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Cuiken

Do I want a Monster Beetle?

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2 hours ago, Ferruz said:

Fantastic shot this one! ūüėÄūüĎĆ

Thanks mate, earlier that day...

bdGlMzd.jpeg

...moral of the story... don't ****** with an angry Lunch Box!!ūüí™ūü§¶

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Possibly by far the largest reason why the re-re Monster Beetle has more gearbox issues than the re-re Blackfoot it's the difference in their universal shafts, each has their pin at different angles:

The Monster Beetle has the pin at the end of the dogbone on the wrong position (same plane as the pin on the wheel axle). This actually amplifies torque oscillation, causing the wobble/vibration. This is more pronounced when the suspension is at full droop (bigger angle for torque oscillation) and free-wheeling (nothing to dampen). This torque oscillation will hammer the diff. The solution/improvement is to get the Brat's regular dogbones & wheel axles as others have pointed out.

The Black Foot has the pin at the end of the dogbone on the correct position (rotated 90deg compared to the pin on the wheel axle). This will better cancel-out torque oscillations. This is a favored design seen on other cars with high droop.

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I personally think that tamiya cars are not the best value for the money(when we look at the performance, durability etc). I really like tamiya cars because of nostalgia + uniqueness that is hard to find from other manufacturers. 

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1 hour ago, OoALEJOoO said:

Possibly by far the largest reason why the re-re Monster Beetle has more gearbox issues than the re-re Blackfoot it's the difference in their universal shafts, each has their pin at different angles:

The Monster Beetle has the pin at the end of the dogbone on the wrong position (same plane as the pin on the wheel axle). This actually amplifies torque oscillation, causing the wobble/vibration. This is more pronounced when the suspension is at full droop (bigger angle for torque oscillation) and free-wheeling (nothing to dampen). This torque oscillation will hammer the diff. The solution/improvement is to get the Brat's regular dogbones & wheel axles as others have pointed out.

The Black Foot has the pin at the end of the dogbone on the correct position (rotated 90deg compared to the pin on the wheel axle). This will better cancel-out torque oscillations. This is a favored design seen on other cars with high droop.

Interesting, first I've heard of this.  Can I use use Blackfoot dog bones then?  If not, happen to have part numbers for the Brat parts needed?  Would love to have a smooth running Beetle.  

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@87lc2 I just checked the manuals and interestingly swing-shafts have the same 19808071 p/n for both the Monster Beetle and the BlackFoot, even though it is different!

Screenshots of the manuals' relevant sections:

MB_BF.thumb.jpg.7782d7157170561824f3fb398788ead9.jpg

All parts should fit interchangeably, but if you order by p/n maybe you might not get the BlackFoot version if the store has old stock (?).

*Edit: I believe the Frog/Brat parts you would need to shift to regular dogbones are (looking at the Frog's manual):

  • 9808038 Drive Shaft (dogbone)
  • 9808039 Wheel Axle
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40 minutes ago, 87lc2 said:

the difference in their universal shafts

Whoa, that makes no sense at all, which i guess is making complete sense in Tamiya terms :P

Looked it up in the manuals and it is exactly as described.

MB-BF-CVD.thumb.jpg.6a50459edb5d98fdae17283eb32c44cd.jpg

So i guess half of the MB diff issues come down to this odd difference in design.

EDIT: Beaten to the punch by @OoALEJOoO :D

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Very interesting, thank you.  I will just source the Brat parts and be done with it.  Really appreciate it!

Odd that they list the same exact PN for different parts between the MB/BF...

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8 minutes ago, 87lc2 said:

Brat parts

The dogbones in the frog/brat are symmetrical tho, no 90 degree pin offset as the Blackfoot has.

image.png.d53488d184bf5f11154ba0bc6f97c5d8.png

Do dogbones make the issues presented by the symmetrical MB universals go away then, being able to move inwards and outwards a bit mitigates it compared to being constrained?

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1 minute ago, Ziddan said:

The dogbones in the frog/brat are symmetrical tho, no 90 degree pin offset as the Blackfoot has.

image.png.d53488d184bf5f11154ba0bc6f97c5d8.png

Do dogbones make the issues presented by the symmetrical MB universals go away then, being able to move inwards and outwards a bit mitigates it compared to being constrained?

That's indeed my thought, the axial displacement must help in reducing oscillation. Having updated my Monter Beetle from its original universals to the Frog/Brat's dogbones, I can confirm that they do eliminate the wobbling.

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Yes, you do want a Monster Beetle. Possibly the best thing Tamiya ever did (to me personally) was to re-re the MB, and with a revised drive (curse those hex drive shafts, consign them to badword where they belong).
It's fun standard out of the box, and is also quite mod-able with several after market bits n bobs out there.

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I'd not quite anticipated this level of love for the ORV chassis.

I think that's my mind made up. Can't wait to problem solve the drive train :)

 

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I've got a similar dilemma as I'm building a collection again and am ready to buy another kit. Really fancy a MB or BF but we already have a LB and MP so think, as it will be a runner another buggy might be better as my memory of MB/BF reliability and durability is that of constant maintenance.....

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7 hours ago, OoALEJOoO said:

Possibly by far the largest reason why the re-re Monster Beetle has more gearbox issues than the re-re Blackfoot it's the difference in their universal shafts, each has their pin at different angles:

The Monster Beetle has the pin at the end of the dogbone on the wrong position (same plane as the pin on the wheel axle). This actually amplifies torque oscillation, causing the wobble/vibration. This is more pronounced when the suspension is at full droop (bigger angle for torque oscillation) and free-wheeling (nothing to dampen). This torque oscillation will hammer the diff. The solution/improvement is to get the Brat's regular dogbones & wheel axles as others have pointed out.

The Black Foot has the pin at the end of the dogbone on the correct position (rotated 90deg compared to the pin on the wheel axle). This will better cancel-out torque oscillations. This is a favored design seen on other cars with high droop.

This is an excellent observation I think a lot of us missed. If we remember back to the introduction of the Monster Beetle, there were many complaints about wobble and vibration. Tamiya (USA at least) went as far as to issue the standard Frog dogbone set-up to those that contacted them and rightfully complained. When the Blackfoot inevitably followed, Tamiya had corrected that problem. There was still this issue of the dogbone end of the universal popping out due to rear arm flex and shallow outdrive cup engagement. 

4 hours ago, Ziddan said:

Do dogbones make the issues presented by the symmetrical MB universals go away then, being able to move inwards and outwards a bit mitigates it compared to being constrained?

Yes, oddly enough, if Tamiya had just stuck with the basic re-re Frog parts instead of "upgrading" to the universals, none of this would have happened. Even the old hex-headed half-shafts were less problematic in that respect. 

I went through the business end of my re-re Blackfoot fairly extensively to get a non-clicking, non-dogbone-ejecting, fully smooth-traveling rear swing arm set-up. The truck has performed flawlessly since its construction.

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5 hours ago, 87lc2 said:

Odd that they list the same exact PN for different parts between the MB/BF..

Yeah, I think Tamiya got caught with their pants down and quietly just made the update to those universals (down to keeping the same PN). No need to panic the world, Juggernaut 1-style, I guess they figured. That might get expensive and embarrassing ;).  

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14 minutes ago, Chest Rockwell said:

I've got a similar dilemma as I'm building a collection again and am ready to buy another kit. Really fancy a MB or BF but we already have a LB and MP so think, as it will be a runner another buggy might be better as my memory of MB/BF reliability and durability is that of constant maintenance.....

You know, as much as I started this thread saying my original BF was dissapointing, I can't say it was unreliable. Years of unforgiving use and I never had any transmission issues (diff or hex drive shafts).

The only recoring issue was that I'd slam it into walls which would push both front wheels backwards and snap the steering servo horn. I think it was the K-parts tree. I bought soooo many of those.

Hopefully I'll just crash less these days. 

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43 minutes ago, Cuiken said:

I'd not quite anticipated this level of love for the ORV chassis.

I think that's my mind made up. Can't wait to problem solve the drive train :)

It is an absolute Tamiya classic mate, possibly the most well known Tamiya in generalūüėé

5 hours ago, OoALEJOoO said:

@87lc2 I just checked the manuals and interestingly swing-shafts have the same 19808071 p/n for both the Monster Beetle and the BlackFoot, even though it is different!

Screenshots of the manuals' relevant sections:

MB_BF.thumb.jpg.7782d7157170561824f3fb398788ead9.jpg

All parts should fit interchangeably, but if you order by p/n maybe you might not get the BlackFoot version if the store has old stock (?).

*Edit: I believe the Frog/Brat parts you would need to shift to regular dogbones are (looking at the Frog's manual):

  • 9808038 Drive Shaft (dogbone)
  • 9808039 Wheel Axle

This is fascinating @OoALEJOoO, I've just checked my MB on the bench and having not run it much since the MIP ball diff swap using the Frog universals (as instructed by the manufacturer as I have an original MB - well sort of, lots of it has been replaced now with rere parts!ūüėā) I can confirm there is a wobble with the rear arms at full droop. Well actually there's vibration at anything less than dead horizontal. The frog UJ's are the same configuration as the MB ones, so if the theory about this issue is correct (which this similarity in Frog UJ to MB rere UJ's seems to back up) then these would also cause the same issue with wobble -

JpROrsN.jpeg

I've just ordered the Blackfoot B parts bag to swap out the UK arms to see if this eliminates the wobble. Can I charge the £25 back to you if it makes no difference @OoALEJOoO?

ūüėāūüėāūüėā

I'll report back on this thread if these parts do the trick and get rid of the vibration. @Cuiken, if this sorts it out, it might be worth picking up a Blackfoot B parts bag before your build and putting the unopened MB B parts bag on eBay or something. This is where I got mine this morning -

https://www.jk-rc.co.uk/tamiya-blackfoot-2016-parts/new-tamiya-blackfoot-2016-screw-parts-bag-b-p

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1 hour ago, Tamiyastef said:

Take a look at this if you want:

Outtakes at the end.

Just subbed. Very cool vid.

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7 hours ago, Sogogi said:

I personally think that tamiya cars are not the best value for the money(when we look at the performance, durability etc). I really like tamiya cars because of nostalgia + uniqueness that is hard to find from other manufacturers. 

This I agree with, there are others out there that offer more for less money. BUT I still buy Tamiya because they (usually) look so good!

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It was @Honza who pointed to me the difference of the MB vs BF universals some time ago. All credit goes to Honza.

I don't own a BF. However, I can give testament that a 90deg universal like the ones in the BF indeed reduces wobble compared to either a regular dogbone or a non 90deg universal. I recently converted a M06 to M06"Ra" by using taller uprights (from the M05Ra) that increase ride-height and droop. The car had considerable wobble with the standard dogbones, even more wobble with regular "flat" universals, and zero wobble with 90deg universals.

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2 hours ago, alvinlwh said:

That is the one I am about to hit buy on a few days ago and I got hit by a leaking roof that cost £950 to fix so unfortunately no MBT for me.

You need to get your priorities straight @alvinlwh, we all know adding a new Tamiya to the collection trump's a leaky roof hands down mateūü§ĒūüėČ

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