Fibreglass seat pans and cowls on R-series BMWs?

[Todd]

One for the historians.

I know the old metal seat pans and cowls had a habit of rusting out something terrible, as I've seen them do it. Some say it was additionally provoked by gases leaking out of the lead acid batteries (I don't know that).

Did BMW, or some other third party supplier, change to fibreglass/GRP based replacements for both parts?

If so, who supplied the latter?

I've been looking at a few old 70s/80s era bikes and trying to work out what they are made of or whether they are original.

Thanks.

* (NB, not my saddle ...)

seat.jpg (79.31 KiB) Viewed 21 times

[SteveD]

Yes, fibreglass, or something not metal, seat bases do exist. No idea the origin though.

[Rob Frankham]

I'm pretty sure that BMW always used steel seat pans on airheads... well, I say that but I don't know about the 'GS series or the 'R but steel was used on all of the mainstream 247 anmd 248 series bikes. The seat cowls (where fitted) were a bit different. The original cowl fitted to the 'S, later '7 series and bikes up to '84 are steel. The 3/4 seats unique to the early 'RS (as a stock fitting) are GRP (fibreglass). Cowls fitted to Mono machines are, I'm pretty sure, plastic.

Plastic seat bases are available in the aftermarket from a number of makers and they vary from very good to quite poor... but that's the nature of the aftermarket, you pays your money and takes your choice. Aftermarket steel bases are also available and, again, quality varies.

Aftermarket manufacturers come and go. Most of the ones that were in existence in the 70's and 80's are long gone now.

Rob