Tamiya FF Club

[OoALEJOoO]

14 hours ago, Honza said:

Dogbones are just different form of universals. Reason why Tamiya's universals chatter even on rear is, that they did them wrong for years, one end rotated by 90°, so instead of compensating vibrations they actually amplified them! I think that only recently, on M07 and TRF420, Tamiya did CVDs in right orientation.

CVDs will help to reduce vibrations caused by dogbone jumping around outside cup when you get beyond their capacity, but only DCJs will remove all chatter caused by variation of angular velocity.

Thanks for the info. Can you elaborate what do you mean by Tamiya doing the universals wrong by rotating them 90deg? Single-cardan universals are not meant to compensate vibrations.

Note that on the FF03 (at least on mine), the vibration occurs well within the dogbone capacity.

[Honza]

4 hours ago, OoALEJOoO said:

Thanks for the info. Can you elaborate what do you mean by Tamiya doing the universals wrong by rotating them 90deg? Single-cardan universals are not meant to compensate vibrations.

I'll try, but bear in mind that English is not my first language, so my explanation might not success

Try to imagine how universal joint moves - it rotates around two axis, one is fixed ( perpendicular to rotational axis) to driveshaft, second to outdrive. In case of dogbone, you have a pin on each end, which act as axis fixed to driveshaft, while combination of groove and ball on outdrive acts as axis fixed to outdrive.

When suspension is high, it creates speed variation on outdrive, which is cancelled by joint on the wheel side. Vibration caused by dogbone end will stay, but since angle there is minimal, they are nearly non-existent.

In case of CVD, the axis fixed to shaft is the larger diameter part of crosspin, so it should be lined up with dogbone pin on the other end of driveshaft. However, until recently, Tamiya had lined up 2mm pin, effectively creating equivalent of dogbone with each end rotated by 90°. In that case, speed variation cased by each end adds together instead of cancelling out.

But In case of FF03, speed variation is not caused by suspension movement, but by steering, so you need something to cancel out vibrations in wheel - which is what DCJs are for.

Difference between dogbone and CVD is small, but CVD is a bit better in terms of vibrations - I gues that's because of lower friction and better force transmission, as dogbone tends to slide in and out of wheel axle, while CVD is fixed.

[OoALEJOoO]

2 hours ago, Honza said:

In case of CVD, the axis fixed to shaft is the larger diameter part of crosspin, so it should be lined up with dogbone pin on the other end of driveshaft. However, until recently, Tamiya had lined up 2mm pin, effectively creating equivalent of dogbone with each end rotated by 90°. In that case, speed variation cased by each end adds together instead of cancelling out.

Thanks for the follow-up and apologies for hijacking the discussion towards the Monster Beetle, but the knowledge should benefit the FF03 as well.

According to the MB manual, the universal is to be assembled with the 2mm pin aligned with the pin on the dogbone end.

The manual would be the "A" position in the picture.  If I understand correctly your explanation, then "A" should be the correct assembly and should not add vibration, but if you assemble it on "B" (rotated 90deg), then it should add vibration, correct?

My experience with the MB (and with the internet, assuming people are building the MB per manual) is the opposite: that the manual's "A" produces the issue. I can't recall if I have tested "B".

My understanding is that the universal introduces torque oscillation (proportional to joint angle), irrespective of the dogbone end. If you grab the threaded end with your finger and put some resistance on it, when you spin the dogbone end with your hand, you will feel the torque oscillation very clearly.

[Honza]

1 hour ago, OoALEJOoO said:

The manual would be the "A" position in the picture.  If I understand correctly your explanation, then "A" should be the correct assembly and should not add vibration, but if you assemble it on "B" (rotated 90deg), then it should add vibration, correct?

Position in wheel axle doesn't matter, because 2mm pin wil be still aligned with pin on the dogbone end. A different driveshaft is needed, like this one on TRF420

Notice that here, 2mm pin is rotated by 90° from dogbone end. It may seem counter-intuitive, but it's the larger part of crosspin (edit: Tamiya calls it cross joint), that rotates around same axis as dogbone pin - if you tilt CVD around 2mm pin, cross joint tilts with it in same way, as dogbone pin tilts in groove, so both ends move around same axis. But in "wrong" CVDs, 2mm pin stays perpendicular to wheel axle, while dogbone pin tilts - so each end rotates around different axis. This doesn't matter on onroad car, where it runs near zero angle, but any chassis with longer suspension travel will experience more vibrations, than with dogbones.

1 hour ago, OoALEJOoO said:

when you spin the dogbone end with your hand, you will feel the torque oscillation very clearly.

Yes, this is caused by geometry of a cardan joint. Extreme case is, when you take old style universals from TA02, for example, you can bend them to right angle and one end will rotate freely some 90°, but whole thing is locked. If you rotate whole joint 90°, then other end of assembly can rotate 90° - it basically jumps in 90° steps - this behaviour is less pronounced at lower angle, but still causes vibrations. Two cardan arrangement helps to cancel out this behaviour.

Dogbone end creates same oscillation, but in case of MB, it is in double cardan arrangement with same angle on both ends, so it cancels out. In case of FF03, you have large angle on outside and zero on inside, which causes vibration, and extra friction makes it more pronounced.

[OoALEJOoO]

@Honza nicely explained, I understand your point now, thank you  I got mixed-up with the cross-joint and cross-pin. And also as you say, it shouldn't make any difference if it's assembled "A" or "B".

28 minutes ago, Honza said:

Dogbone end creates same oscillation, but in case of MB, it is in double cardan arrangement with same angle on both ends, so it cancels out.

This is the part I'm still a bit confused. The MB would have the proper double-cardan but only if the driveshaft used is the TRF420 you show, and not the one shown on the manual, correct?

31 minutes ago, Honza said:

In case of FF03, you have large angle on outside and zero on inside, which causes vibration, and extra friction makes it more pronounced.

This part is golden knowledge to me and it makes perfect sense now, thank you for the insight. Indeed there is only one end having an angle (wheel end) while the other end is straight (differential end), so they don't really cancel out. The only way to cancel out is if the double-cardan is on the wheel end.

[Honza]

50 minutes ago, OoALEJOoO said:

This is the part I'm still a bit confused. The MB would have the proper double-cardan but only if the driveshaft used is the TRF420 you show, and not the one shown on the manual, correct?

Yes, because way how MB has its driveshaft is equivalent of this dogbone

Effectively it's like two universal joints in series, while in double cardan arrangement, they are back to back.

I once created a dogbone like this by accident, when I shortened a dogbone by cutting it in half and connected it using a threaded tube. Vibrations were quite noticeable.

Edit: now I remembered, that DCJs have four holes for CVD pins - it might be interesting demonstration to assemble them with pins 90° apart.

[Nicadraus]

Thanks for clarifying @Honza. 

@OoALEJOoO this thread has already become a discussion of off-topic. Sorry but you'll probably have to create a new thread to discuss that further.

As @Jonathon Gillham @ThunderDragonCy and I have suggested, DCJ or universal will solve your problem. We all have experiences in FF cars, the reason why we all use them, obviously a lot better than stock dogbones. 

 

[OoALEJOoO]

@Nicadraus, I didn't mean to derail the conversation but the knowledge does apply to the FF03 and was framed around it throughout the discussion (FF03 was mentioned on every post). Understanding advice is perhaps more important than just following it.

Now I know why it is that the FF03 benefits from the universal, while other cars (MB) might not. Other people might find this useful.

[Nicadraus]

53 minutes ago, OoALEJOoO said:

@Nicadraus, I didn't mean to derail the conversation but the knowledge does apply to the FF03 and was framed around it throughout the discussion (FF03 was mentioned on every post). Understanding advice is perhaps more important than just following it.

 

Sorry, but it was already irrelevant to the thread. Just because the word "FF-03" was mentioned a couple of times doesn't mean it kept the topic in sync in this thread's discussion.

The DCJ and universal is quite a basic in RC knowledge for some years/decades and didn't have to go on one full page just to discuss that matter. Besides, you were comparing it with the MB which has a totally different suspension system from the FF-03, which is also one of the reasons why they have different effects. MB having rear trailing suspension arms is different from a double-wishbone suspension arm that is also front driven and have other parts such as c-hubs, knuckles and more movements than just rotating, moving up & down.

Need more explanation? Better create a new thread so we can all go back to proper FF discussions.

 

[OoALEJOoO]

7 hours ago, Nicadraus said:

Need more explanation? Better create a new thread so we can all go back to proper FF discussions.

Thanks but no need, @Honza generously and politely already covered ample interesting knowledge on why the FF03 driveshaft ends do not balance each other, and how single and double-cardan joints relate to this.

I do have another FF03 question though:

What are the common wear-out parts of the FF03 that would be good to have extra spares?

[RichieRich]

18 minutes ago, Nicadraus said:

Sorry, but it was already irrelevant to the thread. Just because the word "FF-03" was mentioned a couple of times doesn't mean it kept the topic in sync in this thread's discussion.

The DCJ and universal is quite a basic in RC knowledge for some years/decades and didn't have to go on one full page just to discuss that matter. Besides, you were comparing it with the MB which has a totally different suspension system from the FF-03, which is also one of the reasons why they have different effects. MB having rear trailing suspension arms is different from a double-wishbone suspension arm that is also front driven and have other parts such as c-hubs, knuckles and more movements than just rotating, moving up & down.

Need more explanation? Better create a new thread so we can all go back to proper FF discussions.

 

😮 I don't think there's a need to drop the hammer on a line of responses that are mostly on topic. Isn't it the goal of this forum to help others and pass on some knowledge?

[Nicadraus]

3 hours ago, OoALEJOoO said:

Thanks but no need, @Honza generously and politely already covered ample interesting knowledge on why the FF03 driveshaft ends do not balance the other, and how single and double-cardan joints relate to this.

I do have another FF03 question though:

What are the common wear-out parts of the FF03 that would be good to have extra spares?

Other than the stock dogbones, just mesh the spur really well. An aluminum spur adaptor would be a big upgrade. It'll eliminate the wobbling of the spur that can cause the gear to strip off easily. 

The aluminum adaptor has become really rare now. One option is use the carbon reinforced plastic for the XV-01/FF-04. It'll serve better than the plastic stock one.

[Jonathon Gillham]

If anyone is interested, the aluminum spur adaptor is in stock here and ships worldwide (well, to New Zealand and Wales, I assume the countries in between too which is pretty much all of them)

https://www.rcnz.com/categories/car-accessories/tamiya-ff-03-chassis-parts/tamiya-ff-03-aluminium-spur-gear-mount/

My question about swaybars was missed (or maybe ignored as no one knows the answer?) but will the FF03 swaybars fit the FF04?  I can't find the XV01 set and the FF04 only comes with rear ones.  Its so strange for what is in theory a TRF level kit, its missing aluminum suspension blocks and front swaybars.

[Nicadraus]

5 hours ago, Jonathon Gillham said:

If anyone is interested, the aluminum spur adaptor is in stock here and ships worldwide (well, to New Zealand and Wales, I assume the countries in between too which is pretty much all of them)

https://www.rcnz.com/categories/car-accessories/tamiya-ff-03-chassis-parts/tamiya-ff-03-aluminium-spur-gear-mount/

My question about swaybars was missed (or maybe ignored as no one knows the answer?) but will the FF03 swaybars fit the FF04?  I can't find the XV01 set and the FF04 only comes with rear ones.  Its so strange for what is in theory a TRF level kit, its missing aluminum suspension blocks and front swaybars.

I'm pretty sure that the FF03 sway bars can fit in the FF04 one way or another. You'll probably just need to do a little bending and cutting to get the exact length and angle. 

[OoALEJOoO]

@Nicadraus, @Jonathon Gillham Thanks for the info, price seems a bit steep, roughly as much as 7 spurs . I'll try first seeing how fast it chews spurs with the stock plastic adaptor (which indeed causes some wobble).

[RichieRich]

Guys, are Tamiya 42102 dampers discontinued or just impossible to find? I'd like to get TRF shocks for my FF03 but it's like they don't exist anymore. Is Tamiya replacing them with something else?

[Jonathon Gillham]

19 minutes ago, RichieRich said:

Guys, are Tamiya 42102 dampers discontinued or just impossible to find? I'd like to get TRF shocks for my FF03 but it's like they don't exist anymore. Is Tamiya replacing them with something else?

I expect just impossible to find. They are still supplied on the TB05Pro and TA07Pro (both currently available), although the R models and TA08 all have the SSBB so I imagine thats the way Tamiya mid - high level TC will all go. Given some of the much older shocks are still available I would expect these to be around for a long time yet, as they were standard, or hop ups, for a lot of models.

[ThunderDragonCy]

38 minutes ago, RichieRich said:

Guys, are Tamiya 42102 dampers discontinued or just impossible to find? I'd like to get TRF shocks for my FF03 but it's like they don't exist anymore. Is Tamiya replacing them with something else?

They seem fairly readily available in Europe so I would it's just the current supply issues wherever you are if you can't find them. If you are looking for alternatives the 53571 are a little older but work just as well (I have both sets), or another option I am running on a car designed for 55mm dampers is the 54000 M-chassis dampers with the long eyelets fitted. For on road the shorter stroke is still plenty. You could also do the same with the 42273 TRF Short damper too. 

[Alexei]

my FF-03 is almost complete. needs to solder battery connectors, link up the receiver, make the body and install magnets for mounting the body. the body will be a ABC Hobby Honda Integra Type-R.

also, i have changed to 48pitch gearing. the 26t pinion does not reach the spur with 48pitch so i used an 31t pinion instead. spur gear is 68t.

 

 

[Frankster]

Hi,   Looking at a FF-03 in the future. My understanding is this is related to the TA-06 which also share some components with the TA-05 correct?

Sorry I am a newbie on the FF chassis

[ThunderDragonCy]

@Frankster The FF03 was released around the same time as the TA05 and ran through when the TA06 was launched. The front inboard rocker suspension is basically the same as the TA05. The suspension is similar to both the 05 and 06. They are all interchangeable, as well as later parts. For instance, I have TRF419 arms on my FF03. Once the TA06 came out tamiya offered an upgrade, wider gearcase option for the FF03 to allow the use of the new TA06 gear diff instead of the original ball diff. If you want to get right into it the FF03 drivetrain is actually most directly related to the TRF201X rear motor buggy. 

[Frankster]

4 hours ago, ThunderDragonCy said:

@Frankster The FF03 was released around the same time as the TA05 and ran through when the TA06 was launched. The front inboard rocker suspension is basically the same as the TA05. The suspension is similar to both the 05 and 06. They are all interchangeable, as well as later parts. For instance, I have TRF419 arms on my FF03. Once the TA06 came out tamiya offered an upgrade, wider gearcase option for the FF03 to allow the use of the new TA06 gear diff instead of the original ball diff. If you want to get right into it the FF03 drivetrain is actually most directly related to the TRF201X rear motor buggy. 

Thanks. Is a gear diff better than a ball diff?  I always thought ball was better. I have TA-05 Ver ii and never tried a front wheel drive

[ThunderDragonCy]

Just now, Frankster said:

Thanks. Is a gear diff better than a ball diff?  I always thought ball was better. I have TA-05 Ver ii and never tried a front wheel drive

I have never run a ball diff in mine, but it will be fine. Its a strong unit. 

[Carmine A]

11 hours ago, Frankster said:

Thanks. Is a gear diff better than a ball diff?  I always thought ball was better. I have TA-05 Ver ii and never tried a front wheel drive

I've found them vastly superior to Ball Diffs. Everyone has an opinion.... but I like that after I've found the Oil weight that I like, I don't have to mess with it! Unlike a Ball Diff, that needs frequent fiddling. 

[rich_f]

7 hours ago, Frankster said:

Thanks. Is a gear diff better than a ball diff?  I always thought ball was better. I have TA-05 Ver ii and never tried a front wheel drive

While it used to be the case that ball diffs were the upgrade over gear diffs, I think when people refer to gear diffs these days they are talking about oil-filled gear diffs, which are a big improvement the old gear diffs.