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Old 06-25-2016, 11:02 AM   #1
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Originally Posted by JFP in PA View Post
A far larger factor than RPM is the harmonics of the shaft itself; most IMS retrofits still allow, or even encourage, oil intrusion into the shaft, which can set up strange vibrations as the shaft, now partially full of oil, accelerates under load; none of which is doing the rear bearing any good.
I know, makes you really wonder if the kit got balanced in that Finland backshop before each installations lolll That should have taken care of the harmonics at best.

Was just sayin RPM, often the easiest decision benchmark when CAE data is out of reach. Old formulas. Tons of engineer calculators available online that will let anyone know how much you'll be able to rev up that little sport car during those spirit drives (roller vs balls, etc). Not a taboo thing

MicroPoly - Maximum RPM Calculator

(J - why builders want rollers? any specific reason(s) to this?)
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Old 06-25-2016, 11:22 AM   #2
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I know, makes you really wonder if the kit got balanced in that Finland backshop before each installations lolll That should have taken care of the harmonics at best.

Was just sayin RPM, often the easiest decision benchmark when CAE data is out of reach. Old formulas. Tons of engineer calculators available online that will let anyone know how much you'll be able to rev up that little sport car during those spirit drives (roller vs balls, etc). Not a taboo thing

MicroPoly - Maximum RPM Calculator

(J - why builders want rollers? any specific reason(s) to this?)
They advertise "superior thrust control", which makes no sense because the shaft uses the IMS rear flange as a rear thrust bearing, and even the factory IMS bearing uses the center bolt to limit forward thrust.

We have pulled a lot of OEM bearings, and not once have seen evidence of excessive thrust loading.
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Old 06-25-2016, 11:59 AM   #3
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huh? Completely lost now man. Roller bearings have nothing to do with 'thrust', I'll check again but last time I did it wasn't lolll I would have expected the use of the roller bearing to defeat any great centrifugal force/load that the shaft could have made. Interesting....

Thrust? as in gravity pull under accel? momentum (kg.m/s)? data based on what exactly? If you know. Not that I care to know, just curious
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Old 06-25-2016, 12:50 PM   #4
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huh? Completely lost now man. Roller bearings have nothing to do with 'thrust', I'll check again but last time I did it wasn't lolll I would have expected the use of the roller bearing to defeat any great centrifugal force/load that the shaft could have made. Interesting....

Thrust? as in gravity pull under accel? momentum (kg.m/s)? data based on what exactly? If you know. Not that I care to know, just curious
I'm no engineer, but in this reference I think that "thrust" is referring to motion perpendicular to the axis of rotation.


I would not expect a lot of force in that direction on the IMS, but a slight oscillation at high RPM over time could wear a roller style much more than a spherical ball. ...?
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Old 06-25-2016, 01:13 PM   #5
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I'm no engineer, but in this reference I think that "thrust" is referring to motion perpendicular to the axis of rotation.


I would not expect a lot of force in that direction on the IMS, but a slight oscillation at high RPM over time could wear a roller style much more than a spherical ball. ...?
You are correct in your assumption about thrust.
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Old 06-25-2016, 01:34 PM   #6
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You are correct in your assumption about thrust.
beat me to it. I get it now lolll haha funny, I almost bit (or maybe I did already)

carry on all
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Old 06-25-2016, 01:30 PM   #7
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I'm no engineer, but in this reference I think that "thrust" is referring to motion perpendicular to the axis of rotation.
Oh your dead right, thrust it is. Perfect illustration

Put thrust load on that roller bearing in your picture and it will immediately fail. Not after a few rotations, I mean immediately fail as "it just won't spin anymore".

hence why I was confused with JFP's thrust explanation. In fact, I'm convinced its a spelling mistake he didn't bother to correct. Or perhaps he's trying to make fun of the IMS business-goin'on thing situation. I don't know man.

If indeed that IMS shaft suddenly requires both thrust and load management then one needs a bloody angular bearing on that axis. Beside these sort of shaft design are rare as hell, they are terrible design in fact and are avoided as much as possible. Porsche?!
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