Underdrive pulley

Discussion in 'Engine, Intake, Exhaust and Drive Line' started by Night Runner, May 3, 2019.

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  1. Night Runner

    Night Runner SHO Member

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    I bought my SHO it had a smaller underdrive pulley (I believe that’s what it’s called) so the alternator will spin slower and the power steering pump spins slower too and it has the rev limiter taken off. The question is how do I push the idle up so my battery doesn’t keep going dead. Oh and is there already a thread on this?
     
  2. luigisho

    luigisho SHO Member

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    Get the regular sized pulleys from a parts car
     
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  3. Night Runner

    Night Runner SHO Member

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    Well the thing is that I still would like revs at that high of the power band but I need to set the idle higher so it doesn’t idle at 800 it idles at 1,100 or a certain rpm so he battery stays charge. I believe to do this I need a scan tool, or do I need a tweecer tuner as seen on sho source
     
  4. blk\blk90

    blk\blk90 SHO Member Supporting Member

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  5. luigisho

    luigisho SHO Member

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    I've had them and I don't think they are worth chasing around with a chip and trying to get it tuned. If it were me from the beginning as a younger person, I would chase my tail on this stuff. If it were me after monkeying around with these cars for a long time, I would change it back to stock. The gains are so small it's not worth the hassle. The plug in chips are a pain. I've done every bolt on that was available. Blah. Get better brakes.
     
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  6. SM105K

    SM105K Land Yacht Pilot Supporting Member

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    Agree 100 percent. 10 hp in a 200 hp isnt going to felt anyway. Power steering and charging the battery is more important.

    Always get better brakes. What point is going faster, if you can't stop...
     
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  7. Irish Pride

    Irish Pride Irish Inside Staff Member Super Moderators

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    I have a 4 piece Underdrive set on my SHO and have zero issues with charging. If you have a charging issue I would look at the Alternator before the pulley.

    The 4 piece set consists of the crank pulley being smaller and the PS pump, water pump, and Alt. pullies being larger so my setup actually doubles up on the underdriving. Again, I have zero charging issues.
     
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  8. Irish Pride

    Irish Pride Irish Inside Staff Member Super Moderators

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  9. SM105K

    SM105K Land Yacht Pilot Supporting Member

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  10. Night Runner

    Night Runner SHO Member

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    Well I personally think the guy who owned it before me just set it up with one pulley smaller and keeping the others the same size giving it the charging issue. But I did sit there holding the rpms at about 2000 and the battery held a charge haven't had a problem but the car has been sitting. Maybe it was a fluke, alternator, or the pulley system. And i do know it only adds like 10 hp but seeing how you guys act I'm guessing the harder you push an SHO of my year the worse the repairs are going to be. I might actually put the original one on until i don't have to daily this car.
     
  11. Night Runner

    Night Runner SHO Member

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    Those are nice I don't wanna know the price right.
     
  12. Irish Pride

    Irish Pride Irish Inside Staff Member Super Moderators

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    If the battery went dead from sitting then you have a draw on your system. Something is staying powered up after you turn the car off. That won't have anything to do with the Underdrive Pulley.

    Don't be afraid to drive your car. I daily drive my White 89. I beat on my 89 when I drive it. These cars are not overly difficult to work on but it can get expensive to repair if you have to depend on service shops for the work. If you are willing and able to get your knuckles bloody working on your car then I say go out and enjoy it. There are plenty of us here on the forum to step you thru anything that comes up.

    If you haven't already joined, get on the Facebook groups. SHO Marketplace, Gen1 2 and 3 group.
     
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  13. Irish Pride

    Irish Pride Irish Inside Staff Member Super Moderators

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    All in, you could have Cobra brakes like mine for between $200-300. Probably cheaper if you find a used set from another member. Powder Coating not included.
     
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  14. Night Runner

    Night Runner SHO Member

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    So thinking of that I remembered that after the battery "incident" I made an effort to take the wires off the terminals after I'm done working on her for the night and it might have something drawing on the power but what could that be?
     
  15. Night Runner

    Night Runner SHO Member

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    No problems since then
     
  16. Night Runner

    Night Runner SHO Member

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    I'm guessing cobra mustang brakes I've heard of people doing that and did you do the powder coat yourself?
     
  17. blk\blk90

    blk\blk90 SHO Member Supporting Member

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    Also, wasn't there 2 different styles of UDPs? One was crank only, and one was all the rest?
     
  18. Irish Pride

    Irish Pride Irish Inside Staff Member Super Moderators

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    SHOshop offered a 3 piece without the crank and 4 piece with the crank. SHOSource currently only offers the crank. I have a SHOSource crank and SHOshop 3 piece all installed on my 91+.
     
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  19. Night Runner

    Night Runner SHO Member

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    Yay I think the guy just put the one pulley on the crank to be honest
     
  20. Jim Leyden

    Jim Leyden New Member

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    If I remember correctly the first UDP's used a smaller crankshaft pulley that didn't have a true harmonic balancer in them and the result was crankshaft breakage. The next version used the stock crank pulley and larger P/S, Alternator and water pump pulleys
     

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