Racing seat and 4 point harness in Z4M

intoflatlines · 06-11-2014, 11:09 AM

I understand that this idea is not recommended for street or track use, this is merely an idea for autocross purposes.

A local Z3M guy has an intriguing setup in his car. He replaced the stock seats with racing seats that accept stock seatbelts for street and track driving. But he also has a Schroth harness that he uses for autocross. What he does is attach the bottom straps to the rear seat anchors, and then he fabricated a bar that attaches behind the OEM roll hoop to attach the shoulder straps. There is a wide metal bar that fits inside the roll hoop to prevent the bar from riding up.

Has anyone done something similar to this on a Z4M? I'd like to explore a solution like this for autocross as well (keeping stock seatbelt for street/track of course).

inTgr8r · 06-11-2014, 11:16 AM

Yes it has been done.... custom setup.
The main point of discussion is that it compromises your safety in the event of rollover.

intoflatlines · 06-11-2014, 11:20 AM

Very true - but that would not be a tangible concern for autocross-only situations, right? Another possibility is that if someone did want to use the custom harness for street/track for whatever reason (I don't), you could wear your stock belt at the same time, yes?

Side note - as a racing seat noob, how can you tell which seats can and cannot accept stock seatbelts? Can they all?

3002 tii · 06-18-2014, 09:14 AM

Quote:

Originally Posted by intoflatlines

Very true - but that would not be a tangible concern for autocross-only situations, right? Another possibility is that if someone did want to use the custom harness for street/track for whatever reason (I don't), you could wear your stock belt at the same time, yes?

Side note - as a racing seat noob, how can you tell which seats can and cannot accept stock seatbelts? Can they all?

I have race seats with both harnesses & stock belts installed. I use stock belts to/from track, harnesses on track. All seats should be able to accept stock belts, it's just a matter of finding a way to mount the factory receptacle. Some drill into the trans tunnel, others use VAC or MS mounts.

TexasZed4MC · 06-18-2014, 10:22 AM

At 6'3" its IMPOSSIBLE to get a harness bar or half roll cage in my car and me be able to get my seat back far enough back so I can get in the dang car! Oh well I can only wish.

3002 tii · 06-18-2014, 11:18 AM

Quote:

Originally Posted by TexasZed4MC

At 6'3" its IMPOSSIBLE to get a harness bar or half roll cage in my car and me be able to get my seat back far enough back so I can get in the dang car! Oh well I can only wish.

Simple fix, trade the car for a M6! =D

Barryb97 · 06-18-2014, 01:42 PM

For a half cage this was pretty non-intrusive. https://m.facebook.com/story.php?sto...153589495&_rdr

intoflatlines · 06-19-2014, 10:42 AM

Quote:

Originally Posted by 3002 tii

I have race seats with both harnesses & stock belts installed. I use stock belts to/from track, harnesses on track. All seats should be able to accept stock belts, it's just a matter of finding a way to mount the factory receptacle. Some drill into the trans tunnel, others use VAC or MS mounts.

Thanks! Looks great, by the way

Quote:

Originally Posted by Barryb97

For a half cage this was pretty non-intrusive. https://m.facebook.com/story.php?sto...153589495&_rdr

That is nice. I don't understand what the harnesses hook onto though. I wonder if it would work in a Roadster.

Barryb97 · 06-19-2014, 01:20 PM

They welded a doubler on the back of the bulkhead and yes it would work in a roadster.

intoflatlines · 06-19-2014, 02:49 PM

Quote:

Originally Posted by Barryb97

They welded a doubler on the back of the bulkhead and yes it would work in a roadster.

Is it a member on here? I'd like to get more info on that.

donoman · 06-20-2014, 12:13 AM

Quote:

Originally Posted by inTgr8r

Yes it has been done.... custom setup.
The main point of discussion is that it compromises your safety in the event of rollover.

Wondering why 4-pt harness is not "safer" in a roll-over than stock for the Z4M? Is it due to a lack of mounting locations for the harness sans roll cage?

StickMon · 06-20-2014, 12:29 AM

Assuming no cage, smooshed head?
It's something I've actually pondered.
Whether you would have better chances if you could flop over sideways rather than being held upright with your noggin on the pavement.

inTgr8r · 06-20-2014, 06:06 AM

^WHS
safety during roll over

intoflatlines · 06-20-2014, 10:40 AM

Quote:

Originally Posted by StickMon

Assuming no cage, smooshed head?
It's something I've actually pondered.
Whether you would have better chances if you could flop over sideways rather than being held upright with your noggin on the pavement.

Quote:

Originally Posted by inTgr8r

^WHS
safety during roll over

Really? I get that roll cage > no roll cage, but since we have the hoops, in theory it should be OK with the broomstick test? I guess it could go both ways, the 4 point will keep you lower and tighter to the seat with pretty much no slack, the stock belt will allow you some lateral movement at the expense of allowing some slack before it locks up?

Cybmx · 06-20-2014, 02:26 PM

Have you tried the CG lock?

Kgolf31 · 06-20-2014, 03:23 PM

The Schroth Quick-Fit Harnesses are actually made to run on stock seats w/no roll bar, because your head can still safely move in the event of a rollover.

Of course, no Quick-Fit Harnesses are available for a Z

inTgr8r · 06-20-2014, 06:52 PM

Quote:

Originally Posted by Cybmx

Have you tried the CG lock?

Yes. I didn't like it because it doesn't help with the upper torso.

What I do is pull on the upper belt to latch it then slide my seat forward into the latched belt.
That way the upper torso is held as well.

intoflatlines · 06-20-2014, 08:43 PM

Quote:

Originally Posted by Cybmx

Have you tried the CG lock?

I have not tried it but I don't think it'd help to be honest. I always move my seat back and recline it a little, lock the seatbelt, then move the seat up and incline. It makes the belt very tight. I'm just looking for added restraint of the 4 point since with a 4 point you can make it very tight and secure, more than stock, but not feel like your chest is getting crushed like with stock.

Quote:

Originally Posted by Kgolf31

The Schroth Quick-Fit Harnesses are actually made to run on stock seats w/no roll bar, because your head can still safely move in the event of a rollover.

Of course, no Quick-Fit Harnesses are available for a Z

Yep, I've ridden in several cars with Quick-Fits. That would be ideal but of course, no version available for the Z and nowhere to anchor them. Hence my thread!

Quote:

Originally Posted by inTgr8r

Yes. I didn't like it because it doesn't help with the upper torso.

What I do is pull on the upper belt to latch it then slide my seat forward into the latched belt.
That way the upper torso is held as well.

^ this is what I do. Looking for added restraint with less pressure on my chest (and also I feel like I'm breaking the power seat when I'm using it to make my so snug against the belt).

06-11-2014, 11:09 AM	#1
intoflatlines Lieutenant 67 Rep 501 Posts Drives: Z4MR, E34, E30 Join Date: Mar 2013 Location: Chicago iTrader: (0)	Racing seat and 4 point harness in Z4M I understand that this idea is not recommended for street or track use, this is merely an idea for autocross purposes. A local Z3M guy has an intriguing setup in his car. He replaced the stock seats with racing seats that accept stock seatbelts for street and track driving. But he also has a Schroth harness that he uses for autocross. What he does is attach the bottom straps to the rear seat anchors, and then he fabricated a bar that attaches behind the OEM roll hoop to attach the shoulder straps. There is a wide metal bar that fits inside the roll hoop to prevent the bar from riding up. Has anyone done something similar to this on a Z4M? I'd like to explore a solution like this for autocross as well (keeping stock seatbelt for street/track of course).
	Appreciate 0 Tweet Quote

06-11-2014, 11:16 AM	#2
inTgr8r Lieutenant General 2426 Rep 11,667 Posts Drives: M2 Comp Join Date: Mar 2006 Location: Toronto iTrader: (10)	Yes it has been done.... custom setup. The main point of discussion is that it compromises your safety in the event of rollover. __________________ '21 M2C Hockenheim Silver '18 718 Cayman S Lava Orange (sold) '13 E92 M3 Santorini Blue (sold) '07 Z4 M Coupe Alpine White (sold)
	Appreciate 0 Quote

06-11-2014, 11:20 AM	#3
intoflatlines Lieutenant 67 Rep 501 Posts Drives: Z4MR, E34, E30 Join Date: Mar 2013 Location: Chicago iTrader: (0)	Very true - but that would not be a tangible concern for autocross-only situations, right? Another possibility is that if someone did want to use the custom harness for street/track for whatever reason (I don't), you could wear your stock belt at the same time, yes? Side note - as a racing seat noob, how can you tell which seats can and cannot accept stock seatbelts? Can they all?
	Appreciate 0 Quote

06-18-2014, 10:22 AM	#5
TexasZed4MC Captain 148 Rep 688 Posts Drives: 2006 Interlagos Z4 M Coupe Join Date: Oct 2011 Location: Texas iTrader: (1)	At 6'3" its IMPOSSIBLE to get a harness bar or half roll cage in my car and me be able to get my seat back far enough back so I can get in the dang car! Oh well I can only wish. __________________ Lone Star Chapter BMWCCA HPDE Event Chair, Texas Trifecta Event Chair, & BMWCCA driving Instructor
	Appreciate 0 Quote

06-18-2014, 01:42 PM	#7
Barryb97 Second Lieutenant 17 Rep 231 Posts Drives: 2006 M coupe Join Date: Sep 2008 Location: Kirkland, WA iTrader: (1)	For a half cage this was pretty non-intrusive. https://m.facebook.com/story.php?sto...153589495&_rdr __________________ CDV delete, clutch stop, BMW pedals, Strongstrut bar, CF rad & coil cover, M3 reps, roundel under hood, Intravee II, air bag sticker delete, first aid storage, painted reflectors, headlight washer disable, Skyer CF front lip, Short shift kit, Leather Z arm rest, Stromung exhaust, RPI scoop, RTAB limiters, powerflex bushings, TC Kline DA coilovers, PB big brake kit, Skyer CF rear spoiler and diffuser, oil pressure and water temp guages.
	Appreciate 0 Quote

06-19-2014, 01:20 PM	#9
Barryb97 Second Lieutenant 17 Rep 231 Posts Drives: 2006 M coupe Join Date: Sep 2008 Location: Kirkland, WA iTrader: (1)	They welded a doubler on the back of the bulkhead and yes it would work in a roadster. __________________ CDV delete, clutch stop, BMW pedals, Strongstrut bar, CF rad & coil cover, M3 reps, roundel under hood, Intravee II, air bag sticker delete, first aid storage, painted reflectors, headlight washer disable, Skyer CF front lip, Short shift kit, Leather Z arm rest, Stromung exhaust, RPI scoop, RTAB limiters, powerflex bushings, TC Kline DA coilovers, PB big brake kit, Skyer CF rear spoiler and diffuser, oil pressure and water temp guages.
	Appreciate 0 Quote

06-20-2014, 12:29 AM	#12
StickMon My other car is on Mars 636 Rep 3,124 Posts Drives: 2006 MR Join Date: Feb 2011 Location: Lo-Cal iTrader: (1)	Assuming no cage, smooshed head? It's something I've actually pondered. Whether you would have better chances if you could flop over sideways rather than being held upright with your noggin on the pavement. __________________ Warning: May contain traces of nuts.
	Appreciate 0 Quote

06-20-2014, 06:06 AM	#13
inTgr8r Lieutenant General 2426 Rep 11,667 Posts Drives: M2 Comp Join Date: Mar 2006 Location: Toronto iTrader: (10)	^WHS safety during roll over __________________ '21 M2C Hockenheim Silver '18 718 Cayman S Lava Orange (sold) '13 E92 M3 Santorini Blue (sold) '07 Z4 M Coupe Alpine White (sold)
	Appreciate 0 Quote

06-20-2014, 02:26 PM	#15
Cybmx Private 0 Rep 67 Posts Drives: 06 Z4MR Join Date: Dec 2013 Location: Philadelphia iTrader: (0)	Have you tried the CG lock?
	Appreciate 0 Quote

06-20-2014, 03:23 PM	#16
Kgolf31 Brigadier General 459 Rep 4,531 Posts Drives: 2007 Z4MC, 2012 128i Join Date: Sep 2008 Location: Ohio iTrader: (4)	The Schroth Quick-Fit Harnesses are actually made to run on stock seats w/no roll bar, because your head can still safely move in the event of a rollover. Of course, no Quick-Fit Harnesses are available for a Z
	Appreciate 0 Quote