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| | | | Joined: Jan 2018 Posts: 16 New Guy | | New Guy Joined: Jan 2018 Posts: 16 | Hi again from Germany, I'm working on the 4-speed crashbox, unfortunately the thread in the rear end of the mainshaft has a slight damage. The first few threads are worn but there is enough thread length to use a longer screw. I cannot find the matching screw and so i cannot measure, how many TPI the screw should have. The old online chevy manuals database shows this: [image] https://abload.de/img/u-jointtomainshaftwwu60.jpg[/image] Hmm, bad quality, but the thread sizes vary between 20 or 24 TPI depending on truck type. What thread size applies to my 1946 half ton truck? Thanks in advance again for your help! Sven
Last edited by mototreiber; 03/28/2018 9:17 PM.
Best wishes
Sven
| | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Get the OD of the bolt to start with in ", if it is .5", could be .5"/20 which is a NF thread. .375"/24 is also a NF thread.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Feb 2001 Posts: 1,096 'Bolter | | 'Bolter Joined: Feb 2001 Posts: 1,096 | I just checked an output shaft I have here , from a '46 , it is 3/8" x 24. | | | | | Joined: Jan 2018 Posts: 16 New Guy | | New Guy Joined: Jan 2018 Posts: 16 | Thank you both, instead of the original 1 3/16" length I'll use a 1 3/4" long screw to compensate for the worn threads
Sven
Best wishes
Sven
| | | | | Joined: Feb 2004 Posts: 29,795 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,795 | If there is room to do so, try putting a stud, not a bolt into the output shaft, and secure it with a thread lock liquid like Loctite. Then use a nut to secure the universal joint. That way there won't be as much stress on the thread in the shaft as it will be a "one time" installation and the nut will be the part taking the tightening stress,
Jerry
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