bd0nalds0n

Thanks to PorKen for the pic, I cribbed it from another post.

The three-spoke hubs can become cracked over time and are usually not inspected as part of the timing belt replacement. If the hub cracks, the gear can wobble, eventually leading to camshaft failure. There have been multiple reported failures of this kind.

Inspection of this part should be part of the timing belt inspection process, and should also be part of the cam gear replacement process. Per Jim B, they're around $26.00 each. Very cheap insurance.

RyanPerrella

Great post Brian

You dont happen to have a pic of one of the hubs with the cracks do you?

F451

Excellent. I was wondering what they looked at from that other thread that mentioned them. Thanks for the pics! -Ed

Rob Edwards

So where do they crack? Here's my driver side hub from July, looks ok (?) And, if you remove them to replace them, I guess you've committed to pulling the valve covers and doing a proper re-timing, since re-indexing the cam gears would be a bit tricky.....

Fogey1

Rob Edwards wrote ...
"... And, if you remove them to replace them, I guess you've committed to pulling the valve covers and doing a proper re-timing, since re-indexing the cam gears would be a bit tricky ....."


Why? Assuming the hub can be pulled without rotating the cam (which may be a BIG assumption), mark carefully and don't let anything move. The key on the shaft indexes the hub and the gear is indexed to the original mark or the marks you made before disassembly.

Rob Edwards

The problem is that the marks I made are on the OLD hub, not the new one. And the slot on the cam gear is wider than the indexing pin on the cam (there's what, 7-8 degrees of slop in the cam gear keyway?), so once the hub is off, I've lost my (relatively) precise oval marks to index the cam gear to the hub. I suppose you could just eyeball the marks onto the new hub.

Actually, looking at my hubs, it occurs to me that two of the rotor mounting holes aren't in the center of the spokes of the hub- Where do these hubs crack, anyway?

Sterling- that's a cool trick, I like it! My heart just about stopped when the driver's side cams rotated when I loosened the cam gear bolt. Fortunately the old gear didn't rotate on the hub, and the engine was (of course) at 45o BTDC, so I just tightened everything up and just rotated it clockwise back to the 45o mark I made on the gear.

I guess this is all moot anyway, because given the current thread RE: hp improvements with proper timing, I'd like to properly index my cams per the WSM just so I KNOW the timing is right. I managed to hamfist my way thru a TB/WP without breaking anything, and the marks all lined up before and after, but the devil's in the details.

RyanPerrella

Rob,

why were your gears off, were they worn and replaced?

RyanPerrella

yeah those details can probably be a difference of 20-30 HP if timing is off even 1-2 deg.

Rob Edwards

Ryan-

A picture's worth 10^3 words:

RyanPerrella

yeah its nice and shiny, i mean dull

the cam laying down, to the left, is that the 2nd new one? the sprocket design is different, obviously the dimensions are the same but that sprocket construction is different, i had no idea. That is the new one right?

Rob Edwards

The gear in the background at left is a new steel oil pump gear, it was a WYAIT item. The old one was in pretty good shape, but I put the new one in anyway.

RyanPerrella

awww of course

JET951

you will most likely feel zero difference if your timing is off 1 or 2 degrees, certainly not 20-30 hp