some good roll cage buidling guides

Hey everyone, Im back! - this time I have a car! decided to go with a 1971 bmw 2002 4sp.
Ive been "building" restoring and getting ready to put in a roll cage for the first time... I ordered the tubing and have all my article 253 and so forth... looking for a lead one good book I can use to help me through the process.
thanks

well, the NASA and/or RA rally rule book is a good start (not just FIA 253).


and with a quick search I found this:

http://midmoracing.com/bendit.htm


hopefully that helps

Check out Sean Mcknight at Sears Point (Infinion to you youngsters) raceway. He's built about 1000 roll cages for bimmers and is a really nice guy. Its also a good idea to get a detailed plan down on paper and check with your friendly local scrutineer before you start bending and welding.

There isn't a good book for rally cages. Follow the 253 pretty closely and please send me your proposed design and construction pics. The design is pretty simple but you need all the elements in their correct places. Creativity isn't always rewarded in cage building and what looks ok may end up with a Sawsall involved. If it ain't right you will be cutting it back out.

I'm working at a shop that does a lot of competition builds on 2002s. Fell free to contact me if you have any questions.

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

Quote
Rallymech
I'm working at a shop that does a lot of competition builds on 2002s. Fell free to contact me if you have any questions.

And ask Roberta about how much FUN! putting a 320 rack into a 2002 is..

I had 11 hours of fun on it this week. A laugh a minute.

Hey Robert, why dontcha pop by, I gotta go cut up the tree.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

A friend did a neat swap where he put volvo 240 front disks and calipers on his 2002.

Don't let anyone convince you that putting a rack into a 2002 is worth the trouble.

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

dont worry - keeping mostly stock german parts in this one... and thats trouble enough for now.
thanks for the tips and support ya'll
Im gonna try out that program Jon! but first I gotta get my hands on the tube bender manual - eeeek

Think about how you are going to weld the tops of the tubes. We cut the floor so the main hoop can drop down to get access. Others remove the roof skin altogether.

Stick with the roof V with the tubes coming together at the main hoop. Then you can do a V from the center to the rear stays. The rear V can only be done with a roof V and allows for the easiest egress if you find yourself having to climb out the back window. I know someone who has had to go out a back window once. It's also less gussets.
Give a bend in the a-pillar reinforcement bar outward to get more clearance to steering wheel, etc.
Pay attention to the allowed dimensions in 253. Going as far forward on the a-pillar bar will give you more room to get in and out of the car. Keeping the side X lower can also help.
Same applies to the main hoop. Bring it up from the cage feet and you will end up with a slightly larger hole in the top, again easier to crawl through and also allows for potential of being able to fit a helmet through.
You are allowed 10 degrees of main hoop lay back.
Don't weld the seat belt harness bar into the cage until your seats are mounted so you don't end up having them not ideal or having to do the bar over again.

A good bender is nice. I use Bend Tech Pro software which I'm really enjoying, but it's pricey. I have a JD Model 2 bender which gets pricey with dies but the smaller radius than hydraulic ones like the TJ Diesel bender makes for the ability to get a tight fitting cage.

Lastly, start with a different car. The 318ti is my favorite platform but any E36 would be massively better than a 2002. The ti will want a different engine whereas a 2.5 could be fine for probably ever with chip, exhaust, and intake.
There is no benefit or even logic to building a 2002. They are cute and kinda cool cars, but better for driving around town then trying to build into a rally car ESPECIALLY considering you live in the land of the roughest car beater rallies in the nation.

Quote
Rallymech
Don't let anyone convince you that putting a rack into a 2002 is worth the trouble.

Don't let any genius road-racers convince you of anything.
Especially if they are geniuses.
and roadracers.

I still say you oughtter have sawed off the rear mounts and then done a "DOH! I thought I was supposed to saw them off! Oh NOZE!
Sooooorry! Well at least now we can bang on a front rack 1-2-3 budda bing!
And maybe try something just a tad quicker than the glacial 320 rack with just under 4 turns lock to lock! Imagine that!"

You coulda pulled it off with a straight face.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.



Edited 1 time(s). Last edit at 11/12/2011 06:50PM by john vanlandingham.

It was the bosses idea to do a rear mount rack. I had to try to make it work. I'm still a few degrees off. The fix for this is not going to be pretty. I hate trying to make other peoples bad ideas work! I just don't understand why people want to blaze new trail when there is no real benefit.

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

Quote
NoCoast
Think about how you are going to weld the tops of the tubes. We cut the floor so the main hoop can drop down to get access. Others remove the roof skin altogether.

Yeah no problems. The integrity of the stink floor isn't important so yeah cut up the floor where the MAIN hoop directs force into when the car flips.
Weld quality isn't important, and millions of guys have been doing and telling others to do it for centuries with no thought at all to the fact that the thin flimsy sheetmetal , blobbed back by amateurs calling a collection of rat turds "welding" might be better reinforced rather than sliced up..

And don't pay any attention to those worry warts who build boxes with separable tops so they can slid off the top and drop the cage 4" to access the tops of the tubes. They're probably worried more about survivors suing them that ease of construction. Fawk them.

Quote

Stick with the roof V with the tubes coming together at the main hoop. Then you can do a V from the center to the rear stays. The rear V can only be done with a roof V and allows for the easiest egress if you find yourself having to climb out the back window. I know someone who has had to go out a back window once. It's also less gussets.

Yeah that V in the middle of the main hoop sure helps the center of the main hoop from collapse like they always do..
This way is too passe:


What were they thinking??

Quote

Lastly, start with a different car. The 318ti is my favorite platform but any E36 would be massively better than a 2002. The ti will want a different engine whereas a 2.5 could be fine for probably ever with chip, exhaust, and intake.
There is no benefit or even logic to building a 2002. They are cute and kinda cool cars, but better for driving around town then trying to build into a rally car ESPECIALLY considering you live in the land of the roughest car beater rallies in the nation.

Hey more negative waves, mang. the way you're talking you's think that when a newb smashes a fender and a headlight bucket and a hood or breaks a windshield that its some strain to find replacements...
Come on Grant, lighted up!
No really sane person would build a car if it was hard to find the basic parts, that would be madness. You assume a lot.
She probably is like Al with all those Volvo shells and spare doors and gearboxes and motors and suspension arms and junk-n-stuff..

Only advantage a E36 is ease of finding parts. As if that is important...

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
NoCoast
Think about how you are going to weld the tops of the tubes. We cut the floor so the main hoop can drop down to get access. Others remove the roof skin altogether.

My favorite method is to build raised platforms to weld the cage feet to. Allows the loads to be spread over numerous planes, and you can fit everything first prior to welding. Then you remove the base plates, and lower the cage to allow access to the top for welding.






Here you can see the platform spreads the loads over a greater area compared to going directly to the floorboards. Loads are on the floor, on the vertical surfaces of the inner sills (double shear), and on top of the inner sill.

Quote
Ascona73

Quote
NoCoast
Think about how you are going to weld the tops of the tubes. We cut the floor so the main hoop can drop down to get access. Others remove the roof skin altogether.

My favorite method is to build raised platforms to weld the cage feet to. Allows the loads to be spread over numerous planes, and you can fit everything first prior to welding. Then you remove the base plates, and lower the cage to allow access to the top for welding.






Here you can see the platform spreads the loads over a greater area compared to going directly to the floorboards. Loads are on the floor, on the vertical surfaces of the inner sills (double shear), and on top of the inner sill.

That's ridiculous Bob, just air chisel the floor and bend it out of the way with a crow bar! Then hammer it back, dribble some welds around or at least near by and its done.
I did similar on the few cages I built but I'm a dinosaur, and everything I know is outdated..ask any 20 something.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.