RC10B diff problem

[gnat]

I bought an RC10 a long time ago, played with it for awhile and then forgot about it. It got unearthed again while cleaning the basement and other than a battery that leaked in the remote, all was good and I started playing with it again with my son.

I've never done anything to care for it and it has just kept rocking along. Until this week.

I smacked a bush good enough that I broke one of the front a arms, but a zip tie got that fixed.

While out testing that fix the gear box started making an intermit grinding noise. I figured a gear was going and I might as well run it until it was dead. It finally made a horrid noise and then the motor would just spin. Turned out that the screws holding the gear to the clutch had worked out. After I put the gear back on, all was good.

Then I made my cardninal sin, I bought new parts (springs and some e clips)!

Took it out today and the gear box sounded like it was grinding and as soon as it met resistance off road it would stop and the noise would get worse.

I took the gearbox completely apart and there is no sign of wear or debris. The diff was rough to spin so I opened it up too and again everything looks good.

Put the box together and it spun fine, but sounded horrible. When I reassembled the car and took it outside, it won't move at all even on pavement. Just ugly noises.

Anyone have any ideas what might be going on and how to fix it?

Thanks,
-dave

[RC104ever]

First off, welcome to the board!

Second, it's hard to say without seeing it but I'd start by isolating and eliminating the obvious.

Okay - first check your gear mesh with the pinion (gear that's attached to the motor shaft) and your spur gear (the big one with the spring on it and the small diff balls). There should be a clean mesh and it should move fairly freely and not bind at any point while rotating it by hand. There should be a small amount of rocking between the teeth as a rough rule of thumb.

I'm going to guess that this part is fine.

Next, you will want to check that the diff spring is tight enough. For this part, I believe you tighten it until you can turn one wheel and the other one turns in the opposite direction. If your car isn't moving, this is one obvious area that you should start with and try tightening it first.

Next, its more difficult. Do you still have the original assembly instructions? You may need to check for burrs on the new parts you bought or that the bearings / bushings are all installed correctly. I'm also assuming its a 6 gear tranny (which my instructions above reflect).

[gnat]

Second, it's hard to say without seeing it

Yeah I know. I'm trying to be determined and not just buy a new rig, but I'm not holding out much hope at this point.

Thanks for the pointers anyway.

Okay - first check your gear mesh with the pinion (gear that's attached to the motor shaft) and your spur gear (the big one with the spring on it and the small diff balls).

This is what I figured had gone the other day, but it's all solid with a good mesh and no wear on the teeth.

Next, you will want to check that the diff spring is tight enough. For this part, I believe you tighten it until you can turn one wheel and the other one turns in the opposite direction. If your car isn't moving, this is one obvious area that you should start with and try tightening it first.

While it was out I adjusted this from as tight as possible to the loosest possible. In all cases it spun roughly in my fingers. I'm sure the diff is at issue, but to my untrained eye (this is my second car in 30 years and the gear box is a mystery to me) I don't see anything inside to explain the roughness (all the ball bearings are there and smooth, the bushings are smooth, no damage to the carriers, etc..).

Next, its more difficult. Do you still have the original assembly instructions?

I don't even have my battery retainer anymore

Luckily TA has the PDFs on their website which is how I even figured out that I have a B model...

You may need to check for burrs on the new parts you bought

Sorry that was a bit of a red hearing for levity and I guess I wasn't clear about the parts. The springs were for the rear shocks and the e-clips were for the pins that hold the front A arms onto the chassis. Nothing gear box related.

I'm also assuming its a 6 gear tranny (which my instructions above reflect).

I suppose it depends on how you count them (I have no idea), but at most I have 5 (pinion, spur, one at the end of the clutch shaft, one that it mates up to, and the exterior of the diff).

[harvey]

It sounds like you have a stealth transmission, since you mention the clutch, and a diff at the bottom.

If a (slipper) clutch is too loose, the car won't go very good, but normally they just whirr quietly. If you manage to wear away enough of the orange pad material, you could get some metal on metal slipping, with more noise? It would probably get warm real quick. I've never had this happen.

The diff on the other hand can make a terrible racket if it is too loose. It has been called a 'bark' and that sounds right. Once it starts slipping round things loose their roll and bad goes to worse. (balls get teeny flat spots, rings get lumpy grooves) Slip it a bunch and the balls will melt through the diff gear and that's pretty final. However you mentioned opening the diff up, so maybe it's just loose. Those bitty rolling bits will still look mostly okay and cause roughness never the less. Don't neglect the thrust bearing, either. (have you found a schematic or exploded view of the diff assembly?)

Have you inspected your rear axle cross pins too? Got solid bite on the wheels and all that?

[gnat]

If a (slipper) clutch is too loose, the car won't go very good, but normally they just whirr quietly. If you manage to wear away enough of the orange pad material, you could get some metal on metal slipping, with more noise? It would probably get warm real quick. I've never had this happen.

Nope, the pad looks fine and there is no wear on the clutch halves.

The diff on the other hand can make a terrible racket if it is too loose. It has been called a 'bark' and that sounds right.

I'm used to bigger dogs, but I understand the reference and yes that's what it sounds like.

Those bitty rolling bits will still look mostly okay and cause roughness never the less.

Definitely not seeing anything and the grease makes it impossible to be sure about feeling anything (but definitely nothing major).

Don't neglect the thrust bearing, either.

Where would that be? (I only have bushings BTW)

(have you found a schematic or exploded view of the diff assembly?)

http://www.teamassociated.com/pdf/cars_and_trucks/RC10B2/Team/rc10b2_manual.pdf
http://www.teamassociated.com/pdf/cars_and_trucks/RC10B2/Team/cat_10b2.pdf

Have you inspected your rear axle cross pins too? Got solid bite on the wheels and all that?

Is that the pin in the "axles" that the cross on the back of the wheels slot onto? If so, those are good and other than being bald the tires/wheels are good.

[harvey]

Your thrust bearing is a loose assembly held together by grease. They like to scatter upon disassembly. You start assembly of the diff with the bolt. Then a washer. Dab some black grease on the washer, and stick 6 tiny bearings to the grease. Another washer. Push the balls towards the bolt, pack with grease, but not too much. Shove this into the outdrive, then a diff ring, two bushings (bearings), diff gear, grease the holes in the diff gear, push the balls into the holes, diff ring, outdrive, spring, t-nut. OH. Your T-nut has to have little plastic ears that slide into the slot in the oudrive in order to keep it stationary. If they're mashed off or missing, you won't be able to tighten the diff properly and it will slip. (bingo?)

You really want a pit towel and a clean workspace to get every part of your diff laid out, cleaned and inspected. Without just throwing all new parts at it, it requires some work to determine what has been damaged. Sometimes you can just flip the washers; you should be able to tell once cleaned which side has been used. if that doesn't get the grind out, you may need balls. You'll need black grease for the thrust bearing, and silicone grease (clear) for re-assembly.

[gnat]

Your thrust bearing is a loose assembly held together by grease. They like to scatter upon disassembly. You start assembly of the diff with the bolt.

Ah. Thanks. Mine stayed together actually.

You might have hit on something though as I didn't have any grease when I reassembled. So it might be that I rubbed enough off in my inspection to make an already questionable situation worse.

Looks like all the parts (gear, balls, and bolt) are still available and only about $30 from TA's website. I'll give that a shot and hopefully get this thing back in the dirt.

Thanks for all the help. I'll update again after I rebuild the diff.

[gnat]

The last of the parts got here today so I tore apart the gearbox and rebuilt it.

The only original parts of the diff are the caps that the dog bones sit in. In addition to all the diff bits I also replaced all the bushings in the transmission with bearings and replaced the tension spring for the clutch.

It had mixed results. It sounds better, but still seems louder than I think it should. It will also move under it's own power on pavement, but not nearly as fast and there is a couple of seconds of it not doing anything before it gets going (less hesitation if I ease on the power rather than go straight to full). In the grass it won't get itself moving at all.

My suspicion is that it's the clutch that is doing the slipping due to the lack of "barking", that it acts like a clutch slipping in a real car (yes I drive stick!), and I couldn't get the tension nut tightened very well and it is significantly looser than how I used to run it. I'll take another crack at tightening the nut tomorrow.

[gnat]

Got the clutch tightened up and tightened the diff some more and there is still a lot of slippage going on. It was mostly back to normal on pavement, but still mostly useless in the grass (it will keep itself going though it can't maintain speed, but it's done once it stops).

But not the left dog bone keeps kicking out and it sounds like the spur has been mostly eaten away at this point. The radio also seems to be having issues as the car would just stop responding until I turned the controller off and on a few times (luckily the car wasn't moving when this would happen).

Guess it's time to call it and figure out what my next car will be...

Thanks again for the help diagnosing this and trying to get it back to running shape.

[harvey]

Give yourself some time, then come back to it. Anything can be fixed, and it's a good trans.
Is the nut on the slipper clutch gold coloured? Most fasteners on the RC10 are 4-40 but the slipper clutch uses a gold coloured 5-40 nut. If you use the wrong thread, it may be binding on the treads, making it feel tight before it is. As I said before, if the slipper is slipping excessively, you'll get heat, so do some running without a cover and put your finger on the spur after to see if it's warm.
If you're ejecting drive shafts, check that they aren't bent, then see if you need to add limiters to your shocks. They are added to the shock shaft when it is out of the body, and stop the shock from extending too far. Different setups (mostly lower shock mount locations) need different limiters. You can tell this by slightly compressing the arm and watching the shaft plunge into the outdrive. When the cross pin is fully engaged with the slots in the outdrive, that's where you want to limit the travel to.
Chin up; can do!

[gnat]

Give yourself some time, then come back to it. Anything can be fixed, and it's a good trans.

Of course it can, but I've already put a bit over $100 into it with no joy (well the new battery gave plenty of joy until parts started failing). The reality though is that I'm just not a buggy guy to begin with and other than it's long history of rave reviews I don't know why I went with the RC10. The "monster" trucks fit my usage better with their higher ground clearance.

Don't get me wrong, this thing has taken a lot of abuse both in how I drive it as well as being tossed in a box and forgotten for years. Just not sure the effort/cost is worthwhile compared to putting that same effort/money towards a new one complete with the move to LiPo and brushless.

Is the nut on the slipper clutch gold coloured?

Nope. The old one and new one are silver. It wasn't binding, it was just that the locking ring was stiff since it was new. Tightening it more with the wheels and drive shafts installed was still stiff, but possible.

[RC10th]

What color is the slipper pad?

[gnat]

What color is the slipper pad?

a light brownish-orange. Some variation of tan I guess.

As of the last time I assembled it on Monday there was no real wear on it. I'm sure there is probably some wear now after the slipping that has been going on.

[RC10th]

It can only be one of two things, three actually.

#1 - Slipper
#2 - Diff
#3 - Broken or missing wheel pin

The easiest way to tell is pull the gear cover off, hold the spur gear with your fingers and while holding the spur gear push the car forward.

If the top shaft spins while holding the spur gear and pushing the car forward the slipper is too loose.

If the top shaft doesn't spin it is either the diff slipping or a broken wheel/roll pin. It is easy to check the wheel pins by simply taking the wheels off and seeing if the pin is broken or the wheel slots damaged.

If it's neither the slipper or wheel pin then it's the diff, which will need to be retightened or rebuilt.

Although unlikely it will also pay to double check the pinion is tight on the motor and that the tires aren't spinning on the rims.

[RC10th]

Also about the dogbone depending on what model (pictures help)

If it has true "dogbones" check that the springs are in the axles, they tension the dogbones into the diff cups and if they are missing can allow the dogbones to eject the vehicle. They look like a ballpoint pen spring.