It has been doing this since the built engine went in. It has something to do with the way the transmission is shifting. I have a PI 2400 Stall and a FTVB. Other than that, the trans is stock. What happens is, I will be accelerating and when it goes to shift from 3rd to 4th I get a really loud squeak from my belt. Don't know if it's the SC belt or the accessory belt. It's really annoying and the shift is so hard it's scary. What could be causing this? I assume it has something to with the PI/FTVB combo. Is there a remedy???

 

I’m sure it’s your accessory belt slipping. My trucks done it ever since I put the FTVB on it. Mine does it worse when it shifts as your letting off the throttle.

 

Look for the Belt dust pattern, the offending belt will throw a pattern of dust.
If the dust is on the underside of the hood or the top of the snot it is the S/C and if it is lower,,,well.
If it is on either shorten the belt by a 1/2" or install an aftermarket Idler set-up.
In a high horse power/torque application one should consider the MP style that puts the new pulley in the tension side or passenger side of the S/C pulley.

One could even try installing a new belt,,,your old one maybe dry and on it's way out!!

 

Ditto

 

are you sure it is a belt slipping, and not a band slipping in the tranny?

 

I wouldn't think a band would make a squeak.

 

So you never have listened to God Smack then ??