Bambusiero
SILVER Star
Here is a low cost 300 ft-lb DIY shop-built torque wrench - to handle re-installation of that big 30mm 304 ft-lb harmonic balancer - crankshaft bolt.
This is needed when you replace the front main seal and / or the oil pump cover plate o-ring, which are common oil leaks at the front of the 80-Series 1FZ-FE engine.
Principle of Operation :
The well known "torque wrench extension". Usually, this is used to compensate the wrench's setting for the added length caused by some special tool end added to the wrench, like an open end crows foot.
In this case, however, the usage is a long cheater bar added to your regular 150 ft-lb 1/2" torque wrench, multiplying it's torque setting. The torque applied by the overall tool is the torque wrench click setting, multiplied by the leverage ratio of the total length of the tool, relative to the wrench length. Wrench length is to the middle of the handle, not the full handle length.
Lw = Length of wrench = 16" to middle of handle (overall length is 18")
Lt = Length of tool (cheater bar) = 28", from pivot to pivot.
M = Multiplier ratio of your wrench's torque click setting
Tt = Torque applied by the tool, overall
Tw = Torque wrench click setting
M = ( Lt + Lw ) / Lw = ( 28" + 16" ) / 16" = 2.75
Tw = Tt / M = 304 ft-lb / 2.75 = 110.5 ft-lb (Torque wrench click setting)
Tt = Tw * M = 110 ft-lb * 2.75 = 302.5 ft-lb (close enough to the 304 ft-lb spec)
Maximum torque capacity with this 2.75 multiplier would be 412 ft-lb (at 150ft-lb setting), if you have use for such a monster.
I chose 2.75 because 3.0 (32" tool) looked like the wrench handle might hit the hood latch. Effort to get "click" at 110 ft-lb setting was no problem.
Tools and Materials Required :
1) 3/4" drive breaker bar.
2) 30mm x 3/4" drive 6-point socket, standard depth.
3) 1/2" drive 150 ft-lb torque wrench.
4) 7/8" or 1" x 1/2" drive socket, to be sacrificed by welding to the tool.
You could get one from the junk tool bin at your friendly neighborhood pawn shop, for instance.
5) 1.75" or 1.5" O.D. x 1/8" heavy wall steel tubing x 27 3/8" long.
Just make sure it's inside diameter will fit over the handle of the breaker bar.
6) Welder - MIG, stick - whatever you have.
7) Angle grinder, files, band saw, etc. - for weld fit up.
8) shop press, big vice, big hammer - something to squash the pipe a bit at one end.
Figure out the tube length needed, subtracting for the breaker bar hinge at the socket end, so the length to center of rotation comes out right. In my case, the tube length was 5/8" shorter than the tool design length.
Flatten one end of the tube so both sides of the tube can be welded to the 1/2" socket.
Cut or grind out a weld fit-up pocket into the flattened end of the tube to fit the outside diameter of the 1/2" socket.
Weld the socket onto the tube.
Torque on, dude!
In use:
Tool assembly layout:
The socket end:
1/2" adapter end, side view (squashed):
1/2" adapter end, top view:
p.s. One could use this same principle in reverse, to reduce the torque of a common 150ft-lb wrench to some much smaller range. % error would scale down as well, so accuracy should be good. Details left as an exercise for the reader.
This is needed when you replace the front main seal and / or the oil pump cover plate o-ring, which are common oil leaks at the front of the 80-Series 1FZ-FE engine.
Principle of Operation :
The well known "torque wrench extension". Usually, this is used to compensate the wrench's setting for the added length caused by some special tool end added to the wrench, like an open end crows foot.
In this case, however, the usage is a long cheater bar added to your regular 150 ft-lb 1/2" torque wrench, multiplying it's torque setting. The torque applied by the overall tool is the torque wrench click setting, multiplied by the leverage ratio of the total length of the tool, relative to the wrench length. Wrench length is to the middle of the handle, not the full handle length.
Lw = Length of wrench = 16" to middle of handle (overall length is 18")
Lt = Length of tool (cheater bar) = 28", from pivot to pivot.
M = Multiplier ratio of your wrench's torque click setting
Tt = Torque applied by the tool, overall
Tw = Torque wrench click setting
M = ( Lt + Lw ) / Lw = ( 28" + 16" ) / 16" = 2.75
Tw = Tt / M = 304 ft-lb / 2.75 = 110.5 ft-lb (Torque wrench click setting)
Tt = Tw * M = 110 ft-lb * 2.75 = 302.5 ft-lb (close enough to the 304 ft-lb spec)
Maximum torque capacity with this 2.75 multiplier would be 412 ft-lb (at 150ft-lb setting), if you have use for such a monster.
I chose 2.75 because 3.0 (32" tool) looked like the wrench handle might hit the hood latch. Effort to get "click" at 110 ft-lb setting was no problem.
Tools and Materials Required :
1) 3/4" drive breaker bar.
2) 30mm x 3/4" drive 6-point socket, standard depth.
3) 1/2" drive 150 ft-lb torque wrench.
4) 7/8" or 1" x 1/2" drive socket, to be sacrificed by welding to the tool.
You could get one from the junk tool bin at your friendly neighborhood pawn shop, for instance.
5) 1.75" or 1.5" O.D. x 1/8" heavy wall steel tubing x 27 3/8" long.
Just make sure it's inside diameter will fit over the handle of the breaker bar.
6) Welder - MIG, stick - whatever you have.
7) Angle grinder, files, band saw, etc. - for weld fit up.
8) shop press, big vice, big hammer - something to squash the pipe a bit at one end.
Figure out the tube length needed, subtracting for the breaker bar hinge at the socket end, so the length to center of rotation comes out right. In my case, the tube length was 5/8" shorter than the tool design length.
Flatten one end of the tube so both sides of the tube can be welded to the 1/2" socket.
Cut or grind out a weld fit-up pocket into the flattened end of the tube to fit the outside diameter of the 1/2" socket.
Weld the socket onto the tube.
Torque on, dude!
In use:
Tool assembly layout:
The socket end:
1/2" adapter end, side view (squashed):
1/2" adapter end, top view:
p.s. One could use this same principle in reverse, to reduce the torque of a common 150ft-lb wrench to some much smaller range. % error would scale down as well, so accuracy should be good. Details left as an exercise for the reader.
Last edited: