design.
Thanks for the message Steve, yes it does look a bit tight in that picture doesn't it!
The front hoop is in the same location as original so I'm hoping it should all work as when I first test fit. Will find out soon enough
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