CSL steel panel thickness.

[Paul Baker]

I have been involved with many conversations regarding original CSL panel thicknesses, in particular the "boingy" outer roof skin thickness. I have even been told that CSL's and CSi/CSa roof skins are all the same thickness which I don't agree with.
We have 3 RHD CSL's "2285***" in at the moment and also some NOS BMW front wings/fenders so there really was no better time to take some measurements. I measured it with vernier calipers and then with a ball ended thickness gauge as in the photos.


Due to the age of the E9's, almost every car we have worked on previously have already had their front wings (fenders) replaced before so I can't confirm this thickness.
Most cars have required new wings and rear quarter panels to be fitted so these end up with the new thicker replacement panels.

I must add that these dimensions are FACT, I am not guessing, I have personally measured each car and taken figures in many places on the car to get these dimensions. Average measurements are quoted and achieved by taking readings in many places, this measurement does vary around the flanges and edges that have been formed. When metal is shrunk it generally increases in thickness and when it stretches it gets thinner. I have not measured metal that has rusted thinner or swollen it is all good solid metal.

I am not providing chassis/ VIN numbers of these cars so please do not ask.

Car 1: A CSL that is known to have had a re-shell so it gives a good comparison to the other 2 CSL's. Car has been Envirostripped to bare metal and now has an epoxy primer on it so will affect the measurements slightly.
ROOF - 0.8mm - Average measurement taken around the drip rail, up the pillars and completely around the roof. The max thickness reading was 1mm including paint.
WINGS AND REAR QUARTER PANELS - 1mm - Average measurement taken in many places although this measurement did vary around the flanges and edges that have been formed.


Car 2: A CSL that has been Envirostripped to bare metal but now has a thin etch primer on it so will affect the measurements very slightly
ROOF - 0.6mm - Average measurement taken around the drip rail, up the pillars and completely around the roof. The min was 0.56mm and the max thickness reading was 0.87mm including etch paint.
WINGS AND REAR QUARTER PANELS - 0.8 mm - Average measurement taken in many places with a low reading of 0.7 and max of 0.9mm.


Car 3: A CSL that has been Envirostripped clean and is still in bare metal.
ROOF - 0.6mm - Average measurement taken around the drip rail, up the pillars and completely around the roof. The max thickness reading was 0.7mm and minimum reading of 0.5 mm.
WINGS AND REAR QUARTER PANELS - 0.8 mm - These had been replaced in the past, average measurement taken in many places with a low reading of 0.7 and max of 0.9mm.

NOS front wings/fender - 1mm

Section of removed CSL rear quater panel - 0.56 to 0.6 max thickness.

I hope this helps.
Regards

Paul

 

[Gransin]

Thank you for taking the time to document and write this, seen a lot written about metal thickness, but no hard proof - until now!

 

[pat cooks]

many thanks, will need to check mine when it is stripped. Pat

 

[Aussiecsi]

...wow, so CSL's are made out of alfoil ?

 

[jvrenaudon]

Paul, Thanks for this - it ties in with my understanding from years back. CSLsteel panels and roof were 23 standard wire gauge whereas on other e9's 21 swg steel was used. In 1979 my then six-year old CSL went back to BMW Concessionaires(GB) Limited in Dover for, amongst other things, two new front and two new rear wings. I was under the impression that these would be 23 swg but, well, you know the rest. On a related matter, though, I have seen in the course of the last year two 2285*** cars, both with matching engine and bulkhead chassis numbers, but both show just about as much "boyng" in the roof as my CSi , using the standard renaudon forefinger test. I remember reading on here a theory that some RHD CSL's may have been fitted with the thicker gauge steel roof but I don't recall a firm conclusion being reached on this. Anyway, thanks for the experimentation and the measurements - well worth while for posterity. Best wishes, John.

 

[pat cooks]

somewhere I have a piece of maybe "original" green front wing kept 12 years ago from my CSiL as a pattern for the stripes, I will strip the underseal and paint to check the thickness, won't prove anything but will be interesting to see if it is thin or maybe it had already been changed, I seem to remember that the thinner wings were more expensive even when available so I suspect many had the thicker wings fitted back in the day to save money / increase profit margins.....

 

[eriknetherlands]

So, just to add another factual point on thin gauge CSL panels; here are some pictures of such a CSL rear tail panel

Part number 41 34 1827 340 according the parts book is CSL specific: it is showing 0,76 and 0,77 mm sheet thickness around the keyhole opening. (with factory light grey paint). It weighs in at 3,0 kgs. It also lacks the mounting holes for the rear under riders.

The later black pressing gives a thickness of 0,87mm, and the mass is measured at 3,7 kg (with factory black paint).

 

[Paul Baker]

So, just to add another factual point on thin gauge CSL panels; here are some pictures of such a CSL rear tail panel

Part number 41 34 1827 340 according the parts book is CSL specific: it is showing 0,76 and 0,77 mm sheet thickness around the keyhole opening. (with factory light grey paint). It weighs in at 3,0 kgs. It also lacks the mounting holes for the rear under riders.

The later black pressing gives a thickness of 0,87mm, and the mass is measured at 3,7 kg (with factory black paint).

Nice to see the follow up on my post. That is a panel that I don't have a new CSL one to compare so I'm very jealous. I see that it's not a UK CSL panel as there wasn't a hole for the fog-light on our cars.