Rear Seatbelt Mounting Points - Vert or M3

[Cinnabar325is]

I'm installing an M3 rear seat into my '89 325is. I want to do it properly and that means I need to create a different mounting point for the rear seatbelt buckles. Since the M3 and convertibles only had two person rear seats, their buckles are centered in the seat. Not true for coupes/sedans.

Vivek was kind enough to supply this picture below for me taken from his convertible, but he was unable to provide the measurements at the moment.

Could somebody with an M3 or convertible please take a moment to measure the location of the center buckle mounting point between the the outer two bolts?

Also, how far above the centerline between those two bolts is the middle mounting point?

I want to have this correct before I starting drilling holes in my car! Thanks.

[Cinnabar325is]

Please help me out

[Cinnabar325is]

ttt

[reelizmpro]

I have both of those cars but too lazy to remove my seats...sorry. have u tried finding a picture online? Surely there's a pic somewhere. What about lukes cabby sub box install?

[Cinnabar325is]

I already have a picture, it's posted at the top of thread.

I know I could make an educated guess just looking at the pic, but I want to do this exactly as it should be and I'm hoping someone is kind enough to take a few minutes to help.

[MattPro]

I already have a picture, it's posted at the top of thread.

I know I could make an educated guess just looking at the pic, but I want to do this exactly as it should be and I'm hoping someone is kind enough to take a few minutes to help.

My seat was unbolted already and my vert was in the garage so figured I'd help. Pictures are from an '89 vert. (click for full size)

Here's just the picture you already have but just to make sure my car's the same:


Here's what you want:


Just for reference again (far right hole):


To get the height I tried my best, I lined up the tape measure with the crease and pressed it down flat then let go for the pictures:

Two seat mounts:



Seatbelt:

[iwantspeed]

I have the e30 m3 front and rear seat and have e30m3 rear seat belt buckles plugged into the recepticals just for show.

There is another thing you haven't thought about. I had the same problem.
The e30m3 has a reinforcement plate underneath the center rear seat belt
If you just drill through it won't be as strong
The rear subframe and gas tank are kinda in the way.

You need a picture of an e30m3 from underneath with out the gas tank or subframe.

Here is what mine looks like

http://www.r3vlimited.com/board/showthread.php?t=207014

[iwantspeed]

Here is a picture showing the reinforcement plate and welded nut for the seatbelt mounting points

[reelizmpro]

It's ok...no one sits in nice m3 seats anyway. Just kidding....this thread has been enlightening. I am surprised they didn't just put that plate on all cars.

[Cinnabar325is]

My seat was unbolted already and my vert was in the garage so figured I'd help. Pictures are from an '89 vert. (click for full size)

Thanks a bunch! That's good enough to do what I need.

There is another thing you haven't thought about. I had the same problem.
The e30m3 has a reinforcement plate underneath the center rear seat belt
If you just drill through it won't be as strong
The rear subframe and gas tank are kinda in the way.

No problem, I have the gas tank and rear subframe out of the car already, plus I'm already doing a lot of rust repair and bodywork in the rear. I knew this was the time to properly install an M3 rear seat and buckles.

I will significantly reinforce the area around the buckle mounting point. Not quite the same way the factory did, but it will be strong enough.

And as mentioned, I don't think many people will ever sit back there anyway.

[iwantspeed]

finally found a picture showing the bracket.
this is on absorbant nuts build thread
also looks like you might have to be careful when drilling that hole or you might drill into your brake line
notice only 2 brackets on a standard e30 coupe

[xtos]

I got my M3 seats in my car too. The po didn't have the rear seat belts bolted on and I did not want to drill any holes in the chassis nor did i want to get under the car! So I got a piece of reenforced metal that I could use, drilled holes and bolted it on the existing holes, then drilled a hole on it to get the seat belts on there.10 minute diy and rock solid.