pegdrag

Bit of a discussion of bolt in bars for the GT4 vs welded in bars. We've a lot more people who have years of racing experience in the 993 forums (or thats my impression) and wanted to get some thoughts. There are a lot of vendors selling bolt in bars for the GT4.

Here is the link:

https://rennlist.com/forums/gt4/9397...l#post13384142

race911

You've got a couple of experts in your state, I'd start there. If not, down here in the Bay Area, Tony Colicchio is the go-to guy for about a decade now, and he's fab'd pretty much everything for everything. (Not to mention as a driver he's got a couple of national championships, albeit in BMW.)

Cayman specific, I'll go out on a not-so-much of a limb and say he was doing Cayman hoops/cages when they first were available and Mooty sent a brand new car over to his shop.

Bill Verburg

A can only add that a welded in bar stiffens the car much more than a bolt in, and a full welded in in cage furthers that effect.

pegdrag

Thanks to both of you.

I'm past the point in my career that I'm going to race, but we've seen a bunch of vendors selling bolt in bars for the the GT4 and I'm not sure how one picks one. I'm not sure how well bolt in bars are going to work for something even semi-nasty. I get that most things that happen aren't nasty, but if I were going racing again I'd vote for welded in by someone who has done lots of them. I also get that people like bolt in's for the convenience and resale, but......

In my day (I'm not as old as the hills, but I've been on good terms with the hills for years), we had welded in roll cages....the state of the art has advanced and maybe the bolt ins are ok. Just not sure.

I think I know both of the guys in Oregon.

I'm not sure what I'm gonna do, myself. Mulling it over. Wife says "go back and do some HPDE, you'll enjoy it and not kill yourself, go do some race school".

She might be trying to get rid of me. (gotta stand up now to squint at the screen and shake out the rheumatism).

OverBoosted28

As others have stated, I'm sure weld in is optimal. But a bolt in is surely better than a sharp stick in the eye. May not reap all of the weld in benefits, but may stop the roof from a total collapse.

jscott82

Are we talking roll bars or cages? I don't think I've ever seen a weld-in single hoop bar. Bars really don't add that much of a safety factor to a modern car. They are a perfect place to mount harnesses though... You are much more likely to experience a side impact or diagonal forces that a bar just doesn't help very much with. At a minimum look at the tubing being used. 1.625" x .095" Alloy Steel is the minimum PCA spec material.

If we are talking cages for racing:
There are good weld in cages and there are bad ones... same goes for bolt in.
Most bolt-in cages are compromised though. Not because of the bolts, but because their major design criterial is to be "easy" (easy to install and easy to use). A proper cage with door bars and diagonal supports is a PAIN IN THE *** in all reguards.

Sleepless

I would never run with a bolt in bar. Seen to many shear off in serious wrecks.

golfnutintib

i am by no means an expert at this, but just using some common sense and basic engineering knowledge...

...i certainly don't think it is by accident that vendors like rss et al call these bars HARNESS bars, not roll bars...

...hard to imagine a bar held by bolts will be stronger than good welds... i guess it depends on the size and nature of the bolts... ultimately it is driven by shear forces and fastener design and metallurgy in case of a serious impact or rollover...so ultimately it is completely application-, hardware- and situation-specific

having said all this, i think anyone buying one of the half cages/roll bars/harness bars thinking they will yield MEANINGFUL impact or roll protection over what a modern Porsche provides out of the factory is being optimistic/foolish...

OverBoosted28

I have the DAS bolt in bar. I think that it's not just optimistic (or foolish) to feel that the bar adds an element of safety. It's 1.75" X 0.120 and engineered pretty well. Sure it's not a cage, and it has its drawbacks, but they are outweighed by the benefit, of not having anything. For the street, you need to consider the possibility of striking it in a collision, but proper restraint use, should help avoid that. I'm sure this guy (and some others) is glad he had it.