# Crank shaft sprocket broke



## turtledub (May 10, 2006)

So I have been tearing my hair out trying to figure out why my car will not start. Turns out my crank sprocket ate itself. 
How many of you have had a crank shaft sprocket break on you? Just currious. It seems like a part that should not break.


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## chrisd1891 (Feb 8, 2009)

*Re: Crank shaft sprocket broke (turtledub)*

vr6 or g60 or 16v?


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## TheBurninator (Jan 7, 2009)

*FV-QR*

Crank keyway sheered?
Common problem. Dowel pin the crank and pulley and it will never happen again


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## pileofredparts (Mar 20, 2009)

*Re: FV-QR (TheBurninator)*


_Quote, originally posted by *TheBurninator* »_Crank keyway sheered?
Common problem. Dowel pin the crank and pulley and it will never happen again

dont be too sure
my brothers just sheared the bolt, after a new bolt and 2 dowel pins were installed








going for try#2 tonight
g60s








why dont any other 8v/16vs have this problem?


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## sdezego (Apr 23, 2004)

*Re: FV-QR (pileofredparts)*


_Quote, originally posted by *pileofredparts* »_
dont be too sure
my brothers just sheared the bolt, after a new bolt and 2 dowel pins were installed








going for try#2 tonight
g60s








why dont any other 8v/16vs have this problem?

I don't know, but this is for sure:
ABA - Specs = 66 ft/lb + 90* (1/4 turn)
G60 - Specs = 66 ft/lb + 180* (1/2 turn)
Same damn bolt...


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## pileofredparts (Mar 20, 2009)

*Re: FV-QR (sdezego)*


_Quote, originally posted by *sdezego* »_
I don't know, but this is for sure:
ABA - Specs = 66 ft/lb + 90* (1/4 turn)
G60 - Specs = 66 ft/lb + 180* (1/2 turn)
Same damn bolt...

WTF?








we will be using the ABA spec this time
the damn thing feels like it is going to snap when you do the 180
then 2 days later.................it does


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## sdezego (Apr 23, 2004)

*Re: FV-QR (pileofredparts)*








I know...
I am tossed up on my aba/20v whether I want to use the 6pt or the 12 pt bolt from the 16v. The 6pt is suppose to be a non-stretch type and gets torques to a straight 150 ft/lb.
vw =


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## TheBurninator (Jan 7, 2009)

*FV-QR*

Never really heard of the bolt sheering. Always hear about keyways.
No wonder the G60 has a problem with the bolt sheering though the torque spec is off the charts


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## saysomestuff (Dec 30, 2005)

9A 16v - keyed sheared completely, you could turn the timing belt by hand - valves got bent.


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## sdezego (Apr 23, 2004)

*Re: FV-QR (TheBurninator)*


_Quote, originally posted by *TheBurninator* »_Never really heard of the bolt sheering. Always hear about keyways.
No wonder the G60 has a problem with the bolt sheering though the torque spec is off the charts

Happened to me


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## MikkiJayne (Jan 1, 2007)

*FV-QR*

Wow I've never heard of it _snapping_ clean off, especially on a 16V







I bought a TDI where it had it come loose and trashed the keyway though.
I can't even get close to the G60 spec - I don't weigh enough! So crank pulleys on all my motors are my entire weight hanging off a 2 foot bar







Its been enough so far...


_Modified by MikkiJayne at 2:41 PM 12-3-2009_


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## turtledub (May 10, 2006)

*Re: FV-QR (TheBurninator)*


_Quote, originally posted by *TheBurninator* »_Crank keyway sheered?
Common problem. Dowel pin the crank and pulley and it will never happen again

Explain please. You have my interests. Also anyone have a pic of the back side of the crank gear?


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## sdezego (Apr 23, 2004)

*Re: FV-QR (turtledub)*


_Quote, originally posted by *turtledub* »_Also anyone have a pic of the back side of the crank gear? 

http://forums.vwvortex.com/zerothread?id=1598023


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## sdezego (Apr 23, 2004)

*Re: FV-QR (sdezego)*

My tool is on the last page of that thread, but I will post it here


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## sdezego (Apr 23, 2004)

*Re: FV-QR (MikkiJayne)*


_Quote, originally posted by *MikkiJayne* »_...
I can't even get close to the G60 spec - I don't weigh enough! 

I am only a buck fitty







I use a 3/4" drive big a55 breaker bar. Def can not do it in one motion, but Bentley states that is ok. Like Kevin said, you swear the bolt is gonna snap just tightening it











_Modified by sdezego at 8:09 PM 12-4-2009_


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## still_a_G (Jun 23, 2008)

*Re: FV-QR (sdezego)*

My bolt sheared. Very poor design. German engineering my AS5.


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## turtledub (May 10, 2006)

*Re: FV-QR (still_a_G)*

The crank gear did not look like it was damaged which is good. I think someone called this event volkswagens versoin of variable valve timing. Is there an aftermarked better crank gear? One that will not chew itself to bits? GAP sells the crank and the bolt so as soon as I get a little extra cash I will be making the switch. This is crazy because this exact same thing happend to my brother in law's 16v jetta. Luckily I will not have to get the head rebuilt. I do not think that cranking it with the broken sprocket will damage the crossflow head that I just put on. All this time I thought it was something electrical.
(Runs to knock on wood)


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## 'Hassan' (May 27, 2002)

*Knock on wood*


_Quote, originally posted by *turtledub* »_How many of you have had a crank shaft sprocket break on you?

Never had it happened to me... I lead a charmed life








On a side note, I am wondering what effect (if any) drilling the crank for dowel pins will have on overall balance?


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## Non_Affiliated (Feb 12, 2002)

*Re: Knock on wood ('Hassan')*


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## Non_Affiliated (Feb 12, 2002)

*Re: FV-QR (sdezego)*


_Quote, originally posted by *sdezego* »_
I don't know, but this is for sure:
ABA - Specs = 66 ft/lb + 90* (1/4 turn)
G60 - Specs = 66 ft/lb + 180* (*Til it snaps, then back it off an 1/8th of a turn*)
Same damn bolt...


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## TheBurninator (Jan 7, 2009)

*FV-QR*


_Quote, originally posted by *'Hassan'* »_
Never had it happened to me... I lead a charmed life








On a side note, I am wondering what effect (if any) drilling the crank for dowel pins will have on overall balance?


Should be fine. You are taking out about as much material you are adding and in the same place


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## turtledub (May 10, 2006)

*Re: Knock on wood (Non_Affiliated)*


_Quote, originally posted by *Non_Affiliated* »_









I knew that I had seen a poster for this!


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## prodigy_g60 (Jun 25, 2006)

*Re: Knock on wood (turtledub)*

Just did mine again,using 8V/ABA specs. wonder how many days it will last this time. (praying more then three days)


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## turtledub (May 10, 2006)

*Re: Knock on wood (prodigy_g60)*


_Quote, originally posted by *prodigy_g60* »_Just did mine again,using 8V/ABA specs. wonder how many days it will last this time. (praying more then three days)









Yours only lasted 3 days? There has to be a beefier sprocket out there. Someone call Gruven or get ahold of Spacely Sprockets.


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## corradokyd (Jun 4, 1999)

man i sheared like 3 of them things. even changed out a crank on one of em. 
i blamed it all on my 6puck unsprung clutch...glad thats gone now...
i got aba motor now.


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## V-TEC this!!! (May 4, 2003)

*Re: (corradokyd)*

I had this happen on my old g60, that was fixed with a new gear and pulley. This is also a very very common problem on diesel's. The AAZ engine code ones which are pre tdi. 
There are two solutions to this problem:
1) Dowel pins which can be done with out taking anything apart 
2) Getting the crank welded and remachined for a tdi style gear (D shaped end instead of a keyway - but this will only work on a diesel or a 16v due to the wider gear to accomodate the wider timing belt. 
I have done dowel pins on 3 diesels now and all have been fine.


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## sdezego (Apr 23, 2004)

*Re: Knock on wood (prodigy_g60)*


_Quote, originally posted by *prodigy_g60* »_Just did mine again,using 8V/ABA specs. wonder how many days it will last this time. (praying more then three days)









Yea, you are not having good luck. Are you using a moly lube? If not it will throw off the spec. I also cleaned everything real good and used red loctite on the gear to crank surface, etc.
Anyway, for those who haven't had this happen to them, it will. After 100k I strongly recommend changing this bolt. Seems to fatigue after x amount of cycles. Clutch, driving habits and torque can definitely have a factor, but a proper dowel should correct it for good.
I just had to re-do mine but it was because of an inferior crank seal


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## prodigy_g60 (Jun 25, 2006)

*Re: Knock on wood (sdezego)*

MIne only problem was due to the bolt sheering in half so it was either a 5hitty bolt or a result of being over tightened. 
Shaun what is moly lube?


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## sdezego (Apr 23, 2004)

*Re: Knock on wood (prodigy_g60)*

MoS2 or Moly di-sulfide (aka CV grease) and comes with ARP bolts, etc. It will help ensure the load is distributed across all of the threads as you torque and result in a proper tq.


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## still_a_G (Jun 23, 2008)

*Re: Knock on wood (sdezego)*

This happened to me twice, the first time on a stock bolt that I reused (dumb mistake). The second time on a new VW bolt and new VW sprocket. After the second time I had my father, who is a very experienced manual machinist, install 2 dowel pins with the engine in the car. Not the most precise method but it is holding still.
Also, the key to key-way fitment is too loose. When you tighten the bolt down, the sprocket shifts in the clockwise direction. But when you drive the car, the torque on the sprocket is in the COUNTER-clockwise direction. My theory is that this slight shift allows for the initial loosening of the bolt.
You can avoid this shift by clamping the sprocket while torqueing the bolt. This is probably how it's done at the factory. 
Or you can do like I did and weld material to the key (and use a dremel tool to grind it smooth). This makes for a proper clearance fit into the key-way.


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## Non_Affiliated (Feb 12, 2002)

*Re: Knock on wood (still_a_G)*

Why can' VW just be like other MFR's and use a Woodruff Key or some other Machined key and Keyway on a shaft.


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## TheBurninator (Jan 7, 2009)

*FV-QR*


_Quote, originally posted by *Non_Affiliated* »_Why can' VW just be like other MFR's and use a Woodruff Key or some other Machined key and Keyway on a shaft.


They do.


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## pileofredparts (Mar 20, 2009)

*Re: FV-QR (TheBurninator)*


_Quote, originally posted by *TheBurninator* »_
They do on motors that dont have 8v's.


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## Non_Affiliated (Feb 12, 2002)

*Re: FV-QR (TheBurninator)*


_Quote, originally posted by *TheBurninator* »_They do.

Like said, not on the G60's at least. Also the Alternator shaft has a keyway for a Woodruff keyway on the shaft, but no keyway on the pully. %$&*?


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## sdezego (Apr 23, 2004)

*Re: FV-QR (pileofredparts)*

Funny enough, I was just getting ready to bolt the cog on my ABA/20v and I had ordered both type bolts from the 16v (the 6 pt and the 12 pt). The 12 pt is only 8.8 strength.... The 6 pt is 10.9. WTF. effing vw








I verified the 8v's are 10.9


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## TheBurninator (Jan 7, 2009)

*FV-QR*


_Quote, originally posted by *sdezego* »_Funny enough, I was just getting ready to bolt the cog on my ABA/20v and I had ordered both type bolts from the 16v (the 6 pt and the 12 pt). The 12 pt is only 8.8 strength.... The 6 pt is 10.9. WTF. effing vw








I verified the 8v's are 10.9


I would think there would be more stretch and give to the 8,8 bolt than the 10.9


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## sdezego (Apr 23, 2004)

*Re: FV-QR (TheBurninator)*

agreed, but the 8v bolt is torqued to stretch and it is 10.9








I think I will be using the 6pt and it is actually a few threads longer, but need to verify the specs. I think it is a straight 150 lb/ft like the early 8v, but need someone to verify in the 16v Bentley. Since it is a non-stretch bolts, I will be loctiting, everything.


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## prodigy_g60 (Jun 25, 2006)

*Re: FV-QR (sdezego)*

I dont believe lube would impact it that much for catastrophic damage. Either way Shawn (spelling it different each time sorry







) Where do you get the different bolts? Make a good build thread cause if mine blows again I am following your lead with the 20/20


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## sdezego (Apr 23, 2004)

*Re: FV-QR (prodigy_g60)*

I only get them from the dealer. The 16v started with the 6pt and ended with the 12 point.


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## sdezego (Apr 23, 2004)

*Re: FV-QR (prodigy_g60)*

You would be surprised how much the lube can make a difference when torquing stretch to yield bolts. The specs put the bolt very close to it's elastic limits. What happens w/o lube is that tq'ing puts more stress and the last few threads (closest to the bolt head), rather than distributing across all of the bolt threads. This can result in the bolt "necking" instead of stretching evenly as designed.
The whole purpose of stretch bolts, is so that they act like a spring (i.e. like a lock washer). Suppose to prevent the bolt from coming loose. Loctite on a non-stretch to yield bolt can serve the same if not better purpose








One thing for sure, is that the G60 specs vs ABA are very questionable.


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## TheBurninator (Jan 7, 2009)

*FV-QR*

Shawn I will go digging for my Scirocco bentley later this week if you don't get an answer on the torque spec by then.


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## still_a_G (Jun 23, 2008)

*Re: FV-QR (sdezego)*

I am using a grade 8 from the hardware store and it is holding, but like I said, it's also pinned.


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## sdezego (Apr 23, 2004)

*Re: FV-QR (TheBurninator)*

Thaks Kyle, I think I found the answer though (sort of







)
I assume that the "6 sided bolt" is the 6 point bolt, but the hex head bolt







". The Bentley has been known to be wrong before.. So, I think it is 137 lb-ft, or is it the 111








http://forums.vwvortex.com/zerothread?id=4678642


_Modified by sdezego at 1:55 PM 12-8-2009_


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## sdezego (Apr 23, 2004)

*Re: FV-QR (sdezego)*

Also, as an FYI:
http://www.boltdepot.com/faste....aspx

10.9 = 940 MPa = ~ 136, 000 Psi min Yield strength
Grade 8 = ~ 130, 000 Psi Min Yield strength
So, they are comparable, but I was not aware that you could get a metric bolt in Grade 8 (non-metric hardening strength). I suppose it is possible though.


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## TheBurninator (Jan 7, 2009)

*Re: FV-QR (sdezego)*


_Quote, originally posted by *sdezego* »_Thaks Kyle, I think I found the answer though (sort of







)
I assume that the "6 sided bolt" is the 6 point bolt, but the hex head bolt








". The Bentley has been known to be wrong before.. So, I think it is 137 lb-ft, or is it the 111








http://forums.vwvortex.com/zerothread?id=4678642

_Modified by sdezego at 1:55 PM 12-8-2009_

Fine then... just tighten it to the german spec: guttentite








Really I would think the lower torque spec would be the correct one I would be afraid to sheer that bolt off.


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## mattrip (Sep 5, 2005)

*Re: FV-QR (TheBurninator)*

How are you guys holding the motor from turning when removing and torquing this bolt? After reading this thread I purchased a new bolt from the dealer, but busting that bastard loose is proving to be difficult.
Drop the pan and a block "O" wood between the crank and block?? http://****************.com/smile/emthdown.gif 
I see Shawn's torque plate. Nice but I don't have one.


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## sdezego (Apr 23, 2004)

*Re: FV-QR (mattrip)*

The ghetto way, is to take the wheels off, put lugs in through rotors, take two big screwdrivers and slip them through the brake carriers into the rotor vents. Then put the trans in a low gear and get out your big breaker bar.
I don't really condone this method, but I have done it once before I made that tool LOL
I have a 3/4" drive 2 1/2' break bar and it is still a lot of work








FYI: there is also a flywheel lock you can get, but that requires you take the starter off. a lot of work...


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## turtledub (May 10, 2006)

*Re: FV-QR (mattrip)*


_Quote, originally posted by *mattrip* »_How are you guys holding the motor from turning when removing and torquing this bolt? 


I was wondering this too. To get the bolt off I put a pry bar in the transmission opening to keep the engine from turning. Torquing it back might be a problem because I am only one guy. 
Nobody will work with me..*sniff, sniff*


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## pileofredparts (Mar 20, 2009)

*Re: FV-QR (turtledub)*

take off oil pan
2/4 between crank and block


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