I have a Associated RC10 T4 with a Novak 5.5 brushless motor with a Sphere Competition TC Spec esc. I am running it with a 4200 Mah battery pack. My problem is when I leave the start finish line at full throttle, it sounds like I am stripping the spur gear. I am running a 87 Tooth spur with a 19 tooth pinion. I have checked both the spur gear and pinion and they are meshed together fine. I have adjusted the slipper clutch from tight to loose and it still does the same thing. I need help, I just bought the car and I am deployed in Iraq and need some assistance. THANKS

I "sounds" like your stripping the gears? If the pinion and spur aren't stripped and the motor is bolted tight against the motor plate so it can't move, then your problem is likely elsewhere. The slipper clutch may be too loose causing the motor to rev-up faster than the car is accelerating. This confuses some people because we're used to electric motors winding up as the vehicle speeds up. This is especially true if you punch the throttle from a dead stop and you get little to no tire spin (burnouts) off the line. Simply adjust the slipper adjustment nut on the right side of the vehicle until you have minimal slip. Note that some slip is good as it relives excess force from the gears so they don't strip. Another possibilty is that the ball differential is adjusted incorrectly and is too loose. Even with light tension you will still see a "differential effect" when the vehicle is running. And the vehicle will drive reasonably well with a loose differential, however, loose ball diffs cause a harsh "barking" sound when they slip. It's most noticeable when the car is jumping and lands while you still have the throttle pulled. The sudden bite of traction upon landing after the motor was revved in mid air causes the wheels to match the ground speed while the motor and transmission still have built up inertia. The difference in speed causes the differential balls to slip against the out drives and creates that "bark" sound. To adjust this, you need to remove the right side dog bone so you can access the allen screw inside the outdrive yoke. You must hold the opposite wheel and spur gear while you adjust this, otherwise the opposite tire will turn backwards. Make small adjustments, it doesn't take much to tighten it. Too much tension and the diff will feel stiff and act more like a posi-trac rear end. You didn't mention if the sound is continuous or only during a hard acceleration but, there may also be debris inside the transmission which is running through the 3 internal gears. Open up the case, clean the gears and apply a light dab of grease on each gear. Don't add too much or the grease will cause excessive rolling resistance.

This is a bit of an afterthought but I wanted to add that since you've added the brushless setup, the problems I mentioned in my last post are likely due to the increased power and torque generated by brushless motors. If you had your car adjusted for a brushed motor, especially if you had a lower power battery pack, you wouldn't have noticed excessive slipper slip or a slipping differential. Now that you have a more powerful motor, ESC and probably a higher output battery than before, more torque is being applied to the gears. Remember, the slipper is used for torque control and can save your transmission if used properly. The differential may have been too loose to begin with.

maybe differential problem?

Thanks for the help. I will try your suggestions after I replace my rear shock tower that broke today. Also, the slipping noise only happens durring full throttle on take off, and as it gets up to speed, it will stop. If I ease into the throttle and gradually move to full throttle, there is no slipping noise.

Oh yeah, the battery issue is being fixed as soon as the mail runs. I have two 2s 5000 Mah lipos on the way, since the esc has an internal lipo cutoff. That should help as soon as I check the differential.

That sounds to me like the slipper clutch is letting loose. A loose differential generally won't slip very long, just long enough to create that harsh sound. Most of the time you won't notice it until you try to listen for it. Add some tension to the slipper. It should go away and you should notice quicker off the line acceleration. Actually, you can take the clutch out, lightly sand both of those yellow octagon shaped pads to remove any shine which is caused when it slips. Reassemble and readjust as necessary.

yep that's definitely your slipper clutch. it sounds kind of like a buzzing noise doesnt it?

Yes it sounds like a buzzing noise and I have tried to tighten it up and also loosen it, to no avail. It still does it.

On my T4 the slipper clutch makes more of a whine noise. It's much higher pitched, and a much "smoother" noise then when the diff slips. I would guess based on your description of the sound (plus, since you already tried tightening your slipper clutch) that your differential is slipping. When the ball diff slips it makes quite a racket.

I had to tighten my diff when I went brushless (and I only went with an 8.5 turn Novak). Also, something to note about the slipper clutch. If you hit reverse really hard on a good traction surface (for instance, hit full reverse throttle from a stop), the slipper has a tendancy to loosen itself a bit. This will only happen if the slipper is loose enough to slip when you hit reverse, but it's just something to keep an eye on when you run a lot of power if you use reverse much.

i believe that what you are hearing is the diff barking ... that means ur slipping it a small amount, tighten your diff a hair and it should go away.

+1 On the diff. I had a B4 with an 8.5 BL and it made that awful sound when you pin the throttle from a stop on a grippy surface.Tighten the diff a little bit and I bet your noise goes away.

Hey Thanks for all the help and suggestions. I tightened my diff up and it takes off like a rabbit now. Thanks again, now I can go play around in this sand in Iraq. If I have anymore problems that I cannot figure out, I will surely post on here.