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Need Historic Roll Cage Evidence!


DaveBMX

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Would any of you history buffs happen to have a vintage racing photo of an 02 with a roll cage welded to the rear shock turret tops?

 

Im trying to make sure im good for rallying in the uk and its says that roll cage can only be attached to suspension pickup points if it can be proven that it was done in period.

 

If not i can always alter my design as i havent made it yet!

 

 

". All bars must remain within the

confines of the passenger compartment and must not
be used as suspension pick up point bracing unless
the competitor can prove that this was done in period
to the specific model."

 

 

regards

 

 

Dave

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You'd be safe doing that-

 

the rear spring perches are by no possible means a suspension pick- up point.

 

The springs are all that attach there, while the suspension is held in place by

the rear subframe and its mounts.

 

If you want to get the rear points, you have to get the floor where the rear 

subframe bolt goes thru- and to do that and keep minimum angles,

you'd have to be about 4'6" and move the main hoop forward about 10"

in front of the b pillar.

 

Even then, you could argue that the subframe mounts aren't a suspension pickup point-

those are really the tabs ON the subframe itself.

 

Likewise, in front, if you move the allowed punch- thru points to their maximum height, and

shape that baseplate creatively (and fold it properly) you can catch most of the front 

suspension structure and reinforce it very effectively.  And it's perfectly legal.

 

(yes, you have to read the rules the right way, of course!)

 

t

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Think about what happens if the rear shock mounts move. 

 

They are not the spring perch so the only load going through that point is when the suspension is MOVING, and only the load that the shocks are exerting on it. 

 

All of the load in a steady state turn is put into the unibody at the 2 points at the end of the rear crossmember where it attaches at the floor ahead of the wheel well, the rear differential mounts and the spring perches. 

 

If the shock mounts DO move it will not alter suspension geometry or the contact patch on the ground. 

 

There is the possibility that if it moves over time even small amounts it might cause some metal fatigue and a crack might start somewhere. 

 

I don't believe you gain enough in potential performance improvement to offset the weight of running the tubes through the bulkhead (cross bracing and everything might be as little as 25 lbs) 

 

It would not significantly strengthen the cage for driver/ co-driver protection, in fact it will reduce the crush zone behind the driver that allows the car to absorb an impact and not transfer it right into the driver compartment. 

 

You might run into a problem with the tech inspectors if they really want to be a pain,  is it really worth the hassle, cost, and weight?

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You really need to ask from someone local how they interpret FIA rules there. First what I notice is the word "and" here

"All bars must remain within the confines of the passenger compartment and..." 

 

If you read it "tight" it's already forbidden there because trunk is not passenger compartment.

 

There's many cases in Finland about solutions that have been used for years until somebody in the organization makes new more tight interpretation and then it's not legal anymore.

 

  Tommy

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Gawd, yeah- use the base plate to spread as much as you can, and catch the seam into the doubled

'tube' that goes around the rear wheel wells. 

That's a very strong part of the car, and ties into the lower suspension pickup point and rocker tube

just like you'd like it to.

 

 

Plus, it's easy.

 

 

Plus, the shock and spring mount can move a bit, and you're not going to lose any geometry.

Box your trailing arms if you're worried about that!  It's period- correct- for tii's...

 

heh

 

t

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Attached are some images of the repair work done to the cage in my AlpinA o2 race car.  Sometime after AlpinA sold the car off someone made some "modifications" - not good ones either to the roll cage.  Essentially they cut up the cage in various places and at the important spots where the cage should have mounted to the frame rails, they welded plates onto the bottom of the tubes and then welded and bolted those to the floor.  The sheet metal in the floor is fairly thin and not what you want your cage mounted to.  By most standards today this is pretty lightweight cage with not a lot of tube, but this is what they ran back then and it is a historic car.  Now everything has been tied back into the frame rails, all other welds re-done/corrected.  At the front, we added a bar that ties the cage in from right to left and then that is tied back into the front bulkhead.  AlpinA used a standard dash board which is what will go back in this car, so the bars behind the dash are hidden from view.  Roger Hamlin, Hamlin Fabrication (Sonoma, CA) did all the work on this.

 

 

post-38814-0-69953300-1388271149_thumb.j

post-38814-0-20523600-1388271173_thumb.j

post-38814-0-04207700-1388271195_thumb.j

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post-38814-0-78901600-1388271244_thumb.j

post-38814-0-92743100-1388271266_thumb.j

post-38814-0-13521500-1388271318_thumb.j

post-38814-0-49570400-1388271362_thumb.j

post-38814-0-93235700-1388271408_thumb.j

post-38814-0-99734000-1388271433_thumb.j

 

www.alpinabmw2002.com

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That is correct, they (AlpinA) did a lot of work on the suspension (pick up points) both front and rear.  The rear shocks are AlpinA/Bilstein coil over's with AlpinA springs.  At some point one of the PO's seriously butchered the cage, very curious as I can't think of any reason why they would have needed to make any modifications (other than possibly adding some reinforcing).  Quite a bit of work to put things back right with correct metric tube etc.,

 

www.alpinabmw2002.com

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That is correct, they (AlpinA) did a lot of work on the suspension (pick up points) both front and rear.  The rear shocks are AlpinA/Bilstein coil over's with AlpinA springs.  At some point one of the PO's seriously butchered the cage, very curious as I can't think of any reason why they would have needed to make any modifications (other than possibly adding some reinforcing).  Quite a bit of work to put things back right with correct metric tube etc.,

 

www.alpinabmw2002.com

 

As nice as the Alpina cage is it's not according to FIA rules unless it's certified. It looks that it wasn't or the owner didn't have the certification documentation so he had to make it according to rule book. It only allows mounting with the plates at tube ends. They must be bolted with 3 pcs of 8.8 grade M8 bolts and can be welded but still need the bolts. Anybody can see that the Alpina made mounting is stronger but still no go.  IMO rules are very stupid. e.g.You can't add any tubing that is not in the book though it would increase safety.

 

  Tommy

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