Benefits of 8mm bearings?

[Sam Pascoe]

What are the benefits of having 8mm bearings?

 

New to teching and id like to learn more:) 

[Hangtight]

They can run more smoothly, but they also require a slightly different shimming clearance. They can also fail catastrophically and destroy quite a lot of the rest of the gearbox.

G&P ones have been reliable for me in the past, but I'd  rather have the peace of mind of decent solid bushings over any small difference they might make.

[jcheeseright]

Bragging rights to those who don't know better? 

 

Stick to bushings, less to go wrong and AEG gearboxes really aren't under all that much load. 

[Sam Pascoe]

cheers guys, reason of asking is i sent my srxl to KOA to be rhopped a few months ago, its just been done due to a delay and they installed 8mm bearings and gave the gearbox a service for compensation, so I'm just wondering what that means they have done and what it will mean for me haha 

[Sitting Duck]

Short condensed answer - yeah right.....

 

You "might" be ok with 8mm or 9mm bearings

but this guy is warning people about bearings under the spur gear especially

He has had ceramics fail under the spur - so if a ceramic can fail then that will answer you....

 

 

 

On soft G&G bronze bushings the bushing under the spur will wear the most

Everybody will have their own take - a DSG build steel bushings is recommended

so again bushings are more durable

 

Bearings spin more freely but can fail more quickly in certain builds or points

Bearings will also fail quickly if shimmed badly or under/overgreased

(ceramics do not get greased - well so they say)

 

Just coz bearings spin more freely - that on its own mean jack

a lovely matched up set shimmed perfectly will run just as smooth as a $hit bearing shim job

(actually better depends how terribly the bearing setup was shimmed)

 

Most of the time I would choose 6 bushings - could be all solid or a mix of cross filled type

(what ever I have to hand - it don't matter as long as I feel the $hit runs well)

However sometimes I have put a bearing on TOP of spur gear - not under strain like underneath

This was mainly coz I was running out of shimming space in some builds with chunky spurs/high speed sets 

Bearings sit more flush, not protruding into gearbox, I was out of space and bearing on top with no shim req

(yeah it was a bit tight as actress said to bishop on spur gear with 8mm SHS bushings)

 

Everywhere else was 8mm bushings and had room to shim on bevel & sector

SHS 8mm bushings could do with a little sanding down on table in rotary motion as they are fat bastids on top bevel

(you "may" & not gospel but a rough guide only, need about 0.20mm - even a used 0.1mm shim on top of bevel)

I use bushings under all 3 gears, will use bushing on top of bevel - not lots of room but usually ok

if your pinion is tight and ramming the f*ck into bevel (shouldn't be if you shim correctly)

but if it is really ramming the poor bevel against the wall then a bearing won't last a long time imho

Yes bevel gear spins the most about 4.25 to 6.25 turns per sector revolution (depends on 12:1 or 18:1 set)

but traded against robust durability and smoother running - I personally will just go with bushings on bevel

 

So

BEVEL GEAR - bushings top/bottom

SPUR GEAR - bushings top/bottom, could use bearing on top if room is tight but deffo underneath (see vid)

SECTOR GEAR - tbh by now it don't matter a toss bushings might as well, this gear spins the least in drivechain

(so the smooth spin difference between bearings/bushings will be the least)

 

YES bearings run smoother - if you can shim really well and a modest build it could be OK to use bearings

PERHAPS a mix - I'd use bushings under all 3 gears where energy is being transferred but to each their own

BUT if you can shim really well and take a bit of time an all bushing or 5+1 setup should run pretty smoothly anyway imho

 

NB: This is not the Gospel that all must follow, it is what I have found out through my own experiences

Plenty people use 8mm bearings with a good reliable long lifespan of good bearings/build and perhaps a dusting of luck

Just think the durability of bushings has the edge - but depends on person/build so decide for yourself in the end I guess

[Sam Pascoe]

jesus thats a good answer! ill make a note of that thank you
I'm hoping that they will be okay in my rifle then. thank you 

[Sitting Duck]

11 minutes ago, Sam Pascoe said:

jesus thats a good answer! ill make a note of that thank you
I'm hoping that they will be okay in my rifle then. thank you 

 

I try to keep things concise and to the point

You will probably be fine - you can't really ramp up the stress too much in a ETU G&G

(the 3rnd mosfet is more likely to go kaput before the bearing)

 

Their bronzey bushings probably need to be replaced within a year (depends on use)

You will probably be fine tbh as I said - the stock 7mm bearings in a D-Boys went pear shape quickly

So I swore (a lot btw), I swore never do that again - but 8mm are much more robust than 6 or 7mm bearings

For peace of mind next time at the very least use a bushing under spur perhaps

I wouldn't panic - you can't go crazy mental $hit coz the ETU/mosfet craps out if amps increase too much

So leave it all as is - too many people mess about with $hit that isn't that critical

or keep ripping stuff apart trying to upgrade upgrade upgrade malarky - just use the bloody thing

 

If it was serviced by KOA thenit will be sweet I'm sure

bearings run smoother so if done properly you should see about an extra 1rps - maybe 2 perhaps tops

(but I reckon 1.5rps increase in reality)

any more is down to better shimming than the stock slap it together shim job

(giving you maybe 2.5 to 3rps - you can get a round or two just by reshimming (or less if badly done))

 

you got a round or two more perhaps from bearings & a reshim most likely

it should be fine - worry more about the G&G ETU than the bearings