check for rollcage compliance

[Mean Gene]

I could use some help before I start cutting tube.  I am going to build a 'liner and have designed the rollcage portion of it to what I believe to be legal if I am interpreting the rules correctly.  I am requesting your help if you are an experienced land racer: could you please review my design and point out any areas that would not pass tech inspection.  I know this design probably could have been done better and there are multiple ways of doing it based on your own opinion/interpretation of the rules.  That is fine.  What I am looking for here is will it/ will it not pass tech inspection?  In the rule book it suggests sending drawings to the technical committee chairman.  I did so a little more than a month ago, but unfortunately I have not heard back so I turn to this community for help.  I have attempted to attach the .pdf of the file showing layout and approximate dimensions. 

Thank you for your help.

[wolcottjl]

I would send an email to rulebookinfo@scta-bni.org with your diagram. 

[willieworld]

mean                   what size are the tubes                                        willie buchta

[McRat]

You need a materials list, dia, material, wall thickness.

[John Burk]

Run the roll cage hoops down to the lower rail and use tubular gussets between the hoops and upper rail at all points they meet .

[RidgeRunner]

Might want to do a rough mock up using PVC, conduit, wood or what ever will stand up to practice getting in and out with allowances for safety gear [attached to car as well as worn by driver] clearance.  Bail out drill is also a part of tech inspection. 

Uncomfortable driving position will make it hard to focus on job at hand for the driver.

Newer driver protection regs on Head and Neck restraints etc also bring compromises to "ultimate aero" goals with them in many cases.

Might also want to allow for some extra space to accommadate a possible larger 2nd driver [or potential buyer way down the line].

                                    Ed

[Seldom Seen Slim]

Contact Joe Timney -- owner, Delaware Chassis Works.  He's the president of the East Coast Timing Ass'n -- and you can find him by following the ECTA link on the home page of this website.  He builds chassis and roll cages for a living -- and will be able to give you lots of help and keep you pointed in the best direction.

[Mean Gene]

Willie and McRat:  1.5" OD and .095 wall as rules call out for K displacement under 175mph

John:  I failed to mention gussets were not pictured for clarity.  Regarding running the hoops down to the lower rail: do you mean they should be I piece all the way to the lower most rail, or are you referring to the lack of a verticle member directly beneath the rear hoop?

Ridge:  I have mocked up in PVC and 2X4's.  I am satisfied with fit and bail out ability. 

Seldom and Wolcottjl:  Thank you for the suggestion.  I will do so.

Gene

[Geo]

Gene,

Check the build diaries for reasons why tube is placed where it is. 

Some good points made on the hoop being one piece. 

The rear side diagonal should be longer to make a triangle not a trapezoid of the area next to the driver.  Perhaps move the rear hoop forward and making another vertical bar in this area.

The fore aft head bars may need to be shifted depending on where you head is and the top two bars should continue back and down to meet the bottom cross bar not shown on your drawing.

There are some LSR racers in KC, not to far from you.  If you get to KC we can show you some cars and lie a bit.

Geo

[willieworld]

mean  the minimum is 1 1/2 X .095---from G through K   do yourself a favor and use .120 wall erw---if you buy .095 it will be more like .090  ---i just bought some .095 and it was .090 ----there is a very good pic of a roll cage on page 26 of the 09 scta rule book that is the one i would go with ---it is a tried and true setup --its been used in nhra for years and still is in the rear engine dragster ---if you want a better pic plus a back and bottom view buy a nhra rule book and you will see the same cage there under  rear engine dragster ----there is a good pic in the nhra rule book of the rear of the cage --notice the 2 bars that go from the shoulder hoop to the bottom frame rails that you dont have in your roll cage you will want to add those for lateral strength---if you cant find one let me know and i will post a pic-----------------willie buchta

[Mean Gene]

Geo:  That is a good suggestion on the rear diagonal.  I should have known better than to make a trapezoid.  I think I will extend those like you suggested and move those other bars inward to use as my seatback.  That should produce quite a bit of strength in that area.

Willie:  I'm glad you mentioned that.  I always forget that a wall thickness is nominal and ASTM specs let it vary inside a range.  Good point on the NHRA rollcage.  I designed it like I did to try to keep it as close to the helmet to satisfy the 2" lateral movement rule, but after thinking about it further I am better off going with the NHRA style and welding in an additional support should I end up with too much lateral movement.

Thank you everyone.  I think I have enough to go on to build something that will pass tech inspection, but will still blow up halfway down the course. 

[willieworld]

mean   remember also that you will need a padded head rest behind your helmet  3.C  ---and roll cage padding in the proximity of the drivers helmet  3.B.2---------------------------willie buchta

and dont forget that H & N R   3.A.3.

[Jonny Hotnuts]

Willie and McRat:  1.5" OD and .095 wall as rules call out for K displacement under 175mph

I can guarantee 110% you will regret this decision in the future.
Weight is not a negative factor (and is helpful), and you should always build your vehicle for at LEAST 2 engine displacement sizes over what you think you will run.

Once you run the little K displacement...what then....scrap the entire project?
After you set the records in K you will want to put a little bigger motor and go for the next records the next year. This is just how it goes.

When we started our project we NEVER thought it would go over 200, seriously.
Now we had to correct all the little issues that we should of done to start with and has cost some $$$.
But thank god we opted to go for a larger roll cage and at least that was good to go.

Do yourself a favor and take what I am saying to heart.


~JH

[willieworld]

jonny  the 1 1/2 tube is good in G  H  I  J  K  ---the G record is 145 mph---the H record is 116 mph---no I record ---the J record is 116 mph----no k record----seriously how fast do you think a 500 cc diesel is going to run---if he uses the 1 1/2 tube he will be building the chassis for 4 engine sizes up-- where the record is 145 mph still way below the 175 restriction for the 1 1/2 tube--i wasnt trying to talk mean into anything he seams to be an intelligent person and im sure will read everyones opinion and make a good decision--------------------willie buchta

im in the process of building a car just like mean green ( same classes ) and am using the 1 1/2 tube--the vehicle will run in the diesel streamliner class---a sidecar streamliner class and a motorcycle streamliner class

[dw230]

"When we started our project we NEVER thought it would go over 200, seriously."

Sorry to hijack.
Jonny, I seem to remember a bet we have that when your car runs 250 I will tattoo your logo on my body in the area hidden by my wallet pocket.

I feel comfortable that I will remain inkless.

DW