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Cuiken

Do I want a Monster Beetle?

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3 hours ago, Kol__ said:

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 mate🤔😉

Luckily I spotted the leaky roof before I dropped £200 on the MBT, and before it got really bad, the water had not even gotten down to ceiling level yet.

TRVQcaa.jpg

Amazingly, I was in fact up on the loft grabbing Italian Red spray paint to prepare for the MBT when I spotted the leak. And believe it or not, this is the second time I was up on the loft getting modelling related items when I spotted a leak before it got bad. So can say my modelling hobby actually prevented serious damage to the house!

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9 hours ago, alvinlwh said:

Luckily I spotted the leaky roof before I dropped £200 on the MBT, and before it got really bad, the water had not even gotten down to ceiling level yet.

Wow, good find mate, and well spotted so early. We had a similar issue here last year and it took the roofer 3 attempts to solve the problem and fix the leak! Luckily he only charged us the first time and returned for free until the leak was solved, water ingress in the home can be a right tricky barsteward!

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11 hours ago, alvinlwh said:

Luckily I spotted the leaky roof before I dropped £200 on the MBT, and before it got really bad, the water had not even gotten down to ceiling level yet.

TRVQcaa.jpg

Amazingly, I was in fact up on the loft grabbing Italian Red spray paint to prepare for the MBT when I spotted the leak. And believe it or not, this is the second time I was up on the loft getting modelling related items when I spotted a leak before it got bad. So can say my modelling hobby actually prevented serious damage to the house!

Was similar to what happened with us, we had some damp. If it wasn’t for me going into our loft to get some rc goodies to work on for my time off, it could have been a lot worse. Should reward yourself with a spend on the money you’ve saved 😂

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On 1/13/2023 at 3:58 AM, 87lc2 said:

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.  

No this isn't true 

the reason is that as you put power through the 3 cogs in the diff they are angled and that creates an opposing outward force on both sides. The sides of the gearbox are thin metal and this flexes slightly.

as it flexes, this loosens the mesh on the diff cogs and they can slip. 
 

the higher the torque demand the higher the force the more the cogs spread and the more they slip.

this causes wear of the 3 metal cogs and exacerbates the slipping 

an MIP ball diff fixes it because the ball diff doesn't have the angles mating surfaces that pushes the diff apart.

bit at £80 it's an expensive part when you can get the clamp I designed with @Xeostar for way less and if you do put a 3s brushless combo through it like me, when the diff cogs do finally wear (just like you'll burn out your ball diff eventually) then it's only £10 for new cogs 

plus it looks ace 

JJ

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On 1/13/2023 at 4:25 AM, 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

I swapped to ORV dog bones and it's still the same - it's the spreading of the diff cogs due to their angle 

JJ

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2 hours ago, Problemchild said:

I swapped to ORV dog bones and it's still the same - it's the spreading of the diff cogs due to their angle 

JJ

That's not good news.  So why is the Blackfoot OK and the Beetle a clicker?  Internal diff parts are all the same as far as I know. 

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7 hours ago, Problemchild said:

No this isn't true 

the reason is that as you put power through the 3 cogs in the diff they are angled and that creates an opposing outward force on both sides. The sides of the gearbox are thin metal and this flexes slightly.

as it flexes, this loosens the mesh on the diff cogs and they can slip. 
 

the higher the torque demand the higher the force the more the cogs spread and the more they slip.

this causes wear of the 3 metal cogs and exacerbates the slipping 

an MIP ball diff fixes it because the ball diff doesn't have the angles mating surfaces that pushes the diff apart.

bit at £80 it's an expensive part when you can get the clamp I designed with @Xeostar for way less and if you do put a 3s brushless combo through it like me, when the diff cogs do finally wear (just like you'll burn out your ball diff eventually) then it's only £10 for new cogs 

plus it looks ace 

JJ

 

7 hours ago, Problemchild said:

I swapped to ORV dog bones and it's still the same - it's the spreading of the diff cogs due to their angle 

JJ

 

5 hours ago, 87lc2 said:

That's not good news.  So why is the Blackfoot OK and the Beetle a clicker?  Internal diff parts are all the same as far as I know. 

I think 2 different scenarios are being discussed, one is driveline vibration, the other is the diff clicking. The diff clicking requires the bracing or MIP diff, the vibration is rectified by swapping to the 90 degree bones in the CVD’s rather than the inline original ones.

At least that is my understanding on the discussions

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@Problemchild, @mtbkym01 Indeed, the vibration and the clicking are separate issues. However, my theory is that the vibration worsens the clicking.

The vibration caused by the MB universals translate into higher torque oscillations that are present along all the drive train components -including the diff. The MB universals will hammer the diff more than the BF, thus leading to premature clicking that the BF might only see if abused or after more use.

If you already have a clicking MB, I doubt swapping to ORV dogbones, or even to the BF universals, will make the clicking disappear as the damage/deflection causing the clicking is already done.

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38 minutes ago, mtbkym01 said:

2 different scenarios

This.

But:

The CVDs binding combined with the softer/grippier tires of the MB might mean that diff issues pop up more often in it than the BF due to more stress on it...

Hard to know for sure tho.

ADDITION: beaten again with a better post by @OoALEJOoO :P

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6 hours ago, mtbkym01 said:

 

 

I think 2 different scenarios are being discussed, one is driveline vibration, the other is the diff clicking. The diff clicking requires the bracing or MIP diff, the vibration is rectified by swapping to the 90 degree bones in the CVD’s rather than the inline original ones.

At least that is my understanding on the discussions

Mine is clicking and it has the brace sold on this forum, same as my Blackfoot which is silent.  Also put spacers in the shocks to limit travel and no help.  I'll try swapping the shafts just to see if it helps.  

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Having started this thread to help me decide whether I want to buy a MB after being dissapointed by the BF I had as a kid I now find myself watchign videos of the BF and thinking I might just buy another of those!? Tamiya are weird but my own nostagilc reactions to their cars is weirder.

To be fair the BF r-re is a better car than the original but still. I guess it's just the awesome shell.

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10 hours ago, Cuiken said:

Having started this thread to help me decide whether I want to buy a MB after being dissapointed by the BF I had as a kid I now find myself watchign videos of the BF and thinking I might just buy another of those!? Tamiya are weird but my own nostagilc reactions to their cars is weirder.

To be fair the BF r-re is a better car than the original but still. I guess it's just the awesome shell

To be fair, they're both awesome trucks, and from a rere perspective there's very little difference other than cosmetics really. I would say though that the MB shell is probably better at handling rolls etc. due to being stumpier and more rounded with those Beetle curves. 

So come on, what you gonna go for? MB... BF... 🤷🏻🤷🏻😂😂

I got the BF B parts bag in the post today and firstly I'm going to fit the new UJ to only one side and bench test it. Then we'll know for sure!👍

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MB was the car I really wanted as a kid as well. I’ve had mine 2 years, kept it stock. It does have a couple of quirks, but all in all a fun car. 

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7 hours ago, 87lc2 said:

Mine is clicking and it has the brace sold on this forum, same as my Blackfoot which is silent.  Also put spacers in the shocks to limit travel and no help.  I'll try swapping the shafts just to see if it helps.  

Hi, I suspect something else it at play here with your MB. We've had loads of MBs fitted with braces and they fix the issue, as far as I'm aware this is the only report of them not stopping the clicking. Something else must be going on.

I've got the most abused MB running a 5.5T brushless on 3S and the gearbox takes it, concrete, grass anything. 

This is my poor test mule and it's taken more abuse than any MB should be expected to take just to really give the braces and gearbox the hardest possible life.

 

20230117_201937.jpg

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Today I swapped out the Frog UJ's for the Blackfoot ones.

I first span up the buggy on the bench to assess the vibration again with the Frog UJ's. Pretty bad unless unless the suspension is pushed up to bring the drive shafts horizontal. I then removed only one of the Frog UJ's and replaced it with a Blackfoot one. 

OXgCymR.jpeg

Upon spinning up the truck in this format, the vibration from the Blackfoot UJ side was gone and of course still remaining on the Frog side.

IWqNOPx.jpeg

As previously discussed in this thread, the Frog/MB UJ (bottom in the pic above) is of a different configuration to the BF one (top on pic).

Swapped the other side and put it all back together. I can confirm that with the BF UJ's there is no vibration. Thanks @OoALEJOoO👍👍

J59zKYd.jpeg

NJzOygA.jpeg

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@Kol__ That's an awesome looking Monster Blitzer Beetle :) I'm a big fan of that livery.

That was some quick shipping on the BF parts! Glad you now have a wobble-free runner.

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5 hours ago, Kol__ said:

Today I swapped out the Frog UJ's for the Blackfoot ones.

I first span up the buggy on the bench to assess the vibration again with the Frog UJ's. Pretty bad unless unless the suspension is pushed up to bring the drive shafts horizontal. I then removed only one of the Frog UJ's and replaced it with a Blackfoot one. 

OXgCymR.jpeg

Upon spinning up the truck in this format, the vibration from the Blackfoot UJ side was gone and of course still remaining on the Frog side.

IWqNOPx.jpeg

As previously discussed in this thread, the Frog/MB UJ (bottom in the pic above) is of a different configuration to the BF one (top on pic).

Swapped the other side and put it all back together. I can confirm that with the BF UJ's there is no vibration. Thanks @OoALEJOoO👍👍

J59zKYd.jpeg

NJzOygA.jpeg

I don't get it. I have those Frog UJs on my Blaster (the ones on the bottom in the pic), and they don't seem to have this strange oscillation problem? Yes, they were rough at first, until I put 2mm bumpstops on the trailing arms because the driveshaft angle was just too severe. I don't have a BF set to compare, but it has been smooth as can be ever since. I'm evangelizing again, but the bumpstops seem to work for the old hex shafts, too. It won't make them entirely bulletproof, but it will considerably slow down their wear. FWIW Both the Blaster and my Frog are on stock gearbox internals with no braces. 21t motor w/16t pinion in the Blaster, 17t motor w/18t pinion in the Frog.

Also have to agree, that's a fantastic color combo with the Blitzer decals :D

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@El Gecko The vibration issue is only really visible if you run the car on a bench, with the tires spinning in the air. I think this is because the small mass of the wheels are not sufficient to dampen the oscillation and therefore its amplitude is very visible.

When running, the tires are now coupled to the ground, and now the entire mass of the car is connected to the ground via the wheels. This pretty much makes the amplitude of the oscillation very small and difficult to see. However, the torque oscillation is still there (it is only the amplitude which gets reduced) and it will still stress the drivetrain.

The issue is present pretty much at any droop, but it does become less as the suspension compresses.

Maybe give your Mud Blaster a check on a bench. On my MB, at first I didn't notice the issue until I put it on a bench, although I don't have a real bench, just an old ESC box or whatever is handy!! :)

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On 1/18/2023 at 11:59 PM, OoALEJOoO said:

@El Gecko The vibration issue is only really visible if you run the car on a bench, with the tires spinning in the air. I think this is because the small mass of the wheels are not sufficient to dampen the oscillation and therefore its amplitude is very visible.

When running, the tires are now coupled to the ground, and now the entire mass of the car is connected to the ground via the wheels. This pretty much makes the amplitude of the oscillation very small and difficult to see. However, the torque oscillation is still there (it is only the amplitude which gets reduced) and it will still stress the drivetrain.

The issue is present pretty much at any droop, but it does become less as the suspension compresses.

Maybe give your Mud Blaster a check on a bench. On my MB, at first I didn't notice the issue until I put it on a bench, although I don't have a real bench, just an old ESC box or whatever is handy!! :)

I ran the car on the bench today at all RPMs and did not get any vibration whatsoever with the wheels removed. I definitely would have seen it because the suspension is very soft, which was causing the trailing arms to "jump" under power before I put the bumpstops on. Now that the bumpstops are on, there is no indication of anything amiss--it's perfectly smooth, as it should be (same as the old hex shaft setup, anyway). I know from having the wheels on another car that they're very imbalanced, no matter what tires are on, so that could be a factor too in your case.

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Forgot to mention that the issue is only present when the car is on a bench and with the tires on. This video captures the effect:

Tamiya Monster Beetle 2015 Re-release: Still Problems? Frog Universal Drive Shaft vs. Dogbone Test! - YouTube

Without trying to sound like a nerd (I'll probably still fail miserably :)):

I think there is clear evidence that the issue is not caused by unbalance:

  • When pressing the suspension to make the original MB universals straight (zero droop), the wobble disappears. If it were unbalance, it would remain.
  • Switching to dogbones (or even better BF universals) does not modify any unbalance. Still, it solves the issue.
  • Back when I was troubleshooting my MB, I also suspected unbalance. I placed the MB rear wheels & tires on my Lunchbox and they did not wobble. I also tried putting the LB tires on the MB and, while they did not wobble on the LB, they did wobble on the MB.

So why is the wobble issue not present when the tires are off? My thought is that it's because the torque oscillation is only present when there is torque, and torque is only present with load. When the car is without tires, the load to the motor is tiny (there is a very small rotational inertia to accelerate) which would also make the torque oscillation very tiny. The moment you put the tires, the rotational inertia is orders of magnitude higher, thus requires more load & torque to accelerate. You can see in the video that the wobble is only present during acceleration or deceleration, and that at 2:30 that the wobble actually tends to disappear when the tire reaches stable speed (no acceleration, thus the torque is back to being very small). Another factor is that the mass of the tires change the natural frequency response of the system (tires off = higher frequency harder to see, tires on = lower frequency easier to see).

@El Gecko Try giving it a shot on the bench with the wheels on.

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On 1/17/2023 at 7:04 AM, Ziddan said:

This.

But:

The CVDs binding combined with the softer/grippier tires of the MB might mean that diff issues pop up more often in it than the BF due to more stress on it...

Hard to know for sure tho.

ADDITION: beaten again with a better post by @OoALEJOoO :P

CVDs bind due to the over extension of the suspension. 
 

this also causes the dog bones to escape under power and extension. 
 

I swapped to dog bones and painted them hi-vis orange 

 

JJ

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46 minutes ago, OoALEJOoO said:

Forgot to mention that the issue is only present when the car is on a bench and with the tires on. This video captures the effect:

Tamiya Monster Beetle 2015 Re-release: Still Problems? Frog Universal Drive Shaft vs. Dogbone Test! - YouTube

Without trying to sound like a nerd (I'll probably still fail miserably :)):

I think there is clear evidence that the issue is not caused by unbalance:

  • When pressing the suspension to make the original MB universals straight (zero droop), the wobble disappears. If it were unbalance, it would remain.
  • Switching to dogbones (or even better BF universals) does not modify any unbalance. Still, it solves the issue.
  • Back when I was troubleshooting my MB, I also suspected unbalance. I placed the MB rear wheels & tires on my Lunchbox and they did not wobble. I also tried putting the LB tires on the MB and, while they did not wobble on the LB, they did wobble on the MB.

So why is the wobble issue not present when the tires are off? My thought is that it's because the torque oscillation is only present when there is torque, and torque is only present with load. When the car is without tires, the load to the motor is tiny (there is a very small rotational inertia to accelerate) which would also make the torque oscillation very tiny. The moment you put the tires, the rotational inertia is orders of magnitude higher, thus requires more load & torque to accelerate. You can see in the video that the wobble is only present during acceleration or deceleration, and that at 2:30 that the wobble actually tends to disappear when the tire reaches stable speed (no acceleration, thus the torque is back to being very small). Another factor is that the mass of the tires change the natural frequency response of the system (tires off = higher frequency harder to see, tires on = lower frequency easier to see).

@El Gecko Try giving it a shot on the bench with the wheels on.

It's not designed to be run without weight on the wheels 

With wheels on is it just not that small amount of extra weight extending the travel just that small amount more?

limiting suspension travel is the best way to resolve this issue.

I've put a 1mm thick piece of plastic between the chassis the rear arms and that fixed it - or you can add something to the piston shaft in the damper to stop it over extending 

JJ

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On 1/17/2023 at 1:05 PM, 87lc2 said:

Mine is clicking and it has the brace sold on this forum, same as my Blackfoot which is silent.  Also put spacers in the shocks to limit travel and no help.  I'll try swapping the shafts just to see if it helps.  

The xeostar ones or the multi piece black 2mm plastic ones?

 

was the car already clicking before?

 

JJ

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8 hours ago, Problemchild said:

It's not designed to be run without weight on the wheels 

With wheels on is it just not that small amount of extra weight extending the travel just that small amount more?

limiting suspension travel is the best way to resolve this issue.

When I tested mine on the bench the vibration and wobble were there until the UJ's were horizontal. When I ran it on the floor the vibration and hideous rattling noise it was making was still there. If run like that, it would for sure cause excessive wear, premature end of life of components and eventual early failure of the drive train.

Now this is with the MIP ball diff, which I will say has rather long outdrive cups, so that may well also be a factor here. However, as Nordic Visons vid linked above shows, it is also present on the stock rere MB with standard outdrive cups.

Anyway, all that said, the problem is instantly and completely cured by the BF UJ's. I am a happy chappy now😄 And it appears that fitting the dog bones also provide a solution as well.

And I don't know about your ORV, but with the standard BF springs on the back shocks in of my MB, filled with medium shock oil, using 2 hole pistons and no preload collars fitted to the shock bodies (standard MB/BF set up as I understand it), there is little to no compression of the suspension when the buggy is placed on the ground. The bizarre horizontal angle of the shocks seem to mean they only actuate and compress under load from acceleration, bumps and jumps etc.

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On 1/21/2023 at 10:16 AM, OoALEJOoO said:

Forgot to mention that the issue is only present when the car is on a bench and with the tires on. This video captures the effect:

Tamiya Monster Beetle 2015 Re-release: Still Problems? Frog Universal Drive Shaft vs. Dogbone Test! - YouTube

Without trying to sound like a nerd (I'll probably still fail miserably :)):

I think there is clear evidence that the issue is not caused by unbalance:

  • When pressing the suspension to make the original MB universals straight (zero droop), the wobble disappears. If it were unbalance, it would remain.
  • Switching to dogbones (or even better BF universals) does not modify any unbalance. Still, it solves the issue.
  • Back when I was troubleshooting my MB, I also suspected unbalance. I placed the MB rear wheels & tires on my Lunchbox and they did not wobble. I also tried putting the LB tires on the MB and, while they did not wobble on the LB, they did wobble on the MB.

So why is the wobble issue not present when the tires are off? My thought is that it's because the torque oscillation is only present when there is torque, and torque is only present with load. When the car is without tires, the load to the motor is tiny (there is a very small rotational inertia to accelerate) which would also make the torque oscillation very tiny. The moment you put the tires, the rotational inertia is orders of magnitude higher, thus requires more load & torque to accelerate. You can see in the video that the wobble is only present during acceleration or deceleration, and that at 2:30 that the wobble actually tends to disappear when the tire reaches stable speed (no acceleration, thus the torque is back to being very small). Another factor is that the mass of the tires change the natural frequency response of the system (tires off = higher frequency harder to see, tires on = lower frequency easier to see).

@El Gecko Try giving it a shot on the bench with the wheels on.

Just wanted to follow up here and say that I'm still not sure on my setup. I would like to try a set of the BF UJs to compare, because I do indeed have some vibration with the wheels on (any kind of wheels, not just big ones). It's not just during acceleration or deceleration either. I can hold throttle at a specific RPM and it definitely gets worse at some speeds, which seems to point to a bent axle or unbalanced wheel/tire. There is also a slight "flutter" I would call it, on acceleration, which I had previously just attributed to driveline flex (called "axle hop" in 1:1 cars). This flutter is possibly what you're talking about with the difference in the UJ orientations, but it doesn't seem bad enough to cause any issues on the ground. However I don't have a BF set to compare.

I also discovered some excessive wear on my diff yokes already, probably from when I was driving without bumpstops/trailing arm stiffening. This could also be causing some of the vibrations. Notice the large gap in the yoke opening above the UJ pin, it's because the pin has worn a divot inside the diff yoke--coincidentally the same sort of issue that used to happen with the old hex shafts. Although the yoke remains usable for now, it does have a lot of slop.

 

uj_closeup_01.jpg

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