Undercarriage Bracket US vs Euro spec

[leonine99]

Ok E9 experts - time to ask for some help. As some of you know my CSi is going through an extensive and complete restoration and trying to make the metal work correct. If you look at the photo you’ll see a large bracket added to the undercarriage of a US spec Coupe. My German delivery CSi does not have this. In checking with others it doesn’t seem to be on 1972-73 CSLs or early ultra lightweight coupes either.

I’m wondering if this was a US-spec only add on? I don’t want to improperly add something like this that would make the chassis incorrect for this coupe.

My guess is that this should NOT be on my CSi. These may be a DOT addition for rear crash protection?

Any information would be really helpful and thanks ahead of time
Jeff

 

[leonine99]

I had a thought that may have something to do with this bracket. US spec coupes had to have a higher ride height to meet headlight Requirements and they had strut spacers up front underneath the fender tops. I’m wondering if the bracket here on this US coupe raises the rear height at all to match the increase up front?

Just a thought. Please chime in with any info

 

[HB Chris]

Hard to tell from your pic but that looks like mine. Is that a second piece next to one with a similar shape?

 

[Markos]

I’ll be honest, I can’t make out what I am looking at. I see the arc-shaped steel in front of the spring. Is that what you are referring to? I looked at the 74 sales on BAT and I don’t spot that piece. The sheet metal directly behind it is the inner fender well, which does protrude down last the floor by about 4” or so.

Need more/better pics

 

[Gransin]

I guess he means this one:

I don't have it on my -71 CSi:

 

[HB Chris]

My US 73 has it. US only? Added in 73 for all coupes?

 

[HB Chris]

Item 16, although it says 11/73 - 12/74

http://www.realoem.com/bmw/enUS/showparts?id=3435-USA---E9-BMW-3.0CS&diagId=41_1209

 

[Markos]

Item 16, although it says 11/73 - 12/74

http://www.realoem.com/bmw/enUS/showparts?id=3435-USA---E9-BMW-3.0CS&diagId=41_1209

Interesting!

 

[eriknetherlands]

It for sure is not on my 73 CS Swiss delivered car.
Picture shows my car; the wheel well is spotwelded to the floor with the straight line of spotwelds.
The wooden blocks are under the central differential brace.

I'm positive it does not affect ride height. It adds among others rigidity between the rear of the car (bumper) and the wheel house. The wheel house is considered to be a structural load bearing part of the car (not really at todays standards but anyway...) and I think this U channel adds some strength, so I'm with you on the DOT argument.

I however do not really see how your bracket can transmit forces from the bumper, as the fueltank is in direct line between your bracket and the bumper. Rather then protect, it just makes the fuel tank the sacrificial element in a crash....

Question back: is this bracket perhaps only present on cars that also have the inside trunk reinforcement?

 

[leonine99]

good call guys - I'm not sure if its a US vs Euro Spec thing, but the build on my CSi was 11/8/73 IIRC. So its not something that's missing,at least on my car. I don't know when production was switched over to the '74 model year but one could guess that it was right around this time in Nov, '73 - but that's a guess. So far the Euros don't have it and the US does. I wonder if all '74-'75s have it?

Also looks like #5 in the realoem diagram, the 'support' piece, which it seems you need two of, were in the cars along with the floor bracket as well.

 

[HB Chris]

Jeff, my coupe is May 1973 and has it. Might be related to 1973 2 1/2 mph interim bumper requirements from DOT.

 

[rey949]

@eriknetherlands @HBChris
I see your comment on the trunk reinforcement. what do those look like? my 73 US spec has them and I see my Euro car does not. So these additional Support brackets are US spec only??

 

[HB Chris]

It is safe to say these are US mandated reinforcing pieces. Just like the euro coupes never got the 73 or 74 bumpers that the US did.

 

[leonine99]

Thanks Chris, can always count on your encyclopedic coupe knowledge. Surprised this has never come up before!

 

[Ohmess]

I had a thought that may have something to do with this bracket. US spec coupes had to have a higher ride height to meet headlight Requirements and they had strut spacers up front underneath the fender tops. I’m wondering if the bracket here on this US coupe raises the rear height at all to match the increase up front?

Just a thought. Please chime in with any info

Rear height was raised with a 37mm rubber damper ring at the top of the spring as opposed to the European 28mm.