Hotshot or Frog?

[alvinlwh 5895]

Further examination after getting home, the rubber boot is badly torn up. Really disappointed. 

[Frog Jumper 3662]

I'm sorry it was such a let down for you.  

I know you'll chalk it up to a 30yo model and crappy design and then move on.

I was hoping you would have good luck and learn to enjoy the ORV like I do...

C'est la vie...

Terry

 

[Fuijo 880]

The dogbone popping out may be linked to your spacing out of the rear arm stopper. Personally I would figure out how to fit it without the spacers.

[Frankster 2033]

Nice color scheme.  Sorry to hear about the missing dog bone.  The monster beetle has universals making loosing them much harder

[alvinlwh 5895]

3 hours ago, Frog Jumper said:

I know you'll chalk it up to a 30yo model and crappy design and then move on.

 

7 minutes ago, Fuijo said:

The dogbone popping out may be linked to your spacing out of the rear arm stopper. Personally I would figure out how to fit it without the spacers.

Both maybe correct and related. I did came to the same suspicion myself last night when taking the thing apart and close examination. I decided to try inserting a 1mm spacer into the axle cup to push the dogbone towards the drive cup and reducing spacer to 0.5mm on the stopper. 

The stopper could be restricting movement due to its 30yo manufacturing machine going out of specs thus requiring something to be done and things just fall apart from there. I am just surprised that 1mm is all it takes. It seem to me that only one side falls out while I had the 1mm spacers on both side shows that the manufacturing process is not as precise as it was. 

Another possible solution is to insert spacer behind the bearings to push the drive shaft inwards. 

[alvinlwh 5895]

15 minutes ago, Frankster said:

Nice color scheme.  Sorry to hear about the missing dog bone.  The monster beetle has universals making loosing them much harder

Color scheme is just a reverse of the box art having more pink for a girl's car. It was my choice of paint that gave this unexpected result, good or bad. 

Speaking of universals and MB (and also to you @Fuijo) do they work? I read on some threads here that they stay together at the axle end but still can pop out at the gearbox end? Also, I read a lot of "pop outs" on MB and Frogs even without the spacer mod on the stopper, so it may not be unique to my mod or the Frog? Universals are rather expensive to just try if they don't work. 

[Saito2 6686]

The side that yours popped out is seems to have a longer distance between the drivecups in general.

3 hours ago, alvinlwh said:

Speaking of universals and MB (and also to you @Fuijo) do they work? I read on some threads here that they stay together at the axle end but still can pop out at the gearbox end? Also, I read a lot of "pop outs" on MB and Frogs even without the spacer mod on the stopper, so it may not be unique to my mod or the Frog? Universals are rather expensive to just try if they don't work. 

Personally, I've never had luck with them on the trucks. For the people that contacted Tamiya USA for a fix for their defective Blackfoots (which came with the universals stock), Tamiya USA wound up sending the Frog dogbone set-up as a fix.

https://www.tamiyaclub.com/forum/index.php?/topic/98022-blueprinting-a-blackfoot/

Here's link to extensive thread about the Frog's cousin, the Blackfoot. It might be a bit wordy but there's some stuff in there that might apply to you're problem. There's a clear shot of the universal shaft on the right with less drivecup slot engagement than the left. Hopefully you can use some this. I do apologize for not being more specific about the Frog's idiosyncrasies in my first page post. I'm more of a Hotshot-guy, which doesn't suffer these types of issues but does suffer from a totally wonky suspension system, so I didn't want to sound overly negative about the Frog (which I like too). Part of the shortcomings of these older Tamiyas and working up ways to fix them is part of the intrigue for me, but I can totally understand your disappointment. Don't give up! 

[alvinlwh 5895]

@Saito2I think you are absolutely right. Ignore my message to you regarding the left and right not being equal. I sent that before reading your post.

It is quite long and will take me a while to digest. Also, I do not have many tools or means to machine some of your solution. 

It may take a while to get it running properly, as I said a the beginning of the build defiantly not a beginner's build and I am glad I did not make my wife build it as her first build. 

[El Gecko 1344]

1. Try putting the rear arm stoppers on the opposite sides. IIRC, one side is smoother and allows more free movement of the trailing arm. Also, yes: the stoppers should be screwed right up tight to the chassis sides... no spacers otherwise the driveshafts are guaranteed to pop.

2. The 53908 universal shafts are great, but they need the rear suspension lowered at full extension otherwise they pop out every few seconds.

The biggest issue on any ORV is when the trailing arm flexes while cornering. It's worse on one side as you discovered, but it's almost always the inside wheel that loses a driveshaft, because the inside wheel has the least weight on it, especially under braking, and the driveshaft end is the least engaged with the diff yoke at full suspension extension. Then you add the cornering forces flexing the inner trailing arm out from the chassis even further, and it's no surprise what happens.

I made some little aluminum shims to solve this by slightly limiting the ride height, which to me is an acceptable tradeoff to keep those pesky driveshafts where they're supposed to be. My trailing arms and particularly the opening in the aluminum gearbox halves are all VERY worn out, and it hasn't thrown a driveshaft since. This fix works to smooth out the old style hex shafts as well, because even those bind and crunch and sometimes pop out at full extension. Tamiya should have included these in all ORV kits in some form once the problem presented itself, but I have a feeling they wanted to preserve as much suspension travel as possible.

[Willy iine 18806]

I don't remember my original Frog popping drive axles that easily.   Did Tamiya change something for the worse?  The hex joint wore out on mine (and diff started to skip) so dogbones seems a much better option.   Oh well.. 

[El Gecko 1344]

1 hour ago, Willy iine said:

I don't remember my original Frog popping drive axles that easily.   Did Tamiya change something for the worse?  The hex joint wore out on mine (and diff started to skip) so dogbones seems a much better option.   Oh well.. 

Depends on your definition of "worse". I think they traded one problem for another. I too have never popped one of the original hex shafts, but they don't spin freely at full extension, bumping and clacking as they rotate. If you've got the car on the bench with wheels spinning, lift both rear trailing arms just slightly and you can hear everything clear out.

The bumpstops help keep the driveshafts from attaining such a severe angle, which keeps the hex ends from binding and wearing out as fast, and can also help keep the original-style gear diff together for longer. Part of the problem with the diff is that the driveshafts tug on the ends of the diff yokes, forcing them downward toward the ground and causing a misalignment inside the gearbox. The bumpstops take the "pressure" off the diff yokes and help keep the diff together, straighter, and hopefully lasting longer.

On the other side of things, the diff isn't as stressed with the dogbones and universals because they have less wiggle room before they pop out, but that means the bumpstops are basically required to actually drive it at more than half throttle (IMHO they're required for any ORV if you want to keep the diff/driveshafts of any type in working order).

I would choose the universals because they're attached to the wheel axles, impossible to lose if they pop out unless the grub screw has also come loose. I have original hex shafts in 2 cars, and the one with universals and bumpstops did 12 stints of the last Racing by Post track without throwing any driveshafts. This is a car with sticky 2.2 road tires on Blackfoot wheels, so about the most flex one can get out of those rear trailing arms. Definitely "race-proven" in my eyes. I tried all kinds of other tricks and tweaks, but these bumpstops had the most immediate, significant effect on keeping the driveshafts in.

[Willy iine 18806]

@El Gecko  Thanks for the info.   You definitely have a lot of knowledge with both the original and rere ORV..  I will have to check one out (rere) for myself and play with it some to fully understand the pros and cons.  Unfortunately my pretend RC shop is full again   so I will have to check it out later on when I come back to buggies down the road.

[OoALEJOoO 3127]

The re-re Monster Beetle universals cause a lot of wheel wobble/vibration when fully extended. The orientation of the universal's cross-joints actually increase torque oscillation instead of cancelling it. Indeed the solution is to go back to dog-bones. This was the solution for mine. No pop-outs even on rough bashing (silver stock).

This was apparently fixed in the re-re Black Foot. It's universals have the cross-joints rotated 90deg, effectively canceling out most of the torque oscillations.

[Frog Jumper 3662]

I’m using dog bones in my BarbieFoot 2.  I shortened up the shocks (50520s) on the rear to help prevent the DBs from popping out.

[El Gecko 1344]

2 hours ago, OoALEJOoO said:

The re-re Monster Beetle universals cause a lot of wheel wobble/vibration when fully extended. The orientation of the universal's cross-joints actually increase torque oscillation instead of cancelling it. Indeed the solution is to go back to dog-bones. This was the solution for mine. No pop-outs even on rough bashing (silver stock).

This was apparently fixed in the re-re Black Foot. It's universals have the cross-joints rotated 90deg, effectively canceling out most of the torque oscillations.

I don't remember which version of universals I have, but I thought "torque oscillations" were my problem, too. Until I added the bumpstops and it all went away. Now the car is smooth as can be at any speed. The typical 2.2 monster wheels are not well-balanced to begin with, and the large, soft MB tires make it worse at high speeds.

 

2 hours ago, Frog Jumper said:

I’m using dog bones in my BarbieFoot 2.  I shortened up the shocks (50520s) on the rear to help prevent the DBs from popping out.

I tried shortening the shocks too, but there is always a bit of slop there as it switches from compression to tension, so it was unreliable unless the shocks were limited more than I wanted them to be. The bumpstops are unaffected by slop or any other shock setup.

[alvinlwh 5895]

1 minute ago, El Gecko said:

The bumpstops are unaffected by slop or any other shock setup.

I had seen the bump stop solution before (maybe even posted by you) but the problem is I have no means of matching an aluminium piece that way, unless I managed to find a piece that is the right shape and size,. 

[El Gecko 1344]

3 hours ago, alvinlwh said:

I had seen the bump stop solution before (maybe even posted by you) but the problem is I have no means of matching an aluminium piece that way, unless I managed to find a piece that is the right shape and size,. 

I'm sure I've seen it around and used it as unconscious inspiration but no, this is my first time posting this mod. The pic above is of my Brat, which is the most recent one, still running original hex shafts. The bumpstops made the car incredibly smooth, even moreso than the Blaster with universals and my original Frog with no bumpstops and hex shafts. The Blaster is an ex-MudBlaster that is now closer to a stadium truck with a buggy body, or an "outlaw" buggy with stadium truck wheels. It was my first time trying the universal setup, and instantly had problems. So I went on a wild goose chase doing everything I could think of until installing bumpstops.

The mod itself is quite simple if you have access to a drill, a file and a good pair of side cutters. I made the Brat bumpstops from aluminum sheet and only used a Dremel to knock down some of the larger areas to make it fit. Same with the steel ones I made for the Blaster. While a Dremel makes the process faster, it's not strictly necessary. And for that matter, I don't think it's even necessary that the bumpstops are made of metal. All you really need is a 90 degree bend and a hole for the mounting screw, and the rest can be filed down to fit. Thickness is around 1.5mm, and obviously you'd want to make sure it's even on both sides. But they are really trivial to make, as I've learned.

[alvinlwh 5895]

1 hour ago, El Gecko said:

The mod itself is quite simple if you have access to a drill, a file and a good pair of side cutters. I made the Brat bumpstops from aluminum sheet and only used a Dremel to knock down some of the larger areas to make it fit. Same with the steel ones I made for the Blaster. While a Dremel makes the process faster, it's not strictly necessary. And for that matter, I don't think it's even necessary that the bumpstops are made of metal. All you really need is a 90 degree bend and a hole for the mounting screw, and the rest can be filed down to fit. Thickness is around 1.5mm, and obviously you'd want to make sure it's even on both sides. But they are really trivial to make, as I've learned.

Aluminium sheet is the problem, and bending it. I assume (if I find some) bending it at 90 degrees will not break it? 

Now that you mentioned it, I wonder if I can glue some 1.5mm plastic or something to use as a bump stop? Or even aerial tube? 🤔I think fish tank airlines are 1.something mm thick, cut down the middle and slot on and glued...

[Frog Jumper 3662]

1 hour ago, alvinlwh said:

Aluminium sheet is the problem, and bending it. I assume (if I find some) bending it at 90 degrees will not break it? 

Now that you mentioned it, I wonder if I can glue some 1.5mm plastic or something to use as a bump stop? Or even aerial tube? 🤔I think fish tank airlines are 1.something mm thick, cut down the middle and slot on and glued...

You should be able to find inexpensive and soft aluminum bar metal at your local Home Depot (or nearest UK equal).  Its easy to work with, cuts like butter with a hack saw and file, drills like wood.  Cut one long piece, bend it, then cut it in half.  That way you have two of the same.  Here is what I used in the past:  https://www.homedepot.com/p/Everbilt-1-1-2-in-x-48-in-Aluminum-Flat-Bar-with-1-8-in-Thick-801987/204273937

That example might be a little thick for this applicaiton, but AL is soft and bends very easily.  If you have a bench vice, you could bend it with a hammer it to get it more 90deg.

Terry

 

[alvinlwh 5895]

1 minute ago, Frog Jumper said:

You should be able to find inexpensive and soft aluminum bar metal at your local Home Depot (or nearest UK equal).

That's the problem, the nearest equivalent is closed down and even that one requires an expensive ferry ride to get to. 

Next nearest one is 155 miles away (same expensive ferry ride required). 

[Busdriver 6209]

On 8/19/2022 at 1:19 AM, Frog Jumper said:

 And last thing for now, get the Xeostar tranny brace and fit that right away.  Otherwise be prepared for your tranny getting worn out really fast bc of side plate flexion.  Getting this brace will let you run a mild brushless with no issues.

 

Bit late to the party but this brace comes courtesy of our own @Xeostar. Costs about a tenner and will even ship to your neck of the woods. Send him a pm

[Frog Jumper 3662]

10 minutes ago, alvinlwh said:

That's the problem, the nearest equivalent is closed down and even that one requires an expensive ferry ride to get to. 

 

 

Surely you can find a place to find a scrap piece of aluminum and a hack saw???

ETA:  call these guys:  https://www.orkfab.com/

 

[alvinlwh 5895]

3 minutes ago, Frog Jumper said:

Surely you can find a place to find a scrap piece of aluminum and a hack saw???

Yes I am trying to think of where to find some. Maybe even around the house. 

[Frog Jumper 3662]

7 minutes ago, alvinlwh said:

Yes I am trying to think of where to find some. Maybe even around the house. 

https://www.orkfab.com/

 

I bet if you call them and told them what you're looking for, they can whip it up in about 10 minutes for a case of beers...

Terry

 

[alvinlwh 5895]

19 minutes ago, Frog Jumper said:

https://www.orkfab.com/

 

I bet if you call them and told them what you're looking for, they can whip it up in about 10 minutes for a case of beers...

Terry

 

I know them. Problem is they deal with heavy stuff, like the North Sea pipelines. Not sure if they do trade customers only or not. Still, I am keeping an eye out for scrap piece of aluminium.