So I got myself a Savage X SS on Friday and spent the whole weekend putting it together. It's my first nitro car. Anyways, I've put it all together (just waiting to get a 6V battery pack for the electronics) and I have a few questions before I run it the first time. Bare with me as my terminology probably isn't so good. Also, my knowledge of these things is limited, so it might be basic to you but to me it's all very cryptic.

1. If I tighten the screw that goes onto the end of the crankshaft all the way, it's very hard to make the shaft rotate. If I loosen it just a bit, then the clutch bell rotates freely without rotating the shaft. I'm guessing I must make it as tight as possible?

2. How much must I tighten the locknut on the slipper clutch? How can I test that I have the right setting? The thing is, if I have the engine mounted, it's almost impossible to turn the spur gear to the thing to see if it slips under certain conditions, so I have to test it without the engine in place.

3. If I spin the spur gear only the front wheels rotate, the rear ones don't move. Is this normal?

4. If I try roll the truck backwards the front wheels lock (because the spur gear can't rotate). But if I try rotate only the rear tires backwards, there's no issue. Is this also normal?

I think the main thing that's annoying me right now is the fact that I can't rotate the spur gear when the engine is in place, because it's very hard to make the crankshaft rotate when everythings screwed into place nice and tight. Am I worrying to much, and everything will be fine when I run the thing? Or am I missing something? Thanks in advance.

Some run the slipper clutch fully tightened,make sure you dont break when you land off a jump though.No more then half loosened is good...thats all i know lol

I've had a good look around on articles about installing the clutch, and when everything is done the clutch bell should rotate freely (it should actually be able to spin for a few seconds). Looks like I have some work to do. But the issue with only the front wheels spinning when the spur gear turns? The gearbox comes pre-assembled, so I doubt it's already having issues.

Answer 1: There is a small packet that comes with the Savvy XSS that has a washer with a hex hole in it. This is a changed part for the clutch bell. The screw on the clutch bell must be very tight and have loctite on.

Answer 2: Follow the instructions. Tighten all the way and 1/4 back to MAX 1/2 turns back. You will not be able to test the slipper clutch with your hands, but believe me it does slip. You can see it when you take it apart after a few bashing sessions.

Answer 3 & 4: I think you have your one diff wrong way around. Make sure that when you turn the clutch bell anti-clockwise the wheels spin forward. It could also be that something is wrong inside the rear diff.

That washer with a hex hole in it is for the spur gear, I checked the manual. Plus, the crankshaft doesn't have that kind of shape. I've managed to assemble the clutch so that the clutch bell rotates freely, but the 4 or 5mm wide plastic spacer that comes with the thing is too wide to let you tighten the screw on the end of the crank shaft all the way.

Tighten the locknut on the slipper clutch all the way; as in until you simply cannot move the locknut any more while holding the spur gear? What are the dangers of having a slipper clutch that won't slip?

I doubt I have my diff on the wrong way round, considering that both diff cases come pre-assembled. If I spin the spur gear anti-clockwise, the front wheels rotate forwards, the back wheels do nothing. If I rotate both back wheels forwards, the rear shaft leading into the gearbox (and the disk brakes) rotates as it should, it just doesn't seem that any gears within the gearbox rotate when this happens (looking through those 3 small windows). It looks like the only thing that may be wrong here is with the gearbox, unless the two back wheels engage somehow when the motor's running. I don't know.

Any other ideas? I'll be taking it into the LHS either tomorrow or on Wednesday to see if they know what's up unless you guys can tell me.

My bad on the washer. You are perfectly right on the spacer on the clutch bell (on X it is 86121, XSS 86171) - Manual page 29. Regarding the slipper clutch. Completely tight is when the spring is totally compressed, then 1/4 turn back. If you tighten the slipper too much you don't have a weak point there and with ramps and jumps the excess reverse forces will be transferred to the next weakest point (the clutch, diffs, gearbox or spur gear/clutch bell). The slipper is a managed weak point so I wouldn't suggest tightening it all the way. Some others won't agree with me on that one, but decide for yourself what will work for you. I understand that the diffs has been pre-assembled and was just trying to eliminate small common mistakes (I made some of them myself). Now I'm starting to think the grub screw (86094) is missing on the cup joint (86272) as the front wheels do turn the gearbox (and therefore the spur) and it is a solid axle between the front cup joint and rear cup joint (Check page 51 of manual). The reason the car doesn't want to run with the engine in place is because the clutch bell doesn't rotate freely.

Sorry if I misunderstood your first post, I was in a rush out of the house when I saw it and made a quick reply.

Thanks a lot for the help.

I'll try open up the gearbox today and see what's happening. Like you said, if there's a solid axle between the front cup joint and rear cup joint then both sets of wheels should turn when I rotate the spur gear anti-clockwise. Did I buy a lemon?