MF-01X dogbones/CVDs problem

[alvinlwh 5895]

Building my MF-01X budget rally challenge when I ran into a problem that does not seem to get much mention and don't seem to have any solutions. I am only testing it as a 2WD at the moment and no matter CVDs or dogbones, they just kept popping off. I had applied a similar solution to the 5mm balls to correct the uneven droop to get the max ground clearance only to run into this problem. At the moment, I had dropped it to the lower ride height and it seem to solve it but it also means I lost 10mm of clearance.

Any suggestions?

[Sogogi 3217]

I had to limit the shock length to avoid that…  Though I did put cc-02 wheels/tires.. which may not be something you are looking for.

[Sogogi 3217]

What an irony. I just went out to run my mf-01x… after 10min or so, i lost a rear dogbone.. lol..

[alvinlwh 5895]

4 hours ago, Sogogi said:

I had to limit the shock length to avoid that…  Though I did put cc-02 wheels/tires.. which may not be something you are looking for.

 

3 hours ago, Sogogi said:

What an irony. I just went out to run my mf-01x… after 10min or so, i lost a rear dogbone.. lol..

I have regular TC sized wheels so that gave me back maybe 5mm.

For me the irony is I solved the uneven droop problem and ran straight into this one. This is a known problem apparently, but not often mentioned and I don't seem to find a solution when googling for it. Usually the answer is CVDs, but the first thing that popped on mine was a CVD, on the same side as yours. The only comment I came across was the side that pop is usually the chassis side and CVDs will not help, although I find that with dogbones, it popped the wheel side, but CVD, chassis side.

[alvinlwh 5895]

Will 53218 or 9804237 work better? They may solve the chassis side if they work but CVD will still be needed to fix the wheel side.

[Nikko85 3453]

Yes, the angle of the rear dogbone in particular can be problematic. If you swap to CVA Super Minis you need to use internal spacers to reduce the angle of the arms to stop them popping out. I also found that I used o rings on the outdrives but not the axles, otherwise there was some binding, but I’ll double check.

Once you get the angle right they are fine, I’m not sure if the stock shocks cause an issue, I think it’s just that even the super minis are too long.

Interestingly, what I’m not sure about is if the unequal droop issue is even an issue, given that you need to reduce the amount of droop anyhow, so perhaps we are fixing an issue that is then nullified anyhow.

I should say once I put the internal spacers in I’ve had zero issues at all.

It is annoying that the angle is quite reduced, which limits ground clearance, but for mine I’ve put on much larger tires which helps massively.

[alvinlwh 5895]

23 minutes ago, Nikko85 said:

Yes, the angle of the rear dogbone in particular can be problematic. If you swap to CVA Super Minis you need to use internal spacers to reduce the angle of the arms to stop them popping out. I also found that I used o rings on the outdrives but not the axles, otherwise there was some binding, but I’ll double check.

Once you get the angle right they are fine, I’m not sure if the stock shocks cause an issue, I think it’s just that even the super minis are too long.

Interestingly, what I’m not sure about is if the unequal droop issue is even an issue, given that you need to reduce the amount of droop anyhow, so perhaps we are fixing an issue that is then nullified anyhow.

I should say once I put the internal spacers in I’ve had zero issues at all.

It is annoying that the angle is quite reduced, which limits ground clearance, but for mine I’ve put on much larger tires which helps massively.

I find it quite stiff at the front with 2 o rings but not the rear. However, I am only testing it as a 2WD at the moment (half completed project) on 175mm WB, basically I just connected the front and the rear together and let it run.

I am not using Tamiya's own CVA as they will blow the budget for the budget build challenge but JK shocks, which I measured to be 55mm. I will try to reduce them by 5mm and do away with the droop adjustment. Yeap, quite annoying as it had great ground clearance only to be lost with this drive issue. I used TC 70mm sized tyres so I am supposed to gain 5mm over the kit ones only for it to be lost again. Grrr...

[ad456 331]

@alvinlwh would a shim between the bearing and axle work to push the shaft back toward the cup help any? It’d depend on what length is on the axle as it will shorted how much is there for the wheelnut. It’d certainly put more shaft toward the gearbox outdrive. 

[alvinlwh 5895]

2 minutes ago, ad456 said:

@alvinlwh would a shim between the bearing and axle work to push the shaft back toward the cup help any? It’d depend on what length is on the axle as it will shorted how much is there for the wheelnut. It’d certainly put more shaft toward the gearbox outdrive. 

No, the dogbones are simply too short for the angle, shoving it towards the chassis will mean it pops out at the wheel end. Even CVA pops out and there is no way to shim that one. It is drive caps that are the problem. Now if it is possible to shim them out, it could solve the problem.

[ad456 331]

Ah, Righto. Is there another models drive cups that are longer?

[alvinlwh 5895]

8 minutes ago, ad456 said:

Ah, Righto. Is there another models drive cups that are longer?

That's why I was asking about 53218 or 9804237 as they are listed as upgrades for the M chassis.

[ad456 331]

I might have a set of them. I’ve a CC-01, WR-01 and a Wild Dagger sat in bits, I’m sure one has those on it,  I’ll look when I get home. 

[Nikko85 3453]

A proper fix for this would be fantastic, as as you've said, it's a real shame to loose that ground clearance. I wonder if 1 mm longer dogbones could help? I run 82 mm tires on mine to get around this.

Your other option might be to run TL01 arms and longer dog bones. I did this on my MF01x once and it worked well. You'd then need a smaller 12 mm hex and perhaps more offset tires, but it does help soften suspension and give much more clearance too.

[alvinlwh 5895]

8 minutes ago, Nikko85 said:

A proper fix for this would be fantastic, as as you've said, it's a real shame to loose that ground clearance. I wonder if 1 mm longer dogbones could help? I run 82 mm tires on mine to get around this.

Your other option might be to run TL01 arms and longer dog bones. I did this on my MF01x once and it worked well. You'd then need a smaller 12 mm hex and perhaps more offset tires, but it does help soften suspension and give much more clearance too.

Problem is:

A. Dogbones seems to come in fixed sizes.

B. I will run into the dogbones catching the cups problem then.

I did hear about the TL mod, but the problem with that is additional cost, which is not good for this budget built off.

[Sogogi 3217]

9 hours ago, alvinlwh said:

Will 53218 or 9804237 work better? They may solve the chassis side if they work but CVD will still be needed to fix the wheel side.

I havent tried, but by the look of it, it just is hardened version (more or less). I can see drive cup wearing out in regular version.

[alvinlwh 5895]

14 minutes ago, Sogogi said:

I havent tried, but by the look of it, it just is hardened version (more or less). I can see drive cup wearing out in regular version.

Looks like limiting droop is the only solution. Such a shame as I really liked the clearance offered by full drop.

[alvinlwh 5895]

Just wondering, instead of using spacers inside the shock, this limiting available shock travel, will it not be better to just drop it to the lower ride height? That is what I had done at the moment, and it seem to work. This way I still get the full range of shock movement.

[cstorckiii 168]

Mf01x uses the same rear arms as the M05. The M05 version II  one piece arms use a set screw for droop adjustment. Might be possible to source a set of those.

[alvinlwh 5895]

10 hours ago, cstorckiii said:

Mf01x uses the same rear arms as the M05. The M05 version II  one piece arms use a set screw for droop adjustment. Might be possible to source a set of those.

Really, one should be able to build it without needing to spend more to correct a problem that Tamiya built into it. Further more, this was meant to be a budget build challenge with a cost limit. Really disappointed with Tamiya here.

[Nikko85 3453]

On 3/3/2023 at 7:46 PM, alvinlwh said:

Just wondering, instead of using spacers inside the shock, this limiting available shock travel, will it not be better to just drop it to the lower ride height? That is what I had done at the moment, and it seem to work. This way I still get the full range of shock movement.

If it amounts to the same height then yes, that makes sense!

[alvinlwh 5895]

6 minutes ago, Nikko85 said:

If it amounts to the same height then yes, that makes sense!

Not too sure about the exact ride height of shock spacers, but just dropping the hubs to the lower setting is definitely the less messy solution! I popped the dogbones back in on the lower ride height and it is smooth. Just a shame that the higher height cannot be used.

[Sogogi 3217]

I am not a fan of adjusting oil shocks when I need to take it apart…

[Honza 936]

On 3/3/2023 at 2:08 PM, alvinlwh said:

No, the dogbones are simply too short for the angle, shoving it towards the chassis will mean it pops out at the wheel end. Even CVA pops out and there is no way to shim that one. It is drive caps that are the problem. Now if it is possible to shim them out, it could solve the problem.

XV01 uses slightly longer wheel axles at rear, maybe it'd be possible to shim them closer to the diff?

[alvinlwh 5895]

3 hours ago, Honza said:

XV01 uses slightly longer wheel axles at rear, maybe it'd be possible to shim them closer to the diff?

Sigh, throwing money at a problem that shouldn't be there in the first place is just not on. I expect better from Tamiya, especially this is the second kit with a popping dogbones problem straight out of the box.

[Honza 936]

6 minutes ago, alvinlwh said:

Sigh, throwing money at a problem that shouldn't be there in the first place is just not on. I expect better from Tamiya,

 Throwing money on a problem is the way of Tamiya 😄

I think this is just consequence of hubs being originaly developed for M05Ra. They didn't need to work in the rear