| I don't believe Ash has actually created a new super fix for the VTC noise problem but rather he has fixed the problem using something that was already allowing the fix to happen. I think it was staring him in the face and he just didn't see it. In the picture below Ash basically used newer designed and less worn VTC sprocket internals for his fix. You can also see that the older VTC internals he had replaced are quite worn out. Look at the spline alignment on the old "piston helix" I have circled in yellow. Just sitting there the splines are aligned when they should be staggered from the internal pressure of the six springs as it is with the new one. This is a sign that the six springs inside that piece are shot. The pressure of the springs would certainly add to reduce noise, slop and distance of the "cam helix". Incorrect. You can slightly turn the front piston helix gear slightly WRT the main piston gear. The anti-lash comes into play when you insatll the piston into both the outer housing and the cam helix, where it spaces the two apart from each other like this: 
The springs within the anti-lash mechanism try to force the two piston helix gears together, which have an offset tooth arrangement when they are actually touching each other. Once they are installed, there is a gap and the s6 prings within the piston helix "clamp" the piston helix teeth to the outer sprocket teeth and the cam helix teeth. IF you were to see the teeth on the inside of the helix, you would see that they are offset. It just depends on if you have the top piston helix gear slightly turned or not as to which sets of teeth will appear to be aligned (either the inner or outer). If you look at the other pictures in my original post, you will see that it shows the teeth in a non-aligned state. Your point is moot.
If you look at the old "piston helix" where I have circled it in green, you can see that the thickness is much thicker compared to the new one. This is because the new "cam helix" circled in red now has a collar. The reduced thickness of the new "piston helix" compensates for the thickness of that collar.
The reason that section you are referring to is thicker is because I machined that back stop on the piston helix to allow for the space that is taken up by the thrust bearing I installed. If I didn't do that, it would not allow the piston helix to move all the way back. Again, your point is due to the fact you did not read my original post thoroughly as I clearly stated what I had to do there. Strike two... Now for the part that keeps it more quite. The collar on the new designed "cam helix" acts as a stop keeping it from traveling to far in to the "piston helix" where the older "cam helix" was able to travel deeper making more contact. The collar also makes contact with the surface of the "piston helix" so now as the outside spring pushes on it the "cam helix" will be putting pressure on everything because of the collar. This will help reduce noise and slop even further. Again, you are misunderstanding the modification I made. JUst as in point #2 just above, I machined the back face of the piston helix to allow the helix to move all the way back. In the OEM design, the piston helix moves all the way back to the outer face of the rear plate. The rear plate is the actual stop for the piston helix, but only when it is in an advanced state. This has nothing to do with the noise the VTC makes. Strike three, but we'll just call it a foul and give you another shot. Ash saw the problem of how the old "piston helix" and "cam helix" was wearing out the end plate so he made a new end plate with built up surface area to keep the "cam helix" further out and to help take up the slop. Ash's fix was basically replacing the old end plate with a new one with less wear and using the internals of a newer designed VTC sprocket with less wear which also didn't allow the "cam helix" to travel in as far with it's collar. Negative. The wider thrust bearing I installed provides more surface area for the inner cam helix to rest upon the backplate. The cam helix still has 100% of its motion in my VTCs as it does in the OEM design. The total length of the cam helix is the same even with the new thrust bearing and the piston will still travel the full length. STrike three, you are out. You could in effect accomplish the same fix by replacing a worn out VTC sprocket with a new designed one. With the newer designed internals Ash used, he may have fixed the problem without even needing to create a new end plate due to the better condition of the newer designed "piston helix" and "cam helix" having a collar stop. Negative. THe only difference between the new and old model VTCs is the fact that the old model does not have a piston ring seal on the inner helix, as can be seen in the first image you posted. THe top is an old model and the bottom is a new model. You can see that ~1/8" seat just to the right of the helix teeth on the new model where the ring seal sits. Other than this, there are no differences internally to the VTC mechanism. Even the helix return spring has the same rate in both. JWT's fix with the stiffer outside spring was to put more pressure on the "cam helix" to stiffen up the slop. This may work better with the newer designed VTC sprockets because of the "cam helix" collar appling pressure on everything. I read many post on the web where people had success with this fix. But other people say it had no effect at all. Incorrect. JWT's stiffer front spring applies pressure to the outer sprocket to force it forward more to try and keep the outer sprocket resting upon the rear thrust bearing. That spring has nothing to do with the helix whatsoever. I believe Ash's fix will last as long as a new sprocket would last but only as long as he uses new updated internal sprocket designed parts. I don't think it would be posible to obtain these new parts and be able to sell the modified sprockets at the price of $300 as he inferred. You might as well just buy a new designed sprocket. I have full belief that the modification I have done will resolve the rattle for at least 100K miles given the increase in the thrust face area. Only time will tell, and you can be certain I Will be looking for you at the next 15K mile marker. Below I have included the Nissan technical bulletin on VTC noise. There's not really much to it. They say to replace the outside spring. I looked through all my tech bulletins and could not find anything on a newer designed VTC sprocket. I believe that during the first few years of the Z32, this was a know issue and the fix was presented as it was in this bulletin and for the earlier years a design change was implemented in the VTC sprocket internal design to help reduce the posibility of noise even further. Anyway, Ash wanted my input, so here it is. Is it completely factual? I don't know, it's just my therory of observation. If anything, I think we have all gained much more insight as to how the whole VTC thing works. I DO know that if the VTC parameters are played with in tuning an ECU you had better be very carefull because the wrong settings could very well cause broken valves. LOL, there is no way you are going to break valves by way of ECU Tuning of the VTC parameters.. If you really believe this, please elaborate on how this could occur and I Will proceed to explain to you why this will never happen. I'm sorry to tell you Gary, but you are really far off on this one - beyond left field in fact. It is very clear that your attempt here is to try and pick apart the pieces to claim that what I have done is a problem of some sort or another - I commend your loyalties, but you really just made yourself the fool with this post. I Am sure that Brett will fully agree with the things I have stated above for the sole fact it has no aspect of the contention between he and I about the rattle. Brett? :) NTB92_016_1MJ39_300ZX_INTAKE_CAMSHAFT_SPROCKETS_CAUSING_TAPPING_NOISE.pdf
[ ashspecz.com ]
[ agpowers@bellsouth.net ] Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the tailor.
Albert Einstein
|
