safety devices roll bar owners: plate dimensions please!

[aigel]

Picked up a used safety devices roll bar that has been cut flush, right through the tubing at the front mounting brackets. PO had trouble fitting the nut plates underneath the mounting brackets because the bar hit the roof. To make room he opted to just weld the mounting brackets to the body! While that worked fine for the time being, removing the bar, he cut the tubing because the mounting brackets were too well married to the body ....

I would like to now fab new brackets, and weld them to the tubing. Than fab nut plates that I can weld to the body. Basically, do a proper install as originally intended. (that will allow pulling the assembly by removing bolts). The fit will be good because about 1/4 inch in material is now missing from the tubing ...

Any of you have this rollbar and can pull up their carpet to give me the dimensions of the front brackets and the nut plate? I am especially interested in thickness and thread / bolt sizes.

I could make something up, from looking at pictures that I found here, but was hoping someone can help me out with some measurements / true dimensions.

Cheers, George

[nick-moss]

Here are dimensions for the rear 4 point cage

[aigel]

Nick:

Thanks so much for the info. I think I have a different bar. Mine had brackets like these. Look at the first and last pic posted in this thread:

http://forums.pelicanparts.com/porsche-911-technical-forum/131495-roll-bar.html#post996667

I need to know the dimensions of this foot and the nut bracket that came with it. Plus the size of the bolts. I am also wondering if all three holes were utilized in this setup on the front bracket or only the back top and the side one.

I have a bit of time to research this more closely. On the other hand, the bar is in there now, ready to be welded. I hope I won't loose patience and just weld a plate to the tubing and weld the sucker in.

Thanks!

George

[Chuck Moreland]

Is that plate 3/16 inch? And are the nut plate the same size as these feet?

I'm fabbing my own roll bar with similar nut plates, right now.

[aigel]

Chuck:

That's exactly the info I am after. How thick are the plates and what's the thread / bolt size. How many bolts?

I can play i by ear. I think the plate on the bar is at least 3/16 if not a 1/4 inch. The 1/4 inch will be hard to bend at home due to the big piece of metal soaking up the heat. PCA rules ask for 3/16 if you weld it to the body. So, I think the nut plate and the bar plate can be 3/16. If anything, I'd make the nut plate a bit thicker ...

Hope to hear from someone that actually HAS this setup. TIA,

George

[Chuck Moreland]

I am using 3/16 for both sets of plates. And 4x 3/8 bolts at each location. 1/4 plate would seem excessive, and if the plates pictured are 1/4 then the holes are probably 5/8 inch. I don't think they are that massive!

[aigel]

Chuck:

You think you have enough threads in the nut plate? I mean, the plate is just a plate with threaded holes, right? Or are you going to weld nuts to it?

Cheers, George

[dad911]

The safety devices weld-in plates have bolts welded to the back. IMO Tapping threads in 3/16 plate isn't strong enough.

[Chuck Moreland]

I welded nuts to the plates. I agree, tapping threads would not be enough.

[aigel]

Alan:

Thanks for the input. I agree on the 3/16 plate being to thin to tap. I thought at least 1/4 inch plate with a fine thread would be the way to go. Yikes on the nuts, that means you have to punch some pretty big holes in your sheet metal to accomodate them!?

George

[1fastredsc]

As i battle my roll bar still, one of the options i had to dismiss was welding to the bar. Turns out chromoly which is what safety devices roll bars are made of is a real pain in the ass to weld without sacrificing structural integrity.
As far as the plates, they are roughly 3/16's but have large nuts welded to the back of them. Basically you must line up the nuts on the back to the spot which you want the leg to contact, then drill 1 inch holes into the chassis so that the nuts recess into the chassis allowing the plate to sit flush and be welded.
BTW, GL, you'll need it.

[aigel]

Originally posted by 1fastredsc
As i battle my roll bar still, one of the options i had to dismiss was welding to the bar. Turns out chromoly which is what safety devices roll bars are made of is a real pain in the ass to weld without sacrificing structural integrity.
As far as the plates, they are roughly 3/16's but have large nuts welded to the back of them. Basically you must line up the nuts on the back to the spot which you want the leg to contact, then drill 1 inch holes into the chassis so that the nuts recess into the chassis allowing the plate to sit flush and be welded.
BTW, GL, you'll need it.

Even without exact measurements, things are starting to shape up in a way that I can fabricate decently.

One very important detail: How do you know the bars are chrome moly? All I found online said that they were DOM steel. It would be very valuable info to find out if they are indeed moly or not.

If it turns out it is chrome moly: From all that I know it isn't that big a deal to MIG weld chrome moly if you have a torch to heat treat the welded area to red hot to work the embrittlement out of it. People also put smaller things in ovens and heat treat at 1200F. If you are still uncomfortable, bring it to a speed shop and have them TIG weld it.

Again, please let me know where you found the moly info on the safety devices bars, so I can do a proper procedure!

Cheers, George

[nick-moss]

I beleive most simple Safety Devices cages are FE45 steel, the complicated multipoint cages are 25Cr Mo

http://www.safetydevices.co.uk

[aigel]

Nick:

You seem to come to a similar conclusion than I did from this info: http://www.stable-energies.com/safdev/safety.html shows the #5 type cages to be steel, drawn over mandrel. No word about moly. Time to crank up the MIG?

I really appreciate the help, guys!

George

[dean]

I think if you go with 4"x''4"x1/4" you should be fine. I wouldn't tap 1/4" plate though. I would weld nuts on. Maybe ask the manufacture or SCCA for the rules for roll bars.

[aigel]

I emailed and talked to Stable Energies who sell the Safety Devices roll bars. They were extremely helpful: They spent quite some time with me determining which bar I had. They had the install kit from Safety Devices in stock. That includes the nut plates! So, after $75 for the kit plus shipping, all I will have left to do is weld new feet to the tubing of the bar. I verified with Stable Energies that the bar is indeed steel, not chrome moly.

Thanks for all your help guys! I will report back with how the install went and post a few pictures. It will likely happen the WE after next.

George