Bad rod bearing

[Ernie Vitucci]

Several of the engine rebuilders that visit this site can supply rods to fit the crank if the crank is at a size that they have rods for. Babbitt or perhaps inserted...a full set from one of the engine builders will weigh each the same and the engine will be happier. Ernie in Arizona

[dumb person]

Originally Posted by Werner

Hallo und guten Abend.

I am considering whether it is feasible to solder the damage of the one of the connecting rods on the tread with SN 40? Who has done this? -

I have. Working well. Several years of driving later.

And the gap at the bearings isn't really a problem, it's the only way oil got in them in the model T.

[Werner]

Hallo und guten Tag! Thank you all for your friendly help.

I will replace the connecting rods. Then I drive a long time with rest.

The engine has been revised several times. The cylinder bore is .6 (5th bore) and the crankshaft diameter is only 1.48 (third cut?).

Because it is cumbersome (custom!) and expensive to send the old connecting rods to Bratton's, I will probably opt for the connecting rods (# 8491) with insert cups.

Do you recommend them?

[30 Closed Cab PU]

I think it is recommended if going to inserts, to have an oil filter - not sure. The Babbitt on the inserts is thin, not as forgiving as true Babbitt.


And maybe going to pressurized oil system?


This is my understanding, not sure it is correct.

[Werner]

Good afternoon.

Wade, you are right. The inserts are slightly more sensitive to coarse dirt. But I installed an oil filter. It doesn't matter whether pressure oil or dip spoon oil comes into the bearings.

[Werner]

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An alle,


please, I have a request to check the bearing shell size for the order.

I measure the diameter of the crank pin:

min. 37.558 mm / 1.4786 ";
max.37.567 mm / 1.4790 ".

Then I need the insert bearing .020 # 8541 from Bratton's stock?

Have I understood that correctly?

[KR500]

As long as rods are out wouldn't it make it sense to do an exchange for rebabbitted rods with new shims bored to the present crankshaft journal diameters?

[Werner]

KR400, I have to send the old connecting rods to Bratton's before they send me the reneuwed rods. The total shipping cost for this back and forth is about 140, - + 19 % BTW. In addition, the complicate customs declaration for import to the USA.

The rods with the bearing inserts are therefore easier and faster to buy for me. They also have the advantage that they can be easily replaced.

No matter how I decide, the problem of the correct order size is the same for both variants.

Is my converted stock size correct?

[Synchro909]

Werner, your conversion from metric to imperial is correct and it tells me that your journals are 0.021"/0.022" under size. I don't know if the rods you are considering have shims in them but I'd say that a set of 0.020 undersize rods will do the job. Without adjusting them, you will have a clearance a little wide but by either removing 0.001 of shim or rubbing the cap on emery paper laying on a flat surface, you can easily take them down by the required 0.001 or 0.002" to be spot on. Just keep the caps square when you do this is my advice.

[rotorwrench]

I don't know if it's wise to use shims with keyed in bearing shell inserts. We certainly don't use them on any other insert type bearings. With inserts you grind the crank under size to fit the over size bearing not the other way around. 0.002 inch (.0508 mm) clearance is considered acceptable but much more and it will be loose.

[Werner]

Thank you both for confirming my order size. I have already ordered from Bratton's.

The bearing shells do not get shims. I will adjust it. Narrower is easier than further. My target is a bearing clearance of 0.03 mm. I will check the clearance with plastigage.

[rotorwrench]

That might be a bit tight but it is close. I like .0015 inch but it will likely work at .0012 inch. There has to be some space for oil in there.

[Synchro909]

Originally Posted by rotorwrench

I don't know if it's wise to use shims with keyed in bearing shell inserts. We certainly don't use them on any other insert type bearings. With inserts you grind the crank under size to fit the over size bearing not the other way around. 0.002 inch (.0508 mm) clearance is considered acceptable but much more and it will be loose.

I was talking about babbit bearings. I agree, it's not worth messing about trying to adjust inserted bearings, though I have seen it done.

[Werner]

Guten Morgen.

Unfortunately, I do not find any dimensions for the upper connecting rod eye /piston pin in the documents. I think a gap dimension 0.004 "/ 0.01 mm would be correct with the reamer is o. k.

Right?

[SAJ]

Werner, you have a typo there. 0.004 or 4 thou is far too much for a wrist pin.
0.01 mm is correct. A firm push fit. And a honed finish after reaming is best in my view.
SAJ in NZ

[Kurt in NJ]

from the service bulletins-- piston pin in rod---0.0003" max clearance
fit in piston-- 0.0003-.0005 shrink fit in piston

[Werner]

Guten Morgen.


Yes, that was a translation error calculation from mm to inches. Thanks for the hints!

The connecting rod eyes from Bratton have an oversize of +5/100 (+0.05) mm. I leave them on a sliding measure of -8 µm (-0.008) mm reamers.

[Werner]

Hi!


In the meantime I have measured the modern connecting rods with the replaceable bearing shells on the crankshaft. The gap dimension in mm are .051; .040; .051; .051. Measured with Hastings plastic gauge.

That is a little to much, I think?

I will therefore grind the bearing shells completely using a flat sharpening stone.

[Jack Shaft]

.051mm is .002 inches,acceptable bearing clearance ideally .0015 but .002 is ok

[SAJ]

Werner, do you mean "grind the caps" not the shells? If you grind the shells you will remove the bearing crush.
My bearing clearance was also 0.002 inch with the Snyder's shells. I faced off 0.0005 inches to get a clearance of 0.0015 and I did not reduce the shells, so they ended up with half a thou more crush. Without looking it up I think they started at 0.002 inch crush, measured in the standard way by inserting only one bolt in the con rod and feeling the gap left on the unbolted side with slip gauges.
Engine has done many thousands of miles like this and runs really well.
SAJ in NZ