connecting rod fastener locking device

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Truckedup
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connecting rod fastener locking device

Post by Truckedup » Wed Jun 20, 2018 2:21 pm

Does any current automotive or bike engine, or aftermarket racing parts, use any sort of locking devices on the rod bolts or nuts?
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Post by dwilliams » Wed Jun 20, 2018 2:49 pm

I can't think of any examples past the early 1970s, and those were probably all 1950s designs.

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Re: connecting rod fastener locking device

Post by modok » Wed Jun 20, 2018 8:06 pm

Does any currently used automotive or truck engines, use any sort of locking devices on the rod bolts or nuts?

99.5% no
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Re: connecting rod fastener locking device

Post by tresi » Wed Jun 20, 2018 8:09 pm

I wanting to think I seen something that had the rod nuts cotter pinned. I can't remember what

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Re: connecting rod fastener locking device

Post by MadBill » Wed Jun 20, 2018 8:12 pm

Puzzling when you think about it. For most of the first hundred years of the IC engine, lock nuts or cotter pins were used on many rod bolts. Now not. What's changed?
All I can think of is that perhaps the yield strength of modern fasteners has increased bolt stretch enough that friction torque reliably resits the Murphy Force. :-k
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Re: connecting rod fastener locking device

Post by pamotorman » Wed Jun 20, 2018 8:16 pm

I remember when some con rods had these on the nuts as a safety lock. I used them as a lock nut on the chevy V-8 rocker arm nuts
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Re: connecting rod fastener locking device

Post by modok » Wed Jun 20, 2018 9:07 pm

MadBill wrote:
Wed Jun 20, 2018 8:12 pm
Puzzling when you think about it. For most of the first hundred years of the IC engine, lock nuts or cotter pins were used on many rod bolts. Now not. What's changed?
There was a persistent superstition that if you didn't eat enough garlic and properly dance around a tall pole in the spring, Black Pete would loosen your rod bolts during the winter. He used instant frost to instantly cool the rod from the outside, and loosened them by hand. Thus locknuts, safety wire or cotter pins or staking were used to thwart him, as he didn't carry a wrench.
Once loctite was invented, they used that.

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Re: connecting rod fastener locking device

Post by af2 » Wed Jun 20, 2018 9:21 pm

Before bearing crush yes. Since then no.
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Re: connecting rod fastener locking device

Post by cjperformance » Wed Jun 20, 2018 9:46 pm

If a rod nut comes loose a pin or pressed metal lock nut is not going to do much.
If you used a sturdy lock nut to lock both nuts together on the thread you then make another problem, the clearance between nut and bolt thread is taken up forcing the 1st nut off of its supporting thread face, this adds a little stretch to the fastener (but this can be accomodated for) and shifts the bolts main load point out to the thread faces of the 2nd (lock) nut. If you then have a fastener failure at this lock nut tension point the fastener stretch is reduced, clamping force lost etc, it all takes a dump anyhow.
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Re: connecting rod fastener locking device

Post by Newold1 » Wed Jun 20, 2018 10:20 pm

There is a very effective and proven rod bolt retaining device. It's called a properly torqued rod bolt with proper stretch. Been used for a long time and seems to work well in millions of engines! Use these and you wont have any problems when properly installed. :wink:

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Re: connecting rod fastener locking device

Post by Warp Speed » Wed Jun 20, 2018 11:25 pm

Yep, it's called fastener stretch!

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Re: connecting rod fastener locking device

Post by engineguyBill » Wed Jun 20, 2018 11:48 pm

Yes, I did see an engine once that used cotter pins on the connecting rod nuts. It was a 1920's Continental engine, four cylinders about 5.50" bore, 6 inch stroke and weighed about 1200 lbs. Application was an old Adams road grader and maximum RPM was about 2200. Up-draft carburetor, magneto ignition and it was started by hand cranking.
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Re: connecting rod fastener locking device

Post by cjperformance » Thu Jun 21, 2018 12:14 am

Newold1 wrote:
Wed Jun 20, 2018 10:20 pm
There is a very effective and proven rod bolt retaining device. It's called a properly torqued rod bolt with proper stretch. Been used for a long time and seems to work well in millions of engines! Use these and you wont have any problems when properly installed. :wink:
X-actly !
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Re: connecting rod fastener locking device

Post by exhaustgases » Thu Jun 21, 2018 4:05 am

I'm trying to remember on what engine you could stake the rod cap nut that matched a notch in the cap? The nut had a special flange.
Loctite, only if someone asks for it to be done. Other wise its clean lubricated threads.

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Re: connecting rod fastener locking device

Post by Geoff2 » Thu Jun 21, 2018 5:37 am

Yup, Loctite changed it..

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