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Cam gear end play

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prairie dog

Posts: 30

Joined: Mon Apr 30, 2007 1:18 pm

Location: Winnipeg,Canada

Post Mon Jun 09, 2014 6:18 am

Cam gear end play

My kicker pedal was quite tight and hard to kick over, so I removed the gear case to have a look. The previous owner had replaced the bushings on the gear case side. The fit was so tight that none of the cams would turn individually by hand. I honed the bushings so each cam can be turned by hand. Two questions:
1. There were four thrust washers, one on the engine side of each cam. Should there also be a washer on the cover side of the two front cams?
2. Can the cam end play be checked with the gear case cover on, and the engine still in the bike?
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Pa

Site Admin

Posts: 4652

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Mon Jun 09, 2014 7:11 am

Re: Cam gear end play

The washers you describe are shims. Initially one shim per cam goes on the flywheel side. Additional shims are added to obtain endplay on the gear cover end of the two front cams. The two rear cams receive no shims on the gear cover side. The only ways I know of for checking can shaft endplay with the cover on is with the tappets and tappet blocks out or with the cases split. However, you can get a good measurement if you depth mic the cover gasket surface down to each bushing face, depth mic the case side from the gasket surface down to each bushing face, mic the cover gasket thickness at squish, and add all three measurements up together for each individual cam. Record those measurements. Next mic each individual cam from thrust shoulder to thrust shoulder and compare your each individual measurement to your recorded measurements. This will tell you what you have for endplay clearance without any shims. Shim each cam to correct endplay based on those measurements.
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ohio-rider

Posts: 227

Joined: Tue Jun 12, 2007 7:26 am

Location: Ohio

Post Mon Jun 09, 2014 9:21 am

Re: Cam gear end play

During my rebuild I measured the cam end play using both methods just for fun. First I did it using the method that Pa just described which requires a lot of measuring and some guessing. The guessing part was because I had no idea how much room the new gasket was going to take when squished together during assembly.

I didn’t feel comfortable with the numbers I was getting so I ended up splitting the cases to do it the best way. Surprisingly, I found that the stacked measurements I had taken where actually pretty close to what I found after splitting the cases. Just be sure to lean towards the loose side when averaging all those stacked numbers and you should be ok.
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Dusty-Dave

Posts: 868

Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Mon Jun 09, 2014 12:38 pm

Re: Cam gear end play

You all don't just check it with plastiguage?
Dusty
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Pa

Site Admin

Posts: 4652

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Mon Jun 09, 2014 12:42 pm

Re: Cam gear end play

Dusty-Dave wrote:You all don't just check it with plastiguage?
Dusty


Ya know Dusty....after all the automotive babbit rod bearings I have fitted in the past, you would have thought I would have thought of that.
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Pa

Site Admin

Posts: 4652

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Mon Jun 09, 2014 12:44 pm

Re: Cam gear end play

ohio-rider wrote:During my rebuild I measured the cam end play using both methods just for fun. First I did it using the method that Pa just described which requires a lot of measuring and some guessing. The guessing part was because I had no idea how much room the new gasket was going to take when squished together during assembly.

I didn’t feel comfortable with the numbers I was getting so I ended up splitting the cases to do it the best way. Surprisingly, I found that the stacked measurements I had taken where actually pretty close to what I found after splitting the cases. Just be sure to lean towards the loose side when averaging all those stacked numbers and you should be ok.


You can get even closer if an oem gasket is used because they don't squish but a couple of tenths. When they are dry, they are what the squish will be, if you can get them on the dowel pins and line up all the holes dry.
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ohio-rider

Posts: 227

Joined: Tue Jun 12, 2007 7:26 am

Location: Ohio

Post Mon Jun 09, 2014 4:49 pm

Re: Cam gear end play

I’ll be damned. I never thought of using plastic gauge to measure face clearances, even after all these years using it on O.D’s. And I spent a few hours measuring everything the hard way. I guess it’s one of those old dog new trick things. Guess I went thru all this for nothing then.


Image

By the way, Pa is right the gasket doesn’t squish anything at all.
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37ULH

Posts: 682

Joined: Mon Nov 25, 2002 1:01 am

Location: somerset, oh usa

Post Wed Jun 11, 2014 12:40 pm

Re: Cam gear end play

Since you are already in there and whoever built your engine obviously didn't have a clue, I'd certainly set up a dial indicator on the pinion shaft and see if the runout and end play are in spec before considering starting to put it back together.
If mine, and i found what you found, i'd automatically go through the entire engine.
These engines are pretty forgiving as long as they are properly built to start with.
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prairie dog

Posts: 30

Joined: Mon Apr 30, 2007 1:18 pm

Location: Winnipeg,Canada

Post Sun Jun 29, 2014 12:50 pm

Re: Cam gear end play

I'm going to reassemble the gearcase today and use some plastigage to check the cam endplays. My manual says the endplay should be "free to .005" . Does this mean 0.000 to .005 , or in other words .005 is my maximum endplay?
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Dusty-Dave

Posts: 868

Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Sun Jun 29, 2014 5:17 pm

Re: Cam gear end play

prairie dog wrote:I'm going to reassemble the gearcase today and use some plastigage to check the cam endplays. My manual says the endplay should be "free to .005" . Does this mean 0.000 to .005 , or in other words .005 is my maximum endplay?

That spec was written before dial indicators became common place and before plastiguage was invented they intended you to remove the lifter blocks and check it with a feeler guage. Since there weren't any commonly available feeler gauges under .0015 so they just said it should turn free and be .005 or less. If using plastiguage or Pa s method I would set it between .001 and .005.
Dusty

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