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Author Topic: Big end wear or damage  (Read 3213 times)

Powdermonkey

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Re: Big end wear or damage
« Reply #15 on: February 25, 2022, 03:37:59 AM »
Nev,

I just found a source to reweld and regrind DIESEL crankshafts.  Key words: Diesel crankshaft.  Nobody in MY area will touch a regrind, let alone a reweld on a diesel crankshaft. 

Hillcrestcamshaft.com

Yellownev

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Re: Big end wear or damage
« Reply #16 on: February 25, 2022, 10:25:11 PM »
Nev,

I just found a source to reweld and regrind DIESEL crankshafts.  Key words: Diesel crankshaft.  Nobody in MY area will touch a regrind, let alone a reweld on a diesel crankshaft. 

Hillcrestcamshaft.com

Hi,

I know of a place in the UK who can/will regrind the journals but I'm hoping not to have to have that level of intrusion, thanks for the comment.

cujet

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Re: Big end wear or damage
« Reply #17 on: February 26, 2022, 04:22:15 PM »
I'm not sure of the nut size at the moment. All of my lister spares are in storage at the airport. Maybe if I get out there I'll have a look. 

Found an old manual. The connecting rod nut is 1/2 Witworth. The bearing clearance should not exceed 0.003 inches. I did not see a listed torque. The manual I have simply states:

"This interference or 'nip' is measured by placing the bearing in the connecting rod, tightening both bolts to the normal extent, then slackening one bolt only and measuring the corresponding gap in the rod at the parting line. This gap should be between 0.004" and 0.006". All this does is keep a con-rod cap from crushing the bearings.

So, that's pretty simple, "if" the gap is 0.015" then simply install shims to bring the gap within spec. Tighten the nut and install cotter pin.

The nuts have cotter pins, so the torque is generally to a spec (which I don't have at the moment) then "to the next hole", then insert the cotter pin.

As always, a simple look at the bearing shells will show a lubrication hole that must be aligned. And don't install the "dipper" so tight that it rubs the crankshaft!
« Last Edit: February 26, 2022, 04:49:35 PM by cujet »
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cujet

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Re: Big end wear or damage
« Reply #18 on: February 26, 2022, 04:51:46 PM »
Just a quick note about the connecting rod cap "gap" (with just one bolt tight). Maybe this exists as a way to "tighten up" a bearing with a bit too much clearance. A really nice feature when you need a running engine now!
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cujet

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Re: Big end wear or damage
« Reply #19 on: February 26, 2022, 04:52:51 PM »
Again, if I go out to the airport, I'll take a few pics. That should help A LOT.
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Yellownev

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Re: Big end wear or damage
« Reply #20 on: February 26, 2022, 09:49:30 PM »
Thatís a great amount of helpful information I really do appreciate it. Iíll digest it and if you are able to get a photo to further explain it even better. Many thanks for taking the time to reply in such a comprehensive way. Take care.

cujet

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Re: Big end wear or damage
« Reply #21 on: February 27, 2022, 11:28:24 PM »
I took a picture of a spare (damaged during manufacture) Listeroid connecting rod I had at the airport. I tried to make it contain all the necessary information in one picture.

1) The 2 (two) lube holes on the top bearing shell
2) The "dipper" hole on the bottom that holds the bearings from rotating (where the drill bit is) And why you must be careful not to tighten the dipper against the crankshaft
3) Showing a 13/16th's wrench that fits the nuts
4) The lower bearing shell with just one hole
5) How the "nip" is measured, with a feeler gauge on the left side of this pic (remember the bearings must be installed)
6) I still have not found a torque value for the connecting rod bolts/nuts

And so on. Hope it helps. It's really simple, and the use of just a little care will give great results.
I have hope your crankshaft will be fine with some careful cleanup of old bearing material.

https://i.imgur.com/JCtm2Kn.jpg

« Last Edit: February 27, 2022, 11:35:45 PM by cujet »
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mike90045

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Re: Big end wear or damage
« Reply #22 on: February 28, 2022, 02:14:09 AM »
I don't think castle nuts / cotter pins, have a torque value, the cotter pin keeps the nut in place to maintain the required gap ?

cujet

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Re: Big end wear or damage
« Reply #23 on: February 28, 2022, 03:00:10 AM »
The nuts must be tightened properly! The stress on connecting rod bolts is cyclic and they will eventually fail, "IF" not tightened to a certain level of stretch.

Put another way, once the bolt stretches and clamps the 2 pieces together, the bolt never feels any additional force, as the running loads are lower than the stretch force.
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mike90045

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Re: Big end wear or damage
« Reply #24 on: February 28, 2022, 06:40:36 AM »
The nuts must be tightened properly! The stress on connecting rod bolts is cyclic and they will eventually fail, "IF" not tightened to a certain level of stretch.

Put another way, once the bolt stretches and clamps the 2 pieces together, the bolt never feels any additional force, as the running loads are lower than the stretch force.

Thank you, I didn't know.  I was going to treat them like the castle nuts on the tractor wheels.  So far, I've not had any issues needing to open them up

38ac

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Re: Big end wear or damage
« Reply #25 on: February 28, 2022, 11:28:57 AM »
The bolts and nuts on MOST Listeroid are Whitworth pattern although I have seen a couple that were a hodgepodge of whatever they found in the dirt.  Fuel lines are metric,  some other parts like plugs are odd ball. While it's nice to have a set of Whitworth tools you can get along fine with standard fractional and metric tools sets and you will always need a couple adjustable wrenches.

A note about big end bearings. India machine tolorances are quite large however. I have never ran into an India rod, india bearing combination that required shims to correct too much crush. The inserts will be flush with the cap and rod. However shims may be needed to increase bearing clearances. If you run into a situation like that it is imperative that the shims are large enough toward the crankshaft to get between the inserts without being so long as to contact tbe crankshaft.
« Last Edit: February 28, 2022, 11:39:00 AM by 38ac »
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cujet

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Re: Big end wear or damage
« Reply #26 on: February 28, 2022, 10:05:38 PM »
38ac, I figured you'd have a torque spec. In any case, thanks for the good information!!!!

I honestly do not recall using any shims on my engine. But that was 15 years ago.
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38ac

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Re: Big end wear or damage
« Reply #27 on: March 01, 2022, 02:28:01 AM »
Any torque spec is pretty much useless unkess one plans to leave out the cotter pins.  I bring them to not quite tight and study the slot to hole relationship and advance the nuts accordingly. A person without the feel for that could torque them to 75% of the value listed in a standard torque table and advance from there.
« Last Edit: March 01, 2022, 02:29:59 AM by 38ac »
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Yellownev

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Re: Big end wear or damage
« Reply #28 on: March 01, 2022, 05:02:48 PM »
First off many thanks Mr Cujet for taking the time to go and take the picture and add the explanation - priceless for me to work with. Then thanks to all the other contributors to date. I'll let you know how I get on in the next  week or so. Again a great group of helpful friendly people, take care.

Nev 

cujet

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Re: Big end wear or damage
« Reply #29 on: March 01, 2022, 10:34:19 PM »
Take the cap off, and take some pictures!


Remember, the cap probably only goes on one way, so it might be a good idea to put a center-punch mark on the rod and cap to ensure correct assembly.
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