Exhaust Clamp Torque?


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  • #27626
    David Brazil
    Participant

    Hello.

    I just installed an Arrow decat and muffler and am wondering if anyone knows:

    1) Do the exhaust insert “gaskets” need to be replaced or are they reusable? (These are the ones that go in between the cat and the pipes, not at the header into the head.) They appear to be reusable, but I’ve not seen this type before and am uncertain. Odd material, very light . . .

    2) What is the torque specs on these clamps? Or, in general, how tight should they be? I put it together and tightened it up to what seemed reasonable, but was having some leakage, so apparently too loose.

    The clamps seem a little flimsy, which is what made me think they shouldn’t be (didn’t need to be) tightened too tight. Should they be fully tightened until the ends come together?

    Anyone?

    Thanks.

    #27631
    coelacanth
    Participant

    I believe those inserts are reusable. I did re-use and not seeing any leakage. Repair manual didn’t talk about replacing them neither.

    Per repair manual, the clamps are 8 NM but I never got to that much before the eyelet are touching completely. They are holding up just fine. Do note that you should be using copper paste for those clamp screws for anti-seize.

    #27634
    Vanessa
    Participant

    On page 237 of my SP401 manual it gives the torque for the exhaust clamps as 20Nm. I removed my muffler (to remove the dB killer) and then put it back on using the original gasket and torqued to 20Nm and experienced no leaks.

    Maybe the clamps for the 701 are different to the 401 clamps?

    Strictly speaking, gaskets are not re-usable, but as long as they are not damaged and still fairly new, you can usually get away with re-using them. But it’s not always successful.

     

    • This reply was modified 1 year, 9 months ago by Vanessa.
    #27638
    coelacanth
    Participant

    Per 701 repair manual, engine to header is 20 NM, but the pipe-jointing clamps (flimsy two-piece ones) are 8 NM. (Page 69)

    #27642
    Vanessa
    Participant

    Oops! Oh well, my clamp is over-torqued then :-/

    In my defence, the clamp bolt is M8 size, and 8Nm is quite a low torque for M8, 20Nm is more what I’d expect to use on such a size.

    It took the 20Nm easily though and there is a spacer between the two halves so that no matter how tight the bolt is done up, they can’t touch each other.

    All I can say is that it worked and doesn’t leak.

    • This reply was modified 1 year, 9 months ago by Vanessa.
    #27646
    David Brazil
    Participant

    Thanks everyone for the replies.

    I put some metallic lube (supplied by Arrow) on the gaskets and header parts that were in contact with each other, and there is lots of smoke coming out due to this material heating up and not being happy. The way the smoke from this lube is moving around, I made the assumption that there was a leak, but I didn’t verify at that time, thinking that the clamps were simply too loose.

    But 8N-m is pretty light, so they probably were torqued enough and it’s just the burning/smoking lube that makes it appear that there is a leak.

    I’ll do some investigation later to see if I really have a leak or not – probably the old, hold a rag over the end of the pipe and see if it affects the smoke pattern at the joint. If it billows and puffs differently, I definitely have a leak. No change in the smoke, probably just the lube burning off.

    Again, thanks for the info.

    Cheers.

    #27672
    David Brazil
    Participant

    UPDATE:

    – None of the above . . . the flange of the decat is too long and bottoms out on the flange of the muffler, keeping the parts from coming together enough to adequately contact and squish the gasket!

    The stock flange of the cat sticks out 13mm and seats the muffler section just fine, but the flange of the decat is 16mm long and bottoms out on the flange of the muffler and doesn’t allow the two surfaces to compress the gasket.

    That was unexpected. I thought Arrow was a top-notch exhaust maker.

    I guess not.

    #27674
    coelacanth
    Participant

    I’m sure you tried, but just in case:

    You want to make sure the entire exhaust system starting the header pipe is loose. You put the mid pipe in, muffler in, and loosely connect them with clamps but not tightened. Then start tightening the header pipe to the head, then tighten other parts up. If you try to drop in some part of the exhaust system without loosening other bits, it’s likely they won’t fit well.

    #27675
    David Brazil
    Participant

    I agree with your procedure, but in this case, that wasn’t the problem.

    Even a dry fit together, off the bike, with new/old parts to show the difference, there was definitely a problem with the Arrow decat. The muffler was fine, and fit together with the cat with enough squish to seal the gasket, but when I mated it with the decat, there was a much larger gap than with the cat.

    I measured the extended flange on both parts and the Arrow decat was 3mm longer. This section was bottoming out on the inside of the muffler flange and could not go further into the muffler to compress the gasket.

    I just ground off 3mm off of the decat and am pretty sure that will solve the problem, but now I have to wait for a new gasket to arrive.

    Bummer. We’re just starting to get sunshine and I’ve had a few mod’s over the winter I’m looking forward to trying out. Guess I have to wait another week.

    At least I was able to fix it without having to go back to the vendor/manufacturer – I bought them directly from Italy!!

    Cheers

    #27676
    coelacanth
    Participant

    Sorry to hear and it sure is a bummer. Hope you’ll be able to take her out for a spin soon.

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