Pre-silencer

[Daxklynsmith]

Finally, I am getting some driving done, but the whole sage of rebuilt master cylinders and other ills has meant that the scheduled start and run for a few minutes the past two years means there is now a hole in the pre-silencer exhaust box,
What does this actually Do?
She is a 73 3.0CSA so its unlikely to be on the race track?
can I forego the pre-silencer and maybe price another exhaust system?
any advice from that side of the pond?
anyone manufacture exhausts?

 

[E9erCS]

replace pre-silencer or get whole new system?

Coupe King sells a really nice stainless steel exhaust system, which I just installed on a 1972 CSi and it sounds great! It is about 500USD more than the list price for an OEM system from BMW, but is stainless steel and should last forever.

Alternatively, you can replace just the "pre-silencer" which is still available from BMW, if the rest of the system has some life left.

--Steve

 

[Daxklynsmith]

Yeah, W&N do a complete SS exhaust for €990 plus courier and a pre-silencer for about €270 ,something plus courier, real truth? SS exhaust will outlast the car.
I'm just curious about what it does?
is it noise reduction/ back pressure?
what does a pre silencer actually do?

 

[MMercury]

there is now a hole in the pre-silencer exhaust box, What does this actually Do? She is a 73 3.0CSA so its unlikely to be on the race track?

You weren't exactly clear as to which part of the exhaust is compromised: the lengthy resonator that parallels the drive shaft or the rectangular shaped resonator that is directly in front of the rear axles. Opinions vary as to the need for any or just some of the components. And much has to do with fit, design, weight and costs. You specifically asked about the purpose. Your guess is probably as good as mine in that sound suppression and modulation are the primary concerns. Back pressure with the stock exhaust is minimal at lower revs. Needless to say, additional components hardly reduce back pressure.

Given your intended street use, I would imagine that just about any competent muffler shop could customize a complete or partial system that is non restrictive (free flowing) and relatively quiet. I recently noticed an E3 with a custom exhaust that consisted of three large glass packs. The owner said he thought the stock exhaust (with the big fat rear muffler) was too quiet and not free flowing enough for his modified engine. I can't speak about what it sounded like from inside the cabin, but the exhaust was by no means unpleasant or overwhelming when the car accelerated past me. I have also seen E3 that made use of tubular headers and stock Mercedes exhaust components that sounded like a musical instrument. That owner told me he just used what was available at his friend's garage and he was glad he did. My point is that for your limited purpose, the exhaust seems one of personal preference. In case you were thinking specifically of eliminating the middle resonator (no7 below) early e9's did not have it.

The factory-designed system takes much of the guesswork out of replacement; however, that does not mean it couldn't bear improvements after 35+ years as seen by the stainless exhaust pictured above.

Sorry if that does not answer your question.

There's always: http://www.jaymic.com/shop/parts_cs_products.asp?grp=CSEX&productid=CSEX.1900&page=&short=add

 

[Daxklynsmith]

Thanks NMercury, its the flat intermediate box before the Diff, and the price of £140 is already a lot better than W&n's.

 

[pmansson]

I am looking for part 17 in both diagrams.
the 60mm tail pipe and the heat shield.
None of them available anywhere in Europe.
There are plenty of 55 mm tail pipes, but I want the larger one which came with the CSi.
Both are simple parts and could easily be remanufactured.