Another Flex 3401 vs Rupes 21 Comparison

[SonOfOC]

Lots of comments and views lately in regards to the Flex 3401 and Rupes 21 polisher. Besides the obvious force rotation and large throw, I wanted to add some information that may be useful for those who are on the fence and can’t decide between the two.

Along with owning (3) traditional Da and (3) rotaries, this would be my second Flex 3401 and my second Rupes, the other being the 15 model. I’m a tool junkie and like buying and trying anything that can make my job faster and easier. Okay lets go!

Size and Weight: Rupes is a little longer, the Flex is a little heavier. What I’ve noticed is the handle on the Rupes is more comfortable and causes less fatigue.




Smoothness and Sound: Flex is a little louder. Rupes a little smoother. This measurement is just a free spin speed 6. The noise changes drastically when machines are actually be used on a car. In my opinion, both are night and day compared the PC or Griots DA. The Flex has a deeper gear sounding buzz and the Rupes has a higher pitch whining sound. Makes sense as the Flex 3401 is forced gear driven and the Rupes is free spindle.



Build quality: The Flex is built like a Brink’s truck. Rupes build quality is not poor, but definitely lacking when held and used next to the Flex. Rupes plastic is not as solid and some pieces like the hand placement are loose.



Trigger and Speed control: Flex is better. Flex trigger is continuously variable and the Rupes is either “on” or “off”. Not a deal breaker, but it’s nice to have a variable trigger. The Flex’s speed dial also has more precise action and less play. The Flex trigger lock is easier to engage. I’ve had a difficult time engaging the lock on both my Rupes. It’s a little tricky, requiring some thought otherwise it wouldn’t catch.



Power cable, strain relief, and screws: Flex is better. These are small items, but on premium machines like these some may want to know. The Rupes power cable is of lesser quality and stiffer than the Flex. The strain relief is also of lesser quality as are the screws used to assemble the case. (If I have time I will tear down each unit to see if this trend continues with the internals) The Flex has better build quality and in my opinion can take more abuse. I’ve already cracked the Rupes hand placement piece.



Performance: Both machines are beast of polisher! I can’t really say one corrects faster than the other. I’ve never had the Flex “walk” on me. If you tilt the Flex, it wants to move to one side. It’s an easy hand adjustment by flattening out the polisher and you’re back smooth sailing. The Flex doesn’t “have a mind of its’ own”, all errors come from the user. With the Rupes, I’ve never had the pad stop on curve panels. It would slow, but never stop rotating. Again, any rotational discontent with the Rupes is from technique and not the fault of the machine. What stands out to me is the controllability of the machines. The Rupes is willing to change direction far easier than the Flex.

Conclusion: I love both machines! The Rupes is a great machine, but far from perfect. It is not the game changer-best thing next to slice bread machine that many portray it to be. On balance, both are virtually equal in cutting and finishing ability. The Rupes is a monster with a MF pad, but so is the Flex with a short wool pad. The Rupes with the MF will finish a little nicer, but most of time you’ll still need another step to finish. Unlike many, I do not plan to shelve or sell either my Flex 3401 or Rupes. They are both that good! If you are doing tons of 1 step corrections or production work; then the Flex 3401 is a more suited tool. It is more robust then the Rupes and will not slow down anywhere on the car. If you have limited experience, never used a rotary, and are familiar with the user friendly traditional DA; then the Rupes will fit the bill. It easier to control and requires less effort.

So what about the 21 vs the 15? If I were pick only one, it would be the Rupes 15. 15mm of throw is more than plenty. The 15 is tad smoother and already comes with the 5” backing plate and cost $50.00 less than the 21 model. Happy polishing and remember that your tool arsenal can never be big enough!

[JHL88]

great review. Definately a lot to consider if deciding between these 2. I have a 3401 & a g110v2 and i could see myself selling my v2 for a rupes 21. That big throw on my big demolded/debadged silverado body panels would be great...

[b0b]

Great review. I have been searching this exact topic lately. I own a flex and love it, but want a secondary tool for the smaller places without having to switch BP.

Sent from my SAMSUNG-SGH-I337 using Tapatalk 2

[Mike@DedicatedPerfection]

Very nice review. Thank you for putting this together to help people understand more about each machine rather than just a which is better type of review.

[90sedan]

Very nice review, thanks.

[JHL88]

Great review. I have been searching this exact topic lately. I own a flex and love it, but want a secondary tool for the smaller places without having to switch BP.

Sent from my SAMSUNG-SGH-I337 using Tapatalk 2

Have you thought about the smaller 3in GG? Im still considering that one because it's alot smaller than a regular size DA with a 4inch pad.

[Detailing by M]

Nice review, thanks for doing this.

In my opinion the Rupes is way better.
I used a Flex for 6 months or so and I didn't like it at all
To heavy, spins the wrong way and was just a little better then my G110.

Now that I have my Rupes I love it a lot.
Light.
Quiet, I can talk to my customers as I work.
My work area has doubled in size, So I'm done faster.
Spins the right way
Use less product and way better results then my Flex ever did.

Now I don't hate the Flex, it's a good machine but the Rupes is out performing everything out there. That's not just my opinion but a lot of other great detailers say the same thing.

[rmagnus]

Lots of comments and views lately in regards to the Flex 3401 and Rupes 21 polisher. Besides the obvious force rotation and large throw, I wanted to add some information that may be useful for those who are on the fence and can’t decide between the two.

Nice review with a little different perspective, thanks.

Have you thought about the smaller 3in GG? Im still considering that one because it's alot smaller than a regular size DA with a 4inch pad.

Consider the GGv3 and put a smaller backing plate on it. It will be much more effective. Price difference isn't that big but the difference in power will be.

[psnt1ol]

I been using the Flex 3401 for a while and I just received my Rupes 21 recently. The comparison is on the nose. I am replacing the 6" backing plate with a 5" as well as doing the washer mod this weekend to see if there are any significant differences.

[Bunky]

I have a Flex and Rupes 15 and agree completely with the build comparisons. I do like the top mounted speed control on the Rupes but definitely not as precise as the Flex. The polisher is one aspect of the process so the selection may include variables like having a stock of pads and polishes. I think a lot depends on what you used in the past so some certain styles will lean toward one type or another but do not think one say one turns the wrong way. It may be different.