The TRUTH About Choosing a DA Backing Plate

When i was at Todds house he explained how the flex worked by grabbing a phone jack with a wire attached and spinning it around in the air.I read all the write up's but when someone takes a something laying around and explains something i find that more helpfull sorry i'm a hands on guy also.And thats how i train the guys in my shop also.books can only get you so far need to see it in person.Thanks Todd
 
Junebug said:
First - Great job Todd! Secondly, question for you - 6.5" pads on a PCXP - I started my detailing back with a PC and 6.5" LC pads, after switching to 5.5" and 4", I considered 6.5" too big. So, would the new Cyan/Tangerine pads be the exception? is an upgrade to 6" BP required for best performance?
Thanks!
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Hey James, as you may have noticed, we now carry the Hi-Gloss pads in 5.5 inch and the Hydro pads (Cyan/Tangerine) in 5.5 and 4 inch. Using a smaller diameter pad has many advantages when using a dual-action polisher, although I think these advantages are exaggerated when using too small of a backing plate on a 6.5 inch pad.

When you use a smaller backing plate, you are limiting the amount of the pad that can actually do work, while creating a thick ring of 'dead' foam that prevents polishing tight spots.

Switching to a 6 inch backing plate on a PC with a 6.5 inch pad may shock you at how much better the combo performs, because a lot more of the action of the machine can be transfered through the pad to the paint. However a 5.5 inch pad will still offer more power, you might be surprised by how much the gap shrinks.

The same can be done with the 5.5 inch and 4 inch pads. Polish an area with 5.5 inch pad with the correct, 5 inch, backing plate and it works awesome. Switch to a 3.5 inch backing plate and you will lose a lot of performance.

Kevin Brown tells me to take these to the extreme when proving a theory. If backing plate size doesn't make a difference, then we should all use 3.5 inch backing plates with 6.5 inch pads for the ultimate in safety. If performance is compromised (it is and greatly) then you can bet that using a 5 inch backing plate results in compromised performance as well. Every step smaller then ideal will result in some loss of performance, it is just a matter of finding the linear equation that ties it all together.

So to answer you question (finally) we always recommend using the correct sized backing plate for your application, and no pad is the exception (unless it is a standard pad and requires too small of a backing plate for safety).

swirlhider said:
how does the backing plate size affect the clutch life of pc?
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As noted in Kevin Brown's diagrams there are no clutches or anything that could be considered a clutch (diagramph or centrifical) in a Porter Cable. Physics spin the pad on a random orbital.

bigpoppa said:
Nice write up Todd!

I am guilty of using smaller backing plates with larger pads, sometimes when I have been polishing for hours I am too lazy to change out the backing plate on the PC!
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Thanks BP.

You will likely save time by switching to the appropriate sized backing plate by increasing the results, but I totally feel you. Sometimes it is very difficult to make that 30 second backing plate swap because it can be such a pain!!!

Harleyguy said:
When i was at Todds house he explained how the flex worked by grabbing a phone jack with a wire attached and spinning it around in the air.I read all the write up's but when someone takes a something laying around and explains something i find that more helpfull sorry i'm a hands on guy also.And thats how i train the guys in my shop also.books can only get you so far need to see it in person.Thanks Todd
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Thanks Adam!!!

Also thank you to everybody for your very kind words!!!
 
Been lurking on here for awhile now. Had to say mad props Todd. I love the diagrams and Although I'm a huge rotary buff still after reading this I have a much better understanding on the D/A. Your write up makes a LOT of sense to me. And considering I'm about to make a pad restock purchase I know what I need to be looking for now.. Again thanks man you're a ton of help.

-Jake
 
Good man Jake, I'm looking forward to making a nice order with PAC for some 5.5 and 4'' pads, along with a couple backing plates.

Short note - I had used the same backing plate on my PC for several years and thought it was fine, after getting a PCXP and pulling my spare backing plate out of the cabinent, I was amazed at how much more grip it had - I checked with the same pads on the other one! Just something to think about and Christmas is right around the corner.
 
Thanks for the write up Todd. I have PC 7424xp and I now have some good info to get me going in the right direction!:thumbup:
 
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