Spur Gear Jesus Bolt

[Area51]

Finishing up my E7 build and have noticed up and down play in the main/spur gear assembly as well as radial play between the mainshaft and these same gears. If I hold the main gear, I can grab the main shaft and rotate it slightly each direction feeling slop between it and where the spur gear hub Jesus bolt passes through.

Has anybody had the M3x25 shouldered Jesus bolt come a little undersize at the shoulder or get a soft bolt and have the shouldered area wear down from inserting and removing it over and over? Trying to get a different shouldered bolt to try. I hope it's not the bottom hole in the main shaft being over-sized...

Thanks.

[stevehof]

I have experienced the same issue. I think it is the main shaft. I put a new main shaft in and the slop was gone. However, 20 flights later their is a little slop starting to show up again.  The ship had well over 100 flights on the original mainshaft. The shafts are hollow and maybe just a little too soft and the current tolerance between bolt and hole a bit too large. Since there is no clamping action here the bolt can "beat" the hole until the hole is oversize.  Of course, this just my guess at what is going on... l am going to shim the space between the gear hub and top Jesus bolt collar to limit vertical gear hub play to a few thousands of an inch next time I pull the main shaft. A couple of 10mm washers and a few 10 mm bearing shims should do the trick. I am not too concerned with radial play.

[GAR]

Yep, I know the problem, it's not the screw/bolt.

I have tried 10mm shims in the TT main gear hub, and it helps. But it leads to some other problems that you need to double check.

I have tried two different main shafts and two different one way sleeves; the holes are oversized allowing this up/down movement on NEW parts.

There is a cure. 

First the test.....Remove the four 3mm screw holding the third (bottom) main shaft support bearing. Now push the support upward. Did that remove any up/down movement of the one way bearing sleeve?

If so... Slightly enlarge the four holes in the side frames for the bottom main shaft bearing support; enlarge the holes so the support can be adjusted upward to remove some (if not all) of the up/down movement.
I suggest installing washers on those four screws even if you do not enlarge the holes.

Another trick; Place the belt drive 10mm main shaft washer between the OWB sleeve and bottom support bearing. Are use a 10mm main shaft shims from an Align 550. The shims are a pain to install and not adjustable.

Also...there could be canting movement in the one way bearing sleeve because of sizing difference of "sleeve to main shaft". What works for me is to make sure the Boss on the pinion will not come in contact with the main gear because of helical climb by using 6mm shims between pinion and support bearing if needed. 

[Area51]

stevehof and GAR,

Thanks so much for responding to my questions. While I'm disappointed that we are having these same problems, I'm glad that thre are solutions. I'll try a little shimming until I can get a new main shaft in my hands. It's a shame that the hole in the m/s is a little oversized to begin with and prone to opening up more with regular use.

I'm pretty new to the Synergy forum and was wondering, do you know if Matt has addressed this issue before? Kind of a bummer that I have to try/buy different main shafts after purchasing a brand new kit to find one with a tolerance closer to that of the bolt.

[stevehof]

I'm pretty new to the Synergy forum and was wondering, do you know if Matt has addressed this issue before? Kind of a bummer that I have to try/buy different main shafts after purchasing a brand new kit to find one with a tolerance closer to that of the bolt.

It's hard to tell if this is a wide spread issue or just a few main shafts that got through production with oversized holes. I flew again today and I may have to retract my comment that new shaft was developing play. It has only the slightest up down movement. Nothing like the old main shaft and the amount of vertical movement may not have changed at all in the 30 flights I have on it. In any case, shimming should fix it for good since the gear set would not be able to move up and gradually enlarge the hole in the shaft.

GAR, would you please clarify this statement "I have tried 10mm shims in the TT main gear hub, and it helps. But it leads to some other problems that you need to double check." - Thanks!

[GAR]

GAR, would you please clarify this statement "I have tried 10mm shims in the TT main gear hub, and it helps. But it leads to some other problems that you need to double check." - Thanks!
[/quote]

At this time only one small 10mm washer (or shim for the belt drive that you do not use with the TT) is in the hub of my E7. Plus making the lower bearing block adjustable upward was the simple fix for something I did not like.

Don't forget that shims IN the TT main drive hub moves that hub and OWB sleeve further apart. The 116t main gear hub will freely move up/down more. A used OWB sleeve that has been worn in to one spot by the bearing will hide a problem.

Why do this you ask?

When I converted to TT, I fallowed the instruction of the TT manual and everything was great. But around 100+ flights later the once quite E7 was sounding like junk. Then I watched this vid where the main gear drive is in need of help and decided to try and fix mine.

Synergy E7 Jeti Mezon Testing- Rob McQuillen

[GAR]

stevehof and GAR,

Thanks so much for responding to my questions. While I'm disappointed that we are having these same problems, I'm glad that thre are solutions. I'll try a little shimming until I can get a new main shaft in my hands. It's a shame that the hole in the m/s is a little oversized to begin with and prone to opening up more with regular use.

I'm pretty new to the Synergy forum and was wondering, do you know if Matt has addressed this issue before? Kind of a bummer that I have to try/buy different main shafts after purchasing a brand new kit to find one with a tolerance closer to that of the bolt.

I hate you had this problem, some might not consider it to be a one. I've been in this hobby since Hitler was a Corporal. If you find a perfect heli from the "get go", please let me know.

Out of curiosity, is your 116T main gear solid or does it have the holes?

[stevehof]

GAR, I want to make sure I understand what you did. Are you saying you used the 10mm metal shim from the original set up between the main gear and auto gear, instead of the two Delrin shims? Then just moved the lower bearing block up enough to remove the play? Thanks!

[Area51]

GAR,

My kit came with a main gear with holes.

[GAR]

GAR, I want to make sure I understand what you did. Are you saying you used the 10mm metal shim from the original set up between the main gear and auto gear, instead of the two Delrin shims? Then just moved the lower bearing block up enough to remove the play? Thanks!

NO, NO!

The two delrin shims are still used, they must be installed.

The small belt drive shim is install into the roof of the TT main gear hub. By doing so you are removing some of the up/down movement (of TT hub) because of the large hole in that hub and main shaft.
Truthfuly...you can do with out that shim, it worked before without it.

Making the lower support adjustable is all I suggest doing, and only if your not happy with the amount of up/down travel of One Way Bearing sleeve and TT hub because of over sized screw holes.

Don't forget.........your main shaft needs to free wheel "auto".

This worked for my E7 that was one of the first kits out.

[stevehof]

OK, thanks for the clarification. I'd rather shim at the top since the slant pinion wants to push the main and TT gear set up. If you carefully shim at the top you should be able to retain a free wheeling TT hub as well as reduce or eliminate most of the upward pressure from the TT hub bolt against the top of the hole in the main shaft. Properly done top shims should preclude that bolt from making the main shaft hole bigger after 100 flights or so. Of course, all this is speculation on my part. However, I do intend to give it go if the gear set play seem to be increasing after a couple dozen more flights...