Top shaft slop, transmission and diff graunch... easy fix.

[Dbx]

I've just finished building the chassis of my new scx10ii. It's been a fun build. The quality and attention to detail is a step ahead of my wraith. The below findings and fixes worked for my paricular truck. There may be variations with others.

The first apparent issue i can to was the diff bevel gears. Once assembled, they were graunchy and gravelly in one direction, as many other people have found. I immediately read up on this forum. Unusually some of the recommendations were off the mark for my truck. What i found was that the shaft needs assembling to the diff to correctly complete the workings. The shaft coupler acts as a backstop, correctly locating the pinion on the crown gear = no more graunchiness. There was absolutely no need to try to shim anything, and 'running in' with a drill could have damaged the gears.

The next head scratcher came with the transmission. On first assembly, (step 19 in the book) something was obviously wrong. Very notchy. A bit of reading again, and this time, partial success. The gears are sided, although not meant to be. Flipping the bottom gear improved things. The gears now were mostly smooth. If i pulled each shaft outwards, it ran smooth. If i pushed the shafts inwards, notchyness.
I pulled it all appart again and looked at how the gears meshed. I noticed the big gear was running right up close to the collar on the end of the small gear, and could even see signs of contact on the edges of the big gear.
I took the big gear to the bench grinder and ground a small chamfer onto the edge:

I reassembled, and the 'box was now acceptably smooth. Hurrah..... but whats all this top shaft slop?

I had about 1.5mm axial (!) slop of the top shaft. I measured everything up:

The stack of parts had about 0.2mm clearance inside the cases - pretty reasonable.
The slop was the shaft moving inside the stack. As identified previously on the forum, the pin slot in the top gear appears too deep, so the shaft pin is not restrained between the bearing and the gear:


I can't help but think that the arrangement will make more sence once all the two speed parts are in there too. Either way, i think this slop is more of an aesthetic issue rather than a problem.
Looking at the end bearing with the shaft pulled back against the first bearing, the slop gap can be seen as the shaft end vs the bearing face (out of focus - sorry):


To eliminate the slop, i cut a 1.2mm thick spacer (to match the gap) from a piece of 4mm diameter sprue, and poped that in the end:


This acts as a thrust face at the end of the shaft, taking up the axial slop but leaving a comfortable 0.2mm axial clearance.
Job done. For free. Very easily.

Next i assembled the transfer box (step 20). Arrgghh. Graunchy notchy hell again.
This was again due to the gears being sided. I think there must be a very small amount of draft on the gears from the sintering process.
I made sure the first two gears were reversed to each other (unlike how shown in the book) and then tried the bottom gear both ways to find the smoothest fit.

With blisters on my fingers from all the screwing and unscrewing, i finally had a complete, smooth transmission.

[allanon1965]

not a bad job, but for less than 15 bucks you can upgrade the shaft to the new VP chrome moly shaft that takes care of the slop issue, is stronger, has a machined aluminum sleeve and wont eventually wear out like the plastic spacer will..

also i found that over tightening the plastic case by even a little bit causes it to deform and cause the gears to be notchy... I am patiently waiting for an aluminum case to be made available..

[Dbx]

15 bucks for the vanquish shaft is good value. A stronger shaft will be better. Over here in Europe, the postage alone will be more than that, then plus tax...
The stock shaft is probably strong enough for my rig. The plastic spacer is essentially unloaded and has no moving contacts - it just stops the bearing and top gear from moving along the shaft - I think it's very unlikey to wear to a point where there would be an effect.

The full tightening of the case making the gears notch sounds like the same issue i had, with the big gear overlapping the collar on the small one. Chamfer the edge of the big gear, and you probably find the gears cleanly mesh.

[allanon1965]

didnt realize you were in europe...i was very surprised to see wear on the shaft and plastic sleeve on my top shaft... the big gear can be installed 2 ways but only one is correct on the single speed, no notchiness after i relaxed the torque on the case...

[Traulus]

is there anywhere you can get that top shaft beside the vanquish site?

[allanon1965]

not yet that I know of...

[Say what?]

Originally Posted by Traulus

is there anywhere you can get that top shaft beside the vanquish site?

RPP in stock:

Vanquish Products SCX10 II Transmission Top Shaft

~D

[Maxwell421]

I saw on another thread rpp and a main both have the shaft either in stock or in route, with more reasonable international shipping.


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[raptorpilot]

Hey guys, I'm literally giddy after finding this thread. I worked through every step of this on my own before finding this forum/thread, with identical findings as the OP. Great thread, couldn't be happier right now. Good work Dbx _chris

[Traulus]

Originally Posted by Say what?

RPP in stock:

Vanquish Products SCX10 II Transmission Top Shaft

~D

They don't ship to my country

[Traulus]

Originally Posted by Maxwell421

I saw on another thread rpp and a main both have the shaft either in stock or in route, with more reasonable international shipping.


Sent from my iPhone using Tapatalk

No luck with amain at them oment,they don't have them in stock,they have a good price for international shipping

[Taper]

Originally Posted by Traulus

is there anywhere you can get that top shaft beside the vanquish site?

Vanquish VPS08106 SCX10-II TRANSMISSION TOP SHAFT | eBay

[Dbx]

After discussion on another thread, I annotated this image to clarify where to modify the big gear:

Nice handwriting, i know

[sylvan]

Hi, hi have the same problem with my SCX10 II. In the kit there are some o-rings inside the doors and comparing measurements I think may be compatible. I just put them and they seem to do their job until I get the Vanquish shaft.