BBK Underdrive Pulleys, Need help!

Discussion in 'Fox 5.0 Mustang Tech' started by VoodooChile, Dec 30, 2003.

  1. Okay, so here's the deal, I installed a set of BBK Underdrive pulleys on my '84 GT, and removed the A/C and Smog Pump as well. Well, I was down in the garage trying to size up a new belt and I discovered something.

    Due to the circumference of the bigger water pump pully, the portion of the belt that goes from the water pump pulley to the alternator pulley is at a different angle now, and my stock tensioner barely touches it. There's no way that the stock tensioner is going to be able to work without making it swing a bit lower. My other option is to put the stock water pump pulley back on, but I don't want to do that for obvious reasons.

    Any ideas or suggestions?

  2. Something must not be screwed on right. It should still work with the ac and smog pump off. Everything should be lined up.
  3. I'm not sure how I could have not bolted the pulleys on right? Everything is straight and lines up fine, it's just that the tensioner doesn't have enough reach. fyi, the tensioner on my '84 is on the opposite side of the motor as yours I believe. It's on the passenger side. Lemme see if I have a pic I can link.


    It's hard to see, and those are the stock pulleys, but you can see where the alternator and tensioner are.
  4. I dont know then if they pulleys are all lined up then i dont know why it wont work.
  5. maybe some one else with the same tenison pulley might be able to help. Sorry man
  6. Okay so you removed the AC, did you get an AC delete pulley or move the power steering up where the AC was? If you delete the AC and leave the power steering in the factory location you will have belt routing issues.
  7. I agree with Fox Saleen. If you did not put on an AC delete kit, or reposition the power steering, you are not going to be able to run the belt correctly with the pulleys where they are. I have seen people that just bolted up the tensioner upside down where the AC went, to rig up a system that works. I would recommend the AC delete kit though, or just moving the power steering pump.

  8. Only reason I know this is because I tried to bypass my A/C and smog pump just fooling around at Autozone one day. I found the right length belt to do it, but the routing made the belt on the water pump and the belt on the tensioner touch. Not good. I wondered why... because some Mustangs came with no AC. How did they do it? Then I found out factory Stangs with no AC came with the power steering in the AC's place. That's why you can get the power steering pump relocation brackets from Ford. Hey, we were all new to this Stang thing at one time or another.

    However, if you do have a AC delete pulley or the power steering is on top and your belt is still touching between the tensioner and water pump, the belt must be too long. Check the factory "meter" on the tensioner that shows the range.
  9. Here's a quick drawing I did to show ya. The power steering/AC Delete have nothing to do with this. The belt length doesn't either. It's directly related to the new angle the belt is coming off of the water pump pulley at. [​IMG]
    If I change anything with the steering pump, that doesn't affect the angle the belt leaves the water pump pulley at. The bigger pulley lowers that down about a halfinch to an inch, in effect making the belt ride that much lower on it's way up to the alternator. Sorry for the crappy drawing. =) I think this is going to be specific to guys who have the same tensioner setups as me.

    Edit: I know I'll need a longer belt, but when the current belt is pulled tight against the pulleys (by hand because it's too long), the tensioner barely touches it, as to before it would have pushed a bit of pressure on it.
  10. I don't know how you're trying to route the belt but this is how I got mines routed with the a/c delete kit.
  11. Another view.
  12. Okay... your routing is wrong. It should go like this...

    Top picture is routing if you have AC delete pulley. Also, smog pump deleted.

    Bottom picture is if you moved power steering up to the AC's old location.

    Sorry about the crappy drawings.... but I think it's does the job.

    Attached Files:

  13. yeah i believe u are routing the belt the wrong way. it doesnt go past teh tesioner first, it goes around the alt the then to the tensionjer

  14. Bingo, that's it. I already knew this was the reason before i finished reading the first post.

    When you delete the smog pump, you need to change the belt routing. Just set it up like the above pictures and you are all set
  15. Cool, I just wanted to say thanks guys! I kept trying to route the belt the same way, and I can see that's where I was screwing up!