Underdrive Pullies

foxstang9050 · Sep 15, 2006

Went out to instal my pullies today... would not expect it to be such a pain... i absolutely cannot get the alternator nut to break loose... any help???? I got the water pump and crank right off no problem... but the alt. will not break loose... and also... the new pullies look nothing like the pullies i pulled off... is that normal??? I got them brand new from summit... they've never sent me a wrong part before

marine_2003 · Sep 15, 2006

The alternator nut needs to be taken off with impact stuff.

foxstang9050 · Sep 15, 2006

Anybody know a local store where i can get an impact swivel??

BYRDPE · Sep 15, 2006

You really don't want to use the alternator pulley unless it is smaller than the stock one.
You could have charging issues at idle.
I use the UD crank pulley with a 1 7/8 alternator pulley and the Cobra water pump pulley.

91mustangnick · Sep 15, 2006

i took the nut off with the alt. on and belt on and came right off and put a march pulley on it. bad idea had charging issues becuase the pulley is like 3.25 inches dia. so i put the stock smaller one back on. then upgraded to a 6G 130amp alt.

foxstang9050 · Sep 15, 2006

The alt. pully is slightly bigger so i'll leave it until i get my 130g alt... but the water pump pulley is just flat... and looks like the belt will just slip right off... is that supposed to be like that?

91mustangnick · Sep 15, 2006

my march pulley is like that, they did test and found out that they did not need the sides to hold the belt in place.

iwashmycar · Sep 15, 2006

ya itll be fine...keep the stock alt pulley for now too

foxstang9050 · Sep 15, 2006

great thanks for the help guys

mricci · Sep 15, 2006

I would keep the stock alternator pulley, my charging drops at idle with the underdrive one. Not to steal the thread, but can that cause any problems with anything. It drops to the bottom line on the stock gauge with the a/c and stuff on.

1990LXDropTop · Sep 15, 2006

I've been running FMS underdrive pulleys for over two years now with zero charging issues. I also have the stock 75amp alternator which is 16 years old. The amps do drop a bit at idle with the headlights, heat, etc. on, but it never goes out of the normal range. Just lucky I guess... I would install the alt. pulley just for ha-ha's. You can always swap the stocker back on if you have any issues. Good luck!

foxstang9050 · Sep 16, 2006

one more thing... will i even notice any power gains or should i be more excited about them being anodized blue???

N8Miller · Sep 17, 2006

they are a nice addition for the $79 they are. you will not be like "oh s h i t", but you will be like, "yeah, there is a bit more HP there."

on the nut topic: take it to advance auto, ask them for a favor, tell them what you need, throw the guy $5 for the 3 mintues it will take him. We used to do favors like that alot.

PJB · Sep 17, 2006

I just bought a set of ProForm underdrive pullies for mine on ebay for $80. Theyre also blue.

Do I need a different belt or can I use the same one? I know on a '00 GT you use the original belt but Im not sure about my '92 5.0.

N8Miller · Sep 17, 2006

you will need a diff belt for both the 00 and the 92.

PJB · Sep 17, 2006

I know the guy with the '00 used the same belt. I watched him put the pullies on.

Is there a specific belt for mine or do I just have to measure what length I need?

PJB · Sep 30, 2006

I put these on Thursday and I was able to use the stock belt.
I put all 3 pullies on and the charging does drop at idle and the lights seem to dim.

I want to upgrade the alternator now.

BadAndy · Sep 30, 2006

I have underdrive pulli,s on 2 mustangs and NO charging problems with stock alt, I took the alt to a garage and had them impact off the alt nut, also the stock belt still works, Im talking from exp

Mustang5L5 · Sep 30, 2006

If you use all 3 pullies then you shouldn't need a new belt.

When i did my pullies, i installed a ASP 1 7/8 OVERDRIVE alt pulley to compensate. No charging problems at all with the pullies and the O/D alt pulley. I could have used the stock pulley, but for $20 the ASP pulley was slightly smaller and more importantly looked better.

You can get the pulley off at home if you don't want to impact it off. WHat i do is use a small oil filter wrench. Wrap an old belt around the pulley and then grab it with the oil filter wrench. The tigher you pull the better it grabs. Then put a socket on the nut and give it a swift hard blow with a hammer to "impact" it off. QUick hits on the racket/wrench are better for breaking bolts loose then just trying to muscle them. That's how impact guns work.

enyawix · Sep 30, 2006

Do "NOT" under drive alternator! The charging system sucks in the stock setup.

Underdrive Pullies

foxstang9050

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marine_2003

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foxstang9050

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BYRDPE

91mustangnick

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foxstang9050

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91mustangnick

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iwashmycar

foxstang9050

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mricci

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1990LXDropTop

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foxstang9050

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N8Miller

I need NOS....make it 2 of the big ones

PJB

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N8Miller

I need NOS....make it 2 of the big ones

PJB

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PJB

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BadAndy

Mustang5L5

That is…until I whipped out my Bissell

enyawix

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