Briggs crank turning "Dimension suggestion"

waltsuz

waltsuz

New Member
#1
#1
I am going to pull a crank to have turned to 3/4. Its on a Briggs 6hp, its as now tapered, 4-1/4 long and is .872 in diameter. It has a 1-1/4 schoulder coming from the case to the machined shaft. How far should the shoulder extend beyond the seal to run a TC-2. How long should the 3/4 shaft be?
I could cut it back and just come up with a spacer but I thought I'd ask while its on my mind. Thanks for any advice, Walt
 
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MB165

MB165

Active Member
#2
#2
I measured a 8hp tecumseh. From the surface where the TAV would bolt to, to the end of the shaft is 2.36" Your gonna need to get the shoulder fairly close to the seal.
 
waltsuz

waltsuz

New Member
#3
#3
MB165 said:
I measured a 8hp tecumseh. From the surface where the TAV would bolt to, to the end of the shaft is 2.36" Your gonna need to get the shoulder fairly close to the seal.
Click to expand...
Thanks MB, is the shaft at 2.36 short from being flush to the driver. I guess I'm asking could it be longer. I think most Briggs cranks are longer but can't extend past the driver's outside edge where the center bolt pulls it tight.
 
MB165

MB165

Active Member
#4
#4
Its gonna be a little short with that dimention. There is a adaptor which goes over the end of the shaft for the TAV and you definatley want enough to catch that. Is the TC2 the same?
My GX200 has maybe 3/16", it holds, but there could be more for sure. Id go longer just in case though, most small frame crank stubs are around 2-5/16 to 2-1/2".
 
waltsuz

waltsuz

New Member
#5
#5
MB165 said:
Its gonna be a little short with that dimention. There is a adaptor which goes over the end of the shaft for the TAV and you definatley want enough to catch that. Is the TC2 the same?
My GX200 has maybe 3/16", it holds, but there could be more for sure. Id go longer just in case though, most small frame crank stubs are around 2-5/16 to 2-1/2".
Click to expand...
Yes, on a 1 inch shaft there is for sure. I haven't put one on a 3/4 but I am assuming the length of the driver is the same on the shaft as a 1 inch driver. On an 8hp Briggs and a GX390 the machined surface that's keyed is 2-13/16th's long. I have both running on a TAV-2. I think I"ll do as you mentioned on your first post and cut the shoulder back and leave a 1/4 inch protruding out past the seal to keep it close. From there I'll cut the shaft to 3/4dia. x 2-13/16th's. If needed I can shim the back of the driver to allow the center bolt clearance to pull tight. Does this sound right?? I appreciate your time on this, once its cut, it what it is and I'd rather not bugger it up, Walt
 
J

Jim Donovan

Active Member
#6
#6
A standard crankshaft is 2.297 in length from the step to the end of the crankshaft. This is the dimension that both Max-Torque and Comet used in designing their torque converters. This is the standard used by ALL American engine manufacturers --Briggs, Tecumseh, Kohler, Clinton. Longer is OK but shorter is a problem. The 3/16 keyway has to be full length up to where it tapers up by the crankcase cover.

All crankshafts must be drilled and tapped at the end. The bolt provided is a 5/16-24 but if your crankshaft has a 3/8 hole than you have to come up with your own bolt.

The driver MUST be firmly attached to the crankshaft with no freeplay. Any questions always contact the manufacturer.
 
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