Off track serpentine belt

[Tynan918]

This is the second time my belt has jumped a rib on the crankshaft pulley...

First time I noticed, it was the last belt I had on it, the belt stripped from the same side...

I just replaced the 8" balancer with a 6.75" balancer, and a friend told me maybe because of the different height size balancers, would mean different depth sizes but after measuring the depth on both balancers, they are the same...

...so balancer is crossed out from the list of possible causes.

He said the another possibility he can think of is the crankshaft pulley being wrong depth size, causing the belt to jump a rib...are there different SBC crankshaft pulley sizes between cars and trucks ?

What do you guys think ?

 

[Streetbu]

Depth is not your issue. You have an alignment issue. Take a straight edge across your crank pulley, and see which accessory is set back further or is crooked.

 

[airboatgreg]

Make sure all the pulley grooves are clean. I used the take an awl and brakekleen and clean all the grooves. Make sure the tensioner and all pulleys work smoothly

 

[mikester]

Did you keep your old balancer ? If you did measure it and compare it to the new one. Did you change ANYTHING else when you had everything apart ?

 

[DRIVEN]

I think this was covered around page 50 of the other thread. General consensus was that the balancer isn't all the way seated. If all the other pulleys are on the same plane, the balancer is where you need to be looking. Straight edge or laser time to confirm.

 

[CM1SCW]

His measurement is an 8th of an inch different.

 

[Tynan918]

His measurement is an 8th of an inch different.

Your right. The old balancer is two notch's bigger than the new balancer...

So what do I do ?

Are there any different sized sbc crankshaft pulleys that will close the 1/8" difference ?

 

[mikester]

Your right. The old balancer is two notch's bigger than the new balancer...

So what do I do ?

Are there any different sized sbc crankshaft pulleys that will close the 1/8" difference ?

Looking at the pictures you posted with the tape on the balancer it looks like the end of the tape isnt up against the surface. Are you 1000% sure you measured them right ?

 

[DRIVEN]

Thickness of the ring isn't all that relevant. Overall height is what matters. To my knowledge, all SBC balancers should be the same overall height. Old style Vbelt pulleys were different offset depending on long or short water pump. I believe all SBC serpentine pulleys are the same offset, with the exception of Corvette.

Short answer; if it was aligned before, it should be aligned now.

 

[79 USA 1]

Have to agree with DRIVEN above, the pulley is attached to the center hub of the damper not the inertia ring. There is a chance the damper was not fully seated or is working its way out. Were you get a balancer bolt to tighten up in the end of the crank or were the threads pulled and not usable?