SN-99 race weight/1.75" roll cage thickness

[snakebit]

Well... I'm getting started back on the car. Most of the work so far has been rebuilding from the wreck, suspension etc. the body is straight now and donor car parts installed. Looking at putting cage in real soon. My question is .120 or .095 DOM. All along I was planning .120, but if I'm under 3000#, I can use .095. looking for some insight....

 

John

[CMC#11]

I'd go ahead and run the .120 for safety. You shouldn't have any problem getting to minimum weight so the extra 30 ~ lbs. of cage shouldn't matter.

[KiMifan]

I would use the thinner (lighter) tubing to open up the option of adding additional bracing to the cage to improve its overall rigidity and safety. A well triangulated cage with additional gusseting and strategically placed bars is better than one with the minimum required bars that is simply heavier.

[CMC#11]

I would use the thinner (lighter) tubing to open up the option of adding additional bracing to the cage to improve its overall rigidity and safety. A well triangulated cage with additional gusseting and strategically placed bars is better than one with the minimum required bars that is simply heavier.

Where did I say to build the minimum required cage? A well triangulated cage with additional gusseting and strategically placed bars with .120 will be stronger than .095.

 

BTW, what is your name?

[KiMifan]

I would rather build a cage out of 095 with more bars that weighs the same as a 120 cage with fewer bars, Yes, you could add those same bars to the 120 cage and it would be even heavier, but how heavy do you want the car to be? I'd rather build the car to the light side because things inevitably get added to the car over time and the weight creeps up.

[CMC#11]

I would rather build a cage out of 095 with more bars that weighs the same as a 120 cage with fewer bars, Yes, you could add those same bars to the 120 cage and it would be even heavier, but how heavy do you want the car to be? I'd rather build the car to the light side because things inevitably get added to the car over time and the weight creeps up.

You didn't answer my question, what is your name?

[Glenn]

I would rather build a cage out of 095 with more bars that weighs the same as a 120 cage with fewer bars, Yes, you could add those same bars to the 120 cage and it would be even heavier, but how heavy do you want the car to be? I'd rather build the car to the light side because things inevitably get added to the car over time and the weight creeps up.

 

yes, who is KiMiFan?

[KiMifan]

If Raikkonen ends up at McLaren I might have to change my user name. I hate McLaren!

[TurboShortBus]

All of this 0.095"/more bars vs 0.120"/fewer bars discussion is moot if the car ends up weighing 3001 lbs:

 

3001 - 4000 lbs.

1.750†x .120†Chrome-moly / Seamless mild steel (DOM)

No ERW allowed.

 

Mark

[nape1548534725]

All of this 0.095"/more bars vs 0.120"/fewer bars discussion is moot if the car ends up weighing 3001 lbs:

 

3001 - 4000 lbs.

1.750†x .120†Chrome-moly / Seamless mild steel (DOM)

No ERW allowed.

 

Mark

 

If you build a car that weighs 3001 without driver, ballast, fuel, fluids, and extras, you just built a tank.

[TurboShortBus]

If you build a car that weighs 3001 without driver, ballast, fuel, fluids, and extras, you just built a tank.

While that may be true, he could very well be building a tank with the doors and windows intact, etc. I don't know enough about the project, though.

 

As for how the vehicle's weight is determined, refer to this:

 

15.6.18 Roll Cage Tubing Sizes

For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver.

Based on that, I would not exclude ballast, fluids, or extras; just the driver and the fuel.

 

As a similar example, my 2004 GT weighs about 3020 sans driver and fuel (currently 3261 with a 190 lb driver, 40 lbs ballast, and a gallon or 2 of gas; no cage in the car yet). I have gutted the interior, removed all traces of AC, 2 aluminum seats on stock tracks, and the dashboard is cut in half. The power windows are still intact because the car sleeps outside (3/16" glass @ 2.5 lbs/sf + window motors/regulators @ 7 lbs ea + sawzalling the inner door skins @ 5 lbs ea, so ~25 lbs per door), the passenger seat/track is worth 25-30 lbs, and the stock cats are about 10 lbs heavier than an off-road pipe. Completely ditching the mufflers and tailpipes could be worth 40 lbs. It could be close enough to offset ~150 lbs worth of roll cage in order to stay under 3000 lbs, but is it worth the risk if the car ends up being 3001 lbs?

 

And yes, I know that I'm driving a tank!

 

Mark

[mitchntx1548534714]

As for how the vehicle's weight is determined, refer to this:

 

15.6.18 Roll Cage Tubing Sizes

For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver.

 

Based on that, I would not exclude ballast, fluids, or extras; just the driver and the fuel.

 

 

As raced the day it was teched.

 

Over the years, rules change (2 door bars on each side of the cage), roll cage gussetts, cool suit systems are added, oil coolers, a passenger seat for DE days. sway bars, shocks, rod end bushings, etc. etc. etc.

 

All of a sudden "as raced" is 50lbs heavier.

 

So is the "intent" as raced to minimum CMC legality or as of a particular date?

 

A sound arguement can be made both ways ... depends upon interpretation.

[TurboShortBus]

A sound arguement can be made both ways ... depends upon interpretation.

Oh, I hear ya. I have seen cars that shouldn't have passed drag race tech, let alone road race tech. But, they somehow have their logbook and they are making laps. I'm just building my tank to make sure that it meets the safety rules, as it's most important for me to be able to get home in 1 piece at the end of the weekend.

 

Mark

[mitchntx1548534714]

I'm just building my tank to make sure that it meets the safety rules, as it's most important for me to be able to get home in 1 piece at the end of the weekend.

 

Mark

 

I wish more had that ultimate goal.

 

Too many think they are invisible and invincible.

[TurboShortBus]

6.2 Horsepower/Torque and Minimum Weight

...Minimum weight is as measured immediately after a race, including driver.

At the lightest, this would be with driver and an empty gas tank (with ballast, fluids, and extras). A CMC 1999-2004 GT with iron block would have to weigh 3150 lbs. So, if driver + helmet + fire suit + HANS < 149 lbs, then the car will fall into the 0.120" roll bar category per the CCR. At 150 lbs and above, 0.095" would work.

 

I seriously doubt that, at our level, the ~26% weight increase of a 0.120" cage over a 0.095" cage will make you more like a Luca and less like a Lewis. I'd be fortunate to be a Luca.

 

FWIW, our 2 recent Sebring track record heavy-hitters in TTA and TTC (also the TTC 2009 national champion) were 30-50 lbs overweight. I don't think it bothered them too much.

 

Mark

[TurboShortBus]

I wish more had that ultimate goal.

Too many think they are invisible and invincible.

I just keep referring back to this photo (originally posted at Corner-Carvers.com):

 

Build 'em strong, people.

 

Mark

[mitchntx1548534714]

FWIW, our 2 recent Sebring track record heavy-hitters in TTA and TTC (also the TTC 2009 national champion) were 30-50 lbs overweight. I don't think it bothered them too much.

 

Mark

 

In the real world, on a real track, driving a real car, it doesn't.

 

On the internet ... it's HUGE!

[snakebit]

While that may be true, he could very well be building a tank with the doors and windows intact, etc. I don't know enough about the project, though.

As a similar example, my 2004 GT weighs about 3020 sans driver and fuel (currently 3261 with a 190 lb driver, 40 lbs ballast, and a gallon or 2 of gas; no cage in the car yet). I have gutted the interior, removed all traces of AC, 2 aluminum seats on stock tracks, and the dashboard is cut in half. The power windows are still intact because the car sleeps outside (3/16" glass @ 2.5 lbs/sf + window motors/regulators @ 7 lbs ea + sawzalling the inner door skins @ 5 lbs ea, so ~25 lbs per door), the passenger seat/track is worth 25-30 lbs, and the stock cats are about 10 lbs heavier than an off-road pipe. Completely ditching the mufflers and tailpipes could be worth 40 lbs. It could be close enough to offset ~150 lbs worth of roll cage in order to stay under 3000 lbs, but is it worth the risk if the car ends up being 3001 lbs?

 

And yes, I know that I'm driving a tank!

 

Mark

 

Based on this info I'm playing it safe (in more ways than one), and using .120. My 2000 will weigh the same as your '04. It will be completely gutted as the rules allow, to make room for my 220 lbs. Thanks all for your input.

 

John

middle name Paul

Last name in username

Franklin NC ( 1.5 hours north of Road Atlanta)

Ben Collins fan (The Stig)

[SNAKBITN]

John,what class are you building for CMC1 or CMC2?

 

Robert

[snakebit]

John,what class are you building for CMC1 or CMC2?

 

Robert

 

CMC2

BTW, nice lap at CMP last week....you can't be CMC2 legal...you were pushing AI times!

 

John

[Alien]

As for how the vehicle's weight is determined, refer to this:

 

15.6.18 Roll Cage Tubing Sizes

For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver.

 

Based on that, I would not exclude ballast, fluids, or extras; just the driver and the fuel.

I once asked something in regards to this. If you built a, oh say, third gen 2 years ago, used .095, had a sub 3000lb car and was legal for the 3150 min weight, what happens when the rules are adjusted a year later to a 3200 min weight? Suddenly with the extra 50lbs ballast the cage is now illegal. Then I learned not to ask questions.

[Al F.]

You just have to learn to only ask the questions you really want answered If you and your fuel weigh less than 200lbs you need to eat more.

[SNAKBITN]

CMC2

BTW, nice lap at CMP last week....you can't be CMC2 legal...you were pushing AI times!

That was my personal best at that track.

I'm running 290 rwhp but all cmc2 everything else.Are you coming to RA in Dec?

 

Robert