Something to check when you change your cams

[VRYQUIK]

Here is something to look for the next time that your cams are removed.

This is an engine build at our shop that I’m going to use as an example.
This is becoming a frequent issue.

If the camshafts are removed from your engine for any reason, have someone or yourself inspect the crankshaft surface where it is supported by the cam plate bearing. If there are grooves worn on the shaft, then the crankshaft has excessive run out. Harley has a run out tolerance spec. of up to .015”. Most HD technicians will go by these specifications. It may be hard to convinced them that the factory tolerance is unacceptable. If they argue with you, ask them if it’s normal for the other components to be worn also and what caused them to wear. Then ask what happens to the metal from the wear of these components and where does it go.

Just think about it, all of this metal travels through the oil system and some of it has to eventually deposit itself on the roller bearings. Keep this in mind also, that the rollers and the seats of the roller bearings are hardened steel. The debris will be run over like a steamroller. It has to affect the life of the bearing.

Another “old school” way of thinking, debates where the measurement should be taken to check run out. Service manuals advise to take the measurement at the shaft just outside the crank bearing. Here again, their theory is that the run out doesn’t matter at the end of the crankshaft. If it doesn’t matter, their shouldn’t be important components being worn that is connected to end of the crankshaft.

Remember that the crankshaft runs through the oil pump rotors (drives the oil pump) then rides on a bushing (bearing) in the cam plate. The oil pump is securely bolted to the cam plate and the cam plate is bolted to the engine case while the rotors are secured to the crankshaft.

So you have a crankshaft moving up, down or sideways, (also the oil pump rotors doing the same) while trying to be secured by the cam plate bushing which is trying to keep the crankshaft aligned and not moving. The oil pump that is securely bolted to the cam plate is driven by the moving crankshaft. Run out cannot be acceptable at the end of the crank! Everything is trying to keep the crank running true so, why would it be acceptable to let the crank have untrue movement?

Listed are some pictures of what to look for and what type of damage occurs when the crankshaft has this problem. This crankshaft only has .006” run out but, look at what components are also worn.

I’ve seen a lot worse than .006” run out on other cranks. We are installing a new crankshaft that has been trued and welded. The company that trued and welded the customer's new 103" crank says that the crank run out should be .001” or less after their true and weld service.

YouTube - Excessive Crankshaft Runout on an HD Twin Cam

Grooves on the crankshaft

Grooves on the oil pump rotors (gears)

Grooves on the cam plate where the oil pump is installed

There are several companies that can repair this problem with crankshafts by truing and welding the crank. The customer of this engine has purchase a new 103 ci. crank and has sent it out to be trued and welded so that this will not happen again.

I have contacted the company that performed the "true & weld" service on the customer's new crank to get permission to post a video that they made explaining about this procedure. I will post the video when I get approval.

Thanks good info.

[street bob]

I don't understand how any motor builder(H-D) could say that anything more than .0015 runout is acceptable. It just boggles my mind.

[tommyglide]

Thanks very much for the enlightenment. Something I'll certainly be checking for.

[BluesFan]

Very interesting and thanks.

As to metal in roller bearings, A roller bearing has so little clearance under the loaded rollers that the oil will actually go solid at peak load.

We're talking small fractions of a micron here. You can't see anything smaller than about 30-35 microns. Hair is about 40.

So you are absolutely correct about all that metal floating around, It's bad juju.

Thus my love of great filters.

Also, technically, a particle between 2 surfaces is 3 body abrasion. If that particle embeds in one of those surfaces, it is just like a file.

Clean oil is happy oil.


Thanks again for the runout info, very good to know.

[Fenderplayer]

Good stuff. Thanks Vryquik.

[shovelmike]

Thanks, VRYQUIK, for posting this very important information. It's members like you and other knowledgeable individuals that continue to make this the BEST HARLEY FORUM around.
Indeed, metal debris in any engine is bad news. In a babbit bearing engine there is some imbedability factor that can save you from small amounts of debris. In a roller bearing engine such as Harley there is no imbedability factor (hardened rollers against hardened races as you stated) and it will all go KABOOM in the most inopportune time and place.

[VRYQUIK]

Revolution Performance contacted with me and approved the use of their video.

Hi Clark:
Everyone here likes your article. Please go ahead and use our video. We would also love it if you would mention us by name.
Thanks,
Greg Kerkman

You may want to check out their other videos on You Tube.

YouTube - Crankshaft True and Tig

[HarleyCruiser]

VRQUIK, this is awesome stuff. I think this is one of the most informative post that I have seen on the internet, love the video.
I’ve been talking to Buzz trying to get the details worked out about the online magazine and the tech library set up. It will be a couple of weeks before we are able to get started, but this needs to be put in a permanent place so that it does not get buried in the post.
We might want to change the name, let me Photoshop the photos to add some arrows, ect.
You have hit this one out of the ball park.

[VRYQUIK]

Originally Posted by HarleyCruiser

VRQUIK, this is awesome stuff. I think this is one of the most informative post that I have seen on the internet, love the video.
I’ve been talking to Buzz trying to get the details worked out about the online magazine and the tech library set up. It will be a couple of weeks before we are able to get started, but this needs to be put in a permanent place so that it does not get buried in the post.
We might want to change the name, let me Photoshop the photos to add some arrows, ect.
You have hit this one out of the ball park.

Hey, it sounds great. Do what you need to. I was going to post the video from Rev. Performance in the article but, it will not let me add more than four pictures to a post. Maybe you can add the video when you make the changes. Thank's alot, Clark