Bulletproofing the gearbox

[Overkill]

Yes, mine should be arriving on Monday.

 

[Billyjoe]

Yes, mine should be arriving on Monday.

How/where did you order it? I see all this ALLRACING hopups in Aliexpress, but the gearbox is not there...

 

[Overkill]

I pre-ordered it a long time ago, directly from All Racing Tang on FB.

 

[Overkill]

Reason #2 to use a flanged bearing. When you have a lot of chassis flex the driveshaft can slam into the pinion gear, which can potentially cause some damage.

 

[Gizmo]

The shim(s) take the pressure off the plastic divider. The 2nd shim is only required when using a flanged bearing. That spacer you linked will not work.

My idea was that this naylon shim will fill the gap to the plastic divider of the diff box. Then this will support on impact the flange. Why you think it might not work? Do I miss something?
I understand your approach but with your Shims any pressure will go into the Diff. I expect my big shim will give the pressure partially to the plastic divider and the flange will take most of the pressure first Hand.

 

[Overkill]

The bearing OD is 13mm, and the plastic divider is probably around 1mm thick on each side, so that means the maximum OD shim size is probably around 11mm. The shim you listed was 13mm OD.

 

[Gizmo]

The bearing OD is 13mm, and the plastic divider is probably around 1mm thick on each side, so that means the maximum OD shim size is probably around 11mm. The shim you listed was 13mm OD.

The flange bearing has 1mm thick flange and hence only goes 3mm into the diff case (compared to that the original bearing goes complete 4mm into the diff case). So there shall be a1mm gap to the divider. I want to fill this 1mm gap with the 1mm shim. So in total it will have the „Dimension of a 5x13x5mm flange bearing“.

 

[Overkill]

The flange bearing has 1mm thick flange and hence only goes 3mm into the diff case (compared to that the original bearing goes complete 4mm into the diff case). So there shall be a1mm gap to the divider. I want to fill this 1mm gap with the 1mm shim. So in total it will have the „Dimension of a 5x13x5mm flange bearing“.

Ok sounds good.

 

[WTF MIKE]

I can’t find those shims you recommend. Does anyone else make them?

 

[Overkill]

I can’t find those shims you recommend. Does anyone else make them?

There's a lot of alternative options, here's a few examples.

SWorkz 5x8x0.8mm shims (x3 = 2.40mm)
https://www.amainhobbies.com/sworkz-5x8x0.8mm-washer-10-swx-101016/p213990

Yokomo 5x8mm shim set (x1 = .05mm)
https://www.amainhobbies.com/yokomo-5x8mm-spacer-shim-set-0.05-0.1-0.2mm-yokzc-s50s/p270533

5x8x2.5mm bearing
Then sand the surface to get to 2.45mm width
https://www.amainhobbies.com/traxxas-5x8x2.5mm-ball-bearing-2-tra5114/p3317

 

[WTF MIKE]

There's a lot of alternative options, here's a few examples.

SWorkz 5x8x0.8mm shims (x3 = 2.40mm)
https://www.amainhobbies.com/sworkz-5x8x0.8mm-washer-10-swx-101016/p213990

Yokomo 5x8mm shim set (x1 = .05mm)
https://www.amainhobbies.com/yokomo-5x8mm-spacer-shim-set-0.05-0.1-0.2mm-yokzc-s50s/p270533

5x8x2.5mm bearing
Then sand the surface to get to 2.45mm width
https://www.amainhobbies.com/traxxas-5x8x2.5mm-ball-bearing-2-tra5114/p3317

Thank you I just went with the one from amazon it’s 2.5 I’m just going to sand it down

 

[Dave]

How/where did you order it? I see all this ALLRACING hopups in Aliexpress, but the gearbox is not there...

?

 

[BashingBrian]

The biggest problem I see in the bashing community happens during big air flat landers which creates a tremendous amount of flex. When the rear of the chassis flexes really hard, the center rear driveshaft slams into the pinion gear end and this can make the set screw lose grip. Once that happens you can destroy the pinion bearings, pinion gear, or gearbox pretty quickly. What I have found that works for extreme bashing is simply using a flanged bearing on the outside of the gearbox which makes it so the driveshaft cannot make contact with the pinion gear. Instead all of that force hits the coupler and the coupler hits the flanged section of the bearing and there’s no possible way to damage anything. I also use shims in between the two pinion bearings for added security, so there’s no pressure on the plastic divider.

A high quality flanged bearing from Boca costs $8 and makes the gearbox bulletproof. For the shims, a total thickness of 2.45mm works perfect.

Parts used:
Boca flanged bearing 5x13x4
SMF695-2RS

Boca regular bearing 5x13x4
MR695-2GS

HPI shim 5x7x1.45
103368

Serpent shim 5x7x1.00
909514

Other parts used:
Arrma center rear 5mm steel driveshaft (this is 3mm shorter, only for ET48.3, AR310470)
Knurled set screw M5x5 (BoltDepot.com)
Red loctite


View attachment 1985

When you have a lot of chassis flex the driveshaft can slam into the pinion gear, which has potential to cause some damage if the set screw breaks loose.

View attachment 2512

View attachment 2513

I'm really late to the party as I've only just got my MT410 ?

So basically, I take it that what you need to do ideally is fill that gap between the two bearings with 2.45mm of something metal..??

Also maybe slightly shorter rear drive shaft..??

Is this mod still needed if you run all the M2C mods ie: chassis, braces etc..??

 

[Overkill]

Yes, you can find any assortment of steel shims from Amain. Yes, ideally you will want a shorter driveshaft with the flanged bearing. How much that affects you will depend on how much flex you've eliminated from the chassis and braces. I bash ET's so I use the Arrma driveshaft but for the MT you could use the Serpent driveshaft (600945) and shave the ends flat to make it shorter. Yes, I would do this modification on any setup if you want zero failures.

 

[BashingBrian]

@Overkill

I have found two versions of these that I can order, but which one is the best one to go for..??

Serpent Drive Shaft Center Rear 600945
Serpent Aluminium Drive Shaft 600955

?

I've ordered all the bearings and found some shims.??

 

[Overkill]

The aluminum one should be fine as well, get rid of the flex.

 

[RustyUs]

After having two bearings work their way out (not completely) of the gearboxes, I'm looking forward to applying the same principles used in this thread. But, I'm doing it on a buggy.

Apparently, flanged 5x11x5mm bearings (for buggy) are not very common. And, trying to find rubber shielded ABEC 3 flanged bearings in that size are even harder to find .

Thanks.

 

[swamp2]

Hi, new guy here. Can someone confirm: Does this mod on the regular MT410 need a new/shorter drive shaft? What is the part number? Does it also require shortening by grinding a mm or so from both ends? The OP seems ambiguous on MT vs other Tekno models. Thanks!

 

[NO02]

Hi, new guy here. Can someone confirm: Does this mod on the regular MT410 need a new/shorter drive shaft? What is the part number? Does it also require shortening by grinding a mm or so from both ends? The OP seems ambiguous on MT vs other Tekno models. Thanks!

Works fine on the MT410. Nothing besides the bearings and 2.45mm of total spacers are needed. I did it myself:

 

[Alan0823]

do somebody have experience with this metal diff for ET48? I tried to contact him on FB but no joy.

I have seen they sell metal diffs on e bay but it's for mt410? I'm hoping when I have the money I'll purchase to try them out?