Tutorial: Replacing Center Hub

[SYMAWD]

This is a tutorial on how to replace the center hub on the Blade SR. Because my Jesus bolt was stripped, I also replaced my main shaft. This took me about 35 minutes and that includes taking the photos. Enjoy!

Step 1: Remove blades and canopy.

Step 2: Remove all ball links except for the two attached to where the mixer arm screws into the grip (refer to picture)


Step 3:Remove main gear.

Step 4: Pull head assembly out of the main frame.

Step 5: Remove main shaft collar and swash plate.

Step 6: Remove all weights and paddle from one side of your fly bar.

Step 7: Loosen set screws on the fly bar cage.

Step 8: Slide out fly bar and the cage will fall with it.

Step 9: Remove top screw and the plastic spacer underneath it.

Step 10: Slide off the rotor head.

Step 11: Remove one screw from the feathering shaft and slide one grip off.

Step 12: Push the exposed feathering shaft through the center hub along with the other blade grip.

Step 13: Remove head dampeners from center hub.

Step 14: This is what you should be left with.

Step 15: Take a new main shaft and center hub.

Step 16: slide center hub onto the main shaft and install jesus bolt. Make sure that the flat spot on the main shaft is closer to the top than the bottom. Also there is a wrong way to put the Jesus bolt in. One end of the center hub has threads and the other doesn't. Make sure you start on the non threaded side first so that the threads on the bolt line up with the threads on the center hub.

Step 17: Reinstall feathering shaft.

Step 18: Slide the rotor head back on.

Step 19: Reinstall the fly bar and fly bar cage.

Step 20: Reinstall weights and paddle to the fly bar.

Step 21: Reinstall plastic spacer and top screw into the center hub.

Step 22: Reinstall swash plate and main shaft collar. Then reattach as many ball links as possible.

Step 23: Slide head assembly back into the frame.

Step 24: Reinstall main gear:

Step 25: Reattach servo linkages to the swash plate.

Step 26: Reinstall blades.

[SeanM]

Nice write up! However, this is not the easiest way to replace the center hub. You can replace it without going as far as you did. I would have only removed the linkage that connects to the swash so that I would be able to remove only the center hub/grips/flybar.

[SYMAWD]

I had to do it this way because my Jesus bolt was stripped. I had to replace the main shaft.

[BrandonB]

Good step by step for people rebuilding hub and main shaft combined!
One thing I don't get is why you choose to replace your main shaft. Did your Jesus bolt bend in the main shaft, leaving a raised edge on the shaft? The only part that can strip is the plastic on center hub, as it is all the Jesus bolt threads into.

[SYMAWD]

The Jesus bolt itself stripped. I couldn't unscrew it, the head of the screw was stripped. None of my allen wrenches could grip it. I couldn't even get the bolt to spin.

[BrandonB]

Well, that definatly sounds like a reason to swap out the whole assembly
Its important that the bolt isn't started backwards in the center hub. There is a right and wrong way to install the Jesus bolt into the center hub as one of the holes is slightly smaller than the other (for threads to catch). It only takes one time to mess up the small hole by installing the bolt incorrectly. This is the only thing that I would suggest that you append to your tutorial. Hint hint.

[SYMAWD]

I did realize that on the hub one hole had threads at the end and one didn't. I'll add that note to step 16.

[DKS_ONE]

I don't think the one hole has threads until you put the bolt through it. If you have the hub off and put the bolt into the holes, it will slide right through one but not the other. When you put the bolt in I do believe it makes it's own threads. I could be wrong but I thought that's what it looked like the last time I did one. Either way, that bolt definitely goes in one way only. If you start out threading it in, stop right away and use the other side.

[SYMAWD]

DKS: the threads are already there, I checked before I put the screw in. They are not self tapping.

[Elios000]

when i did this a few weeks ago the new center hubs hole for the Jesus bolt was miss aligned and it took some forcing to get it thread in

WTB CnC centerhub pst

[DKS_ONE]

Originally Posted by SYMAWD

DKS: the threads are already there, I checked before I put the screw in. They are not self tapping.

I stand corrected

[DKS_ONE]

Originally Posted by Elios000

when i did this a few weeks ago the new center hubs hole for the Jesus bolt was miss aligned and it took some forcing to get it thread in

WTB CnC centerhub pst

That happens to me every time I replace a hub (happens more often than I'd like it to). I have to put some major pressure on that sucker before I can get it to start. I wonder if that's why most of 'em wobble...

[SYMAWD]

DKS: I needed major pressure to get it through, but mine was wobble free. It went through the main shaft fine without the hub on and through the hub fine w/o the main shaft, it was when it was together that I had trouble getting it through.

[SYMAWD]

BTW: The head dampeners are the originals. Still looking pretty good after 36 batteries.

[BrandonB]

I've had the problem with the Jesus bolt having a hard time lining up and starting, and everytime, its been because I reused the bolt and there was a slight bend in it.

[SYMAWD]

I used a new Jesus Bolt

[BrandonB]

Just speculating here, but there could have been some flashing left from the mold which forms the nylon hub inside of the hole where the main shaft sits, this would prevent a good seat and the hole on the main shaft wouldn't line up with the holes on the hub.
Don't over tighten the Jesus bolt. A deformed hub is a wobbly hub.

[Elios000]

wasnt that becouse the bolt when in to the hub fine OFF the main shaft and same with bolt fitting in the hole in the main shaft
but when you try with hub on the shaft the threaded side of the hub is slightly higher then the other side

[BrandonB]

Originally Posted by BrandonB

...there could have been some flashing left from the mold which forms the nylon hub inside of the hole where the main shaft sits, this would prevent a good seat and the hole on the main shaft wouldn't line up with the holes on the hub.

If there was extra plastic left over from the manufacturing process, you would be able to stick the bolt in fine with the hub off the shaft, same for the shaft by itself, but the two combined wouldn't work well because the holes wouldn't line up. Look inside the hub where the mainshaft sits and check for obstructions.

[DKS_ONE]

Every time I change a hub I use a new bolt and every time I have a hard time getting the bolt through both the main shaft and the hub when they're together. Separately I can get the bolt through the hub no sweat, but together they never work. I have had this with new hubs on used main shafts and new hubs with new main shafts.