does anyone know why GM decided to not key our cranks for the harmonic ballancers?...ivebeen through two hubs and now a fluid damper, and cant get anything to keep from spinning on there...i guess its the crank...so back out with the motor...stupid on gm's part if u ask me

 

My guess is they figured since the harmonic dampener had no balance there was no reason to key it...just a guess.

Is there a way for you to better press it on?

 

Well, the crank is cut for a key. There is just not one in it. You can put one in there and use a keyed hub or dampner.

 

essentially a crank with no key would be stronger, but thats not why they didn't put a key in. Just cutting the crank for the woodruff key creates 90* stress risers, buy putting in a key its further creates the tendancy to crack. Like I said, I doubt thats why & plus that part of the crank only drives your accessories

Dunno just going on & on.

 

How will that affect the balance?

 

I've never heard an expanation on this that made any sense to me. It just seems like a GM brain fart.

LT1 design committee's crankshaft "To Do List":

Step 1. Cut crank for key.

Step 2. Make hub with no key slot.

Step 3. Act normal. And hope the hub doesn't spin, or at least that nobody notices, if it does.

 

Isn't the LT1 crank the same as normal SBC crank?

 

Mine does!

All you have to do is machine a slot in the hub and put a key in

 

If you look at an aftermarket hub you'll notice that to make a keyed hub cheaply it has to be two parts. On a production line this usually isn't cost effective. the only way to correctlymachine a key slot is to use a broach which requires a hole the same diameter completely through the hub. But on the fatory hubs there is a large obstruction in the middle of the hub which the balancer bolt passes through and causes all sorts of problems when trying to use a standard balancer puller.

The aftermarget hubs actually bore out the front of the hub and then insert a second piece which acts like that washer face in the fatory hub. And this is done after the keyway broaching process. This is an extra step and when your trying to cut costs any extra machining steps you can cut out the better.

I bet the engineers wanted to put the keys in, but the penny pinchers told them to do without.

 

There should be no effect on balance because it is really a dampner and not a balancer. There might be some exceptions were there is a small weight or two used in the holes in the pulley. In your case where you have a complete new rotating assy, you don't need to worry about it. Any replacement hub/pulley or aftermarket dampner should have neutral effect.

 

okay, so the new damper slipped and it ate up the end of the crank...so now i have to change the crank, is there a way to do that in the car? im thinking supporting the motor, dropping the k member, and doing it underneath...seems like it would work, but will i be able to get all the rods off and back on the crank without removing the heads??...hmm...this is very frustrating