How to Install a Lightweight Crank Pulley

I've been eyeballing one piece lightweight crank pulleys since I did the timing belt on the Forester and saw how heavy stocker is. Plus they tend to separate and cause some destruction.

List of aftermarket pulleys and information: Crank Pulley List (Price, Weight, Part #'s)

I went with GrimmSpeed due to the heavier weight, it doesn't cause CEL's like others might when you use it with a lightweight flywheel. Plus Grimmspeed has timing mark and sells a kit for 08+ stretch belts (that I might convert to).

http://legacygt.com/forums/attachment.php?attachmentid=258303&stc=1&d=1510887638

For those that are curious, GrimmSpeed says the pulley has timing marks, they mean mark. It took me 5 minutes to find that single mark...

http://legacygt.com/forums/attachment.php?attachmentid=258304&stc=1&d=1510887638

I was under the impression that the pulley would be 2.6lbs, it feels heavy and is a very high quality piece, to my surprise it came out to be 2.05lbs.

http://legacygt.com/forums/attachment.php?attachmentid=258320&stc=1&d=1510887638

Stock Pulley weighs a hefty 5.65lbs

http://legacygt.com/forums/attachment.php?attachmentid=258321&stc=1&d=1510887638

GrimmSpeed vs Stock pulley

http://legacygt.com/forums/attachment.php?attachmentid=258313&stc=1&d=1510887638

http://legacygt.com/forums/attachment.php?attachmentid=258314&stc=1&d=1510887638

Start removing all of the parts in the way, I was able to do it with the intake and rad fans in place.

http://legacygt.com/forums/attachment.php?attachmentid=258305&stc=1&d=1510887638

Undo the lock bolt then unscrew the alternator tightening bolt, you will have to push the alternator down to remove the belt.

http://legacygt.com/forums/attachment.php?attachmentid=258306&stc=1&d=1510887638

http://legacygt.com/forums/attachment.php?attachmentid=258307&stc=1&d=1510887638

Same deal for AC, undo the idler pulley bolt, that will allow it to freely travel, then unscrew the AC belt tightener.

http://legacygt.com/forums/attachment.php?attachmentid=258308&stc=1&d=1510887638

After the belts are off get a 22mm socket and a breaker bar. Make sure your handbreak is tight and put the car in 5th gear. Use the breaker bar to loosen the bolt, then remove it.

http://legacygt.com/forums/attachment.php?attachmentid=258309&stc=1&d=1510887638

I used a big screw driver to slowly wiggle the crank pulley off

http://legacygt.com/forums/attachment.php?attachmentid=258310&stc=1&d=1510887638

Notice the circular cut in my timing belt cover, also notice the glue on the AC plug. Looks like this car suffered from the crank pulley falling apart previously...

http://legacygt.com/forums/attachment.php?attachmentid=258311&stc=1&d=1510887638

http://legacygt.com/forums/attachment.php?attachmentid=258312&stc=1&d=1510887638

Install the new pulley, make sure it goes on the tooth correctly before you begin to tighten it

http://legacygt.com/forums/attachment.php?attachmentid=258315&stc=1&d=1510887638

http://legacygt.com/forums/attachment.php?attachmentid=258316&stc=1&d=1510887638

Manual calls for 33ft-lbs of torque, but then rotating it to 65*-75* which equals to around 100ft-lbs, GrimmSpeed calls for 94ft-lbs. Reason manual calls for the degree deal, is because the bolt might overstretch, if it does even torquing it properly might mean the crank pulley is still loose. I try to use new bolts for piece of mind for this reason

http://legacygt.com/forums/attachment.php?attachmentid=258317&stc=1&d=1510887638

Reinstall the belts, make sure they are aligned on the crank pulley properly before tightening them or you will shred the belts. Then properly tighten them or they will squeak.

http://legacygt.com/forums/attachment.php?attachmentid=258318&stc=1&d=1510887638

http://legacygt.com/forums/attachment.php?attachmentid=258319&stc=1&d=1510887638

Gains

Now the moment of truth, you're $115 in and how much power does it gain you?

http://legacygt.com/forums/attachment.php?attachmentid=258322&stc=1&d=1510887638

Sadly loosing 3.6lbs from parasitic mass gained no power (in 2nd gear), at least GrimmSpeed didn't promise/advertise power gains. Usually lightweight and underdriving pulleys will gain you 5whp or so, guess all the power gain comes from underdriving and not from being lightweight.

I will say the motor did rev up smoother with the new pulley, I'm driving the car around right now to see if city MPG improves any.

At this point I would say only go lightweight if your current pulley falls apart and you need a new one anyway. My opinion may change once I drive the car in a spirited fashion after the MPG test.

Update 04-25-14: After driving for a while, it does seem like this pulley help improve my low end torque and the car likes being in 4th at 30mph a lot more. MPG gain/loss has been neglectable though.

Hey covertrussian,

What are your thoughts on the crank pully after having it installed for awhile?

Hey covertrussian,

 

What are your thoughts on the crank pully after having it installed for awhile?

I like it, it does help the engine rev easier and it gives me a piece of mind knowing it wont separate. I do also have a preference to heavier pulleys, they run less risk of throwing a CEL and feel like better quality.

I like it, it does help the engine rev easier and it gives me a piece of mind knowing it wont separate. I do also have a preference to heavier pulleys, they run less risk of throwing a CEL and feel like better quality.

Do you still think its a - replace if your current one falls a part piece?

I think you should replace it asap, because if it falls apart the amount of damage it will do will outcost it. My car is lucky it only dug into the timing belt a bit, guess previous owner was smart enough not to keep on driving it, otherwise I could see it breaking the timing cover and tearing up the timing belt.

Also if it breaks the belt tends to slip and hit the AC compressor control switch, which means a new compressor will be needed if it does enough damage.

The biggest benefit from a lightweight pulley and a lightweight flywheel is in rev matching during shifting. And there are two benefits to that: 1) When you downshift a blip on the throttle spins the engine up faster, so you can downshift faster. 2) If you miss match and don't get your revs matched, when the clutch engages the engine will spin up or down faster, reducing stress on the clutch/gearbox/engine. However if you really mismatch your shift that means you may over rev the engine past red line in a heartbeat.

The minor benefit is lower belt speeds and slower alternator - power steering - A/C rpms.

All this really applies to a race engine that lives at high rpm at almost all times and is being pushed to have fast shifts.

I've seen a video of a guy double clutch downshifting so fast you can't tell he's double clutch shifting without slowing the video down. In that case a lightweight crank pulley and flywheel make it much easier.

I wouldn't think that lightweight at the same diameter would provide slower belt speeds. In fact I'm pretty sure that they won't.

Correct, only smaller underdriving pulleys slow the belts down.

hey guys,

i feel like i'm getting some mis-information on the GS crank pulley install. i am being told you have to have the grimspeed tool to properly torque the pulley without pulling the motor out of the car. also being told this separation of the stock pulley is incredibly rare and if it does separate, the chances of it damaging anything are low. thoughts?

hey guys,

 

i feel like i'm getting some mis-information on the GS crank pulley install. i am being told you have to have the grimspeed tool to properly torque the pulley without pulling the motor out of the car. also being told this separation of the stock pulley is incredibly rare and if it does separate, the chances of it damaging anything are low. thoughts?

You don't need the the GS tool at least in a manual. I think it just put it in 5th and undid with a breaker bar. The radiator fan housings might be slightly in your way. I think there is a trick to getting it off with an auto. Resting the breaker bar on the ground and cranking the engine over, but I don't have experience with that.

Torquing was no problem - I just torqued it down, this is once again on a manual though...

if it does separate the chances of damage are very high - maybe minor damage, but you have a drive belt flying around hitting everything it can in your engine compartment.

Gah, too quick for me to respond. Agree on both accounts. Just get the gs pulley, install, and enjoy. Don't overthink it.

Sent from my XT1028

they also stated that the GS pulley can cause damage long term as it is sending harmonics back through the motor. please tell me this is absolute nonsense

Can I ask who's telling you that?

Crank pulley separation is common, not sure if it's as common as turbo failures though. Mine definitly had the crank separated once, you can see the carnage on the AC plug and timing belt cover.

As for harmonics, it's possible, it's the age old debate. Subaru has claimed on multiple occasions that the crank pulley is not a harmonic balancer though. Ultimately it's up to you.

Can I ask who's telling you that?

 

Crank pulley separation is common, not sure if it's as common as turbo failures though. Mine definitly had the crank separated once, you can see the carnage on the AC plug and timing belt cover.

 

As for harmonics, it's possible, it's the age old debate. Subaru has claimed on multiple occasions that the crank pulley is not a harmonic balancer though. Ultimately it's up to you.

i'd rather not say out of respect, as they are a reputable shop in my area that is subaru -exlcusive and does alot of work. not sure why they are so pessimistic about doing the job. i am having them install a KB oil pickup and a few other things for a reliable stage 2 build , and i feel the GS pulley is the last step. but lots of conflicting info.

not sure if it helps but my car is an automatic, 08 LGT w/ 52k original miles

No worries, I was just curious if it was another forum thread. Hopefully this shop is modern enough not to dismiss the information on the internet as all lies like our parents and older gen shops tend to do.

I would say do your research and go with what you feel is best. Personally I didn't care to shell out $100 on a part that didn't gain me any power or gas mileage, but I also didn't want the crank pulley to shred again and possibly take out the timing belt, thus I have the GS pulley on my FXT and LGT.

I've had the crank pulley on my LGT for about 10k miles and so far haven't seen any issues, 10k miles is nothing compared to 110k miles it had before the light weight pulley.

Eh, stage 2 can be detimental to engine/car life too. Almost no mod is without its gamble. Not even stock is without gamble.

Like the old saying (which is true): "gotta pay to play."

Sent from my XT1028

We all know by now that stock is far the least reliable. With banjo filters that clog and kill turbo then engine, and with really lean tune that causes ring land failure.

I've spent more time fixing Subaru issues to make the car more reliable then I've spent making it go fast....

Lol. All so true. GTs and XTs should come with warnings that owners should invest/save north of 4k for future maintenance and repair. Or be prepared for heartbreak or bankruptcy or both.

Sent from my XT1028

how long does the job take roughly? how much is it for the belt(s) that are recommended to be replaced?

First time about 30minutes 2nd time around it took me like 10 minutes. Belts are $15 a pop for Gates ones usually.

It only took me at most a half hour. Untighten belts, undo oem pulley, put on new pulley, retighten belts. Replacing belts would only add another 10 or fifteen minutes. Check belt tightness again a week later to make sure they haven't stretched too much. Pretty simple.

Sent from my XT1028

Dangit, you guys are fast....

Sent from my XT1028

slow day at the office for me haha. i'm sure for you guys too? thanks for the fast responses. if this shop keeps insisting that it's very labor-intensive and not worth it i'll just have another shop do it. i am a noob mechanic, oil-change status haha

my goal is a reliable stage 2 DD. i've had headgaskets done, timing belt, banjo bolts checked/cleaned, KB oil pickup on the way. i disabled the DRL's and flashed to stage 1 myself.

i feel this is the last preventative mod that needs done, feel free to add to my list!

Should release the noob status for this install. 24" Breaker bar from harbor freight and you're set. Assuming you have the socket and wrench for belts. Really not hard at all. Probably save money, downtime and get tools for future jobs.

And i get every other friday off from my 8-5, m-f. So playday today.

Sent from my XT1028