rc4me center diff Super 5SC transmission in my HPI Savage Flux HP

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olds97_lss

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Well, I got the rc4me center diff trans. On my bench, I'm not sure how other guys have installed it. A few things differ that I need to deal with before moving forward with it. I got it for the sole purpose of trying to help my diffs last longer. Even running 4S, I still have busted 3 or 4 diffs on bad rear or front end landings. Hopefully this will help in those situations.

The first issue, the input shaft isn't keyed to the hex washer like the stock input shaft. So, if the slipper slips, an unkey'd washer is going to be likely to spin with the spur and not the shaft which will be prone to cause the slipper to adjust itself on the fly if/when it slips. I used the original flux shaft in it's place.



The second, the gear ratio is different. I'm not smart enough to figure out which way it's different, just that it's different.

The stock flux hp trans I have has the following:
2 gear input, 18/23. The smaller of the two being used. 18 -> 44, the 44 is on the same shaft as the next gear, 33 which spins the output 29.

RC4Me trans:
1 gear input, 21. Spins gear 41 which is on the same shaft as the next gear, 31, which spins the output gear/diff 30.

I'm not sure if this math is right:
stock
18-44 32-29

18/44=.409
32/29=1.103
.409*1.103= .45

rc4me
21-41 31-30
21/41=.512
31/30=1.033
.512*1.033= .53

If that's the case... I'm not sure which is higher geared and by how much so I know what pinion I might want to use to be close to what I have now. I suck at this stuff. If anyone could help, I'd appreciate it. I changed my pinion from a 21T to a 20T just to be safe since I had one on hand. I was intending on changing it anyway since the ESC does run a bit warm as I had the 21T in there when I had tires smaller than the trenchers and never changed the pinion back. In doing so, I'm not sure I can make the pinion any smaller to deal with the new gear ratio if I have to. If I do, I may not be able to tighten the outside screws on the motor plate as the TVP will be in the way. Suppose I could dremel grooves in it...

Here are the RC4ME gears with tooth counts for anyone wondering:




The center diff was missing a shim in the gear side of the diff. The thing uses a weird bearing combination on the cup side. It has one bearing on the cup like a normal diff and another bearing on the shaft itself that goes on from outside the trans case vs inside. The front dog bone cup keeps it in place. The bearing on the gear side of the cup towards the rear of the truck was metal shielded. I replaced it with a rubber shielded one.

The diff cup "cap" in case anyone wanted to see it:



The inside of the diff was nearly dry with only a little bit of grease. Probably makes sense since most people would clean it out and put silicone oil in it anyway.


It didn't have locktite on any of the screws either. One of the output shafts is longer than the other. I didn't realize that until I had already take it apart and cleaned off the grease. I think the longer one goes on the front cup side... now I can't recall.


I used associated 500k in the diff before dropping the spider gears in. I put enough in so that it was nearly to the top of the x bars once they were installed and seated. I put a blob of 200k on top as I wasn't sure which way to go, so figured once the oil mixes, I'll be less than 500 and more than 200. lol

The final issue was when I installed the rear output shaft cup, the plastic grub screw retainer and a hair of the cup rubs slightly on the trans case. I dremeled a bevel in the retainer for a bit more clearance. It's barely rubbing. Guessing after a few minutes of driving, it will remove a bit of material and not rub anymore.

Will post up how it does hopefully tomorrow. It's supposed to be mid-90's here with high humidity... not sure I want to go outside, but I really want to see how this thing does.
 
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olds97_lss

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Well, that trans is for the 5SC so maybe that is why the ratio is different.
Yeah, I saw that, but I guess it didn't register. What stinks is I emailed them a while back asking if the gear ratio was the same as the savage flux and they replied saying it was.

Looking at the parts list for the 5sc, it appears it ran 52/13 spur/pinion. That doesn't bode well for me with 44/20... The tires on the 5sc were a bit bigger diameter, but I don't think nearly enough to offset the gearing I have, 185mm vs 175mm.
 

Codered3232

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Wow thanks for the info. Hope all works out for you. I'm considering doing the same. By the way, the cvds are working great so far on 6S
 
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olds97_lss

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Well, with the 20T pinion and 44T spur, the gearing seemed a bit slower than 21T and the stock trans. I'm not sure if it was slower or if I was just losing power/speed due to front wheel spin. I didn't strap my gps to it to see for sure, but it felt a bit slower in general as I ran it at the same place I've run it before and out in the open for a few high speed passes.

Mixing the 200k/500k oil was a bad idea. Running 4S, I think associated 650-750k would have been better. It unloads the front tires pretty easily and makes it a bit sketchy to hit jumps I'm used to hitting with a short run up. However, it was way less prone to end up on the roof when jabbing the throttle at anything under 3/4 throttle like it usually is. I'll have to see what oil I can find as I think 1M will be too much for my intended purpose of relieving some stress from the diffs.

I took video, will edit that and post it later to show how it reacts on pavement/grass. I ended up snapping a front arm at a new skate park I found 30 minutes away. It's way too small, but I made the drive, so figured I'd run a pack. Hit a small jump badly and landed on one front wheel hard. Busted the front side of the arm.


That allowed the arm to flex too much and made the dog bone chatter, so I called it a day. Got a full set of 4 in the mail already as the only backups I have are the old RPM ones that I removed due to snapping shock ends all the time. Still no busted shock end. :)

I have to say, a center diff really changes the general handling of the truck. I was surprised how different it felt. On dirt, I could pin the brake at a good speed, turn the wheel and it would whip the rear around. Also being able to jab the throttle to shoot a jump was nice. Just needs a bit more power towards the rear.
 
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olds97_lss

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First video:

The lead in on that is kind of long. Was trying to show how the center diff was responding on pavement. Was very cloudy today, even though it was 90F+ at 40% humidity... was like a sauna out. The clouds made for dull looking footage. Sorry about that.

Second where I broke the arm:
 
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olds97_lss

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Got my associated 1M diff oil last night as well as replacement steering cams/saver/cross member from rc4me. Both of the cross member screw holes are stripped out on my steering cams, so will be replacing those hopefully tonight.

Last night, I tore the transmission back out to redo the diff oil. Only ran 2 packs on it, but the gears all still look good in the rc4me trans. The slight binding of the rear output cup went away and it spun as freely as my old transmission. I also found out after a bit of googling, that naptha will break down silicone oil. I took all the guts out and painstakingly cleaned the sun gears with a screwdriver and paper towel, wasn't looking forward to doing the same on all the spider gears, so googled it to death trying to find something that would break down diff oil. I too the spider gears/washers/x-shafts all apart and put them in a little container with some naptha covering them overnight. Woke up this morning and shook the container, the naptha evaporated some and the remaining liquid was thicker, but it wiped off the gears nice and easy.

I had also put the one sun-gear/shaft in the cup, put it in a clamp and put a blob of 500k with a small blob of 1M oil in it last night as well. by this morning, it had settled down and into the cup nice without air pockets. I quickly wiped down the spider gears/washers/x-shafts, put those together and dropped them in/pushed them down into the diff fluid and let it sit while I was at work. The diff is perfectly fully now with the top sun gear/shaft sitting in it as well. Will re-install/finish the diff tonight and hopefully get it all ready to go for this weekend. Guessing I'll end up with around 600k oil, probably a bit thicker. The ratio was about 2/3 500k and 1/3 1M. Hard to tell since you have to basically cut the oil with a knife/stick/screwdriver and drop the blob in.


Wish I had known the naptha thing in the past. Would have made cleaning diffs so much easier. 20 years in this hobby and still learning! I think my naptha has gone bad though. I've had the can for many years. Can't recall what it should smell like, but it almost smells like old bad pump gas that has varnished. Still seemed to work.
 

xtremsavage

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I use the same thing, VM&P Naptha. Been usin that to clean anything that uses shock or diff for a long time. I usually pour some in a cup and I bought one of those ball shaped, spring loaded tea infusers to put the gears in and what ever else I could fit in there to be cleaned. Not all at once of course. I'd usually do the sun gears together with the small shafts and shims. Then the spider gears all together. By usin that, you can "stir" the infuser in the cup of cleaner and also let it sit and soak. You also won't have to worry about fishing out any parts that are sittin in the bottom. I would have an occasional shim slip out, but that was all. The infuser is just big enough to fit the ring gear in also. I'm out of town on vacation til July 3rd, so if I remember when I get home, I'll post a pic.
 
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olds97_lss

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I looked a year or two ago to try to find out what dissolves/breaks down silicone oil, guess I didn't google the right thing. When I looked this time, I came across some woodworking forums that said to use naptha and mineral spirits... not sure why it would be on wood, but that's where I found it. Figured since I had a can a naptha, I'd give it a try.

I know those tea steepers your talking about.
https://www.amazon.com/HIC-Infuser-Stainless-Mulling-Spices/dp/B000I1ZZ24

That would be useful. Then your not digging around in the gunk at the bottom of the container for the shims and stuff.
 

xtremsavage

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I looked a year or two ago to try to find out what dissolves/breaks down silicone oil, guess I didn't google the right thing. When I looked this time, I came across some woodworking forums that said to use naptha and mineral spirits... not sure why it would be on wood, but that's where I found it. Figured since I had a can a naptha, I'd give it a try.

I know those tea steepers your talking about.
https://www.amazon.com/HIC-Infuser-Stainless-Mulling-Spices/dp/B000I1ZZ24

That would be useful. Then your not digging around in the gunk at the bottom of the container for the shims and stuff.
That's exactly what I was talkin about. I got mine from a home goods type store. I can't remember the name of the store though. And the Naptha is used to thin oil based stains for staining wood and use of stains in a sprayer.
 
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olds97_lss

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Got some more wheel time. Now with the 21T/44 gearing I had before as well as 60% 500k/40% 1M associated oil in the center diff. I also replaced the steering cam parts as I had stripped threads. It had the FLM Drag Link bar (I think that's what it's called), but I didn't put that in. I think it adds more aggressive steering. I'm noticing I'm getting sporadic binding on my front super HD wheel cups. I'd order some rc4me cvd's for the front, but they are on back order. I don't have any issue with the rear. I thought the FLM Drag Link bar was adding to the problem which is why I stuck with the stock steering parts from rc4me. I still have the issue though. Now that I look at FLM's site for that piece, it comes with some bushing to use normal 3mm bolts. Mine didn't have those and was using the stock shoulder screws which were too tall. Probably why they stripped out,with the extra leverage of the taller bolt and the drag link moving up/down a lot.

I like this oil combination a lot better than the 75% 500k/25% 200k I first ran. This time when I put it together I replaced the diff cup screws with longer ones as the ones that came in it looked like the first version from back in the day when HPI used short screws, then later used longer ones due to people having them back out all the time.

One other thing I forgot to mention about the rc4me super sc trans case is that it uses shorter screws for the case halves. I didn't change them, but probably should have. Should be fine though as there isn't really any ring/pinion gears inside trying to push the case apart, all the pressure goes the other direction. I also cut an old 6mm bearing apart to cut down the inside race as the 6x13 bearing behind the front trans diff cup kind of just wandered around. The cup is supposed to hold it in place, but there's about a 3mm gap. I filled the gap with the bearing race as I didn't feel like wasting 20 shims on it.

I tried showing how the diff action works in these videos in a few spots on pavement and in the grass. It's weird being able to get on the throttle when hitting a jump vs having to slowly pick up all my speed before a jump. The center diff transfers a lot of power to the front, but it still really calmed things down. I probably lost at least 4 minutes of run time because I'm now able to actually use WOT a lot easier. The gearing with 21/44 and the new trans seems to be pretty close to what it was before. Might be a tad slower, but I didn't notice. I did have a few tires come unglued in a few spots causing the tires to get all wobbly. I ended the day before I damaged a tire from it. One of them was half unglued on the front side.

First from today:

Second from today:
 
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Nice work bud. I should of mentioned I swapped shafts. I was going to look into using the super 5sc gearing It's a 52/13. They also have a beefier slipper setup. But I'm not sure.. It's been running well so I'll probably leave it. If it doesn't hold up, I'm going with the alza center diff setup Oh it thing I should mention, I kind of feel like my esc is getting a tad warm But I busted my thermal gun, so I'm just guessing
 
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olds97_lss

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52/13 would be way too low. I'm still using 21/44 like I had before and it seems a bit slower than the stock transmission. That reminds me, I need to tighten my slipper. It's a hair too loose after pulling it off the old trans. I've been checking my motor/esc temps to make sure it's still ok. I had dropped down to a 20T because the temps were getting a bit high when it was 80F+ outside. With the new transmission having lower gearing, I think the 21T is still good for me.

Did you get the rc4me cvd's? I saw someone get them in the rc4me thread, and I went to go buy a pair, but by then, they were already on back order.

I'll dig through my parts and see if I have o-rings to put in the cups. They don't seem to stay in there very well... but I think I need to try something before I break something expensive... or annoying to replace.
 
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52/13 would be way too low. I'm still using 21/44 like I had before and it seems a bit slower than the stock transmission. That reminds me, I need to tighten my slipper. It's a hair too loose after pulling it off the old trans. I've been checking my motor/esc temps to make sure it's still ok. I had dropped down to a 20T because the temps were getting a bit high when it was 80F+ outside. With the new transmission having lower gearing, I think the 21T is still good for me.

Did you get the rc4me cvd's? I saw someone get them in the rc4me thread, and I went to go buy a pair, but by then, they were already on back order.
No. I haven't grabbed them. I want em tho. Lol

When you say it feels slower do you mean acceleration or top end? Because I would say its definitely feels a tad slower on top end.. But it has ridiculous acceleration now.
 
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olds97_lss

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Yeah, the top speed isn't as high. Acceleration is really good though since now it doesn't want to wheelie so much. Still, with 21/44, I don't think the top speed is much lower than before when I ran 21/44, a bit, but not much. I didn't wring it out completely yet as the tires are a bit out of balance, or the glue was letting go and I didn't know it. I have reglued, so will maybe see how it does tomorrow at wot on pavement.

I found the o-rings. One side had one, the other didn't. The one that was in there was pretty chewed up so I replaced it. They are 7x11x2mm o-rings. I just ordered some 5x11x3mm o-rings from China. Maybe the little extra they provide will help more.
 
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Codered3232

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Yeah, the top speed isn't as high. Acceleration is really good though since now it doesn't want to wheelie so much. Still, with 21/44, I don't think the top speed is much lower than before when I ran 21/44, a bit, but not much. I didn't wring it out completely yet as the tires are a bit out of balance, or the glue was letting go and I didn't know it. I have reglued, so will maybe see how it does tomorrow at wot on pavement.

I found the o-rings. One side had one, the other didn't. The one that was in there was pretty chewed up so I replaced it. They are 7x11x2mm o-rings. I just ordered some 5x11x3mm o-rings from China. Maybe the little extra they provide will help more.
Sorry guys I guess I bought up the rest of the cvd. They have been good to me I would highly recommend them. I guess we will all have to push rc4me fom more. Thanks for the helpful updates on the center diff process looks like it'll be worth the trouble
 
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Sorry guys I guess I bought up the rest of the cvd. They have been good to me I would highly recommend them. I guess we will all have to push rc4me fom more. Thanks for the helpful updates on the center diff process looks like it'll be worth the trouble


I run the extended axles. Are the CVD the same length?
 
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I talked with rc4me, They said they " hope" to have more inventory by July. Doesn't make me to confident. LOL , but I'll wait
 
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olds97_lss

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If they aren't the same length, I'm not sure I'd want them. I'd only want them in the front, don't really need them in the rear. I run the extended super hd axles, without them, the trenchers wouldn't let me turn. They would just hit the shocks.

Ran it after putting in the new o-ring on one side and the missing on the other. Didn't have it chatter at me through 2 sets of packs.

I'm really enjoying the center diff. Had quite a few landings that all but would have guaranteed a busted pinion this weekend. Also, being able to actually hit WOT without it ending up on it's roof constantly is really letting me air this thing out!
 
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You drive hard. I love it. After watching a few of your vids, I can see why you were braking diffs. LOL

I bash really hard. But I don't really do too many flips or jumps. might have to start now tho...
 
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olds97_lss

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You drive hard. I love it. After watching a few of your vids, I can see why you were braking diffs. LOL

I bash really hard. But I don't really do too many flips or jumps. might have to start now tho...
My buddy with his talion didn't break anything on his truck until he met me and saw what you could do. He had been bashing for 6 months or so before we met. He only replaced a couple arms. After bashing with me for a couple months, he's busted arms, cvd's, towers, shocks, banana'd the chassis, blown diffs... But he said he's having way more fun now. lol :)

I'm not even that hard on my stuff when I compare to what guys do on youtube.
 
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I enjoy watching your vids. Please keep sharing

Just installed a new esc. My other broke in a hard crash Anyway.. I'm getting some cogging on my 6s setup.. I'm wondering if maybe I could of done a better job soldering the ESC to the motor.... Any ideas? Normally I've seen cogging with high power servos. I run a capacitor to mitigate that. And it's worked for years.. Now with new esc it's cogging.. Only on 6s tho
Not on 4s
 

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I enjoy watching your vids. Please keep sharing

Just installed a new esc. My other broke in a hard crash Anyway.. I'm getting some cogging on my 6s setup.. I'm wondering if maybe I could of done a better job soldering the ESC to the motor.... Any ideas? Normally I've seen cogging with high power servos. I run a capacitor to mitigate that. And it's worked for years.. Now with new esc it's cogging.. Only on 6s tho
Not on 4s
Actually . It's cogging with 4s too. Gotta be bad solder job.. I rushed it
 
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olds97_lss

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I only run 4S and haven't had any cogging with the MMX/2200kv system or the original blur/2200kv system.

I enjoy watching your vids. Please keep sharing
Thanks! I try to post a video or two any time I run my trucks. 2+ hours of footage edited down to 3-6 minutes usually. My youtube video count is getting up there in numbers. Just bought a used hero5 session to do onboard POV videos. Figured that would add to the videos a bit and make them a bit more entertaining. Was hard to rationalize spending $300 on a camera for just that purpose... gut lucky and won one on ebay for $150. I wanted at least the hero5 because it has built in electronic image stabilization. I don't use that when I wear the camera because I don't move and I record at 120fps for good slow motion stuff and the normal hero5 won't run that frame rate with EIS on. I like slowmo for crashes. I figured 60fps with EIS on would be good enough on the truck.

Silly hobby. lol
 
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I run the original motor But the stock esc sucked. I know it's a Mamba. But the BEC was terrible that puffed on me about 2 years ago. Ran a blx 185 since then That was awesome Then I broke it.

Lol.. Not sure about this hobbywing . I think I going to retry soldering the motor to the ESC
 
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