Cracked cam gear???
08-01-2010, 10:48 PM
#16
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The cam is not necessarily bad. The keyway is roached out. However the keyway doesn’t locate the cam gear on the shaft. It could clean up with some emery paper. Certainly not the recommended procedure. But it could save the car from becoming a parts car or junked.
NF
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08-01-2010, 10:53 PM
#17
Rennlist Member
I saw that also. Running the engine like that would cause the cam gear to be loose and thrash back and forth against the cam shaft key.
Looks like the gear broke at the key slot and the slot in the cam shaft looks all beat to crap.
Thoughts?
Looks like the gear broke at the key slot and the slot in the cam shaft looks all beat to crap.
Thoughts?
08-01-2010, 11:21 PM
#18
Team Owner
Thread Starter
Ken i put those washers on the bolt ( there are 3 of them) so I would not have to thread the bolt all the way in and
so I could turn the cam around.
Neil I dont understand your post .
Are you saying that the key way doesnt take any of the turning force??
I think that it most certainly does take some and it keeps the cam pulley in the correct position.
I wonder if this could be a job for JB weld?? put a new key in the slot then fill in the surrounding area with JB weld the file to fit??
I think i am going to replace the cam and all of the gears
so I could turn the cam around.
Neil I dont understand your post .
Are you saying that the key way doesnt take any of the turning force??
I think that it most certainly does take some and it keeps the cam pulley in the correct position.
I wonder if this could be a job for JB weld?? put a new key in the slot then fill in the surrounding area with JB weld the file to fit??
I think i am going to replace the cam and all of the gears
08-02-2010, 12:51 AM
#19
Rennlist Member
It could have been overtorqued when the gear was replaced originally which caused a hairline crack that obviously grew. These gears really don't like to be overtorqued at all.
08-02-2010, 01:24 AM
#20
Team Owner
Thread Starter
I did find some gouge marks along a few of the cut outs in the gear , this would indicate someone used a tool to hold the gear either while loosening it or tightening it, this could have started a fracture
08-02-2010, 02:26 AM
#22
Captain Obvious
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08-02-2010, 02:29 AM
#23
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Car got towed over to the shop,
got the cover and gear off (well the gear fell out rather),
the cam is toast, about a 1 1/2 years ago I worked on this car and checked the belt tension put a torque wrench on the cam bolt to see if was tight and it was 47ft/lb IIRC
I didnt notice any other weird things anyway the pulley looks like it was cracked for a while as one side is polished where the crack was.
note this is a HTD pulley and the teeth are quite worn.
I didnt swap out the pulleys this was done in 1994
got the cover and gear off (well the gear fell out rather),
the cam is toast, about a 1 1/2 years ago I worked on this car and checked the belt tension put a torque wrench on the cam bolt to see if was tight and it was 47ft/lb IIRC
I didnt notice any other weird things anyway the pulley looks like it was cracked for a while as one side is polished where the crack was.
note this is a HTD pulley and the teeth are quite worn.
I didnt swap out the pulleys this was done in 1994
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greg brown
714 879 9072
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Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
08-02-2010, 12:02 PM
#26
Race Car
So has anyone tried fitting steel 968 cam gears to the 928? I should have tried it when I was working on my wife's 968 back before it was sold 
Dan
'91 928GT S/C
475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ft
08-02-2010, 12:04 PM
#27
Rennlist Member
gear started to loosen .... cam/gear interface wears more ... gear gets even looser .... keyway and key start to get a hammering from gear rotation .... rotation becomes so severe, and keyway/key so trashed, that key starts to roll ... key becomes a wedge that splits gear as it rolls
08-02-2010, 12:13 PM
#28
Inventor
Rennlist Member
Rennlist Member
08-02-2010, 12:17 PM
#29
