Lightweight Flywheel + Crank Pulley: Bearing Failures? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Anthony · 12-16-2014, 01:34 PM

There has been discussion in various places around the internet, usually as a tangent from the original topic, about the possible hazards of running a lightweight flywheel and a lightweight crank pulley. The apparent issue is that running both will upset the balance of your crankshaft to the point where it will cause bearing failure.

I'm not a veteran Subaru guy, but according to the ones I've talked to, it's common knowledge that this is certainly the case on EJ motors. I've seen some eyebrows raise at the idea that this is the same on the FA20 as well.

So I would like to gather some raw data on the subject. Here is the thread that originally drew my attention to this potential issue: Cons to a lowered weight pulley set? The topic comes up on post #15.

Fred E · 12-16-2014, 01:56 PM

I am very much interested in this discussion; thank you for bringing it up. I'm looking forward to seeing some real information!

Anthony · 12-16-2014, 02:02 PM

Yes, I'm tired of the speculations and opinions. I've already put my stock crank pulley back on, just to be safe, so I'd really like to know if that was necessary or not.

weederr33 · 12-16-2014, 05:44 PM

I'm all ears to this considering I'm gonna do a lightweight pulley set soon...

continuecrushing · 12-16-2014, 05:48 PM

Sub'd for info.

I've heard the lightweight crank+flywheel "possible rumor" as well

In for some facts.

JDKane527 · 12-16-2014, 06:53 PM

I'm in for facts, have lightweight pulleys installed and am having a lightweight flywheel installed as we speak.

Digitalanalog · 12-16-2014, 07:19 PM

I've heard this is a no no on other platforms also. The light weight accessorie pullies are fine to use with a light weight flywheel but not a crank pully

FT-86 SpeedFactory · 12-16-2014, 07:30 PM

The EJ series motors eat themselves apart just for fun. Not really a good comparison to ours.

We run all available lightweight pulleys, lightest weight flywheel, carbon drive shaft and wheels that are lighter than stock as well and have so since day one in our race car. It now has over 30K miles and shows no signs of slowing down. Car is boosted for most that time as well. Lightweight rotating components are absolutely fine as long as balanced.

FT-86 SpeedFactory · 12-16-2014, 09:33 PM

Quote:

Originally Posted by Fizz

When you say balanced, do you mean that it's best to use lightweight crank pulleys together with lightened flywheels? Do issues arise when running LWCP with stock flywheel?

Pulley with stock flywheel is fine as well. The flywheel is really the cats meow to me being as light as possible with this car. It revs so much faster, love it!

Fizz · 12-16-2014, 09:34 PM

Quote:

Originally Posted by FT-86 SpeedFactory

Pulley with stock flywheel is fine as well. The flywheel is really the cats meow to me being as light as possible with this car. It revs so much faster, love it!

Thanks. I actually removed my post because I found the answer already....lol. But thanks for the quick response nonetheless.

Element Tuning · 12-17-2014, 12:17 AM

Pretty much false it has anything to do with bearing failures on these flat 4s. There's not any evidence to support the theory than there is evidence to support those same cars with bearing failures probably also used spark plugs

The EJ motors have bearings because there are so many terrible engine builders so the resulting drop in oil pressure causes bottom end failures. FA20s fail also because they have inadequate oil pressure to support higher power and RPM.

I have had more failures without than with and we've built probably over 700 EJ motors and the majority of those engine failures did not have a light weight pulley. My FA20 had failed twice without lightweight pulleys and never with but neither the failure nor the success had anything to do with the pulleys. It was 100% a result of fixing the actual issue which is the lack of adequate oil pressure to support the HP.

Run pulleys and lightweight flywheels without fear of bearing issues but you might have some idle issues

nguyen_er · 12-17-2014, 02:14 AM

I have a lightweight crank pulley, and it's fine but I've been hearing some clacking noise. I don't know if I need to put the stock crank pulley back on and take it in....

industrial · 12-17-2014, 04:14 PM

I have had a lwcp, act prolite flywheel and aluminum driveshaft for 15,000+ miles now. I did have some idle dip issues which were fixed by raising idle to 900rpm. I tried out an ATI harmonic balancer and had more issues with that.

Krovi · 12-17-2014, 05:01 PM

Quote:

Originally Posted by nguyen_er

I have a lightweight crank pulley, and it's fine but I've been hearing some clacking noise. I don't know if I need to put the stock crank pulley back on and take it in....

Flywheel chatter is normal with lightened flywheels.

View Poll Results: Have you had crankshaft bearing issues from LWFW + LWCP?
I have had a LWFW + LWCP for at least 5,000 miles with no issues.	12	92.31%
I have a LWFW + LWCP and I definitely have crankshaft bearing issues.	0	0%
I have a LWFW + LWCP and I may have an issue. (Undiagnosed)	1	7.69%
Voters: 13. You may not vote on this poll

12-16-2014, 02:02 PM	#3
Anthony Weight Nazi Join Date: Aug 2012 Drives: 13 FRS -399lb, 11 335is, 05 Tiburon Location: Biloxi, MS / Gulf Coast 86 Posts: 3,702 Thanks: 5,009 Thanked 3,712 Times in 1,765 Posts Mentioned: 150 Post(s) Tagged: 4 Thread(s)	Yes, I'm tired of the speculations and opinions. I've already put my stock crank pulley back on, just to be safe, so I'd really like to know if that was necessary or not. __________________ Build Thread \| The Venus Project \| Any car which holds together for a whole race is too heavy.

12-16-2014, 06:53 PM	#6
JDKane527 Senior Member Join Date: Jan 2013 Drives: Asphalt Scion FR-S Location: Los Angeles, CA Posts: 499 Thanks: 274 Thanked 215 Times in 136 Posts Mentioned: 10 Post(s) Tagged: 1 Thread(s)	I'm in for facts, have lightweight pulleys installed and am having a lightweight flywheel installed as we speak. __________________ Asphalt Build

12-17-2014, 12:17 AM	#11
Element Tuning Senior Member Join Date: Jun 2012 Drives: Hydra EMS Powered FRS Raven Black Location: Maryland Posts: 839 Thanks: 54 Thanked 1,021 Times in 365 Posts Mentioned: 61 Post(s) Tagged: 2 Thread(s)	Pretty much false it has anything to do with bearing failures on these flat 4s. There's not any evidence to support the theory than there is evidence to support those same cars with bearing failures probably also used spark plugs The EJ motors have bearings because there are so many terrible engine builders so the resulting drop in oil pressure causes bottom end failures. FA20s fail also because they have inadequate oil pressure to support higher power and RPM. I have had more failures without than with and we've built probably over 700 EJ motors and the majority of those engine failures did not have a light weight pulley. My FA20 had failed twice without lightweight pulleys and never with but neither the failure nor the success had anything to do with the pulleys. It was 100% a result of fixing the actual issue which is the lack of adequate oil pressure to support the HP. Run pulleys and lightweight flywheels without fear of bearing issues but you might have some idle issues Last edited by Element Tuning; 12-17-2014 at 09:34 AM.

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12-16-2014, 01:34 PM	#1
Anthony Weight Nazi Join Date: Aug 2012 Drives: 13 FRS -399lb, 11 335is, 05 Tiburon Location: Biloxi, MS / Gulf Coast 86 Posts: 3,702 Thanks: 5,009 Thanked 3,712 Times in 1,765 Posts Mentioned: 150 Post(s) Tagged: 4 Thread(s)	Lightweight Flywheel + Crank Pulley: Bearing Failures? There has been discussion in various places around the internet, usually as a tangent from the original topic, about the possible hazards of running a lightweight flywheel and a lightweight crank pulley. The apparent issue is that running both will upset the balance of your crankshaft to the point where it will cause bearing failure. I'm not a veteran Subaru guy, but according to the ones I've talked to, it's common knowledge that this is certainly the case on EJ motors. I've seen some eyebrows raise at the idea that this is the same on the FA20 as well. So I would like to gather some raw data on the subject. Here is the thread that originally drew my attention to this potential issue: Cons to a lowered weight pulley set? The topic comes up on post #15. __________________ Build Thread \| The Venus Project \| Any car which holds together for a whole race is too heavy.

12-16-2014, 01:56 PM	#2
Fred E Senior Member Join Date: Dec 2013 Drives: WRB BRZ Location: New Jersey Posts: 261 Thanks: 83 Thanked 150 Times in 96 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I am very much interested in this discussion; thank you for bringing it up. I'm looking forward to seeing some real information!

12-16-2014, 05:44 PM	#4
weederr33 Airborne at your service Join Date: Sep 2014 Drives: '17 BRZ Series.Yellow Location: El Paso, Texas Posts: 6,325 Thanks: 4,528 Thanked 5,586 Times in 2,928 Posts Mentioned: 33 Post(s) Tagged: 2 Thread(s)	I'm all ears to this considering I'm gonna do a lightweight pulley set soon...

12-16-2014, 05:48 PM	#5
continuecrushing Join Date: Mar 2013 Drives: 2013 Firestorm FRS Location: Lake Elsinore, CA Posts: 2,707 Thanks: 1,231 Thanked 2,144 Times in 1,003 Posts Mentioned: 73 Post(s) Tagged: 2 Thread(s)	Sub'd for info. I've heard the lightweight crank+flywheel "possible rumor" as well In for some facts.

12-16-2014, 07:19 PM	#7
Digitalanalog Senior Member Join Date: Mar 2014 Drives: '13 BRZ Limited, '95 BMW M3 Location: Colorado Posts: 104 Thanks: 13 Thanked 67 Times in 25 Posts Mentioned: 0 Post(s) Tagged: 2 Thread(s)	I've heard this is a no no on other platforms also. The light weight accessorie pullies are fine to use with a light weight flywheel but not a crank pully

12-16-2014, 07:30 PM	#8
FT-86 SpeedFactory Join Date: Jul 2012 Drives: 2013 Scion FR-S Location: Des Moines, IA Posts: 7,694 Thanks: 1,298 Thanked 3,578 Times in 1,253 Posts Mentioned: 341 Post(s) Tagged: 5 Thread(s)	The EJ series motors eat themselves apart just for fun. Not really a good comparison to ours. We run all available lightweight pulleys, lightest weight flywheel, carbon drive shaft and wheels that are lighter than stock as well and have so since day one in our race car. It now has over 30K miles and shows no signs of slowing down. Car is boosted for most that time as well. Lightweight rotating components are absolutely fine as long as balanced.

12-17-2014, 02:14 AM	#12
nguyen_er Senior Member Join Date: Jul 2013 Drives: 2013 Raven FR-S Location: Wichita, KS Posts: 510 Thanks: 101 Thanked 83 Times in 69 Posts Mentioned: 2 Post(s) Tagged: 0 Thread(s)	I have a lightweight crank pulley, and it's fine but I've been hearing some clacking noise. I don't know if I need to put the stock crank pulley back on and take it in....

12-17-2014, 04:14 PM	#13
industrial Add lightness! Join Date: Apr 2012 Drives: 17' WRX Location: Boston Posts: 1,253 Thanks: 380 Thanked 888 Times in 411 Posts Mentioned: 20 Post(s) Tagged: 0 Thread(s)	I have had a lwcp, act prolite flywheel and aluminum driveshaft for 15,000+ miles now. I did have some idle dip issues which were fixed by raising idle to 900rpm. I tried out an ATI harmonic balancer and had more issues with that.

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