TRM Bolt-in Roll Bar pictures

[Massive Lee]

I hope I am not sounding rude, but please allow me to add my grain of salt as a BMW Club event organizer, instructor and tech inspector. Unless that hoop gets a harness bar at proper height, there is no way I would allow the car to set a wheel on the track unless the occupants agree to wear a regular three-point belt. The rear harness pick-up point appears to be too low for safety if it is between the two wheel wells. Maybe that pictures don't give justice to therear installation though. Under frontal impact, the harness will compress the driver's and passenger's spine if the rear pick-up point is too low.

The harness belt should be within the 20degree range. Even the drawing is not acurate BTW as most drivers are not that reclined.

[155///MPH]

Whoops, my bad. I shouldn't have assumed you meant 6 points.

Roll bar looks to be of top notch design and execution like usual.

JP

[matt]

Wrong one... http://www.schrothracing.com/docs/Ra...structions.pdf

The link you posted applies to competition harneses designed to be used with HANS devices. Frankly, nobody with a HANS is buying a bolt-in roll bar. This bar is compatible with stock belts also.

I'm going to see about adding a more typical harness bar for production versions, but I am perfectly happy with the arrangement in my own car.

[155///MPH]

From the Schroth Harness Mounting Guide:

"SHOULDER BELT ROUTING

�� Shoulder belts must run from the shoulders horizontally or down, at no
more than a 20° angle.
�� In cases where the shoulder belts must be routed down to the chassis
floor, support by a roll cage bar or harness guide at the appropriate
height is essential to establish the horizontal shoulder strap routing off
the shoulder/HANS®. Most racing seats are not designed and tested to
carry shoulder belt crash loads from downward installation. Severe
injury or death could result. A 45° downward shoulder belt installation is
possible with seats that SCHROTH has positively tested to take a load
measured during a 50 kph [31 mph] and 28 G impact. Refer to the list
of SCHROTH approved racing seats in section “Bolts, Seats and Stuff”.
WARNING: 45° downward shoulder belt installation must never be
used with HANS®.
�� For the best restraint of the occupant’s upper torso, anchor points
should not be further back than 200 mm [8”] from back of user’s seat.
�� In the event that the anchor points are further towards the rear of the
vehicle [e.g. using a roll cage bar for wrap around attachment] the
distance between the strap anchorages will narrow or even cross over
as described in following graphs and formulas.
�� It is especially crucial to follow this strap routing when HANS® is in use."

The way you are doing it isn't wrong per se, but isn't what I would consider optimal given the choice.

Its a good read if you haven't gone through it.

http://www.schrothracing.com/docs/Competition_Instructions.pdf

[matt]

Less stretch = more energy transmitted to your body. Although I would guess the amount of stretch in harnesses is pretty low.

We can do a harness bar within the main hoop, no problem. For my own car, I prefer this way.

[155///MPH]

Its not optimal though is it? I am under the impression that those belts should be as short as possible to minimize the belt stretch in the event of an impact. Less belt = less stretch.

I'm just saying you may want to offer some sort of conventional harness bar closer to the seats.

JP

[matt]

Yes, but no longer than bolting them to the rear seat belt mount like I think most people do. (shorter in fact) And it gets the angle right.

It's pretty common... http://e30m3performance.com/tech_art.../Mvc-a038f.jpg

[155///MPH]

It also has a bar between the rear braces that will function as a rear shock tower bar and harness bar.

???? Won't that make for some long harnesses?

[matt]

Hey guys... my car got a little safety upgrade recently. :mrgreen:

We'll be selling these bars soon. I really like the design and it fits really well to the chassis and roof. The base plates are bent from 3/16" steel and follow the contours of the body really well. It also has a bar between the rear braces that will function as a rear shock tower bar and harness bar.

Pricing is TBD on these, but they will be available as fully assembled bars and weld-it-yourself kits. I may also have some cage "starter kits" soon with pre-bent main hoops and A-pillars, and probably some stamped and bent base plates. I will update this with pricing ASAP.

Pics follow. It's just tacked in, it'll be removed to make a jig before being finish welded on the jig. Sorry for the crappy camera phone pics.