:unsure:
Replacing exhaust sytem including headers on a 912UL.
The studs are old and threads not real nice on outer ends where the nut bolt on... and in fact a couple of them screwed out when attempting to remove the nuts as the nuts were frozen on tighter than the studs were in the head.
We have new official Rotax studs and new nuts for the new installation, but are puzzled by the torque specs shown on the CPS site:
940-366 STUD M8X23/20 / TORQUE: 8 NM / 71 IN.LB.
842-950 LOCK NUT M8 / TORQUE: 12 NM / 110 IN.LB.
How can the stud torque be lower than the torque for the nut that's going to go on it?
Does that sound right?
If the stud is spun in at 71 IN.LB when you put the nut onto it at 110 IN.LB wouldn't the stud tighten further?
And also:
Since the studs have no surface that a torque wrench or even regular wrench can grab onto it (it's bare threads on both ends and round threadless stud in the middle) how can we torque it in?
Does one put a nut on it and use that to put the wrench on, spin and torque the stud into the head by the nut, remove the nut, and put the headers on, spin the nut back on and torque the nut down again?
-------
Unrelated to that issue but connected to the exhaust installation, one other question:
Apparently Rotax specifies that the studs be screwed in with Loctite 648.
That seems to be a hard to find item.
Anyone know if using one of the more easily found Permatex thread lockers (Blue, or Red-hi-temp) is satisfactory?
(It appears to us that the old studs we removed unintentionally had NO thread locker of any kind on them.... and they stayed in snug for more than 10 years and 800 hours... so suspect threadlocker in this case may not be that critically specific.)
-------
BY THE WAY:
Is there, maybe here in the downloadable documents, one single place where all the torque specs for the 912 can be found?
--------
Replacing exhaust sytem including headers on a 912UL.
The studs are old and threads not real nice on outer ends where the nut bolt on... and in fact a couple of them screwed out when attempting to remove the nuts as the nuts were frozen on tighter than the studs were in the head.
We have new official Rotax studs and new nuts for the new installation, but are puzzled by the torque specs shown on the CPS site:
940-366 STUD M8X23/20 / TORQUE: 8 NM / 71 IN.LB.
842-950 LOCK NUT M8 / TORQUE: 12 NM / 110 IN.LB.
How can the stud torque be lower than the torque for the nut that's going to go on it?
Does that sound right?
If the stud is spun in at 71 IN.LB when you put the nut onto it at 110 IN.LB wouldn't the stud tighten further?
And also:
Since the studs have no surface that a torque wrench or even regular wrench can grab onto it (it's bare threads on both ends and round threadless stud in the middle) how can we torque it in?
Does one put a nut on it and use that to put the wrench on, spin and torque the stud into the head by the nut, remove the nut, and put the headers on, spin the nut back on and torque the nut down again?
-------
Unrelated to that issue but connected to the exhaust installation, one other question:
Apparently Rotax specifies that the studs be screwed in with Loctite 648.
That seems to be a hard to find item.
Anyone know if using one of the more easily found Permatex thread lockers (Blue, or Red-hi-temp) is satisfactory?
(It appears to us that the old studs we removed unintentionally had NO thread locker of any kind on them.... and they stayed in snug for more than 10 years and 800 hours... so suspect threadlocker in this case may not be that critically specific.)
-------
BY THE WAY:
Is there, maybe here in the downloadable documents, one single place where all the torque specs for the 912 can be found?
--------
