Tubing Needed For E30 Cage?

[Simon Tibbett]

Does anyone know around the basic tubing amount needed for a basic 6 point cage for an E30 coupe?

[rmm3]

4 sticks should do it...they come in random sizes 18'-22' long.

2-1.75"x.095 required bars
2- 1.75"x .065 non required bars

or all .095 if you don't need to save weight.

rick

[Simon Tibbett]

Cool, thanks!

[DTRguy]

I believe you can also run 1 5/8" or 1 1/2" .120 wall for more clearance. Just a thought. Possibly a little heavier overall but I doubt noticeable from car to car as far as handling.

I use 1 5/8" pretty exclusively. Strikes a good balance between the max and min diameters. Plus it just so happens that is the bending shoe set I have for my Mitler bros bender

[TeamDFL]

As mentioned above, about 80' of tubing should be sufficient for a typical 6+2 point cage in an E30. DOM tubing typically comes in sticks of random length (17 to 24 feet). I believe we used about 70 feet in our LeMons E30. I'll check the bend sheets tonight to get a total. If you are new to cage building, an extra 20' of tubing comes in handy if you have to scrap a larger piece.

My personal preference is 1.5x.120 for the added clearance and smaller bend radius at the expense of an additional .1lb per linear foot over 1.75x.095. I need the helmet room. Note the under roof support that was hammered in over the driver side door to make room for the halo in the photo below.

[clopez95m3]

Originally Posted by DTRguy

I use 1 5/8" pretty exclusively. Strikes a good balance between the max and min diameters. Plus it just so happens that is the bending shoe set I have for my Mitler bros bender

Unfortunately that's not a size allowed in NASA and BMW CR road racing

Carlos.

[DTRguy]

Originally Posted by clopez95m3

Unfortunately that's not a size allowed in road racing (NASA, SCCA, BMW CR).

Carlos.

I believe you are mistaken... Sorry As long as it is BIGGER than what the minimum requirement and meets the wall thickness of the said size ie 1 1/2 then it is just added safety. Why would it not be allowed if it exceeds? Oh and BTW my ITC (scca) rabbit has 1 5/8 Cro Moly .095 wall and is completely legit.

[DaveCN]

Originally Posted by clopez95m3

Unfortunately that's not a size allowed in NASA and BMW CR road racing

Carlos.

NASA will allow it - I have checked into it. Not sure on CCA.

[clopez95m3]

Originally Posted by DTRguy

And you are wrong... Sorry As long as it is BIGGER than what the minimum requirement and meets the wall thickness of the said size ie 1 1/2 then it is just added safety. Why would it not be allowed if it exceeds? Oh and BTW my ITC (scca) rabbit has 1 5/8 Cro Moly .095 wall and is completely legit.

Yeah SCCA does I edited that, NASA and BMW CR is in the rule books. At the track anything goes, I wouldn't be surprised if it didn't vary from inspector to inspector.

Carlos.

[Cory M]

Originally Posted by DTRguy

I believe you can also run 1 5/8" or 1 1/2" .120 wall for more clearance. Just a thought. Possibly a little heavier overall but I doubt noticeable from car to car as far as handling.

I use 1 5/8" pretty exclusively. Strikes a good balance between the max and min diameters. Plus it just so happens that is the bending shoe set I have for my Mitler bros bender

I wouldn't recommend 1 5/8" simply because it is an oddball size. Try to go to a racing shop and get brackets for 1 5/8" - there are none, just 1.5 and 1.75. We've got a car with a 1 5/8" cage and the standard brackets for my water bottle, mirror, helmet hook, seat back brace, etc don't fit and I had to come up with my own brackets. There is nothing structurally wrong with 1 5/8", and it should be legal as long as you go with the thickness recommended for 1.5" and not the thinner 1.75", but in my experience it is just inconvenient..

[DTRguy]

Again, look at it logically... If say 1.5" .120 wall is allowed... then 1.625 or 1.750 .120 is allowed. When you get to a certain point, there is allowances for wall diameter hence why 1.750 you can run the smaller wall thickness. For my ITC car, there is an allowance for alloy factored in so I could run the thinner thickness wall, and even thinner diameter but I am still running the larger diameter. It is stiffer and safer. And it wasn't inspected at the track for compliance. I was inspected at my shop where I built it. All of the Lemon's cars I have built for Toyota were also 1.625. I believe that the engineers there that I was building the cars for would have not let me do it in that material if it weren't completely legal.

Originally Posted by Cory M

I wouldn't recommend 1 5/8" simply because it is an oddball size. Try to go to a racing shop and get brackets for 1 5/8" - there are none, just 1.5 and 1.75. We've got a car with a 1 5/8" cage and the standard brackets for my water bottle, mirror, helmet hook, seat back brace, etc don't fit and I had to come up with my own brackets. There is nothing structurally wrong with 1 5/8", and it should be legal as long as you go with the thickness recommended for 1.5" and not the thinner 1.75", but in my experience it is just inconvenient..

I have run into that... the simple fix in the case I have ran into for things like mirror mounts and helmet hooks and such is get the size for 1.5 and trim to fit. Kinda PITA... but It's how I got around it. When I purchased my bender I was figuring on having more drag car oriented things to do for people (I do like in KY) and 1 5/8" is common in drag. Had I known I'd have gone for a 1 1/2" die. My new race car is all that size. So eventually I'll be buying that set (expensive for limited uses).

[clopez95m3]

Originally Posted by DTRguy

Again, look at it logically... If say 1.5" .120 wall is allowed... then 1.625 or 1.750 .120 is allowed. When you get to a certain point, there is allowances for wall diameter hence why 1.750 you can run the smaller wall thickness. For my ITC car, there is an allowance for alloy factored in so I could run the thinner thickness wall, and even thinner diameter but I am still running the larger diameter. It is stiffer and safer. And it wasn't inspected at the track for compliance. I was inspected at my shop where I built it. All of the Lemon's cars I have built for Toyota were also 1.625. I believe that the engineers there that I was building the cars for would have not let me do it in that material if it weren't completely legal.

I'm surprised they have rules for Lemons cages.

I agree with your logic but it's hard to disagree with the rule books. If you get some inspector that measures your cage at the track, yes NASA and BMW club can do this then you're SOL if they tell you you used the wrong sized tubing. A friend had to deal with an inspector at a NASA weekend who wouldn't allow his car to compete due to a weld on an optional tube, and he did this to a bunch of people.

I honestly don't see Lemons disallowing anything. Don't you just bribe the inspectors with liquor?

Carlos.

[TeamDFL]

Originally Posted by clopez95m3

I'm surprised they have rules for Lemons cages.
...

I honestly don't see Lemons disallowing anything. Don't you just bribe the inspectors with liquor?

Carlos.

There is actually a bit of a LeMons stink going on right now regarding bribes. BS judges have always taken bribes but tech is supposed to be legitimate because insurance coverage has safety requirements. At Stafford, the tech guys were soliciting bribes which is not supposed to happen. They will probably clamp down on that ASAP.

BMWCCA/SCCA/NASA tubing requirements are minimums. You can definitely go larger in OD and/or wall thickness if you want. From BMWCCA clubracing Appendix A, 17-B:

"Size. For the purposes of determining roll bar tubing sizes, vehicle
weight is as raced, WITHOUT fuel and driver. Note: There is an
allowance of minus 0.010 inches on all tubing thicknesses. Minimum
tubing size for the required tubes of the roll cage is:"

[DTRguy]

Originally Posted by clopez95m3

I'm surprised they have rules for Lemons cages.

I agree with your logic but it's hard to disagree with the rule books. If you get some inspector that measures your cage at the track, yes NASA and BMW club can do this then you're SOL if they tell you you used the wrong sized tubing. A friend had to deal with an inspector at a NASA weekend who wouldn't allow his car to compete due to a weld on an optional tube, and he did this to a bunch of people.

I honestly don't see Lemons disallowing anything. Don't you just bribe the inspectors with liquor?

Carlos.

I can almost understand if a tube was installed (optional or not) and isn't welded to the specs stated within the rules... Hmmm if said tube breaks free it could maybe create a dangerous situation. So I can like I said sorta understand that. I have many many welds of mine inspected over 20 years. If you follow the rules implicitly then you have nothing to worry about with respect to that. That being said I can see where some inspector might add his .02 to the interpretation of the rules and say Nope I don't care if your car is safer with larger diam tubing. It says x you need x. So I get you. Heck on our rabbit it was a reinspection to replace the original very bad cage built prior to 2007. Car was being rebuilt in 2008... so we used 2008 rules regarding the diagonal and the Petty bar requirements in the rules. It became a question to which set of rules to use! After I explained my reasoning... the inspector agreed that the revised rules of 2008 should apply even though the car has a log number that predates 2007 rules. It almost got ugly in the shop

[Z3SpdDmn]

Originally Posted by clopez95m3

I'm surprised they have rules for Lemons cages.

I honestly don't see Lemons disallowing anything. Don't you just bribe the inspectors with liquor?

Carlos.

Carlos,
Believe it or not, they've been scruitinizing safety very heavily this year. They actually HAVE turned cars away at the track. Kevin did the cages in our Toyota cars and we accepted the larger diameter that still had the thicker wall.

Your point is taken, though. If an inspector decides he doesn't like it, you'd need a rule to defend yourself with. Do the rulebooks not say "minimum diameter" or "minimum wall thickness"?

[TeamDFL]

From NASA's CCR:

"15.6.18 Roll Cage Tubing Sizes
For the purposes of determining roll bar tubing sizes,
without fuel and driver. Note: There is an allowance of m
thicknesses. Minimum tubing size for the roll cage is: "

From the SCCA 2009 GCR 9.4.F.2:

"2. The following table shows the minimum allowed tubing outer
diameter and wall thickness by vehicle weight:"

[Z3SpdDmn]

Well, I think Simon Tibbett has had his question MORE than adequately answered

[clopez95m3]

Originally Posted by Z3SpdDmn

Well, I think Simon Tibbett has had his question MORE than adequately answered

Agreed.

Carlos.