Do Solid Crank Pulley or Harmonic damper Lead to Crank Failures? Can anyone find one?

[GMan]

Hey Guys,

Here is the situation, I just met a guy here in Germany with a solid Aluminum pulley instead of a Harmonic Damper.

I told him what a bad Idea that was and how he would ruin his crank, even referenced some posts on here.

That's when he asked me to prove it, He wanted me to find one 2jz crank that had failed due to having a solid pulley on it.

 

I can not find a single one!!!

He and I scoured the web for hours and not a single broken crankshaft with a solid pulley that has failed.

 

Basically he said that I have fallen into all the hype to led people to buy a very expensive damper without any proof to back it up.

 

So please someone on here help me find an instance of a broken crank so I don't feel like a fool for spreading, in his words, "Internet forum Myths" without proof.

 

He has been running this pulley for 5 years+ on a German spec Supra TTat full BPU.

He has owned his supra since 1995 and told me he has suffered 2 Stock crank pulley failures in that time, The second one took out his radiator and bonnet.

 

After all of this I am starting to get worried about my 19year old (Probably) crank pulley and the difference between a $400 fluiddampr one and the $90 one he has installed.

 

What I did find was lots of stock pulley failures so I'll go for the Fluidampr one if anyone can prove him wrong.

 

Looking forward to some links to carnage.

[antno]

Not answering your question but some Porsches only run a dampener on the air con pulley for when the electro magnet switches over. Rest of the pulley is solid mounted to the crank. That's on a 1990 car (964). Also had the flywheel bolts come loose due to an unbalanced crank pulley

[GMan]

I would imagine loose flywheel bolts, given that they are on the opposite side of the crank and holding sown an item with at least 10 times the mass of the damper, would more likely be due to improperly torqued bolts. This would only be an argument if the car had never had the flywheel worked on. Having changed several clutches and a flywheel on one of my other cars I have never seen a properly torqued flywheel bolt loosen. one of my friend's cars had a rattling flywheel and two bolts were loose. the remaining 6 were all over the place (some way too much, some too low)Leading us to determine the previous owner was a retard who torqued the bolts down by hand without any regard to spec or a torque wrench.

 

Regardless I appreciate your input and look forward to more discussion.

[Swampy442]

Chris Wilson posted an excellent link to a paper about crank harmonics, search for the many crank pulley threads and give it a read. Gives you every possible reason to fit an harmonic damper. Also just get a stock damper, theres no proof an aftermarket one is any less likely to fail over time. Pulleys are actually a service item with a life.

[Scooter]

The aftermarket one that Gman is describing ie a solid ali one will definitely not fail in the manner the stock one does as it simply cannot delaminate into two pieces.

 

However i agree with the reason behind the damper, loads of other manufacturers have them too even in mundane cars.

 

Ok there may not be lots of documented issues with crank problems after fitting such a pulley but there are very few long termers out there from which to get a good indication of the chance of problems.

[Colin-mkiv]

I'd use a solid one if I could get one, but on an N/A engine this probably wouldn't pose much of an issue anyway. It would be for simple peace of mind more than anything.

[GMan]

Chris Wilson posted an excellent link to a paper about crank harmonics, search for the many crank pulley threads and give it a read. Gives you every possible reason to fit an harmonic damper. Also just get a stock damper, theres no proof an aftermarket one is any less likely to fail over time. Pulleys are actually a service item with a life.

 

Hey Swampy, I showed the guy that post along with the Dinan write up on harmonics. I think the science looks sound but the guy's challenge still stands, Find a recorded incident of a broken crank caused by a solid pulley.

 

I am starting to wonder if the guy was right, It's like being told you have to take an expensive blue pill or your dangly bits will fall off. No one can show an example of it falling off but everyone buys the pill and because it hasn't fallen off, we all assume the pill works.

[GMan]

The aftermarket one that Gman is describing ie a solid ali one will definitely not fail in the manner the stock one does as it simply cannot delaminate into two pieces.

 

However i agree with the reason behind the damper, loads of other manufacturers have them too even in mundane cars.

 

Ok there may not be lots of documented issues with crank problems after fitting such a pulley but there are very few long termers out there from which to get a good indication of the chance of problems.

 

The OEMs do put them in there for a reason, I'm just starting to wonder if it's one of those "because that's the way it's always been done" kind of thing. The guy brought up allot of good points about the 10+kg sprung flywheel hanging off the other end of the crank having much more effect than a half kilo ring mounted on a strip of rubber.

 

I desperately want to prove him wrong but maybe we all are.

[Scooter]

I just think it's such a slow burner..............if they had fitted solid pulleys from the off then i'm sure more problems would have surfaced, it's one guy who has had one for 5 years (how many miles?) with as yet no issue.

[Josh]

http://www.mkivsupra.net/vbb/showthread.php?35945-Crankshaft-Pulley-Damper

[Hellstrom]

It could verry Well be like you say that the crank in the 2jz is strong enough to cope without one. However i think that when a car manufacturer builds/develop a new engine even though they use alot or R&D there is really no need to invent the "wheel" everytime.

 

 

Using a damper will probebly eliminate a crank failure if there would be any risk for it to happend. They simply dont want to take the risk. And rather then use R&D on every engine they build they use it to be rather safe the sorry.

 

Also the engine is built to last a verry long time.

 

 

Also the Supra flywheel is dualmass and also dampend.

[Dnk]

I'll stick with what Toyota fitted and after 18 + years and 134,000 miles i'd say

thats a pretty fair test.

 

We just need a solid billet one chucked on a dyno for a few weeks to replicate the hours/milage

and have no issues and then i'll buy one

[Digsy]

It could verry Well be like you say that the crank in the 2jz is strong enough to cope without one. However i think that when a car manufacturer builds/develop a new engine even though they use alot or R&D there is really no need to invent the "wheel" everytime.

 

 

Using a damper will probebly eliminate a crank failure if there would be any risk for it to happend. They simply dont want to take the risk. And rather then use R&D on every engine they build they use it to be rather safe the sorry.

 

Completely wrong, and I've been doing base engine design for nearly 20 years so I know what I'm on about.

 

The fact is that all engine cranktrains will be subjected to the same level of analysis. Its true that the going in position might not be "lets see if we can eliminate the TV damper in the crank pulley this time" but rather at the most fundemental level of design and analysis there will be an assessment of the level of torsional and bending stresses in the crank through the rev range. The aim will be to make the crank as skinny as possible to save inertia and weight and it is at this point that the first stab at the tuning of the damper will arise. If it is found at this stage that there is any chance at all that the engine doesn't need a damper then the OEM will certainly elect not to fit one because it will be cheaper for them. OEMs do not fit parts just for the hell of it.

 

When it comes to any kind of modding, whether it is "acceptable" or not comes down to another bugbear of mine - engine durability. In order for an OEM to sign off an engine for production they have to pass rigourous dyno and in vehicle testing. In the case of the crank pulley, the pulley manufacturer will often visit to do physical measurements of the crankshaft vibration to confirm the damper is correctly tuned. To me, a durable engine will run for several hundred hours (>600) on an engine dyno at full chat without any failures at all. To the end user, durable usually means it will get them to work and back via the shops every day for a few years with the occaisional blat at weekends.

 

I have experience of engines with a badly tuned crank damper that did snap crankshafts very quickly on dyno test. However, I suspect that in the real world this kind of failure would be pretty rare but the key thing is there is no way of knowing.

 

Why not turn the challenge around and ask your mate if he would be happy to fit his solid pulley and then subject his engine to an industry standard durability test?

[dandan]

I know someone who snapped a crank on an A series engine when they removed the OEM version and fitted a fancy (very expensive) viscous damped crank damper.

[Hellstrom]

Completely wrong, and I've been doing base engine design for nearly 20 years so I know what I'm on about.

 

The fact is that all engine cranktrains will be subjected to the same level of analysis. Its true that the going in position might not be "lets see if we can eliminate the TV damper in the crank pulley this time" but rather at the most fundemental level of design and analysis there will be an assessment of the level of torsional and bending stresses in the crank through the rev range. The aim will be to make the crank as skinny as possible to save inertia and weight and it is at this point that the first stab at the tuning of the damper will arise. If it is found at this stage that there is any chance at all that the engine doesn't need a damper then the OEM will certainly elect not to fit one because it will be cheaper for them. OEMs do not fit parts just for the hell of it.

 

When it comes to any kind of modding, whether it is "acceptable" or not comes down to another bugbear of mine - engine durability. In order for an OEM to sign off an engine for production they have to pass rigourous dyno and in vehicle testing. In the case of the crank pulley, the pulley manufacturer will often visit to do physical measurements of the crankshaft vibration to confirm the damper is correctly tuned. To me, a durable engine will run for several hundred hours (>600) on an engine dyno at full chat without any failures at all. To the end user, durable usually means it will get them to work and back via the shops every day for a few years with the occaisional blat at weekends.

 

I have experience of engines with a badly tuned crank damper that did snap crankshafts very quickly on dyno test. However, I suspect that in the real world this kind of failure would be pretty rare but the key thing is there is no way of knowing.

 

Why not turn the challenge around and ask your mate if he would be happy to fit his solid pulley and then subject his engine to an industry standard durability test?

 

Sure, But if that was true why did Toyota make an engine that could systain more the twice the original power, they could have fitted alot lighter crank/rods/pistons But they dident. Afaik

The 2jz would probebly come from the developmentc of the prior 1jz and alos bare in mind that the engine was done way before it was put in a car. And they had a different mind back in those days

I totally agree in modern cars. As they all compete for maximum fun/mpg and such.

 

Obviously they put it there for a reson. But that still dont in anyway say that the crank Will snap, or shoot bearings. Could be But we cant know for certain

[garethr]

Sure, but if that was true why did Toyota make an engine that could sustain more the twice the original power? They could have fitted a lot lighter crank/rods/pistons, but they didn't AFAIK.

The 2JZ would probably come from the development of the prior 1JZ, and also bear in mind that the engine was done way before it was put in a car, and they had a different mind back in those days

I totally agree in modern cars. As they all compete for maximum fun/mpg and such.

Obviously they put it there for a reason, but that still doesn't in any way say that the crank will snap, or shoot bearings. Could be, but we can't know for certain.

I think there are a couple of things to remember when you discuss the durability of the JZs.

First is the 7M, which didn't have a particularly good reliability record. Toyota had a point to prove, possibly regardless of cost.

Second is that it was designed 20+ years ago, probably as much by experience, a slide rule, and "a bit for luck" as by computer. If it was designed now, everything would undoubtedly be much closer to the limit (look at the Nissan R35 GT-R). You can see the start of that process in the later VVTi engines - the VVTi GEs and UZs have much thinner connecting rods than the original engines, and, consequently, much less headroom for power increases on the standard internals.

 

I just figure that Toyota's engineers probably knew what they were doing, and I certainly don't.

Edited April 20, 2012 by garethr (see edit history)

[Scooter]

I think Toyota definitely said lets design it strong then add a bit on top for safety. The end result allows many to frankly take liberties with modding with acceptable real world endurance/reliability. It probably is partly due to the 7M, also Toyota unlike say Honda have no bike hertitage and no massive experience of light internals and revvy engines hence yamaha's involvement in the BEAMS engine. Honda have a reputation for light revvy engines fit for purpose but not for ready to take a 20-40% increase in power without open engine surgery.

 

Is someone running 1.2bar on the j-specs safely..........well yes for a time

Will a getrag take a 600bhp singles power and torque.......again yes for a time

 

So yes a solid crank damper will not result in instant death of the engine but will per all those in the know effect the stresses other parts see, it's not ideal and only time will tell how bad an idea it is.

Edited April 20, 2012 by Scooter (see edit history)

[Swampy442]

I think, regardless of what people put up about pros and cons of dampers, people will still fit solids because they don't believe the wisdom or simply refuse to pay for a new one.

[Colin-mkiv]

I'm afraid it's not a case of 'wont' pay for a new one....I have an NA that I got for nowt and I'm doing bits and pieces with it as a toy. I couldn't justify paying the £300 whatever for a new pulley if mine went because its just wouldn't be worth it. I can buy a perfectly serviceable (for my needs) solid one for a lot less instead of having no choice but to cut my losses and break/sell/scrap my car. I realise that some people will replace the crank for a solid one simply for the lower inertia aspect etc, but I would simply be using one for the economy of it.

[Nic]

.... interesting stuff.....

 

Am I right in thinking a solid pulley would also increase bearing wear?

[Josh]

I'm afraid it's not a case of 'wont' pay for a new one....I have an NA that I got for nowt and I'm doing bits and pieces with it as a toy. I couldn't justify paying the £300 whatever for a new pulley if mine went because its just wouldn't be worth it. I can buy a perfectly serviceable (for my needs) solid one for a lot less instead of having no choice but to cut my losses and break/sell/scrap my car. I realise that some people will replace the crank for a solid one simply for the lower inertia aspect etc, but I would simply be using one for the economy of it.

 

Buy a lower mileage 2JZ-GE instead, it'll be a lot cheaper

[Hellstrom]

I think there are a couple of things to remember when you discuss the durability of the JZs.

First is the 7M, which didn't have a particularly good reliability record. Toyota had a point to prove, possibly regardless of cost.

Second is that it was designed 20+ years ago, probably as much by experience, a slide rule, and "a bit for luck" as by computer. If it was designed now, everything would undoubtedly be much closer to the limit (look at the Nissan R35 GT-R). You can see the start of that process in the later VVTi engines - the VVTi GEs and UZs have much thinner connecting rods than the original engines, and, consequently, much less headroom for power increases on the standard internals.

 

I just figure that Toyota's engineers probably knew what they were doing, and I certainly don't.

 

 

Just for the record. The 7m engines weak spots where never the internal. Well irrc they made the rod bearings wider on 2jz.

 

7m had problem with to low torqued headbolts and bearing damage where mostly caused due to engine mixing water in the oil.

 

IIRC there where a 900bhp 7m on stock internals But iam guessing it was not verry reliable. But still that is allmost 4 times the factory rated bhp.

 

Back to the crank pulley i would never recomand anyone to not use one, But i for sure cant tell if not using one will cause damage.

[Swampy442]

So my point is right then But good luck with it, be nice to have some actual real world experience.

 

I'm afraid it's not a case of 'wont' pay for a new one....I have an NA that I got for nowt and I'm doing bits and pieces with it as a toy. I couldn't justify paying the £300 whatever for a new pulley if mine went because its just wouldn't be worth it. I can buy a perfectly serviceable (for my needs) solid one for a lot less instead of having no choice but to cut my losses and break/sell/scrap my car. I realise that some people will replace the crank for a solid one simply for the lower inertia aspect etc, but I would simply be using one for the economy of it.

[Digsy]

Second is that it was designed 20+ years ago, probably as much by experience, a slide rule, and "a bit for luck" as by computer. If it was designed now, everything would undoubtedly be much closer to the limit (look at the Nissan R35 GT-R).

 

Absolutely spot on. Back in the day high end computer stress analysis was reserved for main castings only because it took so long to construct the models. This would have been in the days before 3D CAD was widspread and all the associated downstream processes could share data. Cranktrain was all done by "classical calculation".

 

Nowadays its routine to do full blown FEA on stuff as mundane as wiring harness brackets.

 

Unfortunately the days of bottom ends with seemingly limitless strength are coming to an end. Engines will continue to have higher and higher specific outputs straight from the factory, but the internals will be pared down to the quick to save cost, mass and friction.

[Digsy]

Am I right in thinking a solid pulley would also increase bearing wear?

 

Bearing wear is mainly down to oi film thickness which is related to the in bay-balancing of the piston and rod (i.e. the crank counterweights). However, what everyone misses with the 2JZ (no matter how many times I mention it ) is that its crank damper is two-mode. It has a torsional AND a bending damper. Crankshaft bending would affect bearing edge loading so in this case I would say running without one may promote bearing wear.