LC Flex 3401 Interchangable Backing Plate Assembly Instructions

Since questions seem to come up quite a bit regarding this system, I decided to put together a quick guide on the proper assembly order of the components in the LC/FLEX 3401 Interchangeable Backing Plate System. This guide specifically shows the user where to install the shims when using the 6" backing plate with the system.

Step 1.
After you have removed the factory supplied backing plate from your 3401, you are ready to begin installing the LC Interchangeable Backing Plate System. Your Flex should look like this:
IMG_0456.JPG



Step 2.
Install the LC drive plate adapter onto your Flex ensuring that the slow fits snugly over the raised portion of the spindle. Your Flex will now look like this:
IMG_0457.JPG



Step 3.
Place the thin shims in the center of the drive plate adapter. This is how your Flex should look at this point:
IMG_0458.JPG



Step 4.
Place the 6" backing plate onto the drive plate adapter ensuring that you have aligned the tabs from the backing plate into the slots in the adapter plate. There should be no gap between the two plates. Now your Flex looks like this:
IMG_0459.JPG



Step 5.
Place the washer (some are calling this a thick shim) in the center of the backing plate. You're almost done and this is what you should see:
IMG_04601.JPG



Step 6.
Insert the socket-head cap screw through the entire assembly, thread the bolt into the spindle, and tighten. You have now completed the assembly of the LC Interchangeable Backing Plate System. Here is a picture of the finished assembly:
IMG_04614.JPG
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I hope this helps clear up some of the confusion regarding how to properly install this backing plate system on the FLEX 3401.

not really what do you do with the shims when you want to use the four inch plate?
 
Whoa! Thanks for taking the time to do this, but this is NOT rocket science.

its not but they give you no directions with this kit. they dont tell you where the two shims go. what are you supposed to do guess?
 
First, let me thank you 02xtreme07SS for putting this together it's very helpful!


That's true but the issue here is that there aren't a set of definitive instructions that show the exact installation method. This could possibly be the reason that some people report failure with this system.

For instance if you view the video from the store's site (also linked in the instructions above posted by 02xtreme07SS) - FLEX XC3401 Changeable Backing Plate System it does not even show the 2 thin shims at all used with either backing plate.

On the bag that the backing plate system comes in it states - "screw, washer & 2 shims for 6" plate". It does not however mention where the 2 shims should go. I didn't know this before looking at these instructions from 02xtreme07SS.

02xtreme07SS doesn't show instructions for the 4" backing plate but the video does show, what seems to be, the original washer and screw being used. This would seem correct and does match what the bag states but again it's not very clear with the instruction.

I think it is humorous that there is a process laid out for nearly everything but skinning a gnat here and one can't find any definitive info to utilize this backing plate system as designed.

its a joke and it hasn't been fixed three years later. i just got it and still dont know what to do with the shims when using the four inch plate
 
The shims were not included in earlier shipments. LC identified some instances where there was shrinkage in plastic on some of the 6" backing plates in the area where the bolt passes through the backing plate and into the adapter. This could potentially cause a gap between the plates in this area and when the bolt is tightened. This would create undue stress on the backing plate at this critical attachment point. The shims fill that gap and create a solid connection through the bolted area. My first LC system didn't have the shims and it has never exhibited and signs of failure.

The 4" backing plates did not have any of the same signs of shrinkage in the plastics like the 6" plates and as should not require the use of the shims. The shims are only required if there is a gap in the attachment area between the 6" backing plate and the drive plate adapter.

As far as I know, there were no reports of widespread problems without the shims, but this is a clear example of LC stepping up and supporting their products.

yeah but they could at least put a paper in the bag to let you know, how many man hours have been wasted trying to find this information in the middle of a detail.....
 
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