Laverdalothar
Hero member
- Location
- Germany
I am currently re-torquing my 1000 SFC's head. I have different torque wrenches for different torques, but was never sure - as they are all at least 20 years old - how good they are and if they do their job well or not.
So - I bought me a tool to actually test them. The result was quite shocking I must say... OK - to start with: the tool I bought is controlled, new and tested. Further to that, all 4 torque wrenches showed completely different symptomes, which were repeatable. My conclusion is, that this would most probably exclude a fault with the testing device.
The 4 were from Würth (professional brand), Wisent (somewhere in the middle but not completely bad) LUX (Obi house brand) and Silka (totally cheap crap).
Adjustment precision:
It already starts with the adjustment of the spanners... none of the four was precise, it was more or less an approximation to the correct value. Most of the scales are so imprecise and sometimes the setting can still be twisted despite being locked, that 20Nm could easily be 19 or 21, etc. The higher the spanner, the coarser the scale. Sometimes, when turning the values up or down, the scale did not move at all for a short time, even though the handle was turned. At first I thought there was a little play in it. But the settings actually varied by 1-2 Nm even with a 20 Nm setting 8| Remember: that's up to 10%...
Replicability of the values (same setting, check several times):
Only one of 4 spanners (the Wisent) produced approximately the same values when measured at the first as well as the 3rd attempt (setting 40 Nm, measurements varied between 39.8 and 40.2Nm - OK for me!). With all 3 other spanners, the first click after setting was the highest measured value, the 2nd and all subsequent ones were lower (at 20Nm, first click 19.5, then between 17.3 and 17.5!). Ergo: If you tighten several screws with it, the torque is correct for the first screw, but not for all the following ones... Unless you relax the spanner after each screw and then readjust it. But then you run the risk of not getting the setting right (see point "Precise setting")
Scatter over the setting range
The torque spanners were very different here. The Wisent, which was really good and precise in the lower range, was a complete disaster in the upper range! With a set value of 120Nm, it only released at over 160Nm!
The Würth triggered OK in the lower range, set at 120 Nm it triggered at 133 Nm
The absolute disaster was the Sika: completely unclear scale and MUCH away from the displayed values, even in the lower and middle range. I will check the setting again...
Calibratability
I have only tried it on one key so far, but the measurement results were so different that I can't say exactly what the problem was. I will try again now that I have the measuring device firmly mounted (2-3 days ago I held it on the tabletop with one hand only and then tried it - of course it doesn't work...).
Conclusion: I will only use the Wisent and the Würth in future. With both I will adjust the torque with the help of the measuring device, make at least 3 clicks and only adjust when the values no longer change.
I am also thinking about buying a brand-name torque spanner. However, I would like to test one first in several areas with my gauge to make sure they work more accurately then.
Conclusion2: I'm beginning to understand why some heads/head gaskets leak again when relying on a torque spanner, that ultimately does what it wants....
So - I bought me a tool to actually test them. The result was quite shocking I must say... OK - to start with: the tool I bought is controlled, new and tested. Further to that, all 4 torque wrenches showed completely different symptomes, which were repeatable. My conclusion is, that this would most probably exclude a fault with the testing device.
The 4 were from Würth (professional brand), Wisent (somewhere in the middle but not completely bad) LUX (Obi house brand) and Silka (totally cheap crap).
Adjustment precision:
It already starts with the adjustment of the spanners... none of the four was precise, it was more or less an approximation to the correct value. Most of the scales are so imprecise and sometimes the setting can still be twisted despite being locked, that 20Nm could easily be 19 or 21, etc. The higher the spanner, the coarser the scale. Sometimes, when turning the values up or down, the scale did not move at all for a short time, even though the handle was turned. At first I thought there was a little play in it. But the settings actually varied by 1-2 Nm even with a 20 Nm setting 8| Remember: that's up to 10%...
Replicability of the values (same setting, check several times):
Only one of 4 spanners (the Wisent) produced approximately the same values when measured at the first as well as the 3rd attempt (setting 40 Nm, measurements varied between 39.8 and 40.2Nm - OK for me!). With all 3 other spanners, the first click after setting was the highest measured value, the 2nd and all subsequent ones were lower (at 20Nm, first click 19.5, then between 17.3 and 17.5!). Ergo: If you tighten several screws with it, the torque is correct for the first screw, but not for all the following ones... Unless you relax the spanner after each screw and then readjust it. But then you run the risk of not getting the setting right (see point "Precise setting")
Scatter over the setting range
The torque spanners were very different here. The Wisent, which was really good and precise in the lower range, was a complete disaster in the upper range! With a set value of 120Nm, it only released at over 160Nm!
The Würth triggered OK in the lower range, set at 120 Nm it triggered at 133 Nm
The absolute disaster was the Sika: completely unclear scale and MUCH away from the displayed values, even in the lower and middle range. I will check the setting again...
Calibratability
I have only tried it on one key so far, but the measurement results were so different that I can't say exactly what the problem was. I will try again now that I have the measuring device firmly mounted (2-3 days ago I held it on the tabletop with one hand only and then tried it - of course it doesn't work...).
Conclusion: I will only use the Wisent and the Würth in future. With both I will adjust the torque with the help of the measuring device, make at least 3 clicks and only adjust when the values no longer change.
I am also thinking about buying a brand-name torque spanner. However, I would like to test one first in several areas with my gauge to make sure they work more accurately then.
Conclusion2: I'm beginning to understand why some heads/head gaskets leak again when relying on a torque spanner, that ultimately does what it wants....