Torque vs lock washer?

perryjosh64 · Jun 16, 2022

Question might be better suited for tool talk category but was not sure as it applies to both general mechanical maintenance and specific tractor repair. If you torque bolts to manufacturer specs do you normally use lock washers as well? Should you or are you just wasting money or potentially problems doing both torque/lock washer? Reason for questions is in process of doing repair work on clutch and transmission on 1964 Ford 2000 tractor with 134 ci engine and 4 spd trans (same tractor as 601). However between I&T FO-20 manual, 1955-1960 Ford Tractor shop manual and CNHistore.com website showing parts diagram some show "picture" of washer but not listing it in parts list or as Im taking bolts off find tractor find lock washer not listed in manual? SO, question is so I dont waste money or follow mistake someone else might have done, if lock was is not specifically listed in manual should you use one?

Steve@Advance · Jun 16, 2022

Most pressure plate covers do use lock washers.

Reason is the cover is a stamped steel product. It is not machined flat.

When you are fastening non machined parts together, there is potential for the parts to shift and settle, and
the head of the bolt to dig in under load, which can relieve some of the initial bolt torque. The lock washer
is there to somewhat help prevent the bolt from losing its grip.

But split ring lock washers can actually cause a different problem, splitting and squeezing out! If you want
to use split ring lock washers, be sure to get a good grade, not the hardware store bulk bin variety.

rustred · Jun 16, 2022

definitly use lock washers, just gets me when i see only a bolt ground into the metal.

Fritz Maurer · Jun 16, 2022

Torque is never a waste of time on a rotating, hard to get to component. Locks are good for close-fitting holes where the force of the bolt can mash the hole smaller as its nearing its prescribed torque. Lock washers also permit closer torque targets as they are made of spring steel and promote a sliding force, rather than the bolt head sinking into the attached piece. Seldom do I ever see a lock washer actually lock a bolt, unless the bolt is soft enough and the edges of the washer are sharp enough, but it does happen... use of lock washers also makes the socket stay on the fasteners better, due to the thickness of the washer being nearly the same as the chamfer on the socket; promotes full socket/fastener contact when you are in awkward position or cannot actually see the bolt.

Shoprat · Jun 16, 2022

Do some research on Disc Lock products. Far superior to
conventional lock washers.

Pete in Holland MI · Jun 16, 2022

Proper torque is required for the proper pre-load to a bolt for it to be able to hold the joint together. If the two
pieces are designed and machined properly, so that no movement at the joint can occur, there is no chance of movement, and
thus little opportunity to affect the tightness of a bolt. If there is a chance, a mechanical means of preventing bolt
turning needs to be incorporated.

Materials being secured have to be factored in. If one/both of the components are something other than the material of the
bolt, it can expand at a different rate, affecting the torque. So can the compressability of a softer material.

As said earlier, lock washers can fail for various reasons.

Long and short, there isn't a clear answer to the original question. Interesting discussion though.

Pete

Russ from MN · Jun 16, 2022

How about a hardened flat washer, loctite, and proper torque! I've seen a lot of lock washers break!

perryjosh64 · Jun 16, 2022

If it helps with discussion, current part in question is the trans input shaft retainer that mounts to casing via (4) 3/8-16 x 1 bolts. When I removed it bolts had split locking washer on them. However none of parts/diagram sources lists locking washers but one manual had illustration showing a washer but not actually listed like other bolts/nuts/parts/etc.? So wondering if its supposed to have lock washers and manual was written when better common sense was more widely known (and Im they dummy) or such manuals/diagrams just dont list or show every washer involved?

Fritz Maurer · Jun 17, 2022

You also have to take into account that someone
may have been in there during the years that you
didnt own the tractor, when what youre seeing and
the parts book dont agree.

showcrop · Jun 17, 2022

I agree with Steve and Pete. I was talking with the owner of a high dollar racing engine shop that was rebuilding a tractor engine for me. I asked him about the "Pal" nuts that Ford used to put on conn rod nuts. His response, which I will never forget is that they prefer to rely upon the stretch of the rod bolt holding tension instead of an added part. That is why conn rod nuts are taller than standard and fine thread. On the other hand as Steve posted, when one part is stamped steel you can't apply anywhere near that amount of torque so you need the added part.

caterpillar guy · Jun 18, 2022

Most of the old trucks had lock washers on the heads of the bolts holding the bellhousing to the flywheel housing. On the old double breasted Yamaha's if they didn't have lock washers they would work loose and break the bolts off. Then you had a couple options 1 change flywheel housing or 2 drill out the old bolts and tap for new bolts if you could otherwise you had to drill out old bolts and helicoil the old holes for new bolts. Never had problems with trucks with Cummins or Cats in them doing that just those detriots. Usually the lock washers were a flat form of a washer. Sometimes split ones were used as a replacement by somebody that had lost one or it broke. I think for a lot of jobs torquing bolts is over rated. Till I was in high school I didn't know they made torque wrenches. Never had one nor used one. Did many engines without one with no failures due to proper torque on bolts.

WilBury · Jun 20, 2022

I was told by a mechanic trained in the early 90's that he was taught that lock washers don't lock, use flat hard washers & torque to spec instead.

On another note, disassembling an old machine with seized bolts, I was able to torch off only the lock washers 'cause they melt first!

This post was edited by WilBury on 06/20/2022 at 08:05 am.

Torque vs lock washer?

perryjosh64

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Steve@Advance

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rustred

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Fritz Maurer

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Shoprat

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Pete in Holland MI

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Russ from MN

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perryjosh64

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Fritz Maurer

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showcrop

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caterpillar guy

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WilBury

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