underdrive crank pully
Burning Brakes
Joined: Oct 2003
Posts: 1,079
Likes: 13
From: east norriton pa
funny, I was just thinking why don't more C6 guys have ud pullies. I gained 9rhwp on my 2001 ss STOCK (except for a cat back)
I was gonna research here how many guys had them on their LS3.
I was gonna research here how many guys had them on their LS3.
Burning Brakes
Joined: Nov 2007
Posts: 1,083
Likes: 3
From: Buena Park CA
I have the SLP PowerBond 25% UD pulley on my 07 C6 A6. The only issue was charging at idle, which was cured by simply reprogramming the computer to increase the idle up to 700 RPM......purrs like a kitten, roars like a lion, no issues.
Melting Slicks
Joined: Sep 2007
Posts: 2,597
Likes: 3
From: READING PA
St. Jude Donor '08-'09-'10
[QUOTE=Jimmy 2 Times;1570773238]funny, I was just thinking why don't more C6 guys have ud pullies. I gained 9rhwp on my 2001 ss STOCK (except for a cat back)
I do have a UD 25% on my LS2. I think the pulley should be pinned anytime you replace a Pulley.
I do have a UD 25% on my LS2. I think the pulley should be pinned anytime you replace a Pulley.
Melting Slicks
Joined: May 2006
Posts: 2,303
Likes: 40
From: Edmonton Alberta
Waste of time and money, mostly a mod done by Mustang owners. For only 7 HP I can modify or add something that gives a better bang for the buck. I had an ASP underdrive pulley and it was a complete POS - had a wobble in it right from new. Replaced with a Powerbond, (stock configuration). Still testing right now but runs true and looks better built than GM's stock junk.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
Lots of F-body and C-5 guys ran them. I got a .1 and 1 mph at the track with mine (F-body) and I know plenty of guys reporting similar results. For about $200 that's a good result and the absolute expenditure fits within most people's budget. If it weren't such a PIA on the C6 to install, I would have one now.
Melting Slicks
Joined: May 2006
Posts: 2,891
Likes: 1
From: NJ..."the way I saw it, everyone takes a beating sometimes."
Waste of time and money, mostly a mod done by Mustang owners. For only 7 HP I can modify or add something that gives a better bang for the buck. I had an ASP underdrive pulley and it was a complete POS - had a wobble in it right from new. Replaced with a Powerbond, (stock configuration). Still testing right now but runs true and looks better built than GM's stock junk.
Heel & Toe
Joined: Sep 2008
Posts: 16
Likes: 0
From: Greenville SC
I've got an 05 with the infamous wobbly factory dampner, but the car doesn't fall into the service bulletin serial number list, plus it's out of warranty anyway. To get a factory replacement costs the same as buying the SLP and paying the dealership to install it. I just got off the phone with the service manager and he's asking about the keyway and if the new bolt seals it up ok, or is ther something else that needs to be done to prevent leakage, like sealant or something. Not happy they aren't more familiar with this mod, but thought I would ask here while trying to get ahold of SLP.
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Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
There are many of those who install a UD without a cam swap. and therefore dont raise their idles.
in fact there was someone here who had that exact issue here a week or two ago with a dipping voltmeter.
The question I have for you is. What happens at 3000RPM(for example) while driving down the road making alot of HP on a 100 degree day. not at a raised idle to make up the 25% loss in flow. 3000RPM minus 25% flow of the stock pulley? Seems to me that car might run hotter or overheat more easily and quickly than one with the stock pulley.Maybe Im mistaken.
in fact there was someone here who had that exact issue here a week or two ago with a dipping voltmeter.
The question I have for you is. What happens at 3000RPM(for example) while driving down the road making alot of HP on a 100 degree day. not at a raised idle to make up the 25% loss in flow. 3000RPM minus 25% flow of the stock pulley? Seems to me that car might run hotter or overheat more easily and quickly than one with the stock pulley.Maybe Im mistaken.
Raise the idle. Consider it a mandator part of getting the 9HP.
Last edited by SpinMonster; Jul 14, 2009 at 07:30 PM.
Melting Slicks
Joined: May 2006
Posts: 2,303
Likes: 40
From: Edmonton Alberta
Lots of F-body and C-5 guys ran them. I got a .1 and 1 mph at the track with mine (F-body) and I know plenty of guys reporting similar results. For about $200 that's a good result and the absolute expenditure fits within most people's budget. If it weren't such a PIA on the C6 to install, I would have one now.
What can you add for $200 that will give you a better bang for your buck? Realize that most modders aren't just throwing on an UD pulley with nothing else. They probably already have cai, headers, tune, and are most likely in the middle of a cam swap and maybe ported intake/heads. As a stand alone it's probably not worth the install price/work but it's certainly a worthwhile addition to the continuing mod process.
1. It's not worth doing unless you have the car already torn apart.
2. It's a PIA to install.
3. A ported throttle body falls within most peoples budget and so does a ported intake.
3. Not just a measly $200.00 - usual price range for a quality underdrive unit (complete) is $300 to $500.
Melting Slicks
Joined: Jul 2007
Posts: 2,052
Likes: 14
I run a 25% with an 800rpm idle and have no issues at all. The car never runs over 200 degress and the charging is in the 13's all the time even sitting at the light in gear (A6).
BTW, there is a large difference in weight between the stock and UD balancer.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,368
Likes: 30
From: dfw Texas
keep in mind, i wouldnt do the UD pully till i did a cam swap, so the whole rack would be out anyway.. has anyone tested 10vs25vs35% power wise? is it wiser to pin the crank when you do this? which pullys seem to be the best quality?
Former Vendor
Joined: Feb 2007
Posts: 17,337
Likes: 39
From: Birmingham, AL www.hinsonsupercars.com 205-909-9402
Pinning the crank is not necessary. ATI is the best quality (hence the price). We use and sell more of the SLP units though and have never had a problem with them. Both are SFI approved.
SLP 25% Underdrive Pulley $179.95
ATI 10% Super Damper $454.99
Seth
SLP 25% Underdrive Pulley $179.95
ATI 10% Super Damper $454.99
Seth
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Yes its only 2 bolts and 2 hydraulic lines....and the tie rod ends. You should move the sway bar down too.Its heavy and has to be moved by turning it and moving it to the passenger side of the engine bay to get it out of the way or remove it.
The point is that it looks simple on paper until you try one for yourself. You always forget how the hydaulic lines were routed to the position they need to be in.
Pro
Joined: Nov 2006
Posts: 667
Likes: 0
From: Eagle River Alaska
I agree with Spin.
It briefs well, It sounds easy, It looks easy on paper, but it's not.
I would add that having an extra pair of hands, eyes, and Service Manuals will also help. When I did my cam job I had my father help me. It was great having that other mind to say no, no, no not like that. Try this instead.
Try to make sure you have everything you need before you start your project. It really sucks to find out you need something and BAM, the place you need to go is closed. That sucks.
Just my .02 cents.
It briefs well, It sounds easy, It looks easy on paper, but it's not.
I would add that having an extra pair of hands, eyes, and Service Manuals will also help. When I did my cam job I had my father help me. It was great having that other mind to say no, no, no not like that. Try this instead.
Try to make sure you have everything you need before you start your project. It really sucks to find out you need something and BAM, the place you need to go is closed. That sucks.
Just my .02 cents.
Last edited by Nightstalker Medic; Jul 16, 2009 at 12:55 AM.
Heel & Toe
Joined: Sep 2008
Posts: 16
Likes: 0
From: Greenville SC
I just got my 05 back from the dealer service department yesterday. They only charged me $490 labor to install the SLP pulley and new belt both of which I bought myself. They didn't have to disconnect the tie rod ends or anything else that would require an alignment. I noticed the voltmeter reading was dropping down to the low 12's at idle with the air conditioner blowing, but once I hooked my 1.5 farad capacitor back uo to the system (i've got a Kicker solobaric L7 12 and 750 watt rms amp), it stays above 13.
It feels so much more comfortable getting the wobbling crankshaft pulley replaced. I was worried something else was going to break besides the belt wearing out twice within 1 year and 3000 miles.
It feels so much more comfortable getting the wobbling crankshaft pulley replaced. I was worried something else was going to break besides the belt wearing out twice within 1 year and 3000 miles.