Okay, with my newly acquired Porter Cable polisher in hand, I finally got to run a test I'd been itching to perform. 
I wanted to see for myself what kind of vibration or balance differences there were using different combinations of counterweights and backing pads. Some people with the Meguiar's W64DA backing pad had mentioned a significant decrease in vibrations when they swapped out their 5" weight for a 6" one. I wanted to see this and also try out a 6" pad/weight combo, which I had less info on.
Thanks to 2wheelsx2xyxthumbs) I had both his extra 6" counterweight as well as the 5" counterweight that came with the 7335 I had (patiently) ordered in. Because the unit already came with a 5" backing pad, I went out and bought a 6" backing pad (and another later on as well). This way I owned all the existing combinations of counterweights and backing pads used by most people here. The first thing I did was take some weight measurements:
5" Counterweight: 1.75 oz / 50g
6" Counterweight: 2.00 oz / 58g
5" Porter Cable 13700 Backing Pad: 3.50 oz / 100g
6" Campbell Hausfeld Backing Pad: 3.85 oz / 110g
6" Craftsman Backing Pad: 3.50 oz / 100g
Meguiar's 6.5" W8006 Polishing Pad: 0.75 oz / 22g
Simoniz (Canada) 6" Buffing Pad: 0.85 oz / 24g
All weights were measured on a simple kitchen-grade scale and were verified a few times each. The absolute weights aren't as interesting as the relative weights. It's interesting to note that the larger Craftsman backing pad actually weighed the same as the smaller PC one. After a lot of debating it, I eventually returned this one and used the slightly heavier Campbell Hausfeld one for the test. While the Craftsman would've been good for actual use, it would've made for less revealing testing, as I couldn't imagine the 6" PC backing pad that comes with the 7336 being the same weight as their 5" one. Of course it should be remembered that the weights don't need to match the backing pad gram for gram when being exchanged because they're at different distances from the center of rotation. The counterweight weights were more out of curiousity than anything else.
While the pads don't seem to weigh very much, they make a fair amount of difference percentage-wise to the overall mass that the counterweights have to balance. So they do seem to matter, and this overturns the idea that the counterweight has to strictly match the backing pad. The Simoniz pad is found up here as an accessory to the Simoniz (Wen) cordless orbital sold at Canadian Tire. I was just curious if the weight is much different from the Meguiar's pads. They probably make for cheap, acceptable finishing pads and I used one for the test.
I did not test the obviously mismatching combination of 5" counterweight and 6" backing pad. I also had to afix a stick-on velcro adapter to these backing pads since they were originally PSA type pads. To do the test I gradually ran the PC from speeds 1 to 6 on the top of a large chest freezer with only QD sprayed on the surface and pad. Here are the combinations I tested:
5" counterweight / 5" backing pad (5/5)
6" counterweight / 5" backing pad (6/5)
6" counterweight / 6" backing pad (6/6)
Because I was changing pads/weights so much, and the test was very subjective to "feel", I ran each combo twice to make sure. The 5/5 combo gave the most vibration, especially at higher speeds. At speed 6 it was almost painful to hold the side handle because it was shaking so much. Up to about speed 4 it was "okay" though. The 6/5 combo was the smoothest overall, being relatively smooth up to 4 or 5, but still giving some vibration at 6. It was still quite a bit more well balanced than the 5/5 combo at this speed though. The 6/6 combo was pretty similar to the 6/5 combo, being very slightly rougher at higher speeds. I was almost expecting the balance to be worse than this, but am pleased it works okay.
Overall, I would say that any size pad using the 6" counterweight is the best, especially if you like the higher speeds or just plain speed 6. One thing I noticed though, was the remarkable increase in vibration when simply going from 5 to 6, where the vibration and noise level jumps sharply. Also, anything up to speed 4 was quite smooth running and easy to handle.
The only thing I regret is not having an actual Meguiar's W64DA 5" backing pad to compare it with. It's noticably thinner than a "normal" backing pad and I can't help but wonder if it's lighter. Anyone care to weigh theirs for me?
Sorry for the massive post, now I'm off to give my PC thread a minor edit...
I wanted to see for myself what kind of vibration or balance differences there were using different combinations of counterweights and backing pads. Some people with the Meguiar's W64DA backing pad had mentioned a significant decrease in vibrations when they swapped out their 5" weight for a 6" one. I wanted to see this and also try out a 6" pad/weight combo, which I had less info on.Thanks to 2wheelsx2
xyxthumbs) I had both his extra 6" counterweight as well as the 5" counterweight that came with the 7335 I had (patiently) ordered in. Because the unit already came with a 5" backing pad, I went out and bought a 6" backing pad (and another later on as well). This way I owned all the existing combinations of counterweights and backing pads used by most people here. The first thing I did was take some weight measurements:5" Counterweight: 1.75 oz / 50g
6" Counterweight: 2.00 oz / 58g
5" Porter Cable 13700 Backing Pad: 3.50 oz / 100g
6" Campbell Hausfeld Backing Pad: 3.85 oz / 110g
6" Craftsman Backing Pad: 3.50 oz / 100g
Meguiar's 6.5" W8006 Polishing Pad: 0.75 oz / 22g
Simoniz (Canada) 6" Buffing Pad: 0.85 oz / 24g
All weights were measured on a simple kitchen-grade scale and were verified a few times each. The absolute weights aren't as interesting as the relative weights. It's interesting to note that the larger Craftsman backing pad actually weighed the same as the smaller PC one. After a lot of debating it, I eventually returned this one and used the slightly heavier Campbell Hausfeld one for the test. While the Craftsman would've been good for actual use, it would've made for less revealing testing, as I couldn't imagine the 6" PC backing pad that comes with the 7336 being the same weight as their 5" one. Of course it should be remembered that the weights don't need to match the backing pad gram for gram when being exchanged because they're at different distances from the center of rotation. The counterweight weights were more out of curiousity than anything else.
While the pads don't seem to weigh very much, they make a fair amount of difference percentage-wise to the overall mass that the counterweights have to balance. So they do seem to matter, and this overturns the idea that the counterweight has to strictly match the backing pad. The Simoniz pad is found up here as an accessory to the Simoniz (Wen) cordless orbital sold at Canadian Tire. I was just curious if the weight is much different from the Meguiar's pads. They probably make for cheap, acceptable finishing pads and I used one for the test.
I did not test the obviously mismatching combination of 5" counterweight and 6" backing pad. I also had to afix a stick-on velcro adapter to these backing pads since they were originally PSA type pads. To do the test I gradually ran the PC from speeds 1 to 6 on the top of a large chest freezer with only QD sprayed on the surface and pad. Here are the combinations I tested:
5" counterweight / 5" backing pad (5/5)
6" counterweight / 5" backing pad (6/5)
6" counterweight / 6" backing pad (6/6)
Because I was changing pads/weights so much, and the test was very subjective to "feel", I ran each combo twice to make sure. The 5/5 combo gave the most vibration, especially at higher speeds. At speed 6 it was almost painful to hold the side handle because it was shaking so much. Up to about speed 4 it was "okay" though. The 6/5 combo was the smoothest overall, being relatively smooth up to 4 or 5, but still giving some vibration at 6. It was still quite a bit more well balanced than the 5/5 combo at this speed though. The 6/6 combo was pretty similar to the 6/5 combo, being very slightly rougher at higher speeds. I was almost expecting the balance to be worse than this, but am pleased it works okay.
Overall, I would say that any size pad using the 6" counterweight is the best, especially if you like the higher speeds or just plain speed 6. One thing I noticed though, was the remarkable increase in vibration when simply going from 5 to 6, where the vibration and noise level jumps sharply. Also, anything up to speed 4 was quite smooth running and easy to handle.
The only thing I regret is not having an actual Meguiar's W64DA 5" backing pad to compare it with. It's noticably thinner than a "normal" backing pad and I can't help but wonder if it's lighter. Anyone care to weigh theirs for me?
Sorry for the massive post, now I'm off to give my PC thread a minor edit...
