[jml]

At some point somebody dimpled the flywheels in my '74 shovel, I assume to balance it. I can't find anything in the FSM or online about crank runout for a shovel, it all seems to be Evos and newer. Is there a spec for shovels? I measured mine at the pinion shaft at .0065".

 

[dan r]

as with any multi piece crankshaft, the closer to zero run-out the better.
attempting to get zero run-out will drive most anyone crazy.

i have always kept at it until it's 0.001" or less on both the pinion or sprocket shaft.
there will be times you may get one side to zero and the other side will be off.
i could be way off with this idea but i have always felt that the run-out must be less than the bearing clearances.

my "guess" is the picture you show is balancing done by someone more familiar with automotive crankshaft balancing.

take a look at the tech archives pages of this forum.
i shown how i have balanced flywheels for over 25 years.

 

[WhizzbangK.C.]

Dan, as usual, has the correct answer. If seeing it in the service manual helps ease your mind, here's some info from mine. Note that the earlier stuff does not give a reading for measurement of runout with the wheels installed in the case, that happened later when the pressed flywheel assemblies started slipping, and the chain to gear cam drive conversions came out. If you're getting .0065 at the end though, you can bet it's about the same with the assembly between centers.

 

[jml]

Thanks. I actually have a very similar manual, but somehow glossed over that. Just so I'm clear, is "Runout (shaft at flywheel)" at the pinion shaft where I measured it? Can I measure "Runout (flywheels at rim)" with the flywheels in the case and a dial indicator through the bore, or is that something different?

 

[WhizzbangK.C.]

Thanks. I actually have a very similar manual, but somehow glossed over that. Just so I'm clear, is "Runout (shaft at flywheel)" at the pinion shaft where I measured it? Can I measure "Runout (flywheels at rim)" with the flywheels in the case and a dial indicator through the bore, or is that something different?

Runout is measured with the flywheel assembly mounted between centers in the truing stand. The runout is measured as close as possible to the flywheel on each side, pinion and sprocket shaft. This is make sure that both shafts are running true to each other in the bearings, and that the drive gear on the pinion side and the drive sprocket on the sprocket shaft side are running true. Read carefully through the flywheel assembly and truing directions in the manual and study the pics carefully, it will be clear. The only thing that checking it at the end of the pinion with the flywheels mounted in the case can tell you is that it is not true. My question would be, if it is measuring .006 at the end of the pinion shaft, what does the pinion bushing in the nose cone look like? I would think it would have to be trashed.

 

[jml]

It's funny you mention the bushing, because that is something else I ran across--the cam bushing is sitting probably 1/8" proud of the boss, and the pinion bushing is at least that much low. Could the shaft being out of true cause it to work down, or was it installed poorly? I've never seen or heard this engine run, so I can't comment on how it sounds or any of that.

 

[dan r]

the cam cover pinion bushing in your pic looks to be normal depth.
all 54-89 bushings are pressed into the cover like that to provide clearance with the gear nut.
brain fade going on here but 0.200" depth sounds about right.

checking run-out on a friends 68 years ago...

 

[dan r]

after i hit post reply i started wondering about the bushing depth...

oops...

i went out and measured a cover and the bushing is 0.125" deep, not 0.200"
yep, oops...

 

[jml]

Can somebody help me understand what I'm missing here? Upon closer inspection I realized that even the picture in my manual of the gearcase cover bushings looks like what I posted, but clearly I don't understand what they mean by pressing them in flush with/against the cover boss.

 

[WhizzbangK.C.]

Can somebody help me understand what I'm missing here? Upon closer inspection I realized that even the picture in my manual of the gearcase cover bushings looks like what I posted, but clearly I don't understand what they mean by pressing them in flush with/against the cover boss.

View attachment 274955 View attachment 274954

You have to read the entire instructions all the way through to get the context. That paragraph tells you to stop pressing the pinion bushing when it is flush in order to start the drill hole for the pin 3/16 deep. Once the hole is started you then press the bushing in the rest of the way, and then finish drilling the hole. This is because the hole is located in the bushing and the boss and if the bushing is all the way in you won't be able to drill the hole in the right place. The cam bushing is pressed in till the shoulder hits and then drilled.

 

[dan r]

yes, install flush, start drilling for the lock pin, press to full depth and then finish drilling to depth.
press in lock pin and peen the bush to retain the pin...

keep in mind if you replace a cam cover bushing, it must be reamed to size in alignment.

while this pic is an early pan (53 and a different bushing type) the pinion bushing must be reamed in alignment with the pinion bearing bore.
you will also need to do this on yours as well once the bushing is fully installed and pined.
same deal with a cam bushing...
sorry, i don't have a pic of this on a 70 and up engine.

 

[jml]

Thanks for all the pointers, guys. At this point I'm going to let sleeping dogs lie and leave the bushings (and flywheels) alone unless things sound like they're going to fall apart when I finally get it going.

 

[JasonMcElroy]

Thanks for all the pointers, guys. At this point I'm going to let sleeping dogs lie and leave the bushings (and flywheels) alone unless things sound like they're going to fall apart when I finally get it going.

To get some sleep at night . . .

At least measure the fits of the pinion shaft-to-bush and camshaft-to-bush. Also inspect to see if there is uneven wear in the bushes which would indicate an alignment issue.

IMO, if bushes show uniform wear and are within .001" loose on each, you're good.

Jason

 

[WhizzbangK.C.]

Dan and Jason have good advice here. Pinion shaft bushing clearance is very important. A lesson I learned the hard way. I rebuilt the lower end of my shovel and set everything up to the tight side of the tolerances. The bushings in the cam cover "looked good" so I just bolted it back on. Less than 5,000 miles later, and over 100 miles from home on the way to a friend's house in Iowa, the engine quit running. Roadside diagnostics revealed a broken pinion shaft. (Aside to Dan, Rev Tramp was riding right beside me when this happened.)

It was a brand new American made part. I figure it broke because there was too much clearance at the bushing allowing the end of the shaft to wiggle back and forth as the cam pushed against it and the bearings were too tight to allow the flywheel end to move. Anyway, lesson learned. Don't do one bearing without addressing all of them. It hadn't been a problem before because the main pinion bearings were worn also so everything was happily slopping around together.

That said, if your runout at the outboard end of the pinion shaft actually is .0065 as you stated in your original post (which is what made me question the pinion bushing to begin with) then a .001 clearance on the bushing is going to cause the same kind of stresses that broke my pinion. You need to carefully check it before you just throw everything back together again. Where are you located? There might be someone local to you who could help.

 

[Hoges]

Good Advice.

 

[JasonMcElroy]

@WhizzbangK.C. Is Rev still around? I quit social media a few years back and have no way to reach him. If you could put me in touch, I'd greatly appreciate it. Thanks.

 

[WhizzbangK.C.]

@WhizzbangK.C. Is Rev still around? I quit social media a few years back and have no way to reach him. If you could put me in touch, I'd greatly appreciate it. Thanks.

Sent you a DM.