Cam gear wobble (up/down): What aligns it besides the dowel pin and the bolt?

[Daveed]

My exhaust cam gear has up/down movement (eccentric) and I have a bad feeling that if I continue driving it "as is" something bad will happen. A little background: rebuilt the motor and had a huge clacking noise...turns out it was the exhaust cam gear bolt not being tight and allowing the gear to wobble. Only drove about 10-20 miles before I found it.

Anyway, I tightened up the bolt and locktighted it but noticed that the hole in the cam gear is bigger than the bolt. Are they supposed to be this way? How does the cam gear get centered (which is apparently isn't yet) if the bolt hole is bigger than the bolt?
hmmm...maybe it got wallowed out

PS WHen my motor cools down this evening I'll go remove it and get measurements.

PSS Is there a locating ridge or something like that on the cam and the back of the pulley?
EDIT: YES, there is a locating ridge on the back of the pulley that goes over/around the end of the cam gear. My cam got a little wore down from the loose pulley. A new pulley helped a little but didn't fix the entire problem cause half the wear was on the pulley and the other half on the cam.

 

[ROOKIE1]

Theres a dowel on the cam that lines up the gear .

 

[atlguyinbama]

You more than likely wallowed it out. The timing belt has a lot of tension on it, and would of pulled on the cam gear at a quite severe angle. The bolt should fit in there nice and snug, as any other bolt would.

If there is play in it, you will need to either replace the cam or the gear depending on which was wallowed out. Either way I wouldn't recommend driving it as it could easily jump time, and cost you in the least a head.

 

[Daveed]

The dowel pin is fine and tight. So it sounds like the bolt hole in the cam gear should be real tight on the bolt. Must have wallowed it out when it was loose...DOH!

 

[atlguyinbama]

Rookie is right as well, the cam has a dowel pin that fits in the smaller hole on the cam gear. The cam gear will never tighten all the way until it is aligned with this dowel pin.

 

[super97gst]

My exhaust cam gear has up/down movement (eccentric) and I have a bad feeling that if I continue driving it "as is" something bad will happen. A little background: rebuilt the motor and had a huge clacking noise...turns out it was the exhaust cam gear bolt not being tight and allowing the gear to wobble. Only drove about 10-20 miles before I found it.

Anyway, I tightened up the bolt and locktighted it but noticed that the hole in the cam gear is bigger than the bolt. Are they supposed to be this way? How does the cam gear get centered (which is apparently isn't yet) if the bolt hole is bigger than the bolt?
hmmm...maybe it got wallowed out

PS WHen my motor cools down this evening I'll go remove it and get measurements.

PSS Is there a locating ridge or something like that on the cam and the back of the pulley?

i saw this happen on a 93 gsx once. what most likely happened is, when you put it back together you drew the bolt up without paying attention to whether the hole in your cam gear was lining up on the dowel pin in the end of the cam. it happens. once you drew the bolt up tight the pin was just pressed up against the flat back side of the cam gear rather than in the hole correctly. the problem this causes is the camshaft can get out of time with the gear, hence the t-belt. then you can have devastating consequences. as stated before, the t-belt puts so much pressure on it and the locating dowel pin on the cam can't get lined up precisely with the cam gear.

the car i said i had seen this happen on had to pull it all apart and re-tap the hole the slightest bit larger than what it had been ovaled out to. then used a larger bolt to put it back together. i cant remember, but he might have had to drill a larger hole in the cam gear for the bolt as well. just hope it didn't swell out the end of the dowel pin on the camshaft from running tight up against the wrong part of the cam gear. at least you didn't drive the car really long though afterwards, maybe it won't be as bad as i say. good luck

btw, there is a possibility that when you get in there might be enough threads left that you can just realign the dowel pin and tighten it back up.

 

[Daveed]

Thanks for the info guys.

As for the dowel pin...I definitely had that in the hole in the gear to begin with. That'd be one heck of a wobble (side to side) if it wasn't Its straight too...found a thread where someone had a dowel pin that was bent

Does anyone have a measurement (with micrometer) of the diameter of the bolt hole in the stock cam gear?


PSI may need to buy that gear from you if it shows a much smaller hole than the one on my car now

 

[Nick_4567]

I have some extra cam gears if you need them. You might want to try and use thread tape and some red locktight before you try to go to a bigger bolt. You might just get lucky and it will solve it I just am not sure how long it will last. try it befor anything else.

 

[Daveed]

Bolt = .436"
cam gear hole = .511"

As for drilling out the cam...I think I'll just get another pulley. The threads are fine and all present inside the cam. I'd probably sleeve the bolt before drilling out the cam and the gear.

I got it almost centered using a pry bar and loosening the bolt some. However, the dowel pin hole is slightly elongated too so I'm gonna replace it sunday with one from a local fellow dsm head.