FLM Super Tranny and diff issue

[RC Dad]

So I had an unusual experience last night. I’m running the FLM super tranny with the traxxas 6882x internal spider gears, without the I-bar (FLM tech desk said that was the way to go).

I was just taking a test run after making some little tweaks to the front hubs and after driving pretty hard on a clay softball diamond, a little bit in the grass, and then just some loops around the asphalt, I parked the car- everything seemed and sounded fine.

Then I went to start up again and the car jerked to the left. When I picked it up, I found the left rear wheel wouldn’t spin freely, it felt like the gears were out of sync. The right side spun by hand normally, but the left remained frozen. I set the car down and gave a quick half throttle blip, and it clicked a little and went back to normal. Has anybody else had this issue with the spider gears?

I was planning on rebuilding this tranny at some point so that I can use the STRC layshaft and VTS slipper, but I’m wondering if I should replace the internal gears and install the I-bar. Any input is appreciated!


Sent from my iPhone using Tapatalk

[Role]

i had an issue with the ibar hitting the gears a bit, no issues without the bar for me

[RC Dad]

i had an issue with the ibar hitting the gears a bit, no issues without the bar for me

Cool. Yeah, hopefully opening up the diff and looking at the gears will tell me something. Did you use the included shims with your diff? I did not, at the direction of the FLM tech. Also, what fluid are you running with? Thanks!


Sent from my iPhone using Tapatalk

[Gripdog7205]

I used and trimmed my Ibar. Super smooth. I’m running 500k oil. I’m surprised to here you’re having an issue. Since I don’t know you, I’d say something was installed not quite right. Please don’t take offense. Feel free to correct me if I’m wrong. Did you use new bearings?


Somehow builds are never done....

[RC Dad]

I used and trimmed my Ibar. Super smooth. I’m running 500k oil. I’m surprised to here you’re having an issue. Since I don’t know you, I’d say something was installed not quite right. Please don’t take offense. Feel free to correct me if I’m wrong. Did you use new bearings?


Somehow builds are never done....

Thanks for the input! I was very careful when putting things together. I dry checked it a few times before adding the diff fluid (I used 50k- too light I’d say), green slime on the o rings, dab of loctite on the screws, slowly brought them all to full tight using a cross pattern.

I used the avid ceramic revolution bearings (metal/rubber seals). For the places where the bearings are exposed to the elements, rubber outward facing. For the bearings that are completely within the housing, I used the ceramic bearings with full metal shields (heard they are a tad more free spinning).

I used the same sequence of Teflon washers as the stock build calls for, and found that the layshaft has a little play (in/out, or left to right if you’re behind the vehicle, looking forward). Unfortunately I didn’t catch that till it was all sealed up, so I just ran with it, knowing that I’d be rebuilding it soon enough, as the hot racing slipper clutch (HD it is not) needed to be upgraded.

I’ve heard a lot of positive feedback for the associated VTS slipper, so I picked up the STRC layshaft that allows for that setup, and found all the parts I needed on eBay.

My guess is that the spider gears bound up on the left side, and when I blipped the throttle everything went back into sync. When I spin the tires by hand now, the diff action is just like new, silky smooth. But I’ll bet I find a tooth in there with a rolled edge. I’ll definitely update the post when I rebuild in the next week or so.


Sent from my iPhone using Tapatalk

[Role]

mine is with 100k, i didnt use the shims, i think the angled part of the bar may scrub on the gears a bit, thats what mine did, i had to take it out , i think the bar isnt really needed , good luck

[RC Dad]

mine is with 100k, i didnt use the shims, i think the angled part of the bar may scrub on the gears a bit, thats what mine did, i had to take it out , i think the bar isnt really needed , good luck

So I took the gear box apart and found no major damage to any of the spider gears, thankfully. I checked it dry a couple times and it felt better with the shims, so I decided to try them out. I also used 100k like you did, but I put the bar in- mostly out of curiosity.

The tech at FLM called the bar a “bandaid” for the stock plastic gear case, said it wasn’t necessary for their’s.





Sent from my iPhone using Tapatalk

[RC Dad]

One thing I noticed originally when I first got this was the sort of almond shaped “male” section that mates up to the female section on the other side. It looks off to me, but FLM told me that was correct machine work. Can anybody here confirm that? Just curious...




Sent from my iPhone using Tapatalk

[Gripdog7205]

Gotta say, I’m not tearing the car apart to find out. But I will say my original diff had to go back twice for poor tolerances. The guys tried to do everything they could to make it seem like me. It was not.


Somehow builds are never done....

[RC Dad]

Interesting... I’ve been patiently trying to get a hold of anybody over there to get a o-ring kit, but they’ve been awol all week, not even responding to the line they text from.

You can see some of the tools and equipment I’m using to rebuild this here...


Sent from my iPhone using Tapatalk

[Gripdog7205]

Good looking setup. Sorry about your trouble. If you can get some measurements and text it to him, I bet he’ll respond. At least I hope.


Somehow builds are never done....

[RC Dad]

For the layshaft, I had to shim by 0.8mm on either side of the top drive gear, just to get the play out. Now in the RPM hybrid case, it’s shimmed per factory specs with 0.5mm on either side, and it has virtually no play (maybe 0.05 of in/out movement, if that).

I’m surprised to have to use so much additional shimming. I figured a CNC machined part would have much closer tolerances, but then, I’m a tree climber, not a machinist.

Here’s a pic where you can see the shims...


Sent from my iPhone using Tapatalk

[RC Dad]

Good looking setup. Sorry about your trouble. If you can get some measurements and text it to him, I bet he’ll respond. At least I hope.


Somehow builds are never done....

Thanks Gripdog! I still think it’s a nice case, and I like that it’s made by a small shop (I’m only guessing it’s small) in the USA. I’ll keep trying to reach them, send the pics and the measurements that I got, see what they say.

Can I get your opinion on the amount of grease I’ve used on the gears? I like the associated black grease, and I feel like I put it on pretty sparingly. I’ve seen a lot of videos online where folks are globbing it on pretty thick. Thanks!


Sent from my iPhone using Tapatalk

[Role]

try this with the diff., put it back together and then place it in a drill chuck, spin it for a while until it get smooth, i think the gears need breaking in a bit, i always did this with my stock diffs , it makes them a bit smoother , good luck, I love my gearbox , tenshock 3,400 kv motor on the way

[Role]

why did you need new orings already ?

[Role]

I also would not shim anything, if you look close you ll see the output gears are very close to the bar ,in the bottom, i bet the output gear is just hitting the bar at times , there are no bearings in the diff case to keep the gears perfectly in place , im sure they move around from left to right and just hit the bar

[RC Dad]

Thanks for the advice on diff break-in! I didn’t actually need the o-rings this time- they’re in fine shape, and I cleaned and re-used them. I just wanted to have them for future reference. I can probably get a good enough measurement with my caliper.

The first time that I built this diff, I went with no bar, no shims, and I had that mystery temporary binding issue. In hindsight, it’s possible some grit got jammed in the wheel bearing because the internal gears looked pretty normal.

I just wanted to see how differently it performed with the change. So I used the 100k, bar, shims on the output shafts. We’ll see...

Do you recall if the machining on your case resembles what I see on mine?

Thanks!


Sent from my iPhone using Tapatalk

[RC Dad]

Good looking setup. Sorry about your trouble. If you can get some measurements and text it to him, I bet he’ll respond. At least I hope.


Somehow builds are never done....

So he did respond today, said he was tied up the last couple of days, moving or something...

He says it looks like the chamfered tool hit that one spot, causing that slightly odd shape. He says it won’t affect performance though. I’m a little dubious, but ok.

He also said that he designed it to be built with the Teflon stock washers, but for sure, those left a bit of play in the top shaft- about 0.6mm to be exact. It definitely felt sloppy.

So I tried it my way, and we’ll see what happens. I also used the STRC top shaft with the VTS slipper. It definitely seems built to hold up better than that Hot Racing one.


Sent from my iPhone using Tapatalk

[Role]

Looks good !

[Gripdog7205]

So he did respond today, said he was tied up the last couple of days, moving or something...

He says it looks like the chamfered tool hit that one spot, causing that slightly odd shape. He says it won’t affect performance though. I’m a little dubious, but ok.

He also said that he designed it to be built with the Teflon stock washers, but for sure, those left a bit of play in the top shaft- about 0.6mm to be exact. It definitely felt sloppy.

So I tried it my way, and we’ll see what happens. I also used the STRC top shaft with the VTS slipper. It definitely seems built to hold up better than that Hot Racing one.


Sent from my iPhone using Tapatalk

I used very little grease. Definitely not globs. I think you’re gonna be good to go


Somehow builds are never done....

[RC Dad]

Looks good !

Feels great too! I got just about all of the slop out of the top shaft, and that VTS slipper looks beefy! Can’t wait to run it this weekend.

I think because the spider gears already some time on them, they were already good and broken in. I can definitely feel a difference (by hand) with the 100k vs 50k. Curious to see how it handles in the dirt.


Sent from my iPhone using Tapatalk

[RC Dad]

All back together! Hopefully for a while this time. I love that this “truck” can go like a bat out of ****, or with a couple of quick little changes to the ESC, tires and pinion gear, go crawling around the trails with our TRX. This thing’s awesome!!

MIP X-Duty driveshafts are unbeatable (I think?), and in definitely in the “no grease” camp. I just use that tuf-glide, no rust, no binding, no problems.


Sent from my iPhone using Tapatalk

[RC Dad]

Oh wow! I got censored!!! I didn’t realize that speaking of the netherworld would trigger gatekeeper. Sorry! Guess I should have said it can go as fast as a bat out of hades???


Sent from my iPhone using Tapatalk

[Role]

what motor and esc do you run?

[RC Dad]

what motor and esc do you run?

I have the castle mamba x 1/10, and a hobbywing 2250kv motor. The motor is a bit heavier than I would like, but it has great low end power, seems pretty versatile. It stays nice and cool too, much better than the castle 3800 that was in there before.


Sent from my iPhone using Tapatalk

[RC Dad]

The VTS slipper works amazingly compared to the hot racing. I set it before taking it out and it never needed re-adjustment. Good call Role! Thanks for the tip.

You can see here how that tuf-glide stuff attracts a little dust, but not much. I drive it on a loose clay ball field, some dirt, etc.


Sent from my iPhone using Tapatalk

[Role]

no gear cover ?

[Role]

Sent from my iPad using Tapatalk

[Role]

Little pool noodle foam trick I use on my sons ruster, it keeps the motor safe on roll overs , and the t bone bumper flexes a little less . my son can do some damage on all my rc’s . he has broken a motor or two and snapped the motor screws with rear end crashes

[RC Dad]

Little pool noodle foam trick I use on my sons ruster, it keeps the motor safe on roll overs , and the t bone bumper flexes a little less . my son can do some damage on all my rc’s . he has broken a motor or two and snapped the motor screws with rear end crashes

Ha! I can relate to your new driver issues. My oldest is only four, pretty good most of the time, but he’s definitely helped me find the weak links in this truck.

I like the foam tube! I was thinking the t-bone flexed a little more than I like. I’ll try your mod there at some point.

I’ve had mixed results running a gear cover. When I did use one, it seemed to hold debris around the gears, even with the bottom cut out (RPM cover comes that way I believe). So I’ve been running no cover all summer and it’s been fine really. I think I started mainly because I was constantly adjusting the hot racing slipper I had previously. That thing was not suited to high power systems, in my opinion.


Sent from my iPhone using Tapatalk

[Role]

I just cover mine with painters tape , keeps out 90% of dirt


Sent from my iPad using Tapatalk

[RC Dad]

I just cover mine with painters tape , keeps out 90% of dirt


Sent from my iPad using Tapatalk

I didn’t realize the RPM cover would mount up to the FLM case! Very clever use of masking tape


Sent from my iPhone using Tapatalk

[RC Dad]

Finally got to the bottom of the binding issue!!! The little pin on the CVD was contacting the inside of the a-arms. I noticed it was all burred up when I was moving the shocks around to put this thing in trail/crawler mode.

Dremel to the rescue. All good. Kind of feel dumb now for tearing the whole transmission apart, only to find this. Also, 100k with the bar installed definitely behaves differently on the track. Not great. But it’ll probably be a good thing in the trails.


Sent from my iPhone using Tapatalk

[Role]

Dude that stinks, put some stock arms back on there , if you crash your going the bend that new transmission, you need some give somewhere , the rpm ones bend too much for me in the back

[RC Dad]

Dude that stinks, put some stock arms back on there , if you crash your going the bend that new transmission, you need some give somewhere , the rpm ones bend too much for me in the back

Yeah, I was thinking about that... that’s why I kept the RPM arms in the front. The main reason I went with so much aluminum in the back was to keep all that power going in the right direction.

My theory (probably wrong) is that if used flexible arms in the rear, all that power would cause flex, and that would eventually lead to smoked bearings, broken gears, etc. And so far, the back arms don’t tend to take as much of the brunt of the damage when crashes happen. I don’t know... You got me thinking now. I do have a set of RPM rear arms.

Do you use the VXL rear arms?


Sent from my iPhone using Tapatalk

[Gripdog7205]

Dude that stinks, put some stock arms back on there , if you crash your going the bend that new transmission, you need some give somewhere , the rpm ones bend too much for me in the back

Nah. You jut bend the mounting stock plate, in my case break it. They sell them individually.


Somehow builds are never done....

[RC Dad]

Nah. You jut bend the mounting stock plate, in my case break it. They sell them individually.


Somehow builds are never done....

I can definitely see those MIP X-duty shafts ripping the output shafts through the case or something. Granted, our Rustler isn’t going 100mph(!!) like yours




Sent from my iPhone using Tapatalk