Quad bearing upgrade for the DX7 gimbals by G-Force

[fireup]

Nope, the X9303 don't have bearings but also has a different construction so changing them out will be harder. I won't be changing them out anytime soon as it looks a lot more involve than the DX7. Also I don't think changing them out to bearings on the X9303 will make that much of a different. It use a better quality pot. than the DX7 but also use the pot. as one of the bearing joint. There's also a metal shaft that ride on the bronze bushing with grease. This will differently last a lot longer than the plastic on bronze bushing on the DX7.

[kingiggy262]

Heys guys I found these bearing that are 4x7x2 but they are only $3 a piece instead of $7.

http://www.allerc.com/product_info.php?cPath=6&products_id=443

I'm thinking something as high quality as the ABEC bearings aren't really needed for this since they won't be under tons of stress.

[Finless]

Nice idea and NICE mod!!!!

Thanks for sharing!

Bob

[Gino CP]

This is an interesting mod. However, I try so hard to detect any slop in my tx and couldn't find any. Honestly I don't know what I am missing. But I like the idea of bearings since they seem like a long term investment so to speak. I like my DX7 to be good as new for a long time.

[WillJames]

Cool mod!! Yea Baby!!

Thanks for sharing Garf!!

[flyboy320]

Another great mod is replacing the voltage regulator in the DX6/DX7 with a more efficient one.

http://www.dimensionengineering.com/appnotes/spektrum_mod/spektrum_mod.htm

Not to hard to do, and greatly improves run time of the TX.

[fogger]

personally I found that just using a 3s lipo solves that problem, and one is much less likely to screw up the radio board this way... Plenty of posts of people screwing up the solder pads while de-soldering the original regulator.

I did that dim-eng mod to my dx6, but on the dx7 I just put in a 3s hyperion pack. It fits like a glove and lasts for weeks.

-Fog

[jrohland]

Hobby Lobby has part number RCRS1133 (http://www.hobby-lobby.com/dragonus-parts2.htm) which is two 4x7x2 bearings for $4.10 (US). They are currently in stock. They do ship to Canada.

Currently it is the 3rd item down on the page the link takes you to.

jrohland

[crabfu]

Thanks Garf for this mod! I just did it, and it's pretty darn cool. I got the bearings here for 3 bucks a piece:

https://www.gravesrc.com/ProductDetails.asp?ProductCode=GWSEPSC-24AC

It was much more involved than it looks, lots to take apart to get to the bearings. On hind sight, I should have taken detail pics for you guys of each step, but I didn't quite know what I was doing, so took my time figuring it out as I went, and didn't think it was worth taking pics at the time.... and no, I am not gonna take it apart ever again :) Actually it's not as bad as it sounds, there are a lot of things to be careful of, like Garf said there are many wires, and I was afraid of not putting things back in the right order. It took me a bit longer to do this upgrade than garf, but not by a heck of a lot. And no, M4x7x2.5mm will not work, it has to be M4x7x2, just by looking at it there is no way 2.5 will fit in there.

Anyway, at my level this mod won't make me any better. I keep hoping for a mod that is magically going to turn me into a sazbo or something, I'm still waiting for that mod. But I did notice that the sticks do move much smoother, and I had to tighten up the gimbals after the mod, it was just way too smooth and felt like it was slipping off my fingers. The throttle stick felt especially good and smooth :) I've only tested it on the sim so far, and will see how it goes out in the field tomorrow.

Overall, it's a real pain to do, and takes a lot of nerves, careful thinking, and time. But in the end I am very happy to have done it to my dx7, maybe tomorrow I will fly like sazbo.... just maybe....

Thanks again Garf

-Crabfu

[crabfu]

ok tried it out on the field today, and had the best flights that I've ever had (which isn't saying much lol). Not sure how much of it was the dx7 bearing mod, since I did do a lot of tweaking with my trex.... but I just felt in total control.... felt so good that I attempted my first tic tocs, successfully!

Thanks again for sharing this Garf!

-Crabfu

[OICU812]

So on the DX7 you need (4) of these ball bearings to do the upgrade, correct?

[kamtsa]

Bearing part numbers would be nice

GWS EPSC-2A4C (4x7x2mm).

Kam

[crabfu]

So on the DX7 you need (4) of these ball bearings to do the upgrade, correct?

Yes, you need 4, one for each axis.

-Crabfu

[4cyclic]

Hobby Lobby has part number RCRS1133 (http://www.hobby-lobby.com/dragonus-parts2.htm) which is two 4x7x2 bearings for $4.10 (US). They are currently in stock. They do ship to Canada.

Currently it is the 3rd item down on the page the link takes you to.

jrohland

These RCRS1133 bearings are 4x7x2.5mm, so they are incorrectly labeled by HL. I just got them and they don't fit .

[4cyclic]

While waiting for GWS 4x7x2mm bearings, I've put in a very small amount of Triflow oil on the 4 bushings to see if it improves the feel, and it does a bit.

As I was not happy with the throttle gimbal movement smoothness , also took the spring plate on the throttle gimbal and used a small file to remove all the teeth off the plastic ratchet part. I then used 600 grit sandpaper to smooth the surface and dabbed a bit of grease on the surface before re-assembly. That throttle/pitch gimbal is now much smoother.

[kamtsa]

I did the mod today on the cyclic (right hand) gimble. It requires a lot of patient and similar to others, it was move involved than I expected. Attached are few pics. First step (after removing the battery, removing the back cover, etc) is to remove the gimble. This is done by releasing the 4 screws on its four corners (there are several screws on each corner, make sure to remove the ones that are closest to each corner respectivly). Then you pull the gimble from the inside and can start working on it. I did not have to remove the RF or any other board to remove the gimble. Howerver, I had to cut the wire tie that holds the wires together.

In general, the potentiometers lock the two axis so you need to remove them (remember the position of each potentiometer so you insert them back correctly). The main locking mechanism in the gimble is a small strap of metal with two screws. The are used to lock the potentiometers, bearings and bushings. You will need to remove them. Also, one of the potentiometers is attached to a printed circuit board that is attached with two screws to the gimble. You will need to remove these screws so you cam remove the potentiometer (with its PCB). Keep digging in until you release the inner bushing. Be careful about all the wires, they are important ;-). Also, use proper static control to avoid ESD damage to the electronics.

Replacing the bushings with the bearings clearly reduce the friction. However, after you put the potentiometers back in, it seems that the inner friction of the potentiometers dominate the friction of the bushing and bearings so I am not sure that overall there is a significant reduction in friction (better flyers than me may notice the difference and/or the improvement).

After you put everything back in, make sure to test your TX thoroughly before try to fly anything.

Kam

[kingiggy262]

I just did this mod and I can definitely notice an improvement over the brass bushings! The sticks are really smooth now compared to before and I didn't notice the internal resistance from the potentiometers on my setup. Overall I am very satisfied with this improvement and would suggest it to anyone else.

This was actually easier than I expected after reading previous post and preparing myself. I didn't cut any tie wraps or remove any control boards to get the gimbals out. I just worked slowly and steady and eventually I was able to get to the bushings that I needed to replace. I added some tri-flow lube to the new bearings and the ones that are already on the gimbals. I then finished with adding some white lithium grease to the slider on the throttle gimbal to make it nice and smooth.

Just one word of caution when doing these is to make sure you do not put a lot of force on the clips when you separate the housing that has the little white tick marks on it because they will break if you force them too hard.

Thank you everyone who contributed to this mod with the helpful descriptions and pictures!

I paid $12 for 4 of these bearings from this website: http://www.allerc.com/product_info.p...roducts_id=443 (http://www.allerc.com/product_info.php?cPath=6&products_id=443)

[flyboy320]

Just one word of caution when doing these is to make sure you do not put a lot of force on the clips when you separate the housing that has the little white tick marks on it because they will break if you force them too hard.


Quite right. Don't ask me how I know this! The one clip I did break did not break right off, just broke about 1/2 way through the clip, but enough so that it no longer held together. I had to use some glue to hold the two parts together, but it did work, and all is good now.

Just be careful.

[kamtsa]

Quite right. Don't ask me how I know this! The one clip I did break did not break right off, just broke about 1/2 way through the clip, but enough so that it no longer held together. I had to use some glue to hold the two parts together, but it did work, and all is good now.

The TX enclosure holds it well in place even if you don't glue it.

I just know it ;-)

Kam

[kingiggy262]

Quite right. Don't ask me how I know this! The one clip I did break did not break right off, just broke about 1/2 way through the clip, but enough so that it no longer held together. I had to use some glue to hold the two parts together, but it did work, and all is good now.

The TX enclosure holds it well in place even if you don't glue it.

I just know it ;-)

Kam

Glad to know that I wasn't the only one that made this mistake! :lol:

[duceduc]

I, too, did the mod and noticed a difference with the gimbols.

Tips: Take your time and don't rush. Be carefully when you pop open the plastic clip that holds the gimbol and gimbol case.

[HeliSmith]

Oh great now I am going to take apart my DX7.. lol

[rotorhead58d]

screw that! no way in hell am i touching anything except for the adjusting screws!

[duceduc]

Here are some random pictures of what I did. Scroll down to DX7 bearing gimbol mod.
Dx7 Gimbol Mod (http://runryder.com/helicopter/gallery/31554/)

[sgrim80]

Confused! All the pics and directions say you need (4) M4x7x2 bearings to do this mod. I only ever see a pic that has a bushing and a bigger bearing in it. You replace the larger bearing with a smaller one? Obviously you replace the bushing but the way the pics show it you would only need 2 bearings. Whats the deal?