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Serious F40/Porshe problem

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  • Serious F40/Porshe problem

    I have a serious problem coming from the channel in the crown gear where the engine shaft fits. It seems that the shaft is rubbing the side walls and wearing them away very quickly. I have over 15 or so Slot.its, and this has happened twice, with the last time coming from a brand new Ferrari F40. The pinion is far enough away to not cause rubbing problems and it actually runs great in the straights, but in the turns, you hear some hard braking type noise...I assume the axle pressing the crown against the motor shaft. I have greased the gears and still no help. In the Porshe, I added a 27t crown gear and I went through 2 before switching to an offset set up and getting rid of the problem. Pics attached. Any help is greatly appreciated.
    Last edited by leejax01; 12-06-2008, 09:28 PM.

  • #2
    Despite the thumbnail attachments, I'm a bit lost here; those look like anglewinder gears sitting beside the car on the plinth.


    • #3
      It is the 27 tooth crow that was in the Porshe. You can see the bronze dust starting in he F40.


      • #4
        I'm wondering if you need to glue your motor in, then. I see you're running with a magnet, so forces could be pretty strong. Not seeing this as a particular "Ferrari" or "Porsche" problem, all the cars use the same pods and drivelines etc. If you hit the trigger on and off (without the body on the chassis) is the motor twisting back and forth?

        Also, and this may be more important, are the inner hubs of your wheels relatively snug against the axle bushings in terms of preventing excessive lateral axle free play?


        • #5
          Use some form of lube(Grease) at the end of the motor shaft in the slot on the gear. That will solve the problem, that shaft and slot takes the side load of the rear axle in the corners. Grey pods require the use offset gears too.


          • #6
            I think Slot.It actually recommends OILING the channel in the gear. The picture that comes with the crown gears has arrows pointing to the channel. And says "! Olio - Oil - Aceite ! Sempre - Always - Siempre".



            • #7
              I have already greased it with the same grease as the other Slot.its, but still the same thing. All my cars are set up the same, so I doubt it is a over magnetized issue. Is there a liner that can go over the motor shaft?


              • #8
                get the thrust bearing (SIPA25)

                cut the motor shaft so it doesn't go into the gear channel. using a dremel cutting wheel w/ the motor under low power will make this a quick & clean operation w/out over heating the shaft.

                install thrust bearing against the needed axle bushing

                i make extensive use of teflon or nylon washers & here is a good place to use them

                i have 2 Slot.its & a couple other in-line cars set-up this way; it greatly minimizes friction in the drivetrain.


                • #9
                  Lube it or Lose it...

                  If there is bronze (or aluminum) dust coming from the crown gear, the problem is a lack of grease in the channel where the motor shaft runs in the crown gear. This is what keeps the gear mesh correct. From the factory, there is a bit of grease in there, but rarely enough, especially for magnet racing. This was a new concept to most of us who had been racing for years as any older cars we had needed spacers and any Scalextric cars etc. use an entirely plastic crown that doesn't need grease. Here is a picture of the rear end of my McLaren. The gear has run its 8-hour leg of the Scaleracing 24 Hour race and then 1 hour of the subsequent 3 Hour race a few weeks later, with no issues:

                  Spacers can be used to keep the axle from moving around, but the simple solution, as designed, is to fill the channel with enough plastic-compatible grease to coat the inside of the channel:

                  After running a small bead of grease in the channel, turn the rear wheels to distribute it evenly:

                  You may want to run the car over a piece of paper to fling any excess off before running on the track to avoid having the marshals display the oil flag for you... The only time I ever had a problem with crown gears was when I forgot to lube it.



                  • #10
                    There was an occasion when the motor shaft was to long on some Slot-It motors and it actually touched the inside of the crown. I don't mean the sides but the part of the crown that would face the end of the shaft.Taking just a touch off the end made all the difference and keeping it lubed. If you rebuild the cars you are having problems with make sure there is some "light" between the tip of the motor shaft and the crown.


                    • #11
                      You can buy this device:


                      I use something similar, with Kleen Flo white grease. But I must admit, I'm also inclined to use a combination of shims or axle stoppers as recommended by Martini917k, particularly for proxy cars that may not see any lubrication for extended periods.


                      • #12
                        Not sure as I actually greased it quite well and it had more grease than most of my other Slot.its, so I am not sure on the problem.

                        Other than that, the F40 is the fastest that I have. It is just a bit faster than the pumpkin Mclaren...although the difference could be due to tires.


                        • #13
                          Synthetic Gear Lube...SLOT CAR CORNER seems to last the longest and is not too messy it seems to have Teflon in it or Plumbers Teflon Grease @ Lowes Both have resolved the bronze dust issue


                          • #14
                            A few suggestions, not very different from the others.

                            First, check the motor shaft after the pinion for any imperfections. It is possible that that there might be a sharp piece or edge that's destroying the gear. It might have resulted from pressing the pinion on the shaft. Try to chamfer the end, and then polish it.

                            Second, make sure the motor isn't wobbling from side to side under load. I always hot glue the motors in place. Sometimes motors (and others) can be far too loose in the chassis or pod.

                            Third, as noted, try and set lateral play via spacers on the axles, to reduce any load on the gear/motor intersection -- you might be able to totally cut the motor shaft and set lateral play using only the spacers as thrust washers.

                            Fourth, my favorite grease for this purpose is Tamiya Ceramic Grease. It's commonly sold in hobby shops and online for RC cars, but it works extremely well in this context. It does not fling off as many simpler plastic compatible greases will do, and it contains additives that reduce friction better than almost anything else you'll find (and is compatible with plastic). Just don't let it get near the electrical stuff on the car.
                            Last edited by JML; 12-10-2008, 05:44 PM.


                            • #15
                              Thanks. I used a new product called Lube Tube which we use as a teflon based lube for plumbing in plastic fittings. It works great and no problems since.