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Discussion Starter #1
I know it's been discussed, but until it happens to you, who thinks their crank pulley with the rubber dampening will just suddenly decide to separate into 2 pieces?

The belt pulley that the serpentine belt (for ps/alt/water pump) is attached to the metal part of the crank pulley with the timing marks etched on it, via a rubber section. Does its job for insulation of vibrations, but over the years (25+) that rubber deteriorates and fails. Fortunately I noticed my belt wobbling, and the crank pulley wobbling a bit too, shut the engine down. Probably saved a major headache from happening.

Those of you with 1jz stock pulleys or even 2jz stock pulleys, think about replacing with a new unit, if yours is more than 10-15 yrs old. Pretty cheap insurance.

IMG_20170808_131833 by toy4speed, on Flickr

New pulley on left, broken pulley (prob 20 yrs old) on the right.
 

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Discussion Starter #4
There are good options for 1jz and 2jz aftermarket crank pullies, not sure about 5m. I had a fluidamper unit for a while, but unfortunately my SDS standalone works off of magnets mounted onto the pulley face, and I need a metal face pulley to do it. Fluidamper was fine until I drilled into the fluid chamber, struck oil.

Yeah, with used JDM motors, hard to say exactly how old or number of miles on the motor. I should have replaced that crank pulley when I first installed the motor.

Don L.
 

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Yowza, thanks for the heads up...of course I did every pulley except that one because I didn't want to tamper with such a critical part. Didn't even consider putting on a new OEM.

Fingers crossed.
 

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The crank pulley was one of the first things I bought when I was building my last 1.5JZ. I've seen a few explode in my time and had customers complaining of a weird vibration. The Fluidampr served me well and was good insurance against catastrophic failure.
 

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I think I am gonna change the one on my 93 GS300. Car has 388k miles on it, and should hit 400k before the end of the year. Being I found a cheap replacement, better safe than sorry.


Edit: OK, just used google and they are like $45ish. IDK why Rockauto has it listed at $320.
 

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Now if only they made 5/6m replacement units...
http://www.atiracing.com/products/dampers/charts/damtoyota.htm

5m and 7m applications. I'm guessing someone could get them to make a 6m one fairly simply since it is essentially a combination of the 5m and 7m pulley. They even have different part numbers for the center sections, but I'm not sure if they happen to be interchangeable between those applications. These guys build their stuff in the US though. If you call the number on their site you can actually get someone in the actual manufacturing department on the phone. I just bought a 7m one, I was hoping to order one without the bolt on AC pulley and save a few bucks but they pretty much told me to just order thru Summit as it likely wouldn't be any cheaper due to the bulk discounts they give Summit vs direct sales. So I did. Still cost me $550cdn, ouch. So much for a crank pulley. At least I ordered the day the Canadian dollar had a good run up to .80cents.
 

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Wow thanks man, for some reason I just hadn't noticed ATI made one for 5m's. Lots of folks make bolt on trigger wheels for ATI dampers too, so should be quite easy to make it time right. If they would make one for 6m's that would be rad, that pulley is about the only hard part to get for a conversion. Might be worth having someone with a 6m pulley sending it in so they can get it right...
 

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Its been done. They have already made several. Russ M. had one back in the day. george has one now. They are not cheap. However if the shell for the 5m will bolt to a 7m crank hub, then itll be a normal cost for a 6m pulley. Would have to call ATI to see if this is possible, otherwise itll be "custom" even though they have already done it, and cost quite a bit.
 

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Having something like this come apart at high RPM can indeed be both scary and dangerous.

Thanks for the reminder these things have a service life!

- Jim
 

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You should really go aftermarket. Even new will separate under high HP applications. The ATI pulley is really required for the Mk2 to lower the engine enough over the sway bar.
 

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Wow thanks man, for some reason I just hadn't noticed ATI made one for 5m's. Lots of folks make bolt on trigger wheels for ATI dampers too, so should be quite easy to make it time right. If they would make one for 6m's that would be rad, that pulley is about the only hard part to get for a conversion. Might be worth having someone with a 6m pulley sending it in so they can get it right...
I have one. I briefly considered it, but I don't run PS and since the trick of looping the PS off the waterpump pulley came out, the demand for legit 6mge pullies has somewhat subsided.
 

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Opinions on non-damped pulleys? Main reason why I left mine in tact, but this is a good spot to ask. Straight 6 is "balanced naturally..."
Begin shitstorm.
 

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its "very well" balanced naturally, its not perfect. All motors still need some kind of dampened pulley or flywheel. Running without one will kill your motor eventually. Yes, I know of Supra peeps that have attempted that and have damaged their motors.
 

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The "harmonic" balancer is more properly called a torsional damper. It's function is to resist and absorb the twisting generated in the crankshaft every time a cylinder fires. Without this, cranks eventually break. And sometimes it doesn't take very long either! The susceptibility of different engines to this type of failure is generally related to their performance and design somewhat as well as how they're used.
Why it's called a harmonic balancer is related to the fact that different configurations of engines have different firing orders, intervals, weights, etc and tend to oscillate at different frequencies and harmonics (multiples) of that main resonance. Without any damping, at whatever frequency (RPM) this peaks at can very quickly destroy an engine.
Most engines are internally balanced meaning that the harmonic balancer and flywheel are not involved in balancing the rotating mass. Externally balanced engines generally have both the harmonic balancer and flywheel as part of the balance.
It's not unusual for aftermarket replacement parts to have bolt on (in) weights for this when a part can be used on the same basic engine that can be either. The SBC is an example where all but the 400 CID are internally balanced. SBF's are an example where there is 2 different amounts of external balance.
 

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Got my replacement for the GS300. Prolly change it next weekend. Dont need that thing going out on the way to work. Don's pics got a fire under my ass. lol. IDK if its ever been changed. Got the car at 256k, and it now has 388k on it. For $40 shipped, its time!
 

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There's a few years of Corvette's (and probably other similar GM's) where there were a number of recalls for harmonic balancer failures and various fixes that didn't work for long. I had a buddy that had one and his came off and destroyed his radiator, hood and a lot of other stuff. Way beyond not a pretty mess and truly scary!
 
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