Quote:
Originally Posted by a big scary monster
Just a thought, but you say your back box needs to be at least 3 inches in/shorter than its present position and your down pipe to exhaust is 75mm a drift? Would it not be possible to cut the 3inches out of the straight pipe and then attach/ lengthen the upturned front section by 75mm, I am joking with the metric imperial but serious about a cut shutvand lengthen. Actually surely it would be possible to alter the bend at the front to get the length to down pipe and that would also solve the long back box problem too. Ed
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Hi Ed,
yes, thanks for the suggestions. I've been looking at these kind of options but BMW have built in some complex curves and bends that are not simple to cut and extended. (And difficult to photograph as well!) I'm sure if I had a very large tube bender and mig welder I could make something fit but I don't so I'm going to try and make some standard Jetex parts fit. It may not be very pretty but so long as it's gas tight I'll be happy.
My first cuts were to remove the only straight section of the rear section.
Exhaust shortening by
marlinpeter, on Flickr
Exhaust modification by
marlinpeter, on Flickr
These appear to be very small silencers, presumably designed to remove a particular frequency. I used a slitting cutting disc in an angle grinder. It was re-assuring to see how thick the pipes are.
I then rejoined them with some Jetex joining sleeves....
Exhaust shortening by
marlinpeter, on Flickr
Cut sections re-joined with Jetex double ended sleeves. Plus 48->50.5mm spacers used to match the pipe sizes. These will be sealed with exhaust assembly paste when finally aligned.
Next, I've removed the front section to manifold pipes....
Front Exhaust modification by
marlinpeter, on Flickr
The first step in modifying the front exhaust section was to slice off the front manifold connection bends to insert an 'S' bend made up of two 45 degree bends. I can't imagine why BMW built the exhaust with one pipe 46mm diameter and the other is 50mm?? Luckily Jetex do 46mm and 50.8mm bends and packing sleeves to convert from 50mm to 50.8mm.
Now I need to re-assemble the front and rear sections and offer it up to the chassis to see where I need to cut next. My current plan is to now get the rear box mounted in the right place and then try and sort out the front pipes to fit.
(I say'my current plan' because I often plan something in my head and then do it different when I get working on the car. I guess my brain is not very good at 3D modelling
)
...peter