Dan's track day to race car progression thread

[DanThe]

This is a bolt in safety devices cage that ive been molesting, I got it cheap as the chap had started to fit it to an E36 but not finished, so the feet had been removed and another piece put in the rear. It was for a sunroof car but ive cut the sunroof gear out of this and lifted the cage up as high as poss, sleeved the bottom of the tube where the feet join with heavy duty CDS, ive tied the main hoop into the B pillar and the front sections onto the A pillar, ive moved the diagonal to the hoop and put a rear piece in for harnesses. The only other sections ive been planning to fit are door bars.

Would it benefit me to brace anywhere else?

Pics-

[GeoffBob]

I' d suggest joining front to rear next to the seat/s to protect against side impact. Two bars in the typical x-pattern is ideal, but one at the very least would be advisable (imo). Makes getting in and out a little more tricky, but could be worth the extra effort one day.

[DanThe]

Yeah I will be fitting bolt in door bars Geoff, did a few gussets this afternoon



I will be getting it sandblasted and powder coated soon so dont want to feel like ive missed bits out later on.
I thought about joining from the rear feet at the arches to the lower section of the main hoop, but I dont think it would make a significant difference to warrant the extra weight, not sure really

[DanThe]

Just been reading a few threads and realised ive fcked up by not having any spreader plates

Can I use a box section like this welded to the floor/sills or would this also need a spreader plate under/around the mounting points?



Ive looked at the blue book a bit, not that this will be used for racing, just want it to be safe

[UweM3]

Personally I don't like this boxes. I didn't want to have something with sharp corners next to my feet. Call me paranoid.
My cage was welded with spreader plates right to the floor



you could add some corner pieces between B-Pillar hoop and the roof bar


but keep in mind, the more bars you add, the more flexible you need to be


I had just one cross bar added in the roof to keep the headroom but would add a second one if I had to do it again.

[gcs325i]

Would a brace between the base of the main hoop to the rear arch/harness bar area be beneficial or over kill? Like wise a low level brace at the base of the main hoop?

[DanThe]

Good point about the ankle breaker Uwe, I will box at the hoop bases and plate the fronts, its a bolt in cage so I cant brace between the hoop and roof bar as it needs to be removable.

Would a brace between the base of the main hoop to the rear arch/harness bar area be beneficial or over kill?

I was thinking about this and couldnt decide, like ive said its only a bolt in cage so structural strength benefits will be minimal, I think such a bar would only benefit the rigidity of the car in a fully welded cage, so wouldnt be much use to me.

A horizontal bar at the base of the cage would benefit in a side shunt situation, depends if I can get the cage out of the car with it in, I will defo look at that though

Thanks chaps

[GeoffBob]

Personally I don't like this boxes. I didn't want to have something with sharp corners next to my feet. Call me paranoid. My cage was welded with spreader plates right to the floor

Agreed.

Dan, see how Uwe mounted a short vertical piece of CDS directly over the points where the rear sub-frame bolts in place under the car. He then welded two diagonals to that tube, and then triangulated the whole thing in. That is well worth doing as it significantly reinforces two very critical points to which the rear sub-frame connects. A further requirement (imo) is to drop something from the frame/cage down to the differential.

[DanThe]

I would do that but this is a bolt in cage Geoff
I will be making a separate rear strut brace and using an E36 diff backplate, cant decide whether to just mount a second hanger on the existing top hat section chassis piece or pull it all out and replace it with box section tied into the rear strut brace. I want to test this car with slicks on the drag strip so it needs to be strong around the diff

Like this -

[UweM3]

I had prepared to tie the diff into the cage but decided against it after driving with a car which had the cage connected. NOISE! you can hear the gears grinding a lot and you also need to mount the subframe on solid bushes and back then I was still road driving the M3 a fair bit so I decided against it.

also be warned about door bars, a real PIA if you drive the car a lot. And watch out for the indicator stalk....

[DanThe]

Same reasons why ive decided to use an E36 backplate, stronger mounting but still mounted via rubber bushes. I dont want to have to wear earplugs, it will still be a road going car.
I will mount the door bars running down/forward so I dont have to climb over as much.

Started to make a few bits of the box today







The card is a template for the next bit I will cut out and weld against the inner sill
For the spreader plate, will a strip under the inner edge of the folded section ive made be enough? Or should I plate under the whole area?

[GeoffBob]

Are you 100% certain you want it bolted in Dan? I'd sand-blast it once you have the basics worked out and then weld it in similar to Uwes. The additional rigidity around the rear subframe mounting points is quite important and well worth the effort (as was implemented on the DTM cars). Alternatively, maybe you could engineer a bolt-in alternative with just the short piece of CDS welded to the top of the mounting point (sticking up) with "ears" as points to bolt to.

Note that this is not the same function as a rear strut brace, and is there to reinforce the points on the body to which the rear subframe attach. It doesn't just stop these points moving (as they will when you replace your bushes with something stiffer), it stops them from failing. It's not to say that without reinforcing these points the worst will definitely happen, but with enough abuse they can tear and finish up like this:



Incidentally, I have an E36 diff cover fitted to my car. I'd recommend cutting the floor of the boot out and running your own square tube across upon which you can weld your own hangers. Here's mine:

[DanThe]

I was going to weld it in, but then I realised the front legs come down passenger side of the dash, rather than follow the A pillars. Plus this is all 38.1mm diameter tube so is not up to current racing spec, if I did weld a cage in id want it to be up to race spec as it would be a permanent fixture.
If I keep it bolt in I can always sell it on later and upgrade to a fully welded cage.

I will look at those rear beam mounts, if I can make the car stiffer then its all good

I found a pic of a rear diff hanger last night

[MrBenn]

Dan, the more full on of the safety devices cage's (B7 I think its called) incorporates the rear subframe points as Geoff advises, and this is still a bolt in cage so it should be possible for you to add it in and keep it removable. I probably have some photos somewhere if you need them.

[UweM3]

I believe a bolt in cage is more of a safety add on in the first place rather than a shell stiffening mod. Sure it adds some strength but this is not the initial motivation of fitting one IMHO.

Therefore I would not make it too complicated with adding rear axle or diff pickups etc.
If you go that far you might just weld it all in.

Just my opinion of course.

[DanThe]

TBH, after taking the cage back out I dont really want to make it much heavier!

I would like to see some pics of that cage if you have some Alex

Had half hour on it today, managed to get the first spreader plate battered into shape and migged in



3mm plate is a bitch to shape up

[MrBenn]

I have this one to hand, I'll dig out some more later on if you want them.

The red lines show all the points its bolted to the shell, some are existing bolt points others required a welded in threaded spreader.
I agree with what Uwe says about bolt in cages but you may as well do what you can to try and make it better.

[rix313]

That's not for sale is it Alex?

[MrBenn]

That's not for sale is it Alex?

Sold it ages ago Richard. (god knows why)

[DanThe]

If you have some pics of the rear beam mount pickup that would be great, im trying to get my head round how it would bolt in, unless longer bolts are used to bolt through the cage?

I take it the roof mountings need a welded in boss, got any pics of these? As you say, if you can improve it then why not, bolting to the roof rails would be good IMO

[MrBenn]

I'll dig some more photos out for you Dan. But you are right, longer bolts pass through the vertical pipe in the cage all the way through the bush. I have a couple of these extra long bolts going spare if you need them.
Photos in an hour or so.

[MrBenn]

From looking at your photos, it seems you've covered most of the points that my cage also used, but here are a couple more photos. (ignore the rust, the shell was scrapped a few years back)








Another thing you could incorporate is these, which bolt ontop of the rear strut towers. It just so happens I have spare pair sat here

[DanThe]

Fantastic

I will defo get some tags into the roof rails, wont add any weight to moan about.
The B pillar tags I made have stiffened it all up a treat now ive gusseted them

I think the rear subframe pickup would be worth doing for the sake of a couple more kg even if it is just bolted through, also as I have some poly bushes to fit to the beam.
I was planning on welding a tube between the rear strut tops and leaving it at that TBH

I got the spreader plates finished and welded up in-between jobs today, cut the cage down and test fit.







Im thinking I should beef up the thickness of the feet, 4mm maybe?

[UweM3]

you are not going to leave that "box" open? I would say at least 3mm thickness and some proper weld nuts on the inside of the box

[DanThe]

No, the closing plate will be the last piece to go in. Im just test fitting at the mo, I will make another plate with welded nuts and weld it on the underside of the box

[DanThe]

The cage is very close to the roof rails, I lifted it as high as possible when I started messing so any ties to the roof will have to be underneath. I will have another think about this, dont want anything sticking out that could cause head injuries.





I have room to tie the front top bar though,



Will make brackets similar to what I did on the B pillar -



I had a look at the rear subframe mount, the one bar will be near vertical as it will end above the wheel arch





After all that head scratching I did get some work done eventually, got the front spreader plates in and made some feet for the main hoop out of 3.5mm plate







I will plate up to the sill on those front spreader plates too

[Demlotcrew]

Looking good Dan, having some of those brackets welded and tied to the A and B pillars will help no end! My cage moves a lot when under strain.

This is what the current cages from Safety Devices come with for the rear.



Andrew

[DanThe]

That looks to be probably the best box ive seen, welds to many strong points

Got any more inspiring pics?

[Demlotcrew]

I dont have many buddy, but of the ones i do, i can share:

excuse wax oil all over the shell, it doesnt look anything like this now!




Just to add, i spent a lot of time, shaping the boxes to absolutely fit as tightly as possible to the body of the car, a tedious process but it was worth it as the weld would be stronger.

Andrew

[DanThe]

Looks like the door bars are quite low

[Demlotcrew]

Yes i believe for FIA and MSA approval they have to be at the same level as your hip, not 100% on that one!

Andrew

[Demlotcrew]

Just took this photo for you.



Andrew

[DanThe]

Perfect! The bends are obviously to keep the brackets at 90 degrees

[Demlotcrew]

Dan, do you need me to measure from the floors to the brackets on the front and rear of the beam?

[DanThe]

The pics are fine, thanks for the offer though