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Powerforce harmonic damper install??

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Thanks for that input Katman! I don't feel so noob-like now.

 

With 20 damper install experience that sheds some bright light on my situation...

 

I'm going to have to convince them of this when I call them back AGAIN tomorrow (that the L-Series don't use a press fit, rather they use more of a tight slip-fit). I wish I could get my hands on some real OEM damper specs!!

 

According to my calculations above, even if you size it as a press fit (which it shouldn't be) at LMC, their size is still a tiny bit small for that application. For a slip fit, it is impossible.

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Actually, Motorsport Division at Nissan recomended Locktite Green for Damper Bores to make sure there was not any chance of fretting or working the keyway in competition engines.

 

If you have a turbo engine that you rev to higher revs regularly, I'd be more comfortable with a tight damper that I had to heat to install (along with loctite) than a stock slip fit.

 

Granted, given the interference fit that was measured in this case, that is dead wrong. But 3 to 8 tenths of a thousandth is acceptable for a 'tight fit' and in some cases even more can be had and easily assembled with slight heating as noted by Dragonfly.

 

What it came like 'stock' has little to do with it, if you want something that won't rattle around, 'tight' is better then 'line to line'...

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...What it came like 'stock' has little to do with it,...

 

You're absolutely right Tony D, now why didn't that dawn on me...:hs:

 

... if you want something that won't rattle around, 'tight' is better then 'line to line'...

 

Agreed. I didn't consider that rattling (or key working) could happen if the fit isn't tight enough.

 

Who knows, I might get a inkling to bounce the rev limiter off 7->7.5k if I ever get an EMS installed...and I sure don't want to ruin components (or worse) after all that work and tuning time. I'm really liking 6k now that I've chased out that EFI Gremlin!! :mrgreen:

 

So 3-8 tenths of a thousandth (maybe tolerate a tiny bit more) and some green loctite...

 

Your mechanical wisdom is always appreciated! :icon14:

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If it's loose it's not right, if it's tight you may mar the crank or push out the key, either way don't trust mfg. to give you something perfect for your application. Green loctite is also given in the package of the BHJ product for a Z application. Well if the manufacture doesn't make are perfect fit, you can see if you can correct it, just don't rush the job.:wink:

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A little about me first... I am a Metrologist (calibration technician) for a living, so this is the kind of stuff I keep up with.

 

Most manufacturers if they do not advertise that they have an ISO certification (usualy 9001 or 17025) then they predominantly (but not always) do not use calibrated tools and instruments that are directly traceable to NIST. Even though the mfg. may have an SFI compliance for their part/s it doesn't mean that each part is dimensionaly the same. It happens that SFI is just up the road from me and I took it upon myself to talk to one of their techs about SFI 18.1 requirements for harmonic dampers. Because of liscensing etc. the spec is not available to the public but I was able to look at it and talk with them about it, the SFI spec 18.1 does not have any requirements for dimensional repeatability or accuracy, it does however require that the part pass a series of reliability test and then a sample of the part under test (damper) shall be machined out and tested on a standard tensile test machine...

 

What I am stating above is that just because a part meets or exceeds an SFI spec that part may still not be dimensionaly correct. For those of you who are pulling out your digital calipers to check everything there is something you should be aware of as well. The typical digital caliper has an accuracy of + or - 0.001 under ideal conditions, so you should only use use it to make a relationship measurement from one part to another and not as true dimensional measurement, if you want a true dimensional measurement for the ID of the damper you should use a very accurate and calibrated dial bore gage in a controlled environment.

 

I am starting to ramble now so I will just sum it up with: Don't trust any part to be exactly what it claims because it will usualy be close enough but not always right so don't be afraid to send it back and ask for a different one.

 

Dragonfly

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What I am stating above is that just because a part meets or exceeds an SFI spec that part may still not be dimensionaly correct.

 

This is concurrent with what my understanding of several items I have checked upon as well. When spin-testing Turbomachinery Impellers, the dimensional integrity is not determined, it's more of a 'spin to fail' or 'overspeed' mode of testing. As long as what they are checking for passes their criteria, they get their certification.

 

This is not to say they are making something useless, this sounds more like a bore tolerance mistake---and those things happen. If they make it good, by either reworking it or replacing it with one of dimensionally accurate machining---then it's all good.

 

The SFI rating regarding Structural Integrity is important to me---Clutches, Flywheels, etc.... Same for a Damper---you don't need a chunk of something flying off doing impromptu bodywork (either vehicular, or personal!) during a run!

 

Tolerances are always subject to buggering it up. They need to make it good, and I'd say the SFI rating is a 'good insurance' for any part put on the car, and is---as Dragonfly says, not related at all to how it is supposed to fit.

 

Myself, I may have been tempted to have it finish-ground slighty undersized as I mentioned above. The impellers I work with can have as much as 0.003+" Interference on a 1.5" shaft! Freeze the Shaft, Heat the impeller in a 600F oven, and hope it all goes together without cocking and binding halfway down.

 

Believe it or not, those parts DO come apart when it's time for overhaul as well. It just takes...er....'effort'! LOL

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Just to revive this thread - has anyone else found the professional products damper a little to tight or was this just a one off problem?

 

I need to buy an SFI damper and am trying to decide between this one or an ATI or something else. I'd obviously sooner spend $200 on the PP unit than over $400 on the ATI but with quick guys like 510SIX using the ATI, I'm concerned that the PP damper might not be very good quality.

 

This is for my 260Z which regularly sees 7000RPM at the drags.

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I finally got the damper honed out. I took it to Dan Hutchkins (one of Portland's premiere engine builders). He used a mic on the crank snout:

 

Crank snout diameter: 1.3772" (~34.9809 mm)

 

I asked that he make it between 3 and 8 tenths of a thousandths under. He made it six tenths of a thou under.

 

He had to take 1.1 thousandths out (0.0011 inch).

 

In his shop, he had a V-8 big block made of a piece of billet Aluminum!! He said it cost ~8 grand. :shock:

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Funny to see this come back.

I just caught the L24 damper on my L28+ had slipped about 5 degrees recently .

 

So ordering a replacement from MSA today. Heard they are a tight fit.

 

T

They are, however the ID measured exactly the same as the stock unit I removed. PITA to remove, I heated the new unit up and it tapped on over the key and drew it on the rest of the way with the bolt.

Edited by SleeperZ

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Just recently sent mine back to MSA (the 80055). No way was that going on

my crankshaft with any method without a machine shop fitting it.

It was machined that small. Maybe all the Z cranks made had a wide variance

in OD.?

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On 3/22/2012 at 12:00 AM, srgunz said:

Just recently sent mine back to MSA (the 80055). No way was that going on

my crankshaft with any method without a machine shop fitting it.

It was machined that small. Maybe all the Z cranks made had a wide variance

in OD.?

 

Same here, tried this weekend and the pulley was not going on at all. What a ridiculous waste of time.  

 

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On 1/16/2018 at 10:22 AM, hatepotholez said:

 

Same here, tried this weekend and the pulley was not going on at all. What a ridiculous waste of time.  

 

 

Well, crap...  Mine is way to tight to put on by hand too, and I have had it for at least a couple of years now.  Was about to drill it for a crank trigger.  How many people have had these work, everyone need to hone or ?  

 

Jason

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This is why I don’t like MSA . POS product that doesn’t fit and they keep selling it. It was not machined properly PERIOD . Sent one back for the same reason - too small. There isn’t variances in tolerances on our engines - it’s just a bad product

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On 1/21/2018 at 8:42 AM, madkaw said:

This is why I don’t like MSA . POS product that doesn’t fit and they keep selling it. It was not machined properly PERIOD . Sent one back for the same reason - too small. There isn’t variances in tolerances on our engines - it’s just a bad product

 

I bought mine from Zcardepot, but they took care of me. They said they can  fix it or issue a full refund, I took the full refund, I had my original one rebuilt per @Tony D 's referral to Dale manufacturing(http://hbrepair.com/) I should be getting it by this Friday.

 

 

What's funny is I called MSA first to see how the fitment was and they said they didn't hear of any issues :rolleyes: ya ok!

 

 

 

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