Are Z4 roll bars...

[ZEEFOUR]

Are the roll bars track worthy? I belong to the national Benz club which is having a track day at Summit point raceway, while the perferred car is a mercedes i was thinking of taken the Z4 instead, but when i read the fine print, it said "only cars with track worthy roll protection for convertibles are allowed, Z4, Boxster, and a few others are not allowed" and they stated that for mercedes SLs that a hard top had to be used. I thought the Z4 roll bars were crash/track worthy

[inTgr8r]

Each track is different.
- some say hoops must be 2" above the helmet.

I had no trouble here at a BMW CCA DE event.
That said if I was tracking on a regular basis.. I'd want a cage.

[ward]

BMWCCA where I am won't let any convertibles run

there are other groups that are fine with the stock configuration though

[LeifG]

Originally Posted by inTgr8r

Each track is different.
- some say hoops must be 2" above the helmet.

I had no trouble here at a BMW CCA DE event.
That said if I was tracking on a regular basis.. I'd want a cage.

Yes...exactly. The club I ran with while I lived in CT allowed you participate in track day as long as the top of your helmet was still at least 1 inch below the horizontal plane between the top of the roll bar and the top of the windshield.

Though it does depend on the particular club and sometimes the track on the specific requirements.

[ZEEFOUR]

Thanks guys, i guess with a helmet on you are close to being even with the roll bars

[inTgr8r]

Originally Posted by ZEEFOUR

Thanks guys, i guess with a helmet on you are close to being even with the roll bars

... Depends how close your azz is to your hat rack.

[Daveop]

After seeing how a car acts when its flipped on a track, I wouldn't want to run a roadster on a track either With that said theres obviously nothing wrong with a properly designed open top car, look at the old open top lemans gt1 cars

[AlanL]

This is one of the main reasons I bought a Coupe.

Up until this season I have been a pretty hard core track junkie typically doing at least 12 events/year. I switched from driving Audi S4's a couple of years ago to a lighter Honda S2000 roadster, but wasn't comfortable with the roll hoops in that car. They were quite similar to the Z4 hoops.

Almost every club has different rules for rollover protection and some will let you drive the Z4 roadster as is. Others are clamping down pretty hard on all open top cars and I think this trend will continue as long as insurance companies are able to influence the clubs.

Our regional CCA chapter in Seattle had a rule stating that all drop top cars had to have a 5 or 6 point harness with your roll hoops and 2" of clearance to your helmet, but you would have to be insane to install a harness without a true roll bar having at least 4 points of contact with the frame. I did put such a bar/racing seat/6 point harness in my S2000 and certainly felt a lot safer than I ever did with my OEM roll hoops, but the bar made the car so stiff it was almost unusable as a daily driver.

BMW CCA has made it an option this year for chapters to rule convertibles out entirely and the Puget Sound chapter did elect to do that this year. It does not matter what safety options you add to the car in this case - if your car doesn't have a builtin C roof pillar you can't drive it on the track.

I ordered my Coupe with the intent of continuing my track habit this year, but the insurance companies have thrown a pretty nasty monkey wrench into my plans. Almost every major insurance carrier changed their policy coverage exclusion language this year to state they they will cover nothing that happens if it happens at a facility prepared for racing or high speed driving. They used to only exclude coverage if you were driving at a timed event or practicing for one, but this is inclusive of almost all club track events as we know them. There was at least one accident at my local track in Portland last summer where a guy totaled an E46 M3 and his insurance company said have a nice day.

I have driven in over 80 such events without an incident, but I am not willing to take a chance on wadding up my new Z4 with no chance it will be covered.

[FloridaBoy]

Originally Posted by AlanL

There was at least one accident at my local track in Portland last summer where a guy totaled an E46 M3 and his insurance company said have a nice day.

Ouch.

[ay8306]

It is interesting the perception if safety a "tin" roof gives. Well designed roll hoops coupled with a good harness can actually provide more safety than a typical car roof. In the case of the Z4, the roll hoops and the windshield frame are solidly integrated into the vehicle structure and provide rigid cage for the driver in the event of a roll over.

It is not uncommon for all or a portion of a "conventional" roof to collapse in a roll over. So, if a track is concerned enough about safety to arbitrarily ban convertibles then they should also require steel race cages for other cars.

[Vroomer]

I haven't told you all my Alpine 500 story from this year, have I? The 1959 Austin Healey Bug Eyed Sprite one?

[rosierobins2003]

SPILL and make it NOW. Vroomer!!!

Rosie

[inTgr8r]

Originally Posted by ay8306

It is interesting the perception if safety a "tin" roof gives. Well designed roll hoops coupled with a good harness can actually provide more safety than a typical car roof. In the case of the Z4, the roll hoops and the windshield frame are solidly integrated into the vehicle structure and provide rigid cage for the driver in the event of a roll over.

It is not uncommon for all or a portion of a "conventional" roof to collapse in a roll over. So, if a track is concerned enough about safety to arbitrarily ban convertibles then they should also require steel race cages for other cars.

I know you refered to Z4....
But I know of a Z3 that the windscreen did not hold up during roll over.

[AlanL]

Originally Posted by ay8306

It is interesting the perception if safety a "tin" roof gives. Well designed roll hoops coupled with a good harness can actually provide more safety than a typical car roof. In the case of the Z4, the roll hoops and the windshield frame are solidly integrated into the vehicle structure and provide rigid cage for the driver in the event of a roll over.

It is not uncommon for all or a portion of a "conventional" roof to collapse in a roll over. So, if a track is concerned enough about safety to arbitrarily ban convertibles then they should also require steel race cages for other cars.

One of the main arguments I have always heard is that the tin roof will at least hold you arms in while the car is rolling over. Some clubs (Porsche for instance) require that convertible owners drive with their tops up for this reason. I do agree that a well done bar with 4 points to the frame is safer than the average hardtop car anyway.

I have yet to see a well documented case of a modern car with a complete roof collapse. There was a photo of a car that got circulated for a while on the net showing what looked like that, but it turned out that firemen had cut the top off to get the occupants out and then put the sawed off top back on the wrecked car before the picture was taken. The hard top will collapse enough that you should not wear a rigid 5 or 6 point harness unless you have a bar too.

[3GFX]

Has anyone measured the diameter of the tubes without the trim?

[Huz-Z]

Most folks here know that the E85 roll bars are welded to the structure of the car. It’s my understanding that together with the windshield frame which is a reinforced structure, they are designed to support the weight of the car in a roll over without collapse.

https://z4-forum.com/forum/viewtopic.php?t=64487

[Steeler]

3GFX I vaguely recall the tubes being 1.5” diameter

[Huz-Z]

Here is an account of how the car performs in a roll over:

https://www.bimmerfest.com/forums/sh...s/19005?page=1

[3GFX]

Originally Posted by dbarton62

3GFX I vaguely recall the tubes being 1.5” diameter

Thanks!

BMW 41117064655 41117064656 are the left and right part numbers. I was hoping the info would be useful for time attack. Unfortunately the car needs an aftermarket roll bar setup.

Originally Posted by Huz-Z

Here is an account of how the car performs in a roll over:

https://www.bimmerfest.com/forums/sh...s/19005?page=1

This is why I'm surprised it needs a cage/diagonal cross brace setup for competition.

But safety first, rather be safe than sorry.

[T-Bears]

It's fine for a regular trackday/ HPDE.