clubstylus

stylussprinter wrote:The tighter you fix the silencer the greater the stress on the manifold . Also bolt size is irrelevant -- it's the bobbins that hold the weight and they normally fail at the metal/rubber join when hung as opposed to compressed

Yes - of course they do, I thought that after posting
BUT thinking aboult how little the engine actually moves - it wants to rotate around its crank, but there's 2 beefy and stiff mounts preventing that and the result is that the whole car tries to rotate about the crank instead, so I can't see why the rubbers will perish quickly? Surely I'll get 3 or 4 years out of them????

norma wrote:

stylussprinter wrote:The tighter you fix the silencer the greater the stress on the manifold . Also bolt size is irrelevant -- it's the bobbins that hold the weight and they normally fail at the metal/rubber join when hung as opposed to compressed

Yes - of course they do, I thought that after posting
BUT thinking aboult how little the engine actually moves - it wants to rotate around its crank, but there's 2 beefy and stiff mounts preventing that and the result is that the whole car tries to rotate about the crank instead, so I can't see why the rubbers will perish quickly? Surely I'll get 3 or 4 years out of them????

Well , you've done it that way now so just wait and see It'll be simple enough to make a one fixture compressed bobbin mount ' if and when ' it fails so you might as well leave it
Only thing to watch out for will be checking the bobbins now and again as they're hung so if they do come apart the complete manifold plus exhaust weight will be on the manifold bolts/threads Mine will stay on top and be supported even when the rubber goes but will just vibrate on the chassis bracket to grab my attention

Yep - good point. I will have to carry around a bit of wire just in case!

I have now decked out my inner wing to look like the inside of the Challenger space craft ....




next job - cut and fab 4-1 collector.......

The bobbin on my exhaust failed even though it was mounted correctly(compressed), it lasted two days

Phil


Stylus lead buried in garage with no enthusiasm what so ever to sort it

I've had the same one for 4 years Perhaps it was under tension sideways did you have to push it across towards the chassis to get it in the hole

stylussprinter wrote:I've had the same one for 4 years Perhaps it was under tension sideways did you have to push it across towards the chassis to get it in the hole

When i picked it up from Nathan there was an annoying rattle from the exhaust so i stuck my head in behind the wheel and couldn't see a problem, it was only when i took the wheel off i noticed the bobbin had sheared at the joint, the exhaust would quite happily sit on top of the bobbin but for some reason it just sheared off again

Phil

After a long delay (which was mostly caused by having to fit a new bathroom) I have a 4-1 collector with 1 7/8" in and 2.5" out.
I also have 6x180 deg mandrel bends in 2" and 6m of tube in 1 7/8".

This has been done as the 1 7/8" is an interferance fit into the 2" bends, therefore I can fabricate the whole primaries section without touching a welder, then when I'm happy, I'll file off the blunt edges of the 2" bends (for flow) and get the whole lot welded up.

Watch this space.....

Collector viewed from 2.5" end

Trial assembly - not much room for the pipe bends

My collector's at least half that length . It just means you'll need some nice looping curves to lose the length on the closest pipes

Damn right I will!

After first run, I found exhaust to be too loud and boomy so i ordered some Basalt (Thanks Rob) I've just removed the roll of rammed in glass which was doing exactly fook all, and replace with lurvely basalt - difference is amazing, no more booming and much quieter - car now totally ready for Laon - yipee!

UPDATE:
2 years, 5000 miles & 3 track days later, exhaust bobbins are still hanging on nicely - contrary to stylus sprinter's predictions

You're a lucky chap they are designed to be compressed because it's purely the rubber being glued/vulcanised to the metal plates , taking the weight