Under drive pulleys question

seantesarski

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I am extremely new to the Mustang scene and have been reading a sh*t load on here before I post, However ...

My 95 gt has CAI, MSD ign, headers, x pipe, exhaust, 373's. I was looking at slapping some under drive pulleys on it too. Ive been reading that it gives people charging issues and other problems. Any experience on that here? I'm going to put a bottle on it but I also want to add some more to it without doing cam or heads.

Cheers
 

ttocs

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Had them, sold them, lost two alts in the process. Keep your stockers is all I will say I know others that lost them and really wanted them back. If you do a lot of city driving I don't recommend them.
 

Musturd

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I've never had a problem with it but they're not worth the money
 

95opal

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Been running UD pulleys for over 20 years on numerous stangs never had a charging problem. Your headlights may dim while sitting at a light but if that bothers you just don't use the alt pulley.
If you do buy them just make sure you buy aluminum ones..the cheap steel pulleys are worthless. ASP is your best bet
 

Win

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Came on my current 95... Promptly took them off and got rid of them. I would say don't bother.

95opal I think your tunes keep your rpms higher which is why you never had a issue with them

on a stock rpm setting you will see a significant loss of power output from your alt. At idle
 

CC'S95GT

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I was given a set of billit UDP's, the set didn't include the alt pulley. I don't know what brand they were and they're not marked anywhere either.
I have experienced no charging problems at all.
I didn't notice any pwr gains either.
 
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seantesarski

seantesarski

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I was given a set of billit UDP's, the set didn't include the alt pulley. I don't know what brand they were and they're not marked anywhere either.
I have experienced no charging problems at all.
I didn't notice any pwr gains either.
Yeah I dont think i'm going to bother. For the headaches that can come with a basic bolt on, I don't think its worth it.
 

95opal

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Don't let them scare ya a little voltage drop at night isn't going to leave you stranded or kill your battery. Crap its been proven over and over pulleys are a great bang for the buck Bolton. Its been common knowledge for over 2 decades. Remember 10hp increase may or may not be felt in the buttometer but you will pick up hp across the board.
[MENTION=8860]Win[/MENTION]
Ive used them on stock foxs dating back to the late 80s ... never once had a battery die or been left stranded because of pulleys. My last combo idled at 750 no problem there either
 

MustangChris

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didnt have an issue on my 4.6 regarding charging, but the money is better spent elsewhere.
 

Win

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Don't let them scare ya a little voltage drop at night isn't going to leave you stranded or kill your battery. Crap its been proven over and over pulleys are a great bang for the buck Bolton. Its been common knowledge for over 2 decades. Remember 10hp increase may or may not be felt in the buttometer but you will pick up hp across the board.
Win
Ive used them on stock foxs dating back to the late 80s ... never once had a battery die or been left stranded because of pulleys. My last combo idled at 750 no problem there either

well that's why then... 750 rpm will spin enough to not have any issues.

94-95 Idles at 600 ish stock. I can't remember what 96-98 or 99-04 idle at.
 

the5.ohh

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Don't waste your money man.. Other than looking nice, they do almost nothing to justify the cost or changing the pulleys. put that $100 plus toward a good set of rear lower control arms
 

ttocs

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the science behind it...

The alt will spin slower no matter what pulley you put on the alt after swapping out the crank pulley. When doing this it does two things: It first increases the load on the alt since its output has been reduced, and the load remains constant and qwen that happens it generates heat. The other problem with slowing it down is that you reduce its abilty to cool itself since it is designed to pull air through it as it spins.

Most kits I have seen come with instructions to bump the idle up a little bit and if you do that and do not do a lot of city driving, don't have a high powered stereo then you should be fine. But again add in a higher powered stereo, lower voltage and slower sping added in with city driving in the summer and you alt will melt down shortly.

You will NOT install the pullies, start the car up and notice any real gain don't care what anyone says...
 

RichV

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You guys must spend an awful lot of time on idle. :)

never had had issues either, cooling or charging.
 

ttocs

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you have NO idea........ The local nick-name for my city is "stop light city". The lack of planning that this city does means it fixes everything with a stoplight. This is too such a point that we have an interstate straight through town and well of course every business needs an entrance to it ever 40 ft so it has a 45 mph zone and I would guess 25 lights in a 12 mile stretch. They built an expressway perpendicular to the interstate so we can get across town easily - and again the lack of planning and every business wanting access directly too it means today that there are 38 lights in a 22 mile stretch, 50 mph zone but you rarely get up too that speed.
 

95opal

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well that's why then... 750 rpm will spin enough to not have any issues.

94-95 Idles at 600 ish stock. I can't remember what 96-98 or 99-04 idle at.


Yeah win I realize what a stocker idles at and as Ive said Ive ran them on stock and bolt on cars including Bolton fox bodies with zero issues.


You guys must spend an awful lot of time on idle. :)

never had had issues either, cooling or charging.


I with ya on that Rich these guys must cruise at idle to be having all these problems... Well actually not one person has stated a specific problem or failure. IDK
 

410sn95

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Personally have underdriven acc. stock alt. 700rpm idle with no real issues, other than a slight voltage drop at night, headlights on, stopped with foot on brake, heater full blast and stereo cranked to 11. (94 Mustang)

Make sure your electrical system is healthy. Healthy alt., Good batt., good cables, clean/solid connections. Underdrives sometimes magnify a pre-exisisting issue.
 

Suspect

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one of the first mods i did on my car.. stayed on the car when i had the 331 and the 408.. no problems. but now that the blowers on theyre on the shelf.
 

ttocs

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I personally saw two alts, one on my car and one on a buddies that mysteriously burned up about 5 months after pullies were put on. Sure, could have just been their time but strange that I know the rebuilt one I put in is still working now.

Best advice I can give you on them is, don't buy them new. They are always coming up for sale and be care full not to find the guy looking to sell/trade for your pullies as if you change your mind they are easy to take off and easy to sell. I sold mine for the same amount I had in them, minus the alt of course. But hey I have only worked on automotive electrical systems, specifically mustangs since the 94 gt I currently drive was the 2nd of its body in town spending, got a degree in electronics and then worked as a car audio vid installer for 15 yrs.
 

fiveohwblow

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I want to see if I can find the link to the thread, but a well known east coast Ford guy, known more for his SVT Focus tunes, took a bone stock 5.0 and put it on the dyno. He then proceeded to remove the accessory drive belt altogether and did another pull on the dyno, 10 minutes apart to allow similar conditions. He picked up 2.2 HP at the rear wheels. That was the day I quit wasting my 100 bucks on UDP. Your call, your car but I have yet to see anyone else do this exact test with UDP and prove more than a 2hp difference as well. Not worth it to me.
 

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