Loose crankshaft woodruff key

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David Follett
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Loose crankshaft woodruff key

Post by David Follett » Sat Jul 20, 2019 3:18 am

The slot in my crankshaft is worn and the woodruff key is loose. The key is new and pulley not worn. The pulley is tight against the crank but moves a few degrees left or right when I turn the alternator to adjust static timing. Should I try to fit key with epoxy, JB Weld or something or leave as is and set timing using a timing light. Not sure with engine running if movement of pulley is toward BTDC or ATDC to compensate.
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raygreenwood
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Re: Loose crankshaft woodruff key

Post by raygreenwood » Sat Jul 20, 2019 8:16 pm

You really need to post a few pics of the slot on the crank and especially the tapper joint...both hub and crank snout.

See...here is the thing....the key is not there to keep the fan and hub from turning. If your hub is installed correctly....it should be stuck tight enough that you need a puller to move it in any direction.

That crank snout and hub tapered joint is a Morse taper or similar type of tapered joint (there are many kinds). It literally has tons of swaged friction force.

If it turns at all...the joint has failed...and THAT is what beat the key and slot up. The key is not designed to hold side force. It simply a locator. Likewise...the bolt in the center....is just a safety and helps for install. It is NOT what is holding the hub to the snout. Friction, interference fit and distortion do that.
Ray

Cathy Follett
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Re: Loose crankshaft woodruff key

Post by Cathy Follett » Tue Jul 23, 2019 4:34 am

Thank you Ray. Had to use another sign on to reply. Interesting information about the fit of crankshaft hub to the shaft. Will try to send picture when I next get it apart. How do you get the hub on tight enough to create enough friction, interference to keep it tight? A Raby DTM pulley is fitted to the hub with 3 bolts and also a center one. The slot in the crank is too big/worn for a key to fit tightly. Any suggestions to set timing since the pulley is moved a few degrees from TDC and not sure if advance or retard with engine running?

Ol'fogasaurus
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Re: Loose crankshaft woodruff key

Post by Ol'fogasaurus » Tue Jul 23, 2019 11:17 am

Do you have a picture of the Woodruff slot in the crank? This would be to see what kind, if any, damage has been done. I have seen some really whacked up slots before which is why I was asking.

Also measure the Woodruff key itself or have it measured to see if it is damaged. The slots in the crank and the pullyshould be very close in width as I remember. I'm not sure that double off-set Woodruff keys are still available, single off-set keys used to be but that was for resetting the timing of an engine (https://www.bing.com/search?q=offset+wo ... lang=en-US). A machinist might be able to make one for you but that would be expensive and I am not sure about the heat treating that could be needed also.

There are charts that can be found on the different sizes of Woodruff keys assuming your key itself is not the problem (https://www.bing.com/images/search?q=40 ... ORM=IQFRML https://www.bing.com/images/search?q=Wo ... ORM=RESTAB). Remember that there are both ANSI and ISO dimensions for things.

Lee

David Follett
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Re: Loose crankshaft woodruff key

Post by David Follett » Wed Jul 24, 2019 9:12 am

Thank you. I'll post a picture as soon as I remove the hub again. I never checked the slot in the hub but will.
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Ol'fogasaurus
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Re: Loose crankshaft woodruff key

Post by Ol'fogasaurus » Wed Jul 24, 2019 10:02 am

David Follett wrote:
Wed Jul 24, 2019 9:12 am
Thank you. I'll post a picture as soon as I remove the hub again. I never checked the slot in the hub but will.
Good idea on checking the slot.

(thinking ouit loud) I also wonder if the Woodruff key could not be the proper one as not everyone understands that as simple as they are they are also complicated. One of the reasons I posted the off-set keys was to show that builders use to change the cam to crank relationship for say... more bottom end power (grunt) or top end (a sloppy fit is not one of the applications :roll: :lol: ). A woodruff key is a woodruff key in so many peoples mind so the fit is not always there 'cause they just get a woodruff key; seen and heard of that before myself.

Lee

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raygreenwood
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Re: Loose crankshaft woodruff key

Post by raygreenwood » Wed Jul 24, 2019 9:13 pm

Cathy Follett wrote:
Tue Jul 23, 2019 4:34 am
Thank you Ray. Had to use another sign on to reply. Interesting information about the fit of crankshaft hub to the shaft. Will try to send picture when I next get it apart. How do you get the hub on tight enough to create enough friction, interference to keep it tight? A Raby DTM pulley is fitted to the hub with 3 bolts and also a center one. The slot in the crank is too big/worn for a key to fit tightly. Any suggestions to set timing since the pulley is moved a few degrees from TDC and not sure if advance or retard with engine running?

The really important thing to look at is the taper area of the crank...and the corresponding taper in the steel hub that bolts to the fan.

They must be CLEAN and shiny. If they have very fine surface rust that can be cleaned off with steel wool...no big deal. If they have actual rust pitting....and/or and dents or raised areas like where someone used a pliers or dinged the crank on something.....they are now scrap....unless you have that area welded and professionally angle ground on a lathe or mill to restore the taper joint.


Just so everyone understands....the woodruff key on this part...has absolutely nothing to do with keeping the fan hub on the crank snout. It is 100% just for location. So dont get too hung up on the key.

But if the keyway is damaged in teh crank snout...its because it got hammered sideways...when the taper joint came loose.

This taper joint works exactly the same way a ball joint or tie rod spindle works. How does it get so tight?....you have an exact taper with an interference fit. The little 8mm bolt in the middle clamps it with enough force to swage the joint together. Once teh joint is together with an interference fit...the function of that bolt is now just a safety back up. 100% of teh holding power for teh fan hub...is that tapered joint.

Just like a tie rod....right? you stick in in the socket of the steering knuckle and tighten down that 12mm nut. Eight year down the line you go to change the joint and remove that nut....and the tie rod spindle will NOT come loose without a puller or a pair of 3 lbs sledge hammers.

In fact...90% of the time it requires a puller to remove the hub from the crank snout in a type 4. Ray

Bruce.m
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Re: Loose crankshaft woodruff key

Post by Bruce.m » Fri Jul 26, 2019 8:47 am

Or a “pusher” ;-)

VW Tool 185. Make your own copy.
(Screw bolts through the hub, pushing against the tool, to jack the hub off.)

David Follett
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Re: Loose crankshaft woodruff key

Post by David Follett » Sun Jul 28, 2019 6:01 am

Thank you again Ray. I'll remove pulley and inspect shaft & hub. Hopefully no heavy scratches or gouges, clean both and refit.
Another question - At about 3,000 - 3,500 rpm's timing is about 35 degrees and maybe 12 at a 1,000 rpm idle. When I set distributor to give me about 28 degrees at 3,000 engine idle is not the smoothest and harder to start. Distributor is a 009 and as you stated last year not the best. Any suggestions for now until I can find a T4 distributor?
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Ol'fogasaurus
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Re: Loose crankshaft woodruff key

Post by Ol'fogasaurus » Sun Jul 28, 2019 10:45 am

David Follett wrote:
Sun Jul 28, 2019 6:01 am
Thank you again Ray. I'll remove pulley and inspect shaft & hub. Hopefully no heavy scratches or gouges, clean both and refit.
Another question - At about 3,000 - 3,500 rpm's timing is about 35 degrees and maybe 12 at a 1,000 rpm idle. When I set distributor to give me about 28 degrees at 3,000 engine idle is not the smoothest and harder to start. Distributor is a 009 and as you stated last year not the best. Any suggestions for now until I can find a T4 distributor?
David, as I understand there are several versions of the bus 009 dist, cast vs. stamped (?) with some versions being better than others. That being said the timing comes in early on them about 26°. I recommend that you have the dist. "spun" on a machine to see what the condition of it is; e.g., internals could be worn, the mechanical advance could be haywire or just what the condition really is.

https://www.thegoldenbug.com/en/vw_tech ... istributor

If you want mechanical advance the .010 dist. has been recommended but not to use the vaccuum side, the mechanical advance only.

I use one myself but I was warned about them too so mine was "spun" on a Sun Machine.

Lee

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