where can I get a smaller alternator pulley?
Any downside to installing a smaller balancer?
Thread Starter
Melting Slicks
Joined: Feb 2006
Posts: 3,400
Likes: 3
From: Sarasota Florida
Any downside to installing a smaller balancer?
I will be doing a H/C/H upgrade this winter and I am thinking of installing a 10 or 25% underpully at the same time. Are there any downsides to this mod?
Le Mans Master
Joined: Jun 2002
Posts: 8,352
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From: In the pit, trying to love someone.
Some people have problems with their charging system, changing the alternator pulley for a slightly smaller one corrects the issue. I have a 25% pulley on mine with no issues for 2 years now.
Thread Starter
Melting Slicks
Joined: Feb 2006
Posts: 3,400
Likes: 3
From: Sarasota Florida
Le Mans Master
Joined: Jun 2002
Posts: 8,352
Likes: 103
From: In the pit, trying to love someone.
I think some of our sponsors carry them, but honestly, I would see if you actually need it first. Most people do not.
http://thunderracing.com/catalog/?ac...vid=7&pcid=111
ASP sells the underdrive and overdrive pulleys. You want the overdrive, **IF** you need it.
http://thunderracing.com/catalog/?ac...vid=7&pcid=111
ASP sells the underdrive and overdrive pulleys. You want the overdrive, **IF** you need it.
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
The smaller ones do not damp out crankshaft harmonics as well, which is one reason the ATI only does 10% reduction. Although admittedly I have not heard of anyone having a problem either.
Race Director
Joined: Oct 2002
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Over 2 years on mine (25% Powerbond), not a single problem or complaint.
It makes sense to do this with a cam install, especially with a big cam, since the idle speed is usually raised it will help compensate for the shower alternator rotation caused by the smaller crank pulley. (Idle is about the only time the car's electrical load might exceed the alternator capacity).
Also, for for really big-cammed cars that may see 7000+ rpm's...overspeeding the alternator (with a stock balancer) becomes a valid concern, and an underdrive pulley will help in that regard. You could actually extend the life of your alternator by installing the underdrive if you spend a lot of time in the high rpm's..
I would not swap alternator pulleys unless you do experience charging problems because of it.
But I've never heard of anyone actually having that problem, even guys with big stereos...
It makes sense to do this with a cam install, especially with a big cam, since the idle speed is usually raised it will help compensate for the shower alternator rotation caused by the smaller crank pulley. (Idle is about the only time the car's electrical load might exceed the alternator capacity).
Also, for for really big-cammed cars that may see 7000+ rpm's...overspeeding the alternator (with a stock balancer) becomes a valid concern, and an underdrive pulley will help in that regard. You could actually extend the life of your alternator by installing the underdrive if you spend a lot of time in the high rpm's..
I would not swap alternator pulleys unless you do experience charging problems because of it.
But I've never heard of anyone actually having that problem, even guys with big stereos...
Team Owner
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Instructor
Joined: Jun 2006
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From: Siloam Springs AR
I'm in the same boat
Can anyone speak about the BBK underdrive system. It is a 2 peice Crank/alternator. It looks pretty sweet and is reasonably priced. I am on the fence trying to decide what I want to spend the money on. I am not a racer but I do want nice looking quality pieces if I am replacing something.
BBK - 2 peice and nice looking
Powerbond - Cheapest I've found and positive reviews
SLP - Looks like a good unit and pretty afforable
ASP - Little bland looking but I'm sure its good
ATI - Pretty good looking but hard to find a supplier
Anyone care to rate these. I am looking for the best bang for the buck. I am leaning to the bbk just because I would have 1 more billet piece. Powerbonds I've seen going for <200 so maybe thats all I need. Without any experience feels like I'm rolling the dice, but they all sound like they are capable units.
BBK - 2 peice and nice looking
Powerbond - Cheapest I've found and positive reviews
SLP - Looks like a good unit and pretty afforable
ASP - Little bland looking but I'm sure its good
ATI - Pretty good looking but hard to find a supplier
Anyone care to rate these. I am looking for the best bang for the buck. I am leaning to the bbk just because I would have 1 more billet piece. Powerbonds I've seen going for <200 so maybe thats all I need. Without any experience feels like I'm rolling the dice, but they all sound like they are capable units.
Race Director
Joined: Oct 2002
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Can't comment on the others...but the SLP and PowerBond are the same exact part, same manufacturer.
If you choose to pay more for the SLP, the difference in cost is how much you paid for the included stickers.
If you choose to pay more for the SLP, the difference in cost is how much you paid for the included stickers.
Melting Slicks
Joined: Feb 2007
Posts: 3,194
Likes: 10
From: New Smyrna Beach Florida
I've had an underdrive pulley for a few months now when it was installed along with a cam. No problems with cooling or charging as I have feared in the past. Idle was increased by 25 RPM.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Ive have a POWERBOND on since April and have NOT had any issues at all. It is a very well made unit. Installation was a snap. I pinned mine to the crank while I had everything apart.
BC
BC