Flex 3401 Modified Backing Plate

XxBoostinxX

New member
Well, the other day I got tired of my 4 3/8 backing plate eating into my Hybrid pads. So I decided to sand it down for an exact fit backing plate. What I did is found a bolt to go through one side of the backing plate and tightened it down to the backing plate. Then i attached it to a drill and sanded on it while it spun. It wasn't really hard just tedious and time consuming. It took me about two days because I lost my patience on day one.


I forgot to take any before pictures, but overall I am pretty happy with it.
3c7be1edd14be4f6e539b145b01cf05f.jpg
71b8c4ecec24dc3889bf706e6d0121d0.jpg
a4c80efb40f54508f54e9af1bc35e1c8.jpg
b56e9dde8586e75076f2f1d70bc15bd8.jpg
9f5e982ff6beeb5c76924c8c0955bb6b.jpg
9b5d365e98705375b482749be4220c17.jpg
 
Pretty Please...no more naming of basic concepts


- Running your hand over a MF towel to feel for contaminants

- Decreasing pressure on the last polishing passes

- Wiping a car clean with a wet MF towel

- Extension on a polisher
 
I am a little confused....

Why would you trim down the 4 3/8 backing plate to fit the hybrids.

My understanding is that the Lake Country interchangeable backing plate system comes with a 4" bp which is a perfect fit for the Hybrid pads, and that the 4 3/8 bp is designed to be used with (for example) Lake Country 5.5" Hydrotechs....

I am assuming you don't have the LC BP system and therefore modified the 4 3/8 BP with be a substitute for the 4" BP supplied in the kit....?
 
Pretty Please...no more naming of basic concepts


- Running your hand over a MF towel to feel for contaminants

- Decreasing pressure on the last polishing passes

- Wiping a car clean with a wet MF towel

- Extension on a polisher

Point being? Too much to remember? Lol

I am a little confused....

Why would you trim down the 4 3/8 backing plate to fit the hybrids.

My understanding is that the Lake Country interchangeable backing plate system comes with a 4" bp which is a perfect fit for the Hybrid pads, and that the 4 3/8 bp is designed to be used with (for example) Lake Country 5.5" Hydrotechs....

I am assuming you don't have the LC BP system and therefore modified the 4 3/8 BP with be a substitute for the 4" BP supplied in the kit....?

I did it because the lake country backing plate system is known to fail. Sorry I wasn't very clear in the OP. I was going to buy the LC system, but the reviews are getting worse. It is known to crack due to the excessive amount of heat that the 3401 generates. Some are even saying it fails on their first polish job and 3-4 hours of use. So I didn't want to spend $40 on something that is known to fail. Plus I have a ton of Hybrid pads, but fear of destroying them when it was larger. It would eat into the back side of the foam and slowly destroy the pad.
 
I did it because the lake country backing plate system is known to fail. Sorry I wasn't very clear in the OP. I was going to buy the LC system, but the reviews are getting worse. It is known to crack due to the excessive amount of heat that the 3401 generates. Some are even saying it fails on their first polish job and 3-4 hours of use. So I didn't want to spend $40 on something that is known to fail. Plus I have a ton of Hybrid pads, but fear of destroying them when it was larger. It would eat into the back side of the foam and slowly destroy the pad.

Thanks for the clarity...

I have the BP system and seems to be holding up fine (touches wood) after a fair amount of use - at least if it does fail we now have a 'plan B', so thanks for sharing your 'modding tip'. Much appreciated.
 
Thanks for the clarity...

I have the BP system and seems to be holding up fine (touches wood) after a fair amount of use - at least if it does fail we now have a 'plan B', so thanks for sharing your 'modding tip'. Much appreciated.

Anytime . Glad to hear yours is holding up.

I shouldn't get all the credit. I stole the idea from Kevin Brown. He is always selling sanded exact fit backing plates.
 
Very cool. Thanks for sharing.

Hopefully one day Flex or LC will make a one piece 4" plate for this machine.
 
This is a really neat idea. Now that it's been 6 months, how do you like using the smaller OEM bp?

Also, what did you use to sand it down with? Did you simply hold a piece of sand paper in your hand while the BP was turning on the drill? I've thought about doing this, but on a lathe.

TIA!
 
This is a really neat idea. Now that it's been 6 months, how do you like using the smaller OEM bp?

Also, what did you use to sand it down with? Did you simply hold a piece of sand paper in your hand while the BP was turning on the drill? I've thought about doing this, but on a lathe.

TIA!
I love the smaller BP, but to be honest I have only used it a handful of times. I just don't use my Flex much since owning my 21es.

If you look at the cut down BP you will notice how it now has slots in the sides. I was really afraid it would affect its stability, but it hasn't changed any that I have noticed.

Yes, I just used sandpaper and held it with my hand while it was spinning. Actually stole the idea from Kevin Brown ;) . If you do it with the sandpaper prepare for it to get dusty and definitely wear gloves. It can get a little hot.
 
Great mod brother! This will be my next step(and I thank you for this write-up) if my LC fails me again lol. Decided to give another go
 
I love the smaller BP, but to be honest I have only used it a handful of times. I just don't use my Flex much since owning my 21es.

If you look at the cut down BP you will notice how it now has slots in the sides. I was really afraid it would affect its stability, but it hasn't changed any that I have noticed.

Yes, I just used sandpaper and held it with my hand while it was spinning. Actually stole the idea from Kevin Brown ;) . If you do it with the sandpaper prepare for it to get dusty and definitely wear gloves. It can get a little hot.

Sweet! Thanks for the info and tips. Is there any reason you didn't use a sanding block w/ the sandpaper vs holding the paper directly? Just curious if there's pros/cons of doing so.

This is a great hack since I don't have the budget for a new machine but would like to use the hybrid pads over my current CCS ones.

Thanks again man!
 
Great mod brother! This will be my next step(and I thank you for this write-up) if my LC fails me again lol. Decided to give another go
Thank you for the kind words! Anytime bud. I hope it works out for you this go around.

Sweet! Thanks for the info and tips. Is there any reason you didn't use a sanding block w/ the sandpaper vs holding the paper directly? Just curious if there's pros/cons of doing so.

This is a great hack since I don't have the budget for a new machine but would like to use the hybrid pads over my current CCS ones.

Thanks again man!
Funny you say that. I actually started off with a drywall sanding block I had lying around and it eventually cut into the block. Once I wore out all the sides that's when I swapped to sandpaper. I mainly was just trying to do it with what I had available at the time without spending any extra money.

No problem bud. Good luck!
 
I might do this with the stock standard BP for 6.5" pads,sand it down so that it covers more of my 5.5" of pad's .The 4 3/8 bp causes my pads to "mushroom" up.
 
I might do this with the stock standard BP for 6.5" pads,sand it down so that it covers more of my 5.5" of pad's .The 4 3/8 bp causes my pads to "mushroom" up.
The problem I had with the 4 3/8 BP is it started to cut into the foam of my hybrid pads. Nothing more I hate than ruining brand new pads.
 
oh no.

I somewhat recently picked up a 3401, along with the LC 4" bp. Haven`t tried the LC plate yet. But does anyone know if they are still failing like before?
 
oh no.

I somewhat recently picked up a 3401, along with the LC 4" bp. Haven`t tried the LC plate yet. But does anyone know if they are still failing like before?

I`ve had my 4 inch Lake Country interchangeable backing plate for about 8-9 months now. I use the polisher all the time, I have had no problems with it. I am always careful with the backing plate anyways.

I never go above speed setting 5 (you really don`t need to go any higher than that anyways), and I don`t use all of my weight on the polisher. I let the weight of the polisher do most of the work.
 
I`ve had my 4 inch Lake Country interchangeable backing plate for about 8-9 months now. I use the polisher all the time, I have had no problems with it. I am always careful with the backing plate anyways.

I never go above speed setting 5 (you really don`t need to go any higher than that anyways), and I don`t use all of my weight on the polisher. I let the weight of the polisher do most of the work.

Awesome! Thank you, Jesse. - I don`t like maxin` out ANY tool, and do my correction at speed 5 usually. Thanks man
 
Do you think that if enough detailers with a 3401 want or need a 4" (100mm) diameter backing plate designed specifically for the 3401 that Flex would actually manufacture such a backing plate???
 
Back
Top