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Removing broken Cross-Brace bolts

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  • [Corsa D] Removing broken Cross-Brace bolts

    One of the "joys" of working on cars is how one "opportunity" can lead to another!

    You might have seen my thread on Emissions problems (oil in connectors causing issues, etc..) - That is very nearly sorted now (I hope!) - but I need to replace the bottom O2 sensor. Naturally, that is seized solid into the exhaust pipe, and is resisting all attempts to remove it - including penetrating oil, ring spanners and propane blow lamp application....

    So it occurred to me to remove - or at least drop the front down of the exhaust, to get better access to the O2 sensor.....to do this, as far as I can tell, one has to remove the cross-brace which goes between the front sub-frame lugs. Easy enough job, I thought....but turning the bolt a couple of degrees, it is obvious to me that the threaded section is not turning....same on the other bolt! I think someone has tried to remove this, and has realised that if they carry on turning, they will snap the bolt head right off!

    I may need to carry on and snap the bolts, as a) I still need to remove/lower the exhaust and b) bolts that are on the point of breaking aren't really doing much anyway, and I guess that a properly attached cross-brace is a requirement for body stiffness?

    So has anyone had this situation, and how did you get the broken bolts out?
    Last edited by Corsaman; 12-08-2018, 11:05 AM.

  • #2
    If you can't get anything on the back of the captive nuts.
    another way to remove the flexy front pipe . Is to remove the air filter box .jack up the engine on the sump with a piece of wood and trolley jack. And remove the 5 bolts on the engine mounting.

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    • #3
      Originally posted by Restorer View Post
      If you can't get anything on the back of the captive nuts.
      another way to remove the flexy front pipe . Is to remove the air filter box .jack up the engine on the sump with a piece of wood and trolley jack. And remove the 5 bolts on the engine mounting.
      I see thanks - so does that give clearance to take the whole exhaust off?

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      • #4
        To take the whole exhaust off you will need to take the back box of first. It splits over the back axle .

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        • #5
          I have never done this particular job and cant visualise it. But if you have been able to move the bolt head a couple of degrees without the thread moving you may already have weakened the bolts or studs to the point they might fail. But if there is an alternative way of doing the job it will be very tempting to leave them as they are. Drilling out and re tapping broken bolts and studs is a nuisance.

          Have you used a specialist penetrating fluid ,or something like wd 40 which is also a dispersent, but a jack of all trades, master of none. Proper penetrating fluid may work better, especially if its given a good soak, and left to penetrate overnight. Some have reported good results by using a penetrating oil, then later a squirt of wd40 to aid disperse of that oil even further into the thread. Also try tightening the bolt slightly before trying to remove it. Sometimes that breaks the hold on a thread better. But of course it might just shear!

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          • #6
            Originally posted by Restorer View Post
            To take the whole exhaust off you will need to take the back box of first. It splits over the back axle .
            Ah! Thanks!

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            • #7
              Originally posted by Bugman View Post
              But if you have been able to move the bolt head a couple of degrees without the thread moving you may already have weakened the bolts or studs to the point they might fail.
              Yes, sadly I think that is true! I fear a former owner (or an exhaust fitment centre) has had trouble with these bolts, and has left them weakened! They started to twist with quite a low torque applied (say 10ft-lbs?) - and then I noticed that the thread wasn't turning....

              I think I might as well "bite the bullet" and let them break, sort the exhaust/O2 sensor out, then drill the bolts out (or pay someone else to do it!) Amazing to think that this started out as an Electrical problem!

              I am continuing to douse the O2 Sensor thread with penetrating oil...half the problem is not being able to get proper hand access to whatever wrench or spanner I put onto it! I f I can drop the exhaust a couple of inches, I might be in with a chance!

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              • #8
                Update - Quite a successful day today - I decided to undo the crossbrace bolts whatever happened, and much to my amazement, they came out intact! So they weren't twisting after all, just with the amount of gunk over the threads, and poor light, I couldn't see the threads move!

                In another result, I also managed to undo the 3 very corroded nuts bolting the exhaust to the Cat section - even if it did involve hammering a 12mm 6-point socket onto one of the 13mm nuts! I will use new nuts when I refit it!

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