I put in a new H&K air flow system and a magna flow cat back and after doing so I get a squeal when the trans shifts. I think it's the belt but I'm not sure. Anyone else have this happen after doing similar mods?

 

It's the accesssory belt. Even if you replace it with a OE belt, it will start again. If you want to get rid of it, get a Goodyear Gatorback. Others have reprorted that using them gets rid of the noise permanently. Do NOT use belt dressing of any kind.
Noise happens when the belt slips when evrything slows down. Engine drops in RPM, accessories are still going at the higher RPM, belt slips when slowing them down.

 

Thanks for the info. I'll be switching it out soon now that I know what the problem is.

 

Hey fellas,

I dont know if this is related and i dont mean to hijack ur thread but my 2000 f-150 w/ a 4.6 does the same thing. When i have it floored and tach it up, right after it shifts, i hear a squeal. But i only hear its under hard acceleration. Is the my belt slipping or what?

 

Yep. Same problem. Belt slip.

 

I clicked on the JC link for auto parts which was so conviently located in our thread and they don't even have the part. What's up with that? Do a search for a serpentine belt and you get crap for a honda.

 

after i installed my shift kit i would get bely slipage also replaced my belt with a goodyear gatorback from autozone for $20 and never had a problem since, good luck

 

My 5.4 01 does the same after a rapid accel. I guess i'll get one too, if thats all it takes to fix it. Ive replaced belts on other vehicles but never on my f-150, is it pretty easy?

 

it is cake takes about 60 seconds if you got a extra set of hands to hold the breaker bar to unload the tension on the pulley, you wont have no problem, good luck