Does Cyclone Diff Untighten with Use?

[Alex_TTO1]

Having one or two problems with my cyclone S. The rear diff appears to be loosening each race. I tightened it and within a half hour or one or two packs, its a lot looser. There is no obvious fault and theres been no crash.

Anyone say if this is normal? How often do you have to tighten the diffs? Wondering whether to buy another diff.

[shrew]

try rebuilding it with thread lock

[ianjoyner]

take the diff apart and check that the outdrives are okay, I found that the tube protruding from one outdrive broke on both my front and rear diffs. I ended up replacing the plastic outdrives with Hot Bodies aluminium ones. They don't come loose now, but I have broken two screws.

Ian

[Mark Stiles]

I have found that the diff tends to loosen a bit after you first run it after a rebuild, but after tightening it back up its fine. I use the aluminium outdrives and they are excellent.

Try the aluminium outdrives, and possibly a new thrust spring and nut to see if that cures the problem.

[Coppins999]

I've had loads of problems with diffs coming loose on the Cyclone. Taking the diff apart and putting a drop of threadlock into the nut and onto the screw shaft then leaving for ten minutes for it to dry a bit seemed to help. Basically it gums up the screw thread a bit better than screwlock applied in the normal way.

Also new nyloc nut for the diff helps, particularly if you overtighten the diff at any point. Remember to tighten up slowly a bit at a time.

[Alex_TTO1]

Update: more problems!

I completely stripped both front and rear diffs as they came loose. I rebuilt with thread lock (tamiya blue type) and left overnight to dry. In the morning the diffs were initially stiff. Tried to run and after 1 minute (I am not joking I mean 1 lap) both diffs were hopelessly loose. I think I am going to have to go with solid front and rear axles (spool) simply to solve this one. OR I could try superglueing the diff screw permemantly I guess. Searching the forums for "thread lock diff" shows a lot of problems already mentioned along similar lines.

[bodymot]

Tried tamiya blue type, found on diff set’s too hard then brakes under pressure. Try loctite 243 lock n seal. You can get from any motor shop, put a drop in the diff nut tighten as normal (manual) run on track then test for play 9 times out of 10 you will have to retighten after first run but after that should be ok just check before each race. You can tighten diff with out taking dive shafts out and with wheels still on car, just put a small allen key in the small hole on diff out drive (side were screw head is) and turn opposite wheel clock wise a bit at a time to take play out ( don’t over tighten or diff screw will brake )
Hope this helps

[Mark Stiles]

Are you sure you're building the diff properly?

Onto the screw you should have a thrust washer (against the screw head), then 6 small balls covered in grease, followed by another washer, and then a spring. Use plenty of grease on the balls and rings, and make sure you tighten it enough. You should be able to hold one wheel and the pulley, and just about turn the other wheel with your hand.

Use some very fine wet and dry paper to sand the diff rings and thrust washers down until the grooves left by the balls are gone. Then clean all the parts thoroughly with motor spray/brake cleaner before building the diff.

I have to say that in the 2 years I've been running the cyclone I've never had a problem anything like you describe.

I would advise against using super glue or adhesive of any kind other than thread lock on the nut.

Using a spool front and rear is a crazy idea; I wouldnt bother.

[Frankie]

I have to be honist and say i had it on my cars and it cost me a few races, however i put the Edit screw and nut on and that sorted it.

[Warren]

Rebuilt mine today, did everything in the magazine that was released recently. After a battery pack (say 10 minutes of outdoor racing) the diff became loose. Just tightened it back up until it stopped slipping and went back out. I think if you bought a edit diff screw and a new socket you'll stop it from opening again. Mines been in it for the last 3 months and it hasn't failed me yet but i'll be replacing the socket before racing on thursday so there shouldn't be any problems after that.

[Alex_TTO1]

I appreciate everyones input and I acknolwedge there are probably ways to build the diff to have no problems.....as a beginner I simply dont know how! Also remember that I bought the cyclone in the new FACTORY assembled RTR kit and within a day (2 packs) the rear diff was literally falling to bits it was so loose.

Also on rebuilding I did follow the instructions and have the fiddly little spring, the tiny bearings and the thrust washers in place so I am pretty sure I built it right, plus I rebuilt front and back twice so I am getting some practice. The stock outdrives (metal) are fine, pristine in fact. I have neither overtightened nor under-tightened it and there is a small difference in loosening between front and reaf diff. In fact I discovered they are interchangable so I am going to swap the "OK" front to the rear and substitute a spool on the front even though this cost me £20, as I see a solid axle front and rear is probably crazy.

The sand paper sounds like a good idea but I have no idea what an EDIT screw is and cannot find on google. As my cyclone is brand new RTR I wrote to HPI support but yet to get any action.

[Alex_TTO1]

Sorry I realise now an EDIT screw is simply the diff screw made by EDIT.....product id=17846 & catcode=611 from modelsport (edit code ED050010). Would replacing the screw itself really make a difference?? Maybe a double lock nut on the end, I understand that would help as it currently locks into plastic thread.

[Mark Stiles]

Replacing the screw itself could make a difference if the thread on the original one is worn. This is unlikely, although the Edit diff screw is a worthwhile upgrade; its far stronger than the standard kit screw.

All of my diff nuts are made from brass (I think) and are inside a plastic casing. The screw goes all the way through the nut and out the other side when the diff is assembled, so the plastic casing on the back of the nut locks the screw thread in place (like a nyloc nut)

If your diff nut is all plastic then it is likely that this is worn, and could be causing you problems. We use all plastic diff nuts in 12th scale, and they do wear out and need regular replacement.