I'm starting to plan the cage for my JP car and have been wondering about the differences between US cages and Euro cages for a while now. For Euro Cages I've been looking at the motorsports cages, as seen here (http://e30m3performance.com/tech_articles/cage_symposium/e36_mclaren/e36_mclaren1.htm)


The couple of main differences that I see are the following.
1. THey use X door bars instead of Nascar bars
2. They don't have the Cross bar and Harness Bar that US cages do.
3. THey mount the Harness to the back of the cab
4. THey Halo the ENTIRE ROOF, not just the Center

I have to Review the rules, as I forget how many points a Prepared car is allowed. But what are the opinions/thoughts on these differences????

1. THey use X door bars instead of Nascar bars
2. They don't have the Cross bar and Harness Bar that US cages do.
3. THey mount the Harness to the back of the cab
4. THey Halo the ENTIRE ROOF, not just the Center

I have to Review the rules, as I forget how many points a Prepared car is allowed. But what are the opinions/thoughts on these differences????

1) NASCAR bars aren't a requirements for US cages...a lot of people choose them though.

2) Cross bar and harness bar are definitely a requirement for US cages that aren't required for FIA cages.

3) Harness mounting to the back can be argued as better or worse depending on who you talk to.

4) Not in all cases...BMW did it on the E36 Motorsport cage, but not on the E30, E46, or E90 cages.

Prepared cars are allowed 6 points (A pillar, B pillar, and 2 rear downtubes) + 2 foot protection points. I've seen really good cages and really bad cages built to both sets of rules. Find a good fabricator who understands load paths and triangulation...there's a LOT more to building a cage than just welding some bars together to meet the "rules". I scratch my head sometimes wondering what the fabricator was thinking when I see some of the cages posted here.

4) Not in all cases...BMW did it on the E36 Motorsport cage, but not on the E30, E46, or E90 cages.



IIRC, the late DTM92 cars had a similar cage. See:

http://e30m3performance.com/tech_articles/cage_symposium/tictac/tic-tac_dtm.jpg

Not a great pic, but I am certain there are others floating around.

Another insteresting difference I noticed from the link Steve J. posted IIRC regarding construction of the WTCC. It appears that the sides of the cage are built then the cross bars are welded in position. For some reason, US cages must have a continuously bent b-pillar. Trying to find this link again.

Mike

IIRC, the late DTM92 cars had a similar cage. See:

http://e30m3performance.com/tech_articles/cage_symposium/tictac/tic-tac_dtm.jpg

Cool...I didn't realize the C-pillar hoop made it's way into the last of the E30's.

Another insteresting difference I noticed from the link Steve J. posted IIRC regarding construction of the WTCC. It appears that the sides of the cage are built then the cross bars are welded in position. For some reason, US cages must have a continuously bent b-pillar.

At the club level, it's always been speculated that the contiuously bent B-pillar with a diagonal is easier to build correctly for the "least common denominator", i.e. Joe Schmo who thinks it's a good idea to build his own cage in his garage. Building a 5-piece B-pillar, the most important safety portion of the cage, isn't something to be left to just anyone who owns a pipe saw and a Mig welder.

Cool...I didn't realize the C-pillar hoop made it's way into the last of the E30's.



At the club level, it's always been speculated that the contiuously bent B-pillar with a diagonal is easier to build correctly for the "least common denominator", i.e. Joe Schmo who thinks it's a good idea to build his own cage in his garage. Building a 5-piece B-pillar, the most important safety portion of the cage, isn't something to be left to just anyone who owns a pipe saw and a Mig welder.


That is what I was thinking but not quite sure how to say it so elegantly. Thx! Too bad for us here in the US as it appears that very safe cages can be built with fabricated B-pillars.

Oh well....

Mike

http://e30m3performance.com/tech_articles/cage_symposium/e36-1/index.htm

Thats my car!!!

I just removed the blue foam at the drives head friday for an SCCA official. PTG added a bar for the harnesses to move them just behind the driver.

My old E36 had a Motorspotr replica cage Mcmillin did. very similar, but because of rules, was not tied into the rear diff/subframe. Awesome cage design though, very simple, but when executed well, it offers a very rigid and safe chassis.

Check the minimalist cage in this M3 GTR (http://vorshlag.smugmug.com/gallery/2997059#162481977):

http://vorshlag.smugmug.com/photos/162481977-S.jpghttp://vorshlag.smugmug.com/photos/162481838-S.jpg
http://vorshlag.smugmug.com/photos/162481860-S.jpghttp://vorshlag.smugmug.com/photos/162481716-S.jpg

Efficient design, no extraneuous cage tubes, very little wasted weight. I like it. Some of the cages in see in club racing BMWs have 2 or even 3 times more tubes. I guess if you need the ballast...

I'm not sure I would call the GTR cage minimalist...it has bars running to all 4 pickup points for the rear subframe as well as bars running to the rear trailing arm mounts. There are 3-4 bars running through the front fire wall on each side. It "looks" minimalist because it doesn't have the diagonal and harness bar that are required in US-spec cages.

Efficient design, no extraneuous cage tubes, very little wasted weight. I like it. Some of the cages in see in club racing BMWs have 2 or even 3 times more tubes. I guess if you need the ballast...

What cages have you been looking at?

The pics don't show a diagonal on the main hoop or a harness bar. How did that car get by tech? I figure in BMW CR whoever looked at it didn't know any better but in Rolex? Maybe they had different rules at the time. Who knows.

Calros.

Carlos - Those may be old pictures, as I'm pretty sure that Danny had added a diagonal and harness bar to the car for BMW CCA Club Racing. Then again, FIA cages are approved as per the BMW CCA rules, but I don't remember whether the rules require that you add a diagonal and harness bar or not.

IIRC, the late DTM92 cars had a similar cage. See:

http://e30m3performance.com/tech_articles/cage_symposium/tictac/tic-tac_dtm.jpg

Not a great pic, but I am certain there are others floating around.

Another insteresting difference I noticed from the link Steve J. posted IIRC regarding construction of the WTCC. It appears that the sides of the cage are built then the cross bars are welded in position. For some reason, US cages must have a continuously bent b-pillar. Trying to find this link again.

Mike

My former E36 CM car had the double hoop design...or at least a version of it let's say. It liked that cage quite a bit, it was a nice design. There were a few things I'd have done differently had I designed the cage but overall it was very well done. Weld quality was exceptional of course.

I've considered doing this in my E30 when it gets a new cage this winter but I'm undecided yet and I still have plenty of time for that.

Fair - With regards to some of your comments in your SmugMug gallery about the pictures:

The fuel door hole covering isn't a "shortcut"...it was done that way so that it can easily be opened up. Different tracks/pits require the fueling to be done on different sides of the car. The car is setup such that it can quickly be converted to fuel from either side depending on the track.

The V8 in the car was never banned from any series. It's running a 5.0 liter V8 from the M5, which is still legal to be run in Grand-Am Rolex. You are thinking about the 4.0 liter V8 that PTG and Schnitzer ran in the ALMS series.

As for the cage being minimalist, I think the pictures are deceiving you. If you've poked your head inside a GTR cage for a ALMS or Grand-Am Rolex car, you'll find that it is anything but minimalist. It actually has more total bars and ties into more points than the cage in our car (minus the harness bar and diagonal)...and our car has 2 bars that could be considered "extra" because we removed the open rear bulkhead all together and used triangulated bars to add the chassis stiffness back with less weight.

The most recent GTR cages are fairly complex, they are integrated into both subframes, and have a tube frame rear suspension (similar to what I am doing).

Definitely not your average basic bare bones cage.

Fair - With regards to some of your comments in your SmugMug gallery about the pictures:
Noted/updated those entries with some of your comments. Thanks. :)

The most recent GTR cages are fairly complex, they are integrated into both subframes, and have a tube frame rear suspension (similar to what I am doing).

Actually, I "think" Danny's M3 had a "tube frame" rear suspension coupled with a custom "subframe" to brace things together, but I may remember wrong. I believe there are a lot of pictures of the underside of that specific car on the old DTM Power website.

My former E36 CM car had the double hoop design...or at least a version of it let's say. It liked that cage quite a bit, it was a nice design. There were a few things I'd have done differently had I designed the cage but overall it was very well done. Weld quality was exceptional of course.

I've considered doing this in my E30 when it gets a new cage this winter but I'm undecided yet and I still have plenty of time for that.

Jack how are you going to do this with-in the CCA rules...inquiring minds would like to know.

-tony

Jack how are you going to do this with-in the CCA rules...inquiring minds would like to know.

Legally, I guess you would need to use traditional downtubes from the main roll hoop in addition to the bars running to the C-pillar hoop?

Legally, I guess you would need to you traditional downtubes from the main roll hoop in addition to the bars running to the C-pillar hoop?

That's the only way I could see doing it legally with how the rollcage rules are worded.

-tony

Jack how are you going to do this with-in the CCA rules...inquiring minds would like to know.

-tony

I'm not totally decided on how this cage will be done yet so it's just one possibility. However, to directly answer your question, the car is not being built specifically for CCA use. I would like to, and certainly plan to, run in CCA as well but I'm going to do the cage I want first (well, assuming it works for where I plan to run it) then worry about whether or not I can run it in other series.

Again, it's just one possibility and I'm not married to it, I just always kind of liked those designs. Actually thinking about them a bit it's probably not such a great idea to have another main hoop where there is cage weight up high. Particularly in an area where there is no need for passenger protection.

I'd guess since E36's were really the first cars to utilize this design (although I know E30's did as well) it could be a function of how best to reach the rear shock towers and still pick up other suspension components. Right now a lot of E36's are technically not correct with their rear shock tower mounting scheme....according to the rules.

I'm not totally decided on how this cage will be done yet so it's just one possibility. However, to directly answer your question, the car is not being built specifically for CCA use. I would like to, and certainly plan to, run in CCA as well but I'm going to do the cage I want first (well, assuming it works for where I plan to run it) then worry about whether or not I can run it in other series.

Again, it's just one possibility and I'm not married to it, I just always kind of liked those designs. Actually thinking about them a bit it's probably not such a great idea to have another main hoop where there is cage weight up high. Particularly in an area where there is no need for passenger protection.

I'd guess since E36's were really the first cars to utilize this design (although I know E30's did as well) it could be a function of how best to reach the rear shock towers and still pick up other suspension components. Right now a lot of E36's are technically not correct with their rear shock tower mounting scheme....according to the rules.

The double main hoop design picks up the load from a rear coil-over suspension slightly better, but it is probably not worth the small gain, given the high weight.

Reguarding E36 rear shock mounting points, given the new CCA rules you are correct. We have begun mounting them slightly different this year to make the bars mount 360 to the plate and then tie the other bars in.

-tony

The double main hoop design picks up the load from a rear coil-over suspension slightly better, but it is probably not worth the small gain, given the high weight.

Reguarding E36 rear shock mounting points, given the new CCA rules you are correct. We have begun mounting them slightly different this year to make the bars mount 360 to the plate and then tie the other bars in.

-tony

Agreed. I think it was likely an interim design that may have looked good on paper. Or perhaps some flunky FEA guy focked up some of the material properties and they didn't realize it til it was too late. ; )

I've seen that there have been modifications to rear mounting points in more E36's these days.

Cheers.

The double main hoop design picks up the load from a rear coil-over suspension slightly better, but it is probably not worth the small gain, given the high weight.

-tony

Actually thinking about it a bit more it's very unlikely that I'm going to run rear coilovers so I won't go to the rear towers anyway. I dunno, still mulling it all over though. I've got 6 months to decide before the car goes in so I'm not in a rush. Who knows, I may change my mind about suspensions between now and then too.

I guess if you need the ballast...

...you should cut the tubes out and stick it to the floor. Hehe.

World Challenge cars have some of the best 'minimalist' cage designs in the larger body cars. All weight must be removed on a large car like the E90 or Mazda six to run against a Neon and actually make weight. The last few years have made production bodies much bigger and the rules haven't added much weight... We are able to build a body now that is as light as the E36 or E46 but stiffer with much less tubing but it takes alot of fabrication.

Well, SOME WCT cages, I've seen some ugly jobs done by privateers who were starting in WC, GT included.

Something definitely worth noting that you touched on is the newer chassis' are far more rigid than chassis' from the past. This is why the E46 motorsport cages can be so simple and more focused on roll over safety rather than adding in the structural rigidity, because the car is already stiffer than before.

Well, SOME WCT cages, I've seen some ugly jobs done by privateers who were starting in WC, GT included.

Something definitely worth noting that you touched on is the newer chassis' are far more rigid than chassis' from the past. This is why the E46 motorsport cages can be so simple and more focused on roll over safety rather than adding in the structural rigidity, because the car is already stiffer than before.

EXACTLY! There are always degrees of quality of work...it can be plotted against time as well. ; ) A good friend of mine does SCCA tech inspection for WC and boy does he have stories...not that I'm surprised.

I have a pretty good understanding of my chassis limitations so I have work to do to design a good cage to make it better than a typical club cage if I want to get some performance out of it. It should be a fun challenge and I'm looking forward to it. Ultimately there will be compromises depending on class limitations, cost/benefit, and how far I actually want to take a 20 year old chassis as a dedicated club car. If I were starting with a butt ugly E90 that might be different......; )

Suspension is still a big variable for me as well. Once again, how far do I want to go for a 20 year old chassis as a dedicated club car? I'm trying learn all the options right now and what is best for me. I can pretty much do what I want where budget is my only limitation. Course that's a big one. Feel free to pass along suspension advice privately. ; )