MIP Blackfoot diff question

[Saito2 6673]

Upon assembling a new Blackfoot re-release, I noticed the stock plastic bearing retainers that fit in the stamped metal gearbox sideplates are particularly sloppy, allowing the diff gear to back and forth and side to side (basically, all around). The MIP diff replaces the retainers and bearings with a larger, single flanged bearings. Do these fit with more precision than the stock pieces? I don't want to go back to the universals (I have Frog 'bones in there now), but that moving diff gear worries me a bit.

[Hobbimaster 190]

Yes, The bearings in mine where a nice snug fit. I then used a little shoe goo to close up the little indexing hole on the stamped gearbox plates, that is no longer used when removing the plastic retainers.

[moffman 5746]

Yeah mine too nice and snug!  and the Uj's were nice and smooth aswell my monster beetle I had to change to frog dog bones because it was vibrating like mad and for the life of me I knew where it was vibrating from but couldn't actually see the problem? It was the strangest thing ever??

[ruebiracer 1043]

4 hours ago, Saito2 said:

Upon assembling a new Blackfoot re-release, I noticed the stock plastic bearing retainers that fit in the stamped metal gearbox sideplates are particularly sloppy, allowing the diff gear to back and forth and side to side (basically, all around). The MIP diff replaces the retainers and bearings with a larger, single flanged bearings. Do these fit with more precision than the stock pieces? I don't want to go back to the universals (I have Frog 'bones in there now), but that moving diff gear worries me a bit.

Hi Saito,

on my Monster Beetles I always glue the bearing carriers with a dab of Shoegoo inside the sideplates. Gives a snug fit, less hazzle during assembly and an additional sealing against debris on dusty conditions. In case, they can be pressed out again and the shoegoo rubbed off the parts...

 

[Saito2 6673]

5 hours ago, ruebiracer said:

on my Monster Beetles I always glue the bearing carriers with a dab of Shoegoo inside the sideplates. Gives a snug fit, less hazzle during assembly and an additional sealing against debris on dusty conditions.

Thanks for the tip.

Nothing is overly precise in those ORV 'boxes but this re-re is noticeably sloppier than my vintage ones. I imagine that's not doing wonders for maintaining a good gear mesh inside. 

I'm kinda stuck on what to do. On one hand, the right rear dogbone end of the universal looks ready to pop out as others have found out. Not wanting to deal with that, I just installed the re-re Frog full dogbone setup. I considered the MIP diff as a solution to the sloppy bearing carriers but they supposedly don't work with the Frog dogbones, only the stock Blackfoot universals. It looks hard to obtain both goals. I will give the Shoegoo a shot so I can retain the Frog axles. Thanks.

[ruebiracer 1043]

53 minutes ago, Saito2 said:

. On one hand, the right rear dogbone end of the universal looks ready to pop out as others have found out. 

Have you thought about shimming the right outdrive inside the metal diff gear? to make it more symmetrical? Should work with a 4mm outer diameter shim put in the metal diff gear before inserting the outdrive...

[Problemchild 2149]

2 hours ago, Saito2 said:

Thanks for the tip.

Nothing is overly precise in those ORV 'boxes but this re-re is noticeably sloppier than my vintage ones. I imagine that's not doing wonders for maintaining a good gear mesh inside. 

I'm kinda stuck on what to do. On one hand, the right rear dogbone end of the universal looks ready to pop out as others have found out. Not wanting to deal with that, I just installed the re-re Frog full dogbone setup. I considered the MIP diff as a solution to the sloppy bearing carriers but they supposedly don't work with the Frog dogbones, only the stock Blackfoot universals. It looks hard to obtain both goals. I will give the Shoegoo a shot so I can retain the Frog axles. Thanks.

What you need is a @Xeostar gearbox brace rather than the expensive MIP diff

 

JJ

[tamiya3speed 462]

The universal will pop out if nothing is done.  Mine goes at least once per run.  My intention is to add internal limiters to the damper but just havent done it yet.  Having said that, I do love running my Monster Beetle.

[Problemchild 2149]

The only way I’ve found is to limit the extension of the suspension 

in  another post I showed a picture of how it’s done in the 1:1 world

 

so I made my own temp solution 

 

this has worked really well but it needs a slightly better solution (this is for my beetle running 3s brushless)

JJ

[Saito2 6673]

The issues with the re-re rear end assembly are so numerous and interconnected, I've had the back of the truck apart in some fashion probably over 20 times by now, but that's all part of the fun. I limited my rear shocks travel through internal shock limiters. That alone took numerous attempts a shimming to get maximum travel while still aiding driveshaft retention. The zip tie looks a whole lot easier. Also part of the problem is the flexing of the rear trailing arms exacerbated by the leverage of the bigger monster tires over the Frog. The standard bearings protrude from their bores in the trailing arms slightly too. If there were some accurate way to deepen the outer bore and recess the bearing more, the universal shaft could be shimmed from the backside, engaging it further in the drive cup/diff outdrive too. In the end, going to the dogbone setup eliminates the need for much of all this but then one is stuck using the stock diff.

For the stock diff, I have created braces for the gearbox sideplates to stop separation but was perplexed by the slop in the bearing carriers. Last night I worked out a solution involving shoegoo and aluminum foil (of all things) to take up the radial clearances in the carriers which I'll detail in a separate thread. Hopefully this will be the last time for reassembly. Good thing I love ORV monsters.

[ruebiracer 1043]

5 hours ago, Saito2 said:

The issues with the re-re rear end assembly are so numerous and interconnected, I've had the back of the truck apart in some fashion probably over 20 times by now, but that's all part of the fun. I limited my rear shocks travel through internal shock limiters. That alone took numerous attempts a shimming to get maximum travel while still aiding driveshaft retention. The zip tie looks a whole lot easier. Also part of the problem is the flexing of the rear trailing arms exacerbated by the leverage of the bigger monster tires over the Frog. The standard bearings protrude from their bores in the trailing arms slightly too. If there were some accurate way to deepen the outer bore and recess the bearing more, the universal shaft could be shimmed from the backside, engaging it further in the drive cup/diff outdrive too. In the end, going to the dogbone setup eliminates the need for much of all this but then one is stuck using the stock diff.

For the stock diff, I have created braces for the gearbox sideplates to stop separation but was perplexed by the slop in the bearing carriers. Last night I worked out a solution involving shoegoo and aluminum foil (of all things) to take up the radial clearances in the carriers which I'll detail in a separate thread. Hopefully this will be the last time for reassembly. Good thing I love ORV monsters.

Still I find the old frogshot diff mod with an internal screw through the diff the best solution. Forces stay inside the diff, drivetrain can be kept with a little slop to run free and smooth, and the forces trying to separate the differential and the sideplates do not kill the ball bearings and "brake" the drivetrain during high torque accelerations. But everyone likes it differently on those old ORV boxes.

On the Rere Tamiya got it totally wrong with shock overall length and spring length. On my friends REre I cut the springs shorter to reduce preload, and on my Runner and the one from my nephew I use Top Force rear springs. They give a a liitle sag in the rear and are much weaker. So before the trailing arm twists, the suspension is moving and the drive shafts goes deeper into the outdrive reducing the danger to pop it out. Hope you get my intention...

[Saito2 6673]

4 hours ago, ruebiracer said:

Still I find the old frogshot diff mod with an internal screw through the diff the best solution. Forces stay inside the diff, drivetrain can be kept with a little slop to run free and smooth, and the forces trying to separate the differential and the sideplates do not kill the ball bearings and "brake" the drivetrain during high torque accelerations. But everyone likes it differently on those old ORV boxes.

True. I admit, I was being a bit lazy making the gearcase braces instead of going with the old frogshot mod. Even if the braces prevent gear skipping, the ball bearings weren't designed to take thrust loading. The other reason I'm probably going to move toward the old frogshot mod is to free up the dogbones. In stock form, the drive cups/outdrives require a specific amount of o-rings to keep the drive cups seated in the diff. The problem is (without the aid of telescoping driveshafts) the dogbones begin to bind as the suspension compresses, certainly not helped by the more extreme angles they operate within (compared to an RC10 for example). There is a noticeable tight spot in the trailing arm's travel from this. One can't do away with the o-rings to alleviate the binding or the drive cups could move out of the diff at full extension. The only solution is to make the diff self contained, in a way, via the mod. One thing leads to another...

[ruebiracer 1043]

On 3/11/2021 at 9:09 PM, Saito2 said:

True. I admit, I was being a bit lazy making the gearcase braces instead of going with the old frogshot mod. Even if the braces prevent gear skipping, the ball bearings weren't designed to take thrust loading. The other reason I'm probably going to move toward the old frogshot mod is to free up the dogbones. In stock form, the drive cups/outdrives require a specific amount of o-rings to keep the drive cups seated in the diff. The problem is (without the aid of telescoping driveshafts) the dogbones begin to bind as the suspension compresses, certainly not helped by the more extreme angles they operate within (compared to an RC10 for example). There is a noticeable tight spot in the trailing arm's travel from this. One can't do away with the o-rings to alleviate the binding or the drive cups could move out of the diff at full extension. The only solution is to make the diff self contained, in a way, via the mod. One thing leads to another...

Thank you for the insight on the Frog dogbones! Didn´t have them so far, as I was using the universals on my main Monster Beetle runner since 2011. I had that shutter a little bit in the beginning, but somehow they got smoother and smoother over time.

Good luck for your updates. Once fixed they are so nice fun runners...

Matthias

[irocdave12 0]

About to build a Rere MB kit so very interested in this topic. So you guys are saying tamiya rere design has a problem with the dog bones popping out at the drive cups when using the MIP diff? So if I understand this correct if MIP had the cups stick out a little longer this wouldn’t be a problem? I was looking into buying the MIP and want a good reliable car. I can certainly limit the shocks with spacers inside to not allow so much arm drop possible but I’d like to do it right. Will the old thorp and Robinson diffs still work with the rere gearboxes? I have a NOS thorp set up with telescope drive shafts so if there has been a design change to the gearbox which wouldn’t allow me to use the old parts I would think that would be a fix for the issue? What is the screw mod talked about. I never heard of it before even back in the 1980’s when I was playing with the originals Any info much appreciated 

[Frog Jumper 3656]

Your Thorp will work just fine.

I can’t comment on the MIP as I’ve never installed the one I bought.

Terry