planning for race track overload this fall + midget project

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n1gzd
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planning for race track overload this fall + midget project

Post by n1gzd » Sat Aug 20, 2011 8:47 am

Well, even though I am having to work a lot of extra hours at work this summer in order to make an extremely agressive delierable schedule at work I am continuing with my plans to really take advantage of some fun stuff coming up. I am planning on doing NHMS-3, hot pass spectator at Lime Rock Historic, then hot pass spectator at Watkins Glen vintage celebration then COM Watkins Glen.

Hopefully I don't get fired after being out of work that much (I gave notice for the September events last January though).

I am really excited (but a little maxed out on my credit cards - have all winter to catch up).

Anyone else attending either of the historic events? I am really hoping to participate in some of them as a rookie next year.

The safety related fabrication parts parts of my Midget project are almost completed.
Here are a few pictures (still a work in prorgress). They were taken with an iphone (wide angle lens distortion). Some of the shots make it look like the hoop is higher on one side (it is not). I have a lot of work left to do but here are some progress shots. I chose to install two seats (one for instructor when needed). Because of this I wanted a roll bar bracing design that is equal for both sides. This is not a common thing to do for MG Midget vintage racing (usaually a much lighter weight single seat design is used). I probably have at least 40 more pounds added because of having this symetrical bracing.

picture from before headrests installed:
http://www.pangalacticconsortium.com/ca ... ge500.html
http://www.pangalacticconsortium.com/ca ... ge503.html

Installation of seats:
http://www.pangalacticconsortium.com/ca ... ge523.html
(custom re-inforcement of seat bottom and bracket for installation).

Seat back bolted in two places to strong bracket welded to seatbelt brace:
http://www.pangalacticconsortium.com/ca ... ge509.html

There is an under panel hoop with bracing from the main hoop also:
http://www.pangalacticconsortium.com/ca ... ge515.html

Without the seats:
http://www.pangalacticconsortium.com/ca ... ge525.html

fuel cell in trunk view:
http://www.pangalacticconsortium.com/ca ... ge527.html
I am thinking of using carter fuel pumps - anyone like those?

fuel cell underneath showing reinforcing straps (not what holds it in):
http://www.pangalacticconsortium.com/ca ... ge528.html

Another view without the headrests showing rear seat belt attachment points and headrests (9x6 inch) - proper foam not installed yet.
http://www.pangalacticconsortium.com/ca ... ge530.html

zchris
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Re: planning for race track overload this fall + midget project

Post by zchris » Sat Aug 20, 2011 11:34 am

The quality of work is good, the design not so much. I'm assuming the shop does mostly drag race stuff. The front hoop will make a nice kneecap remover if you get into a frontal impact. The hoop should be above the steering column. As your body goes forward in an impact your legs will get crushed on that low hoop. You must remember that belts stretch on impact. And more than you might think. I would not ride in this car. The builder should know better. Also the rear facing legs should not have any bends in them. It becomes a weak link in a roll over or if you back it into a wall. Remember you have no roof. The load applied rearward while moving is large if upsidedown. The rear leg is now nothing more than a spring. I have never understood why drag racers think these designs are safe or even helpful in making there car more ridgid. Sorry to be the bearer of bad news. I'm not even sure that a vintage race group would allow the rear leg design. Niether Nasa or SCCA would.
Chris

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Re: planning for race track overload this fall + midget project

Post by Stynger » Sat Aug 20, 2011 12:19 pm

zchris wrote:The quality of work is good, the design not so much. I'm assuming the shop does mostly drag race stuff. The front hoop will make a nice kneecap remover if you get into a frontal impact. The hoop should be above the steering column. As your body goes forward in an impact your legs will get crushed on that low hoop. You must remember that belts stretch on impact. And more than you might think. I would not ride in this car. The builder should know better. Also the rear facing legs should not have any bends in them. It becomes a weak link in a roll over or if you back it into a wall. Remember you have no roof. The load applied rearward while moving is large if upsidedown. The rear leg is now nothing more than a spring. I have never understood why drag racers think these designs are safe or even helpful in making there car more ridgid. Sorry to be the bearer of bad news. I'm not even sure that a vintage race group would allow the rear leg design. Niether Nasa or SCCA would.
Chris
FWIW Chriis is a very experienced cage builder. That's what he does.
A lot of thought go's into building a cage. Sometimes the easy way out is not the safest. Putting the hoop under the dash was the easy way, not the safest.
I'm glad you posted the pictures, with constructive feed back you can modify your car and make it safer. In wheel to wheel racing you don't want to second guess your safety choices. Sometimes you only get one shot.

Chris built cages for me, Gordon, Will, Bill H also Jeff and Troy's cars to name a few COM members as well as untold SCCA cars etc.

There is a science as well as an art to cage building.
Les.

COM Instructor

NA Miata D-TYPE
#77

Drive it like you stole it!

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Re: planning for race track overload this fall + midget project

Post by breakaway500 » Sat Aug 20, 2011 1:26 pm

Rebecca,you are a very determined individual! :D

How come you did not go with the orange rollbar?
Image

I don't know much about the rules regarding vintage rollcages,so maybe you are required to have more than a 4 point setup. Still,it might have been something that could have been added onto...I dunno.

Those rear legs on the fabbed unit are odd,that they take a bend before the mounting plate... :?

Love the Buick,by the way! :P

I did not know Chris designed and built rollcages! Very cool! 8) :sunny: (I will have to pick your brain on a "project" I am contemplating.. :shock: )
When you're fast there is always traffic

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Re: planning for race track overload this fall + midget project

Post by dinoracer » Sat Aug 20, 2011 5:37 pm

Cool Car, but def. consider the change to the roll bar suggested.

What's the monthly rent on an airplane hanger? I could use that kind of space.....
Tom Cannon

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n1gzd
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Re: planning for race track overload this fall + midget project

Post by n1gzd » Sat Aug 20, 2011 7:45 pm

Chris and everybody else,

Thanks for your comments. I am grateful that someone with your experience can give some feedback. I have previously discussed both of the issues that you brought up with my fabricator.

Regarding the hoop under the rollbar instead of over:
The dash panel on this car is barely tell enough for one row of small instruments (not very much to it). There is a considerable amount of space under the dash (between my legs and the bottom of that hoop. The panel is very high up compared to your legs comared to newer cars. Even with the stock seat which was a lot higher, it would not have been possible to hit my knees near the underside of the panel even if my body slid forward a lot causing my knees to bend more.

You can kind of see that this is true from this picture (but if my legs were in the picture this would be more evident):
http://www.pangalacticconsortium.com/ca ... ge515.html

Because there was so much room under the panel my fabricator thought it was better to put it just under the steering column in order to prevent the steering column from getting crushed down onto me. Does this make sense at all? I wil revisit this and try and get some pictures to demonstrate this.

By the way, after reading your message, I drove my regular car (my Saab which I have been driving with COM) home (from the show in Merrimac). I noticed that bottom of the panel in the area in front of me (which is made of very hard plastic) is much lower than the height of my knees. If I were to violently slide my legs forward 2 or (possibly 3 if slow crash) inches my knees would slam right into hard plastic. My legs would not fit under the dash of this car (or any other modern car that I can think of that has stock seats). It is worse in my husbands old PT cruiser (my knees when driving it are about 1 inch or less from running right into a hard plastic surface ( the bottom of the panel is several inches lower than my knees). This is also the case with my husbands new HHR (and most of the cars that I looked at today). Clearly most modern cars are a hazard to your knees.

However, in contrast with my MG (and all of my old cars), the entire bottom side of the panel is higher than my legs.
I want this MG to be as safe as it can be so I will revisit this and report back.

Regarding the bend near the end of the rear braces:
We discussed this a lot because there was a dilemma because of the small size of the car (total length is only 11 feet long). The main hoop really needs to be where it is (there is one obviously strong place to put it). We made this three inches higher than the top of my helmet (1 inch higher than is required). I did this so that I might be able to have an instructor that is a little taller than me (the instructors seat is mounted an inch lower too). It appears that the best place to anchor the rear braces is on the aft end of the reinforced area next to the wheel wells (and right over the rear shock mounting area). That is where the reinforcing plate was put. According to the SCCA roll bar rules, the braces must form at least a 30 degree angle. Mine is at 35 deg. We could have terminated the rear brace closer to the front of the car by puttting the mounting plate further to the inner edge of the reinforced area (would have to be closer in because it would hit the wheel well) but then we would not benefit from putting this over the rear suspension and the angle would be pretty close to the minimum alowed.

You can see the problem here:
http://www.pangalacticconsortium.com/ca ... ge527.html

We figured that since I am using one DOM wall thickness higher than required and I have more bracing than required that this woudl be ok for a car this light (and I found other cars with similar bends). I agree that this is not the preferred way to do it but we thought it was a safe compromise. I am assuming that you disagree.

How would you recommend fixing it?:

1) remove the rear braces and fabricate new ones that anchor closer to the front of the car (that would be ugly to have to do).
2) Add some extra small braces at the base of the ancor area where the bend is (easiest fix but would be a little funny looking). I would favor doing this.

Regarding the question about why I did not use the orange roll bar:
1) not tall enough.
2) no diagonal bracing
3) rear braces don't look very strong (at a funny angle)
4) unknown metal and welding quality (no history known)

queston about my hangar:
It is a condo that I own. The condo fee has averaged about $210/month (goes up and down depending on how much snow plowing is needed - we have a very large area to plow). Not bad for 5 cars and a plane (I get my money's worth). I feel lucky to have it. We don't own a house and I have no garage space at home. I am not complaining but there is no heat and no restroom (need to improvise for those).

Rebecca

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Re: planning for race track overload this fall + midget project

Post by n1gzd » Sat Aug 20, 2011 7:52 pm

regarding the question about whether 4 point bracing is required for vintage racing. For my class the answer is no. SCCA roll bar is all that is required but they consider that to be the minimum. Most of the cars that I have studied have bracing front and aft. In euroupe most of them seem to have complete roofline shaped roll cage. I did not want to do that because it would add more weight.

I could add it later but I did not think that for now with my whopping 60 hp engine I was going to be going all that fast (but not as slow as you might think).

I have attached a picure of a typical car (and you can see another one in the background). Most of them have one seat (no instructor seat) so the same protection is not needed on both sides).

Rebecca
Attachments
JohnMcCue-MG-Midget-BD.jpg
JohnMcCue-MG-Midget-BD.jpg (111.81 KiB) Viewed 1315 times

n1gzd
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Re: planning for race track overload this fall + midget project

Post by n1gzd » Sat Aug 20, 2011 7:55 pm

Mark,
I did not quite understand your comment:
"Those rear legs on the fabbed unit are odd,that they take a bend before the mounting plate... "

The rear legs do indeed take an odd bend, however, they are welded to the middle of the mouting plate.
I did not understand exactly what you meant.

Rebecca

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Re: planning for race track overload this fall + midget project

Post by zchris » Sat Aug 20, 2011 10:28 pm

Rebecca, the rear brace could have been straight by making the frame wider by boxing out that section of frame. And or by sectioning the wheelhouse. As for the front, I'm speeking from history. A guy in a 2002 BMW back around 1990 with a bar under column setup, badly damaged both legs sliding into turn 3 at NHMS. I believe his dancing days were over. And it was not a major crash. The issue with a tube down there is the shape of the object your legs will hit. A large flat panel will not brake bones easily. A protruding bar will. It is never a good idea to put that bar under the column. I cringe whem I see poeple race with a bar down there. Always makes me think how it would feel to have my knee caps torn off. UGH. Sorry about the graphics.
Chris

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Re: planning for race track overload this fall + midget project

Post by breakaway500 » Sun Aug 21, 2011 7:01 am

Hi Rebecca.I was only wondering why the fabricator had taken the extra time to bend the end of the rear supports,however,you cleared that up. You should take some pictures of someone seated and see how far from that lower bar they actually are. If a person were to submarine out of their harness, that bar would be the next restraint.. :shock: Plastic dash panels are designed to absorb impact. I have had a few cars brought into my shop that had been in accidents with beltless occupants,and it is amazing how well the dash cushioned their impact (this was before air bags..) The one thing you don't want to do is make your cockpit a dangerous place to be. 8) :sunny:
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Re: planning for race track overload this fall + midget project

Post by n1gzd » Sun Aug 21, 2011 10:18 am

I will get these pictures. The harness also has two anti-sub straps.
I definately don't want the car to be less safe with the roll bars than without it. ;)

Rebecca

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Re: planning for race track overload this fall + midget project

Post by WillM » Mon Aug 22, 2011 7:22 pm

Stynger wrote:
FWIW Chriis is a very experienced cage builder. That's what he does.
A lot of thought go's into building a cage. Sometimes the easy way out is not the safest. Putting the hoop under the dash was the easy way, not the safest.
I'm glad you posted the pictures, with constructive feed back you can modify your car and make it safer. In wheel to wheel racing you don't want to second guess your safety choices. Sometimes you only get one shot.

Chris built cages for me, Gordon, Will, Bill H also Jeff and Troy's cars to name a few COM members as well as untold SCCA cars etc.

There is a science as well as an art to cage building.
Very well said. Chris' experience comes from years of building roll cages and competing as a nationally-licensed SCCA racer. I'm sure he's accumulated a lot of wisdom from behind the welding goggles to behind the steering wheel. It is a unique insight that not many will have.

- Will
96 Miata #72 SC
PRA 4 :sunny:

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Re: planning for race track overload this fall + midget project

Post by n1gzd » Mon Aug 22, 2011 9:30 pm

Here are some pictures:

http://www.pangalacticconsortium.com/temp/hoop/

One of the pictures shows driver with foot on brake (knee is at highest then). The driver seat could probably be lowered another inch if the steering wheel were smaller (which it will be).
The passenger seat is slightly lower then the driver seat.

Rebecca

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