Drive shaft torque tightening

PostPost by: Donels » Mon Dec 26, 2016 8:28 pm

I am rebuilding my +2 which was fitted with solid drive shafts with uj's but source unknown. They are well engineered and secured by 3 black socket-head bolts at each end. Upon disassembly they did not seem to be very tight and I am now reassembling but have no idea on torque figure. In the absence of a figure I intend to use a standard torque for a 3/8 bolt. Can anyone advise of known torque tightening figures?
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PostPost by: alan.barker » Mon Jan 02, 2017 10:10 am

I would suggest nice clean threads and a little Loctite
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PostPost by: mikealdren » Mon Jan 02, 2017 10:44 am

Does it have UJs or CV joints? The latter are far superior for drive shafts as they accommodate plunge and (as their name suggests) give constant velocity, UJs only really work in pairs and/or with smaller changes in angle. I have seen earlier shafts with UJs and splines, it may be time for an upgrade?
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PostPost by: Donels » Mon Jan 02, 2017 10:52 am

They have UJ's. I suspect they are Sue Miller or TTR and are in excellent condition. I agree CV's would be better but why waste these. Any ideas on torque tightening figures?
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PostPost by: alan.barker » Mon Jan 02, 2017 11:04 am

To stay on subject.
Cap head screws are HT so i think they can take a high Torque + loctite.
I imagine 35/40 lbs/ft Sorry i don't have a torque figure.
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PostPost by: CBUEB1771 » Mon Jan 02, 2017 2:31 pm

The Workshop Manual species 35 to 40 ft-lb for the rotoflex attachment bolts. This is for the normal automotive grade fasteners used by Lotus (SAE Grade 5, or equivalent, approximately 120,000 psi tensile strength). I would stick with this value. Some of the UJ and CV based axle replacements are supplied with higher grade fasteners which would allow a higher torque. For example, ARP specifies 70 ft-lb for their 7/16 UNF fasteners in 180,000 psi tensile strength alloy steel. I have a recent set of UJ-based axles from TTR and curiously the supplied instructions do not include a torque value.
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