DESC210 - New Build Gear Diff MM4 no drive Slipping

[raymondkerr]

Built my DESC210 last week with the kit ball diff and ran the car for a couple of heats adjusting the slipper to suit. Running with a speed passion 8.5, after a couple of runs, I lost drive and no amount of slipper adjustment would work, decided to rebuild the ball diff carefully as per the durango guide, but with no success.

Decided to buy a Gear diff and built as per durango guide and installed today in Mid Motor 4 Gear, carefully checking that all the gears and layshaft where installed correctly and that nothing was missed. The diff when installed in the gearbox turns perfectly free by hand, when installed in the car, I get very little to no drive, sounds as though the slipper is very loose, even when tightened up the slipper still bad slips and there is next to no drive. I have been careful to check that the slipper pads/plates are installed correctly and that the slipper screw and spring with washers are installed correctly and in good condition, but nothing appears to be working. The kit is brand new and has only been run for a couple of heats.

Is there anything obvious that I may have missed, I have had the gearbox and slipper assembly stripped out twice with no success, haven't tried any other motor config as I really want to run MM4.

[graveltrap]

Possibly a squashed crush spacer on the layshaft, due to over tightening the slipper, but I thought the part had been upgraded by Durango.

[raymondkerr]

after doing a bit of research on the forum, I decided to check the layshaft spacer and bearings, both are still in perfect condition, bearing works fine and the spacer doesn't appear to have any damage at either end. I've looked again closely at the manual to ensure that I haven't made any mistakes, and then re-assembled, but still the problem persists. I even replaced the slipper nut for a new one. When I gently apply throttle whilst hold one of the rear wheels, the spur gear hesitates then starts to rotate, when on the bench gentle throttle does appear to work and both wheels start to move, but when on the ground with load, I just get lots of slip. I'm reluctant to tighten the slipper much more than about 4-5mm in from the end of the screw, tried slowly applying throttle and then turning the screw in until I get bite, but its not tightening. The slipper pads have a slight rub on both sides as I've tried to use both sides of the pads, but they are far from worn, the pads on my 410 are way worse and still perform ok.

I'm completely puzzled at this point, not sure where to go from here and what to try next. ???

[OneKiwi]

Just a thought is the motor ok? Can the rotor be buggered? Are you able to test another motor or test the motor in another car.
Does the motor spin up ok?

Try with other slipper pads, get the thicker ones like schumacher or AE HT ones. What spur are you using? Stock or another brand?

Id replace the little bearing as well, anyway just to make sure.

Are you still using the gear diff?
Are all idle gears whole?

[jo90]

Check you havent screwed through the gearbox long screws and they are protruding out and catching on the back of the slipper. A guy at the club last week had done this and it basically jams the gearbox.

Put about 1-2mm spacers on the 3 long bolts before you screw them in and through into the motor mount plate, then check all this again.

[ekt]

After reading all the things you've already checked, I would try put a spacer on the layshaft before you put the slipper plates on.

[raymondkerr]

Thanks for all the advice, I havent been able to look at the car again, but will spend sometime at the weekend and i'll try the above. I did check the long gearbox screws just to make sure they werent jamming the spur, but i havent tried a spacer on the layshaft.

[Chris Doughty]

Originally Posted by ekt

After reading all the things you've already checked, I would try put a spacer on the layshaft before you put the slipper plates on.

the quote above sounds like its the most likely solution to me.

I think maybe on petit RC I have seen a picture detailing this method, I can't find the details now.

[raymondkerr]

I'll have another look on Petit myself, just haven't had time to look at the car in the last couple of days, by spacer - are we just talking about a washer ? or is it a specific part that I need to order ?

Raymond

[Chris Doughty]

I can't find the post with the picture, but basically, you can add 1 or 2 of these shims on before you slipper plates

http://www.team-durango.com/part-inf...artNo=TD709015

any washer/shim of this size will do, they are an 8th scale nitro clutch spacing shim so people might have them spare in their boxes

[raymondkerr]

thanks Chris, I should have some of these in my box, I'll give it a go and let you know the outcome.

[raymondkerr]

tried the shims today, started with one, then tried two, but the slipper still isn't tightening to allow any drive at all. Took the gearbox apart again and checked all the gears, no wear and all the shims etc are in the correct place and the condition of the layshaft spacer is perfect, showing no wear at either end. I also checked my gear diff and it is built fine with 1000wt oil. The slipper pads are only slightly glazed - but the car has one ran for 2-3 heats, so I would have thought the pads would still be fine. I replaced the slipper nut for a new one, and ensured that I have a small washer at each end of the slipper spring before tightening up the splitter nut. I have also tried another motor which I know works fine in my 410, so I have ruled out any problem relating to the motor.

at this point, Im really struggling to find a solution, all gears are perfect and the slipper pads fit into the spur gear and the plates appear to be pressing against the pads, so I can't see how they would move when applying power.

Having owned a 210 in the past, I've never had any problems previously with a 2WD slipper and gearbox, really now at the point of giving up. Can't think of anything else to try??

Raymond.

[mattr]

Check the pins that hold the idler gears haven't either moved into the wrong hole (not sure if you can build it like that, but worth checking) or damaged the casing, allowing the idler to come out of engagement with the diff.

How much of the gearbox moves when you attack it from either end?
If you turn the out drives, does the lay shaft turn? Or the spur gear?
If you turn the wheels, does the spur move?

If you turn the spur do the wheels turn?

Just trying to work out where it's not working.
Could also try some AE slipper pads, they are the same size, but slightly thicker than then stock ones.

[raymondkerr]

Hi Matt

I have re-assembled and checked the idler gears and pins, everything there seems fine including the holes in the gearbox case where the pins locate. I have the correct washers on either side of the idler gears where the bearings insert.

When I turn the outdrives by hand the spur doesn't turn, however when I rotate the spur by hand, the outdrives do turn at the same time. If I remove the slipper/spur assembly and turn the outdrives by hand, the layshaft rotates also.

The slipper nut is tightened about 5mm in from the end, not too tight, but not loose either. There is still alot of fine adjustment available, but even when tightened more, theres still next to no drive under load, on the bench the wheels rotate as normal with minimal throttle.

Raymond

[mattr]

You do have the drive pin in don't you?
Cos that's all I can think of. If the rest of it is together and made correctly.

[raymondkerr]

Yeah, drive pin is there. Kinda confused now as I can't see anything else that I may have missed. I even put a small dab of glue on the inside slipper pad, just to hold it in place on the spur as it was very loose before when inserting onto the motorplate, just in case it was coming loose and rotating on the plate.

Raymond.

[qwerty]

BUMp

[dpackster1980]

Did you clean all of the alloy or and metal parts down with brake cleaner before assembling the kit? The general rule is to wash everything just in case there's residual oil or contamination left over from the manufacture process. Take the slipper apart, wash the alloy plates in brake cleaner and reassemble.

[rcjunky]

Next time you try it, hold both tires, but also have a finger on each rear axle, if it has a broken of missing roll pin, it could basically be diffing out just spinning the axle in the rim

[qwerty]

Just received the AE slipper pads from aMurika solved the problem its better than ever, the pads (ae b4 t4) snaps into the spur gear because of the snug fitting very nice to see i find it always tricky to hold the pads in place when i want to mount the spur with this one it's a pice of cake