MMS Pulley Problems
MMS Pulley Problems Installed my mms crank pulley last night and pulled it on the dyno. at first everything was great car hit 10 lbs right away and then at 4800 boost dropped off. i thought the belt may have slipped so i tightend the belt and again same thing but sooner. then i noticed the pulley was not on straight. i used lock tight and used a jack handle to tighten it and after half a dyno run same thing everytime.also it appears my pulley is missing the the 3 pins like the ATI on has . would this be the problem if so can i put bolts instead of pins in there. also i searched this topic and i read about cutting the crank bolt how do i know if i need to do this the orignal one never came loose?
No one else has any suggestions? I thought alot of you used to use this setup before the sd-concepts kit was out. also can i tap the 3 holes and just install bolts instead of pins?Any help would be great.
Originally Posted by BLWNZ
Installed my mms crank pulley last night and pulled it on the dyno. at first everything was great car hit 10 lbs right away and then at 4800 boost dropped off. i thought the belt may have slipped so i tightend the belt and again same thing but sooner. then i noticed the pulley was not on straight. i used lock tight and used a jack handle to tighten it and after half a dyno run same thing everytime.also it appears my pulley is missing the the 3 pins like the ATI on has . would this be the problem if so can i put bolts instead of pins in there.
also i searched this topic and i read about cutting the crank bolt how do i know if i need to do this the orignal one never came loose?
also i searched this topic and i read about cutting the crank bolt how do i know if i need to do this the orignal one never came loose?
Yeah you definately need the pins/bolts. Did it have the pins on it when you installed it? Without them the force on the pulley will make it spin against the crank bolt and washers. This will then eat a depression into the blower crank pulley making everything loose. Maybe you can take the pins out of the stock ATI pulley and use those in the MMS pulley.
You may also want to watch for this:
Something I ran into a was shearing the pins off because of engine braking. The force exerted on the pulley during exceleration is taken up by the pins resting against the spokes of the balancer. However during hard decel in gear, the drag from the blower slowing down would pull the crank pulley off the spokes of the balancer. Then the next time I jumped on it the crank pulley would snap back against the balancer spokes. A few cycles like this and the soft aluminum of the pulley would wear down around the crank bolt untill it was so loose you could move the pulley back and forth by hand. Then it would shear off the pins and cut grooves into the spokes of the balancer. My solution was drilling the spokes of the balancer to accept the pins of the blower crank pulley. That way it's locked in both ways. I also pinned the crank during this and haven't had any problems since.
As far as the bolt, you'll know if it needs cut if the crank bolt bottoms out before everything is tight. If your supicious, take off a couple threads. Then Lock-tite and 250 ft-lbs.
i think the holes have been enlarged for the pins so the stock ati ones will not work so i guess my next question would be that if i tap the pulley and drill and tap the balancer and putting bolts in will not hurt anything.
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Joined: Nov 2001
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From: Raleigh, NC
I kept killing mine... two or three hard pulls and the pins would knock right out.
At about 11 PSI I was able to avoid that by drilling larger 3/8 holes and putting in a 3/8 bolt, washer, lock washer and nut.
Problem is, the crank bolt would still loosen, and it was a matter of time before I'd mangle those bolts and was eating channels into the spokes of the balancer.
I finally got up off my ghetto-rig self and got the ATI 8-rib with the other ATI's Superdamper and pinned the crank.
In the end, the only solution to your problem is to pin the crank.
At about 11 PSI I was able to avoid that by drilling larger 3/8 holes and putting in a 3/8 bolt, washer, lock washer and nut.
Problem is, the crank bolt would still loosen, and it was a matter of time before I'd mangle those bolts and was eating channels into the spokes of the balancer.
I finally got up off my ghetto-rig self and got the ATI 8-rib with the other ATI's Superdamper and pinned the crank.
In the end, the only solution to your problem is to pin the crank.
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