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You seem to have ignored the most basic criteria. That is that it should be a quick and easy test for the home owner to carry out!Hello Tony, that is a nice job ! - well done mate.
I personally strongly believe that any test of the VCU should be done - where possible - in a situation that involves the VCU actually rotating, not a static test. This far far more informative. Your method is extremely good and probably by far the best test I have ever seen documented.
Now, I don't want to start a flame war re OWUT et al. Everyone is entitled to their opinion, and of course, those opinions may and well differ between folks.
So with your extremely valuable input we now have three basic tests (4 if you include include the Bell Engineering video)
This is my take on the 4 tests.
- By far yours is the most accurate and detailed that I can imagine and if you measure shaft rpm and load as it increases you have basically built a crude but highly accurate dynomometer. again I think this is excellent (I love things like this and thinking out of the box). By taking readings and mapping them as the rpm increases up to 75 one should be able to plot a load graph. Negatives obviously are the time and complexity for the vast majority of users. !!
- Second best test (imho of course) is the Bell recommended reverse test. The main reason being that it also puts a rotating load on the VCU - not a Static load that causes a partial single rotation. This is an actual 'turning' VCU test. It may however be difficult for some owners to 'judge' if it 'feels' that there is a tightening or brake binding issue - other users would have no issues in ruling the brake binding out quite simply.. Most users would certainly be able to tell though. A great and reliable test !. - One I would certainly recommend for the vast majority. It is simple to do - at any time - and often will be part of normal driving where the issue could be picked up 'as it happens' - gets my vote all day long
- Third best test is as per the old Bell video with the VCU on the 'bench' tested with a given load and measuring the time -(much like the OWUT)/ This removes all other parts of the transmission that may effect the readings slightly. It is very basic - but without a vehicle to test it on whilst the VCU is actually turnin there is really not much in the way of another option - unless of course - a VCU Dyno was built. I do not for one minute believe that the condemnation of the OWUP by Bell is in any way vindictive or derogatory. The test Bell shows is for a newly reconditioned VCU. what is the difference to a non reconditioned VCU one may ask ? - well again (imho) the recon VCU has known clean plates, known quantity of fluid and known type of fluid. It is simply the best test they can do on a recon VCU without a dyno. Given that they are starting from a known state of the unit in terms of fluid / plates / air gap etc then this is reasonable. An 'old' vcu can show similar performance however it is not representative of actual turning performance. In other words, it is more likely that a VCU that has issue may well perfrom a similar SLOW test but will fail a driven test. Remember Bell are testing newly built units with known good plates and fluid and air-gap. However, this is totally impractical for users as A. they do not have a fully recon unit to start with. (and Bell are probably the most respected VCU recon experts). B they would have to take the VCU off the vehicle - but - even that would be pointless as it only gives a limited about of info with a totally unknown quantity regarding the internals. I am saying that (again imho!) that what happens at slow partial turn tests with a vcu with an unknown internal state is not representative of a VCU in a fully recon state or definitely in a driven state.
- Last indicator of choice (FOR ME !) - but very popular amongst others - is the OWUT. I hold little faith in this personally. I think that a VCU showing an apparently normal 'time' for the test could indeed be faulty when actually rotating. I also feel that high (long time) test may actually be of use to indicate a potential fault. However -all thing being equal the test is only showing the static (non turning - driven) state of the VCU.
- The BEST test in my opinion is Tony's DIY Dyno - it is simply brilliant and has KNOWN figures to refer to !
- The MOST USEFUL test imho is quite simply the reversing tightness test - absolutely simple to do at any time and definitely indicative of a real issue.
- The LEAST USEFUL of the list (AGAIN ! IMHO) is the OWUT. Quite simply becuase it tells you little and is superceded by the far more reliable 'reverse tightness' test'
- Bell have absolutely no 'axe to grind'
Obviously I know this is contrary to the opinions of folk I really do respect - that is why I must stress again that the above informed / experienced (usually by both opinions are my own. Nothing more. I fully respect other peoples opinions and welcome discussions.
Joe
I like Tony's test, but that still means dismantling the drive train. I prefer the option of using the rear wheel, as that involves no dismantling of the car.
Bells test is, most likely the best, but how many owners wish to dismantle their car on a regular basis ( the prime need for this test us that it easy to do).