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I've been playing with the collars on my CGTS, so I have some feedback for anyone starting this job. I was one of the early adopters, and currently have about 2,500 miles with this mod.
It's worth noting that there isn't a linear correlation with exhaust volume compared to how far you keep the valve open. I've come to the conclusion that the sound volume is very similar whether the valves are only allowed to open 25% or 75%. Think about it this way: even a small 1/4" leak in an exhaust pipe will result in a lot of sound escaping. It's the same with this mod: even a small opening will allow a lot of sound to take the straight-through path.
So, after moving the collars around a couple of times, where I've finally landed is with the collars near the very bottom of the rod, so that the exhaust valve is probably 90% closed off. I tried putting the collars on the bottom of the shaft, because that would have been easy! That kept the valves open just a hair - but it also resulted in a very slight rattle which I think was the exhaust valves moving slightly because of road bumps and hitting their close position. So I moved the collars up by the thickness of a US quarter ($0.25)...basically I loosened the collars, let them slide to the bottom of the shaft, and then slid them up slightly so that a quarter could be squeezed in between the bottom of the shaft and the collar. Then once the collar was tightened, I pulled out the quarter that I was using as a spacer. So far (<100 miles), I'm really happy with the results.
So that's my suggestion for people doing the collar mod: a little actually goes a long way! If I look at the picture that @lowbee just posted above, I'd estimate that he has the equivalent of 2 or 3 quarters of spacing (vs. my one quarter of spacing). But his pics are nice and clear, so they make a great reference!
One last tip: if you are installing the 6mm collars from McMaster, you can fit them over the shaft by unscrewing one side completely, and leaving the other side attached - just barely - and spreading the two halves to slide the shaft between them (sorry that this sounds like a sexual reference to my adolescent mind). It's a LOT harder to separate the two halves and try to join them on the car...yet that's exactly what I did the first 4-5 times I was testing the collars.
So I completed my collar install. Started about halfway, maybe a little closer to the bottom. It's much improved. Then today I pushed those collars nearly all the way up, simulating a wire tie solution.
And I love it. No manners. Proper loud.
My wife is going to hate it. Lol car feels so much faster now.
5 min adjustment for any wife included long trips.
I have seen @Josh_357 ’s collar mod for the Soul rear valved unit. It is pretty clever, and adjustable. Maybe he’ll post some pictures. I would love to try it, but I’ll have to remove the unit which is a pain and expensive if you don’t have a lift.
I have seen @Josh_357 ’s collar mod for the Soul rear valved unit. It is pretty clever, and adjustable. Maybe he’ll post some pictures. I would love to try it, but I’ll have to remove the unit which is a pain and expensive if you don’t have a lift.
Built it but never tried it. Drill and tap M6 hole, add a bolt and a jam nut.
Dropped the collars down Approx 9mm from the top. Exhaust is not quite as loud, still good, but drone is all but gone!
What measuring points are you referring to when you say 9mm? Are you measuring the distance from the vacuum valve bracket (where the collar bottoms out) to the closest edge of the collar? I measured 18mm but I was measuring from the surface of the vacuum valve bracket to the furthest edge of the collar, meaning the edge of the collar that does NOT bottom out on the bracket.
The further away from the bracket you place the collars, the more difficult it is to get the collar to not strike the nuts that hold the valve to the bracket. This is because the valve doesn't pull the actuating shaft straight into itself. There is some lateral movement there, and the further away you place the collars, the more the collar moves laterally into the nuts.
So lets say that you placed the collar loosely on the rod. If you slid the collar all the way up, that would be the top. I then slid the collar down until the distance from collar top was 9mm from full top position. Seems to be working fine.
Curious as well, picture would be helpful. Awaiting my car and was going to try middle, collar up "high" to prevent pretty much all movement, then "lower" so they close almost all the way to see which I preferred.
That's exactly what I did. Up "high" sounded great but had too much drone for me.Dropped approx 9mm which is the thickness of my collar. See post #315 by lowee.
So lets say that you placed the collar loosely on the rod. If you slid the collar all the way up, that would be the top. I then slid the collar down until the distance from collar top was 9mm from full top position. Seems to be working fine.
I'd say that's about where I am as well. I just found it easier to get a good measurement from the bracket to the edge of the collar that is furthest away from the bracket.
just installed my collar a few nights ago (THANK YOU to the amazing rennlist folks for posting thier experiences with it) and WOW, changes the experience of driving the car around town, i think i have about 5mm from the top
just installed my collar a few nights ago (THANK YOU to the amazing rennlist folks for posting thier experiences with it) and WOW, changes the experience of driving the car around town, i think i have about 5mm from the topmgot the mcmaster 6mm with 16mm OD mentioned above
If yours behaves like mine when I tried it there, you may notice some drone in the 2-3k range at low-mid throttle. I ended up bring it down to the same position @lowbee showed in his post #315 earlier. No drone but much better mid-range sound. At that position you can detect a very slight quietening if you toggle the PSE off at idle. See: https://rennlist.com/forums/718-gts-...l#post18226951.
If yours behaves like mine when I tried it there, you may notice some drone in the 2-3k range at low-mid throttle. I ended up bring it down to the same position @lowbee showed in his post #315 earlier. No drone but much better mid-range sound. At that position you can detect a very slight quietening if you toggle the PSE off at idle. See: https://rennlist.com/forums/718-gts-...l#post18226951.
07-02-2022, 04:57 PM
If I look at the picture that @lowbee just posted above, I'd estimate that he has the equivalent of 2 or 3 quarters of spacing (vs. my one quarter of spacing). But his pics are nice and clear, so they make a great reference!
