Over tightened end caps

[Reckless Rat]

As an old fisherman said. It's not the size of your bait that matters, it's how you dangle your maggot. If our erstwhile spannerman only has a 6" ring spanner, small hands and a physique like a long term desert island castaway then he might be OK. However, if he's built like Popeye's Bluto and has a King Dick then he might be doomed... rather than trashing this already somewhat fraught project it might be prudent to reset the bottom end to 20ft/lbs using a properly calibrated torque spanner. Same for the top end.

[Charles P]

Torque wrench calibration failure can lead to problems if "Popeye Tight" is the default or inexperience creeps in. The "bendy beam" one's are perfectly good for most uses and don't go out of calibration.


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C

[Dave Mann]

In my employment I had to investigate a number of big end bolt (1.5" diameter) failures I never came across a failure due to over tightening, it was always under tightening.

[Bob Culver]

It is generally reckoned that artisans overtighten small bolts and undertighten large ones. 5/16 is small and and 1.5 inch is very large. Spanners should be of appropriate length. The very short ring spanners are a reasonable match for mild steel and the longer for HT. 11 hp SV Hillmans, with long stroke and heavy pistons, had 5/16 16 to 20 lbs ft.
If bolts are repeatedly tightened to near or beyond yield, fatigue clocks up in a very few cycles, whereas operating at modest tension accumulate none. Best to use a separate set for fittng bearings etc.

[Alan]

Why argue about it. It’s simple. If you have a torque wrench use it. If you don’t, then get one.

[andrew34ruby]

Why argue about it. It’s simple. If you have a torque wrench use it.  If you don’t, then get one.

But I've been repairing cars for over fifty years without a torque wrench. Why do I need to get one now? (not arguing, just asking).

[Colin Wilks]

But I've been repairing cars for over fifty years without a torque wrench. Why do I need to get one now? (not arguing, just asking).

I suppose if you have a British Standard Wrist and don't work on modern cars then it's up to you, but I wouldn't fancy judging a modern one time only stretch bolt that specifies, say, 85 n/metres plus 90°.

For me, using a torque wrench guarantees consistency across a set of fasteners such as head studs, where I lack your confidence to judge by feel alone.

[Ray White]

I can tell you what is tight. Land Rover Pitman Arms are on tight. It took a 24" Stilsons wrench with a 6 foot long pole for me to undo one on a P38 Range Rover. (Replaced the lower oil seal rather than buy a new box!)

Austin Seven engines require a somewhat lighter touch. That is why the tool kit has small spanners.

[Chris KC]

I'd be interested to hear more Dave - however - I'm going to hazard a guess that 1.5" big end bolts have a somewhat higher setting torque than A7's and rarely touch 6500rpm?

[Dave Mann]

Try two men on an 8' spanner to give 1.0 mm stretch on the bolt, torque wrenches were banned.