swisstonihasher

Hey all,

Has anyone removed their restriction on 3" system, the flange that fits between cat and mid section pipe? It's odd setup in that it has the springs with the bolts to allow a tiny bit of flex I guess. I've looked at flexi hose style coupler I can have welded/fitted on but I dont like the design of them (and heard they leak), I was wondering if I can cut out the guts of the flange with the taper restriction (which goes down to 2 1/4 inch ) so I still use the spring bolts but I'll still have a step in the actual flange of the mid section pipe which has 2.5 inch bore (the step sticks out by approx 3-4 mm, and is 5-6 mm long inside the flange itself).
Not sure what's best to do...


To confirm, the mid section has a flange which is thin/rounded on edges and not 10 mm solid steel item, which connects to another 4mm thin flange (with the restriction) which then fits with gasket to the flange of the cat, well other way around really if you follow gas flow....

markjmd

iTrader: (11)

I recently fitted a flexi-joint into a 2.5" straight-through center pipe for my classic, and had no problems with it so far. Since fitting this I've got rid of the spring bolts that connected the old resonated center pipe to the downpipe, and swapped them for bigger solid bolts, as my flexi-joint is less than a foot from where the pipes join (in the first angle section), so there's still a bit of give there if needed.

The background for me doing this is that the de-resonated center pipe I'd bought was a few inches too short, so this just seemed the most practical way of making it fit. I measured each angle section against the stock pipe, figured out that it was the front-most one which was a few inches short, then carefully cut out exactly the right amount to make up the difference once the flexi-joint was added. Local welder completed the job for me in around 10 minutes, and definitely no leaks. It's all stainless steel, so should last as long as the car.

TonyBurns

iTrader: (3)

Flexi joints suck, you need a solid exhaust system really, a flexi joint will heat up and if you have any movement in the exhaust/engine mounts it will break the flexi joint (they go pretty easily anyway).
Best to bin it and get a solid replacement part

Tony

markjmd

iTrader: (11)

Tony
Maybe it's just down to fit or quality of components, but I know I've had flexi-joints built in to the factory pipes on other cars I've owned in the past, and they've outlived the rest of the bodywork. On the old G-reg 2l Prelude I had for example (my last but one daily driver before the scoob), the flexi-joint in the downpipe was still fine up until its last MOT, and it was over 15 years old with nearly 200K on the clock when I finally got rid of it (cat-C write-off, after some t**t in a van rear-ended me in a traffic jam).

I'm not really sure why it would matter that a flexi-joint heats up or why it would be more likely to break than any other kind of joint either.


cheers
Mark

swisstonihasher

Thanks guys, sounds like flexi isn't so bad after all. I've found another way which I'm trying for now which involves removing the restrictor flange and the step in the mid section box (its actually all part of the same kit, it just looked like it was welded in place). I've now got a full 3" system with the not so rigid flange of the mid section to be fitted with double thickness gasket from USA (when it arrives), I'll then see if it leaks, if it does, I can do cheap fix of having thin wall sleeve welded inside the bypass tube so the flow goes over the top of the gasket joint. The better news is I can refit the restrictor a angled boss etc with cat when required with this setup, so gas flow should be slower through the cat...perrrrr-fect hopefully.