Serpentine belt coming apart - Page 3 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

RZNT4R · 12-26-2018, 10:21 PM

Something that has a lot of inertia that is often overlooked is the alternator.

Gates has retrofit kits for 1ZZFE corolla where they replace the hydraulic damped tensioner with a simple sprung one, and replace the alternator pulley with a one way clutch to improve the setup.

The alternator may be ratio'd at many times the speed of the engine, and that rotor is nothing but laminated steel and wound copper. Of course the blower may not be helping, but every time the engine has a hickup, the inertia in that rotor shoves the belt pretty hard It might be a cheaper avenue to look for a decoupled alternator pulley than for a hydraulic tensioner

Ultramaroon · 12-26-2018, 10:52 PM

The inertia from the accessories do add together. I like the idea of a sprag clutch. I think HKS designed one into their supercharger. Wonder why others don't.

The cheapest fix would be to smooth out that cold idle.

gtengr · 12-27-2018, 09:56 AM

I have an extra flanged idler pulley from the used Cosworth kit I picked up (bought a new pulley and gaskets from Cosworth just because). I could sell it pretty cheap. I believe there's about 15-20k miles on it but cannot say for sure. I don't have any reason to think it's bad, but the bearing in it is serviceable and could be replaced as a precaution.

Ultramaroon · 12-27-2018, 02:25 PM

Quote:

Originally Posted by gtengr

...flanged idler pulley...

Excellent.

BirdTRD · 12-27-2018, 06:54 PM

Quote:

Originally Posted by gtengr

I have an extra flanged idler pulley from the used Cosworth kit I picked up (bought a new pulley and gaskets from Cosworth just because). I could sell it pretty cheap. I believe there's about 15-20k miles on it but cannot say for sure. I don't have any reason to think it's bad, but the bearing in it is serviceable and could be replaced as a precaution.

Interested. Which pulley does it replace? The green one has a flange and the Edlebrock kit adds the red ones.

gtengr · 12-27-2018, 08:29 PM

Quote:

Originally Posted by BirdTRD

Interested. Which pulley does it replace? The green one has a flange and the Edlebrock kit adds the red ones.

I misspoke earlier it's actually the tensioner pulley.

BirdTRD · 12-27-2018, 08:50 PM

PM'd

Ultramaroon · 12-27-2018, 09:36 PM

Here is where the belt goes slack.

12-26-2018, 10:52 PM	#30
Ultramaroon 義理チョコ Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 31,865 Thanks: 52,120 Thanked 36,513 Times in 18,917 Posts Mentioned: 1106 Post(s) Tagged: 9 Thread(s)	The inertia from the accessories do add together. I like the idea of a sprag clutch. I think HKS designed one into their supercharger. Wonder why others don't. The cheapest fix would be to smooth out that cold idle. __________________ service manuals

12-27-2018, 09:36 PM	#36
Ultramaroon 義理チョコ Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 31,865 Thanks: 52,120 Thanked 36,513 Times in 18,917 Posts Mentioned: 1106 Post(s) Tagged: 9 Thread(s)	Here is where the belt goes slack. __________________ service manuals

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12-26-2018, 10:21 PM	#29
RZNT4R Professional Mechanic Join Date: Apr 2010 Drives: 2017 86 6MT Oceanic Location: Quebec, Canada Posts: 789 Thanks: 17 Thanked 633 Times in 371 Posts Mentioned: 12 Post(s) Tagged: 0 Thread(s)	Something that has a lot of inertia that is often overlooked is the alternator. Gates has retrofit kits for 1ZZFE corolla where they replace the hydraulic damped tensioner with a simple sprung one, and replace the alternator pulley with a one way clutch to improve the setup. The alternator may be ratio'd at many times the speed of the engine, and that rotor is nothing but laminated steel and wound copper. Of course the blower may not be helping, but every time the engine has a hickup, the inertia in that rotor shoves the belt pretty hard It might be a cheaper avenue to look for a decoupled alternator pulley than for a hydraulic tensioner

12-27-2018, 09:56 AM	#31
gtengr Senior Member Join Date: Nov 2016 Drives: 2017 BRZ Location: USA Posts: 655 Thanks: 326 Thanked 258 Times in 177 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	I have an extra flanged idler pulley from the used Cosworth kit I picked up (bought a new pulley and gaskets from Cosworth just because). I could sell it pretty cheap. I believe there's about 15-20k miles on it but cannot say for sure. I don't have any reason to think it's bad, but the bearing in it is serviceable and could be replaced as a precaution.

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