Best Underdrive Pully
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
The best one out there is the ATI, but it only comes in a 10% under drive. They were working on a 25%, but I was told at Carlisle last year some of their tech people didn't want to do that as they felt it would comprimise their ability to dampen the crankshaft harmonics, which is the real job the dampener has to do. The hub is also has a key machined into the hub so you can easily pin the crank with their pinning kit.
Racer
Joined: Dec 2005
Posts: 261
Likes: 0
From: Metro Detroit MI
The ATI is definetly the most serious race balancer however if you are looking for more than a 10% underdrive check out out the new SLP balancer
http://www.thunderracing.com/catalog...vid=7&pcid=111
SLP has stepped up the bar with their underdrive pulley/balancer combo's last year and is doing very well.
http://www.thunderracing.com/catalog...vid=7&pcid=111
SLP has stepped up the bar with their underdrive pulley/balancer combo's last year and is doing very well.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Originally Posted by freemanjc
vettnuts,
Do you have alink where I can get it from. Alos, do I need to get an belt as well?
R/
Free!
Do you have alink where I can get it from. Alos, do I need to get an belt as well?
R/
Free!
ATI Super Dampers
I have the belt part numbers at home.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
George,
To avoid the end pinning, I would see if a machine shop can cut a keyway in the length of the hub. Should be an easy job. You might be able to call ATI and ask them for the dimensions of their keyway.
To avoid the end pinning, I would see if a machine shop can cut a keyway in the length of the hub. Should be an easy job. You might be able to call ATI and ask them for the dimensions of their keyway.
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Racer
Joined: Oct 2003
Posts: 377
Likes: 2
From: Palm Beach Gardens FL
I could get that done but I will call them to see if it would weaken the hub, the ATI pinning kit actually makes a square keyway in the crank?
I guess the supercharging folks don’t use an ASP
I guess the supercharging folks don’t use an ASP
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Originally Posted by George V
I could get that done but I will call them to see if it would weaken the hub, the ATI pinning kit actually makes a square keyway in the crank?
I guess the supercharging folks don’t use an ASP
I guess the supercharging folks don’t use an ASP
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
No, actually it is just a drill and ream operation, but the pin that is used engaged the key on the hub. I like this setup better than the end drilled as I think removal and re-installation will be much easier if you have to ever go in again.
Here's the ATI crank pin kit.
And here it is on my motor (aluminum foil, etc. is to keep the chips out):
Here's the ATI crank pin kit.
And here it is on my motor (aluminum foil, etc. is to keep the chips out):
Last edited by vettenuts; Jan 24, 2006 at 06:50 PM.
Racer
Joined: Oct 2003
Posts: 377
Likes: 2
From: Palm Beach Gardens FL
Bob
Its hard to see the pinning in the photo. So trying to visualize this process, there is basically a hole drilled straight down into the crank, and a keyway cut in the hub, how do the two keep this together?
Its hard to see the pinning in the photo. So trying to visualize this process, there is basically a hole drilled straight down into the crank, and a keyway cut in the hub, how do the two keep this together?
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
To be honest this whole "cutting of a keyway" is causing some confusion.
99% of the folks whom "pin their crank" simply install the damper, then bolt on the guiding plate that contains a hole drilled in it that sits exactly in the middle of where the edge of the crank and the inner edge of the pulley meet. You drill to a pre-determined depth, insert a pin, put the crank bolt back on and you are done. Simple, eh?
99% of the folks whom "pin their crank" simply install the damper, then bolt on the guiding plate that contains a hole drilled in it that sits exactly in the middle of where the edge of the crank and the inner edge of the pulley meet. You drill to a pre-determined depth, insert a pin, put the crank bolt back on and you are done. Simple, eh?
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I have seen two methods of "pinning the crank" (that sound perverse 
)
The first is the way someone like Magnusen does it, where a fixture is bolted to the crank and a hole is drilled endwise to the crank snout with its center on the hub ID/crank snout OD. So the hole is split between the two mating parts. When I looked into this method, I wasn't sure how you would re-align the pin again if the damper had to be removed.
The second method is where the pin is put in at a 90* angle to the crank snout, which is the one I have above in the photo made bt ATI. The fixture bolts onto the snout and then a drill guide is first put into the fixture and a hole is drilled. Then the drill guide is removed and replaced with a ream guide, and the hole is reamed. The pin is then installed in the shaft. The ATI damper has a keyway milled into the ID of the hub, such that during installation the keyway slides over the pin. The crank bolt prevents the pin from falling into the inside of the crank snout.
)The first is the way someone like Magnusen does it, where a fixture is bolted to the crank and a hole is drilled endwise to the crank snout with its center on the hub ID/crank snout OD. So the hole is split between the two mating parts. When I looked into this method, I wasn't sure how you would re-align the pin again if the damper had to be removed.
The second method is where the pin is put in at a 90* angle to the crank snout, which is the one I have above in the photo made bt ATI. The fixture bolts onto the snout and then a drill guide is first put into the fixture and a hole is drilled. Then the drill guide is removed and replaced with a ream guide, and the hole is reamed. The pin is then installed in the shaft. The ATI damper has a keyway milled into the ID of the hub, such that during installation the keyway slides over the pin. The crank bolt prevents the pin from falling into the inside of the crank snout.
Racer
Joined: Oct 2003
Posts: 377
Likes: 2
From: Palm Beach Gardens FL
Good explanation on both methods, thanks. It sounds like the guys with the ASP drill into the front, but your right, if you have to take the pulley off it will never go back on the same way. 
