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Old 04-26-2020, 03:41 PM   #1
Werner
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Default Bad rod bearing

Bad evening!

Today we made the first big drive after reversing the engine & gear. I'm unlucky with my car! A bearing damage is in the offing. The engine knocks increasingly louder. With the stethoscope I hear the loudest point on cylinder 2 on the oil pan. Does it make sense / is it possible to try to replace the connecting rod without removing the engine? Only the head and the pan away?
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Old 04-26-2020, 03:45 PM   #2
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Default Re: Bad rod bearing

Just remove the pan first and inspect.
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Old 04-26-2020, 06:15 PM   #3
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Default Re: Bad rod bearing

If it is a bad rod bearing, you can easily identify which one by shorting out the spark plugs one at a time. When the noise stops, that is the cylinder with the problem. Then, drop the sump and take off the head. The rod can be removed and replaced without removing anything more. I did it on a friend's car one day on the side of the road.
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Old 04-26-2020, 09:38 PM   #4
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Default Re: Bad rod bearing

As long as the crank journal isn't damaged.
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Old 04-27-2020, 05:06 AM   #5
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Default Re: Bad rod bearing

Hallo und guten Tag.
I get to lay down under the car this afternoon and remove the oil pan to open the bearing shells.

Then we'll see.
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Old 04-27-2020, 06:47 AM   #6
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Quote:
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As long as the crank journal isn't damaged.
I should have mentioned that!
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Old 04-27-2020, 07:56 AM   #7
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Default Re: Bad rod bearing

Id pull the engine if it was mine,work standing up,clean and position the engine for installing the pan correctly. It takes longer but youre work is easier and the results will better.
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Old 04-27-2020, 09:55 AM   #8
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Default Re: Bad rod bearing

I have done it. Required removing the pan and head. You will need a ring compressor to get the piston back in. I tried doing everything through the bottom at first but i couldn't get enough room to take the wrist pin out. Others may have had more luck. The trick is finding another rod on the cheap and keeping the oil pump in place while putting the pan back on.
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Old 04-27-2020, 11:35 AM   #9
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Default Re: Bad rod bearing

Werner,

If you can hear it in the pan, it may just be the dipper making contact with the tray.
Pull the pan and look for a mark.
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Old 04-27-2020, 11:58 AM   #10
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Default Re: Bad rod bearing

Gutten tag Werner,

I agree with John, check the rod hitting the pan first. If it is the rod bearing clearance, the babbitt might be able to be adjusted by shim removal?
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Old 04-27-2020, 02:19 PM   #11
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Default Re: Bad rod bearing

Guten Abend.

Thank you all for anticipations.

1) There are bearing damages. The flanks of the soft metal bearing shells have chipped off on the outer edge. Z 2 the damage goes up to 1/4 in the area. That was the cylinder that pounded loudly.
What can the edge chipping come from?

2) Can someone explain why the babbit clearance is set with the shims? The supporting hydrodynamic lubricating film is interrupted by the gap.


The surface of the crankshaft is o. k.
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Old 04-27-2020, 02:32 PM   #12
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Default Re: Bad rod bearing

The damage shown should not cause an audible knock in my thinking. Knock is caused by too much clearance or a mechanical interference. What was the clearance measured on these bearings?
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Old 04-27-2020, 04:27 PM   #13
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Default Re: Bad rod bearing

Just a suggestion, take the rods and make sure they are straight.
It may just be the picture, but the rod looks loaded on the side that is babbitt is broken out of.

Do not worry about the shim gap between the cap and rod, the bearing is not pressure fed anyways.

John
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Old 04-27-2020, 04:53 PM   #14
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Default Re: Bad rod bearing

The rods & caps are tinned prior to pouring babbitt. Sometimes they don't get a good tin job and the babbitt doesn't stick as well as it should. Even with everything well coated a bearing can experience cracking & chipping of the babbitt if the bearings are well worn or the babbitt is thin.

Shimming is done for several reasons. The most common reason is to be able to tighten a worn bearing set by removing a shim or shims. The other reason is that folks had a tendency to sand the parting surface the cap on a flat piece of glass if the shims were all gone instead of exchanging them for a rebuilt set. This makes the next babbitt job too thin so more shims have to be used to keep from hitting steel while cutting the bores to size.

Last edited by rotorwrench; 04-27-2020 at 05:20 PM.
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Old 04-27-2020, 06:35 PM   #15
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Default Re: Bad rod bearing

Shouldn't the grooves in the bearings be cut like the ones in Herm's picture?
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Old 04-27-2020, 09:11 PM   #16
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Default Re: Bad rod bearing



Hydrodynamic lift principle occurs 90 degrees from the bearing shims..if the rod turns out to be true I've seen where folks have dabbled a little solder in the blown out area and dressed it off with good results
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Old 04-28-2020, 11:32 AM   #17
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Default Re: Bad rod bearing

Guten morgan Werner,
Shims were always installed when new, by Ford, in order for the owner to be able to adjust the clearance as miles were accumulated. This was particularly needed in Model T's as they had no oil directly into the rod bearings. You might try carefully adding solder to the thrust (sides) of the bearings and hand filing to fit. Your bearings look to be still serviceable. Grooves such as you have were mostly used in pressured oiling systems, but yours, IMO, are better than the standard big X grooves as the have more surface area, and are obviously getting adequate amounts of oil.
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Old 04-28-2020, 12:09 PM   #18
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Default Re: Bad rod bearing

When the dippers hit that puddle of oil in the dipper tray, there is pressure to the oil that injects in there with each revolution. There is no way to measure it but it does get a good squirt each time. The higher the rpm, the higher the pressure. The X shaped grooves spread a more even flow of oil over the whole journal than a single groove can.

If the rod bearings still have a usable clearance, a person would need to check the center main journal. They take a beating compared to the others and they will knock if the clearance is too much.

A person would have to get all the oil off of an area that they want to try to solder. Even with flux, it's hard to get it to tin so the stuff would stick.

Last edited by rotorwrench; 04-28-2020 at 12:19 PM.
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Old 04-28-2020, 03:42 PM   #19
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Default Re: Bad rod bearing

Hallo und guten Abend.

I measure a bearing clearance of 0.03 / 0.04 / 0.01 / 0.005 mm (millimeters!). The crank pins are clean and smooth. One has a tiny scar like a cut fingernail. (s. picture).
The cylinders (honing marks) and the slotted-jacket pistons are in a good condition and have modern piston rings (1 nose ring) with no vertical clearance play.

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? -


The problem with the shim gap is that the hydrodynamic lubricating film, which has an average thickness of only 0.003 mm (3 µm), is interrupted. In order for the hydrodynamics to work properly, a trouble-free (= smooth) 360 ° course must always be guaranteed. This is independent of pressure pump oil.
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Old 04-28-2020, 05:14 PM   #20
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Default Re: Bad rod bearing

This link is for a similar question: https://www.practicalmachinist.com/v...epairs-207306/

There is a maybe on solder but a person would want as much tin as possible. The connecting rods are a lot easier to rebuild than the blocks. I know your in an area where there aren't a lot of Model A rebuilders but there may be someone close to you that can work babbitt for general purposes. The rods can be poured again and each one fit to your crank as needed or just refit the bad one if you want. It would last a lot longer than way.
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Old 04-28-2020, 05:29 PM   #21
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Default Re: Bad rod bearing

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
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Old 04-29-2020, 02:44 AM   #22
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Default Re: Bad rod bearing

Quote:
Originally Posted by Werner View Post
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.
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Old 04-29-2020, 09:02 AM   #23
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Default Re: Bad rod bearing

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?
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Old 04-29-2020, 09:27 AM   #24
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Default Re: Bad rod bearing

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.
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Old 04-29-2020, 01:08 PM   #25
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Default Re: Bad rod bearing

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.
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Old 04-29-2020, 01:35 PM   #26
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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?
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Old 04-29-2020, 02:05 PM   #27
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Default Re: Bad rod bearing

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?
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Old 04-30-2020, 04:35 AM   #28
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Default Re: Bad rod bearing

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?
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Old 04-30-2020, 05:44 AM   #29
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Default Re: Bad rod bearing

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.
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Old 04-30-2020, 09:13 AM   #30
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Default Re: Bad rod bearing

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.

Last edited by rotorwrench; 04-30-2020 at 09:20 AM.
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Old 04-30-2020, 09:43 AM   #31
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Default Re: Bad rod bearing

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.
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Old 04-30-2020, 02:33 PM   #32
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Default Re: Bad rod bearing

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.
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Old 04-30-2020, 06:40 PM   #33
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Default Re: Bad rod bearing

Quote:
Originally Posted by rotorwrench View Post
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.
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Old 05-12-2020, 03:52 AM   #34
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Default Re: Bad rod bearing

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?
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Old 05-12-2020, 05:04 AM   #35
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Default Re: Bad rod bearing

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.
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Old 05-12-2020, 08:23 AM   #36
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Default Re: Bad rod bearing

from the service bulletins-- piston pin in rod---0.0003" max clearance
fit in piston-- 0.0003-.0005 shrink fit in piston
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Old 05-13-2020, 04:29 AM   #37
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Default Re: Bad rod bearing

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.
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Old 05-15-2020, 04:02 PM   #38
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Default Re: Bad rod bearing

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.
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Old 05-15-2020, 04:13 PM   #39
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Default Re: Bad rod bearing

.051mm is .002 inches,acceptable bearing clearance ideally .0015 but .002 is ok
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Old 05-15-2020, 05:01 PM   #40
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Default Re: Bad rod bearing

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.
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Old 05-16-2020, 02:23 PM   #41
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Default Re: Bad rod bearing

SAJ, I meant to grind the connecting rod caps with the inserted bearing shells together on a lapping stone. Only some few µm.
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Old 05-16-2020, 05:20 PM   #42
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Default Re: Bad rod bearing

Werner Yes I was sure you meant that. I was worried someone less knowledgeable would think you were grinding just the insert shells.
If you leave the shells in the caps and surface them on a stone, you will remove the protrusion of the shells and the crush which is important for tightness and bearing shape. That is why I stoned the caps without the shells in place. I could have then removed 0.0005 inch from the shells to retain the same crush, but did not bother. So my bearings have a very slightly bigger lemon shape than before I resurfaced the caps.
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Old 05-22-2020, 02:01 PM   #43
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Default Re: Bad rod bearing

Wunderschönen guten Abend!

Since the day before yesterday my machine has been running again with the new piston rings and the inserted connecting rods.

Yesterday I drove 40 carefully miles with less than 40 mph. The motor now runs as quiete like a freshly oiled sewing machine.

I would like to thank now all the helpers here who supported me with advices!


Info: The new 'imported connecting rods' with inserts weight 775 grams. The old ones with babbits 720 g. The weight difference are only 5 grams.
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Citroen 11 CV, 1947
Hercules W 2000, 1976; (with NSU-Wankel Rotary Engine), Canadian version
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Old 06-17-2020, 02:17 PM   #44
Werner
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Location: Germany, near Aachen
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Default Re: Bad rod bearing

N'Abend!


After now 430 slow (max. 40 ml / h) running-in miles today I measured the warm engine compression. 70 PSI at all cylinders - it's looking good!
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Werner


Ford Model A, Roadster, 1928
Citroen 11 CV, 1947
Hercules W 2000, 1976; (with NSU-Wankel Rotary Engine), Canadian version

Last edited by Werner; 06-17-2020 at 02:24 PM.
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