RedFrits 0 Posted April 20, 2009 Hi all, I took my DB-01 out for a bash at my friends farm (nice area to bash) and suddenly I heard a strange noise. When I took my DB-01 up and gave it some trothlle, only the front wheels where turning and I heard a stranger noise than the 1st one I heard.. Keep in mind that I drive a Mamba max 7700kV with a 19T pinion. Since the weather was nice and I had the time I dismounted the rear diff and this is what I saw: How can I prevent this? I can not find delrin pulleys for balldiffs?! Share this post Link to post Share on other sites
BiggusDitchus 38 Posted April 20, 2009 That looks like you were running the diff too loose! Share this post Link to post Share on other sites
94eg! 825 Posted April 20, 2009 That happens because of an excess of heat. This amount of heat can only be generated by the diff slipping. The friction of the plates sliding aganst the balls will easily generate enough heat to melt any plastic nearby. It is extreamly important to set the diff so that it does NOT slip, yet loose enough that it still works. I suggest replacing the damaged parts, and then tightening the diff per the kit instructions. You should NOT be able to slip the pulley by hand while holding the two outdrives like this: BTW: It is very easy to build the diff incorrectly on this car. If the thrust bearing is on the wrong side, the diff WILL come loose as you drive. You won't know it till it's too late. This means pay VERY close attention to where the parts go as you assemble the car. Screw & thrust bearing on one side................spring, hut holder & nut on the other (in the longer outdrive). Share this post Link to post Share on other sites
RedFrits 0 Posted April 21, 2009 Thanks for the info! Does anyone know where I can get Delrin pulleys for the DB-01 (Tamiya nr. 84051). I can not find these available anywhere. It's the pulley for the balldiff. and Delrin seems much tougher than the standard plastics used. Share this post Link to post Share on other sites
dimblum 1 Posted April 21, 2009 Thanks for the info!Does anyone know where I can get Delrin pulleys for the DB-01 (Tamiya nr. 84051). I can not find these available anywhere. It's the pulley for the balldiff. and Delrin seems much tougher than the standard plastics used. Vellrip shows 3 in stock: http://www.vellrip.com/store/product_detai...p=1767&c=15 To my knowledge this part was made using the same plastic as the stock pulley, Tamiya just made these in black as a limited edition item. The stock pulleys will hold up to any motor you throw at it once the diff is set correctly. I made the same mistake of running mine a little loose when I first built mine .. Afterward I ran them too tight and flattened some of the diff balls 94eg! is correct.. Once the diff is set per the instructions, it will work like a charm.. Tamiya unfortunately did not make the instructions very clear.. Per the photo that 94eg! attached in his e-mail, you slide an object (flat wrench, allen keys, etc) into each outdrive. Hold them in one hand to lock the outdrives in place. Grab the pulley with your index finger and thumb, then try to rotate it toward you. If you can rotate it with little effort, then it is too loose and needs to be tightened a little more.. Keep tightening the screw until the pulley no longer turns under force with the outdrives locked - then stop.. Tightening the diff beyond that point is not a good idea.. Put each diff back in your car and you will be good-to-go.. Hope this helps. Dan Share this post Link to post Share on other sites
94eg! 825 Posted April 21, 2009 Vellrip shows 3 in stock: http://www.vellrip.com/store/product_detai...p=1767&c=15To my knowledge this part was made using the same plastic as the stock pulley, Tamiya just made these in black as a limited edition item. Yes your correct, the original pulley was made of delrin as well... Share this post Link to post Share on other sites
cubsfan2009 0 Posted April 21, 2009 If you need new diff balls as well I would recommend upgrading to ceramic nitride ones. Much tougher than stock steel and don't absorb heat so less chance of melting. Share this post Link to post Share on other sites
94eg! 825 Posted April 22, 2009 Standard kit steel balls will be fine if the diff is set properly. Ceramic balls will still destroy the diff plates if the diff is slipping, and cost 10x as much... Share this post Link to post Share on other sites
HunterZero 73 Posted April 23, 2009 Note the 'twisted' arrow, and the details on the diff joints in the assembly instructions. It's a bit vague and easy to miss, but it's telling you to turn the diff over at this point before you follow the instruction to put the diff bolt through. If you forget to do this and build it with the bolt back to front, the diff will 'undo' itself and ruin itself as you've seen. - James Share this post Link to post Share on other sites
mrbiccies 6 Posted April 23, 2009 I like to put a little thread lock on the diff screw thread, stops the nut from loosening which I have had happen in the past...... Share this post Link to post Share on other sites
94eg! 825 Posted April 23, 2009 Note the 'twisted' arrow, and the details on the diff joints in the assembly instructions. GOOD EYE SIR! I never even noticed that twisted arrow. Seems a bit silly, but that is reason people keep loosing their diffs... Share this post Link to post Share on other sites
WW-nut 0 Posted April 23, 2009 Twisted arrow, what twisted arrow I thought. It's like some kind of brain teaser, and then I spotted it. How subtle - and what rubbish instructions - bet lots of people missed that. Share this post Link to post Share on other sites
94eg! 825 Posted April 23, 2009 Twisted arrow, what twisted arrow I thought. It's like some kind of brain teaser, and then I spotted it. How subtle - and what rubbish instructions - bet lots of people missed that. My friend missed it on the rear diff, but the not the front. The big clue was that the red foam spacers didn't fit right inside the outdrives when the dog-bones were installed... Share this post Link to post Share on other sites
RedFrits 0 Posted April 23, 2009 Note the 'twisted' arrow, and the details on the diff joints in the assembly instructions. It's a bit vague and easy to miss, but it's telling you to turn the diff over at this point before you follow the instruction to put the diff bolt through.If you forget to do this and build it with the bolt back to front, the diff will 'undo' itself and ruin itself as you've seen. - James Well, actually I did not miss that one. It was mounted correctly so that was not the problem.. I think it was just not tight enough... Share this post Link to post Share on other sites
HunterZero 73 Posted April 24, 2009 My friend missed it on the rear diff, but the not the front. The big clue was that the red foam spacers didn't fit right inside the outdrives when the dog-bones were installed... That's a huge clue you might have missed something with a Tamiya kit. Everything usually fits so perfectly on them, if something doesn't quite fit right, you've usually put it together wrong! - James Share this post Link to post Share on other sites
HunterZero 73 Posted April 24, 2009 Well, actually I did not miss that one. It was mounted correctly so that was not the problem..I think it was just not tight enough... No worries. I have seen people miss this step, and the instructions for the DB01 diffs are vague enough that it was worth pointing out to people following this thread, just in case. It is easy to miss. It needs a bullet point near the arrow that says "* Turn over". DB01 is a sweet car, the most common assembly issues with it are either diff problems (either back to front assembly or not tight enough), or people finding it too difficult to get the kit machine screws screwed into the hard plastic. Oddly enough, the part of the car people most expect to have trouble with, the belt drive, is rock solid. - James Share this post Link to post Share on other sites
RedFrits 0 Posted April 24, 2009 DB01 is a sweet car, the most common assembly issues with it are either diff problems (either back to front assembly or not tight enough), or people finding it too difficult to get the kit machine screws screwed into the hard plastic.- James Building it gave me blisters on the inside of my hand actually! It was a pain getting those screws in. Some grease did the trick for most... The belt is pretty solid, I did not expect that. Only thing is that due to the diff melting my belt got damaged/worn. I replaced it alerady and it runs smoothly again. Share this post Link to post Share on other sites
WW-nut 0 Posted April 24, 2009 DB01 is a sweet car, the most common assembly issues with it are either diff problems (either back to front assembly or not tight enough), or people finding it too difficult to get the kit machine screws screwed into the hard plastic.James Instead of buying a set of hex screws or tapping the holes, I am considering buying the hop-up carbon chassis - would it resolve this problem or is it just as hard turning the screws into the carbon chassis? Ta Nige Share this post Link to post Share on other sites
dimblum 1 Posted April 24, 2009 Instead of buying a set of hex screws or tapping the holes, I am considering buying the hop-up carbon chassis - would it resolve this problem or is it just as hard turning the screws into the carbon chassis?Ta Nige I rebuild my DB-01 recently with the Carbon Chassis.. It was actually "harder" to turn the screws into this material then it was for the Kit Chassis.. I solved the screw problem before I built my DB-01 for the first time by buying a set of Stainless Steel screws from RC Screwz: http://www.rcscrewz.com/product_info.php/s...roducts_id/2767 It's an excellent kit.. The only screws that weren't quite right were the ones that held the motor mount in place.. This wasn't a problem since those screws go into pre-threaded metal. I just used the kit screws for the motor mount and the stainless steel screws for everything else. Hope this helps. Dan Share this post Link to post Share on other sites
WW-nut 0 Posted April 24, 2009 Cheers for your reply Dan - thought I'd get pay a little more and get the carbon chassis instead of the hex screws, but think there's no way round it I need to get the hex's. Just waiting for my Durga to be delivered so this thread has helped alot, ta everyone. Share this post Link to post Share on other sites
HunterZero 73 Posted April 25, 2009 I have the RC Screwz set for my Durga too. I also have the alu suspension blocks front and back, and the slipper. One of the best cars Tamiya has ever released for the price, IMHO. - James Share this post Link to post Share on other sites
RedFrits 0 Posted April 26, 2009 I have an additional question: What would be the advantage of the center one-way-pulley: http://www.stellamodels.net/catalog/produc...roducts_id=3500 Second questions: Would I need two of these since I do only see a pulley for ONE belt?! Share this post Link to post Share on other sites
dimblum 1 Posted April 26, 2009 I have an additional question:What would be the advantage of the center one-way-pulley: http://www.stellamodels.net/catalog/produc...roducts_id=3500 Second questions: Would I need two of these since I do only see a pulley for ONE belt?! Happy to help. To answer your second question: You will only need "one" center one-way pulley. They are only designed to change how the front wheels operate, so only one is used to drive the front belt.. Now for your first question: A center one-way is not for everyone, but I sure like it. It serves to help steering control and also helps when landing a jump. It gives you the best of 4WD and 2WD control at the same time. Here is how it works: The center one-way bearing replaces the standard 18T pulley used to drive the front belt of your DB-01 (there are two 18T pulleys on the center layshaft of your DB-01, one for the rear belt and one for the front belt). It allows the front wheels to independently 'free spin' in a forward motion -faster- than the motor can drive them. Here is one example of a one-way in action.. Let's say you are making a hard right turn; normally the outside wheel will want to turn more than the inside wheel since it has more distance to travel on the ground. Without a one-way, both front wheels will try to spin at the same rate with only a little slip from the differential.. With the one-way, the outside wheel can turn 'faster' on the ground than the inside wheel while the motor still provides power to the wheels (this works whether you are on or off the throttle)... It will also allow the front wheels to turn at a faster rate than the motor when you land a jump. This gives you better control after the landing and less chance of a rollover if you land off center. It sounds kind of confusing, but makes a lot of sense once it is installed and you are driving around the track. Here is a great link I found which explains it in a little more detail: http://www.geocities.com/agusyt/OneWays.doc Please let me know if you need more info or photos of my one-way installed.. Hope this helps. Dan Share this post Link to post Share on other sites
SidewaysLS4 0 Posted April 27, 2009 DB01 diffs are very strong, at least with ceramic diff balls. I'm running a Medusa 4 pole motor on 3S with 3.875" diameter tires in my DB01, and the diff never breaks. Belts and pulleys on the other hand.... Share this post Link to post Share on other sites
94eg! 825 Posted April 27, 2009 Even with the kit standard steel balls, the diffs are very strong. We've been running a 15T with NO slipper and they are still smooth & solid. As long as they don't slip, they will last forever. BTW: If you sand the diff rings before you assemble the diffs, this will give you a smoother diff. I think you use 800-1000 grit to do this. Just put a drop of oil on the sand-paper and swirl the diff rings around in it. Then give them a wash and your good to build. This makes the diffs smoother and gives the balls more traction. Either way, be sure to recheck that the diff still doesn't slip after a short break in period. This is very important as well... Share this post Link to post Share on other sites
