First outing with my son and the Durga ended with two broken diffs
 

Well, as my title stated, our first bash in a parking didn't end on a good note. Found both front and rear diff pulleys torn apart.

Much like this person's pics,
http://www.oople.com/forums/showthread.php?t=20313

So what should I do now? I've read bits here and there about using a 501x diff but I don't know what parts I would need. Is there a complete set to buy or bits and pieces?

Everything else looks good so if I keep with the Durga instructions, it looks like I just need the two 37T pulleys. What do I need if I want to upgrade to the 501x diff? Just slap in a 501x pulley or is it more complex than that?

I've personally (mentioning no names) rebuilt a diff like this for someone - there was no glue on the diff rings and no grease on the diff balls. I'm of course not saying that you didn't build the diffs as per instructions but blowing 2 diffs simply shouldn't happen.

I'd have thought the diffs slipping would cause this - but the one I rebuilt was down to the rings slipping on the plastic holders from what I could see.

As long as the diff rings and balls are still in good condition then you'll just have to replace the pulleys. If you're using the original stuff then pay close-close attention to the build steps, degrease and glue the rings with some sort of flexible strong glue would be best.

The 501X diff halves work on the metal-metal friction - which should stop the diff rings spinning, and it should only really be needed on the rear as the front won't have enough torque to threaten the Durga diffs if built correctly.

If this was genuinely your first time out with the car then be aware you'll have to keep checking the differentials as they bed in - since they can loosen slightly and begin to slip, which could also have been the cause.

Let us know if you need any help - the Durga is a great car

This confuses me alot.

First I read that (if I use a high power motor) need to replace the rear diff halves to 501x dif halves.

Later I read that the only thing needed to replace is the diff pulley...

It might be that english is'nt my mother tounge but I really get confused with all this.

I was replying regarding fixing these broken diffs - which might not have anything to do with 'powerful motors' at all. If you build them well even the stock diffs should handle most abuse you can throw at them - the 501X diff is definitely a good idea if you're racing.

Thanks Jimmy, it was our first time out with the car. I think I did build the diffs correctly but can't be sure as the Durga is only my 2nd time building a RC car and the 1st time was over 25 years ago!

I will probably get new Durga pulleys then and watch my build more closely. I am running a Novak Havoc BL on this and I remember the last thing before the car was not responsive and it was when it hit a large pothole at a high speed. Maybe that put the jolt and cracked the diffs? I don't know, next time I'll make sure the parking lot is clear of pot holes. :)

the issue with the stock diffs, is having to rely on the glue to hold the plate in place. Once the glue goes, it slips, and no matter how much you tighten the diff, it still slips under load, heats up the diff and eventually melts the pulley. This usually happens on the rear diff, as it takes most load.

Guys, so if I decide to go with changing to the 501x diffs, I just need the halves and the rest of the existing parts of the ball differentials from the Durga fits, correct?

501 diff
 

Jimmy re-built my rear diff for me - thats why i kept loosing races!! ----- only kidding jimmy it was a great help at the time and appreciated.



To modifly as people are suggesting with 501 diff havles you need


1) 501 diff halves (try davesrcmodels in ireland at least thats where mine came from - other would be goldstarstockists - good for tamiya parts)

2) Origonal cetre pulleys

3) additional reccommendations are to fit tungsten carbide diff balls (generate less heat) fit 10 of them and use 2 standard metal balls opposite each other i.e. 12 and 6 o'clock.

I have done the above to mine and run an LRP 5.5 turn in it and have had no probs so far....

Durga is a top car in my humble opinion - A final coming soon when i can drive the thing properly

501 diff
 

just to clarify my comments below yes you only need standard parts (option for ceramic balls) and 501 diff halves, bearings and shims as standard

Thanks Shanks, that clarifies quite a bit for us beginners. :thumbsup:

have seen this done a lot on other cars, usually caused buy wheel spinning or doing dough nuts,

Just laid an order of ceramic diff balls. Will take my rear diff apart tonight to see what kind of damage is done so far.

Next thing will be to order the 501x diff halves, clean my metal plates from glue, and hope everything will be ok in the future.

Looking forward to hear what you find when you take it apart. I'm going to take a pic of my diffs and upload later, err...at least what's left of them.

Here's whats left of both my pulleys.

http://img133.imageshack.us/img133/1590/pulleys.th.jpg

Will take it apart in a couple of hours, these are the diff balls I ordered.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=310139120081, took 12 of them so I can if needed replace all of them. I guess it's the best thing to do.

Diff
 

Hi
Best to use 10 ceramic and two steel set opposite each other ie 12 and 6 o clock apparently the steel ones keep the track clean this came from a tamiya pro driver

no prob
 

no worries pal - beginer myself well 4mths into it.

diff look and sound more comllicated than they are - as does lots of this rc stuff - best advice is take things apart and look and work out what the crack is yourselve - usually more simple than first thought - and then next time around dodle...dont bother me whther diff goes or not now cause it only takes 15mins to re-build and sort

Forgott to post after I took my diff apart.

The diff actually looked totally ok, no plastic had changed, the metal plates where still glued to he plastic, the only thing would be that the grease seemed to have almost vaporated, there where very little of it left in there.

Will order the trf501x diff halves just to be shure now that I have ordered ceramic balls (wich where shipped less then 12 hours of ordering).

My only wory now is to get the diff tighten up enough, but not to much, this is a issue I have always had my worries about when building a new car.

I ordered the ceramic balls too and the 501x diff joints as well as new plates since mine are still also glued to the plastic of the Durga diff joints. Also ordered additional pulleys just in case. This car just got a bit more expensive but my son and I are looking forward to getting it back out for the summer.

A brief update; received the TRF501X diffs, ceramic balls, replacement pulleys. Put everything together and this time I paid special attention to the tightening the front and rear diffs. Tightened and backed off 1/4 turn.

I have a question regarding the slipper though. I have the 54018 slipper clutch installed and the instructions state the standard position for the nut is 3mm in. I find at that setting, it is tight with very little slip and I backed off so it's 2.5mm in for now. I'm gunshy after tearing both diffs. Haven't run the car, it is just sitting on the shelf until the weekend. For those using the same slipper, do you follow the instruction sheet and set it 3mm or do you set it by feel?

I found that tightening the diffs fully and backing off the screw 1/4 or 1/2 turn caused lots of problems with the DB-01 diffs - crushing of the spring, damage to the K4 part that holds the locknut and damage to the thrust bearing.. I know this method works for other diff designs, but it did not seem to be the intention for the Tamiya diff.

I have since followed the directions Tamiya provided in the DB-01 manual: hold the diff in one hand while locking both diff joints with allen keys etc. Now tighten the diff screw little by little until you can no longer turn the pulley with your other hand - then 'stop'..

Setting my diffs this way has eliminated all problems. The diffs work perfectly for racing - even after running a 6.5T..

P.S. The default setting for the slipper clutch (3mm) has worked pretty good so far. I can hear it slip and catch with higher power motors much easier than lower power motors.

I think you may be right about backing it off a little if you are running say a 13.5T or higher turn motor.

Hope this helps.

Dan

Thanks Dan, I'll retry the directions in the manual for the diff.

i bought a secondhand durga a while back and the rear diff pulley wheel was shot i thought it was from just abuse but ater reading these threads i now know the cause so have re built with a new diff pulley wheel, but seems it will happen again so the only option is to use 501x rear diff halves, can anyone put me in the right ddirection as to where i can get hold of some please

They are rarely found on ebay, bought mine from RC mushrooms ebay store. Keep you eyes open.

Its a stupid situation tbh. Here we have possibly the largest, most well known RC manufacturer in the world and you cant even get some parts for current kits anywhere :mad:

Ive tried a dozen shops UK & worldwide and no-one seems to have certain consumerable parts like the 501x/Durga metal diff halves in stock, or know when they are going to get any more. Which is silly when you consider the 501x is only 3 years old and the 511x, Durga etc are still current models.

501x bodies ? Nope. 37t diff pullies ? Possibly, i'm waiting for a reply of stock from one shop. Front 501x hexes ? Same as 37t pullies. White wheels ? Nope. Diff halves ? Nope.

Deep breath..... OK rant over :D

As soon as a modelshop e-mails me to say their in stock or a even a possible re-stock date for diff halves ill post it here. After ive got mine ordered of course :lol:

If it's an UK modelshop I wouldn't hold your breath Matt. Hobby Co don't/won't order TRF parts from Tamiya as they claim there is no demand:thumbdown:

I've had 37T pulleys on backorder with Fusion for over a month.:thumbdown: After reminding them on Friday, I have 1 on it's way (I ordered 2)

If you want Durga diff halves, I have a NIP set you can buy, I may have a spare hex or two as well.

501 diff halves are rarer than an honest politician, I got lucky and found a used set.

I'd advise you to get a pair of 18T layshaft pulleys for spares as well, my lad has done a couple of them.

Problem is Pete, its not just the UK ones.... US, Hong Kong and Euro shops ive tried or left e-mails with. Some parts, like the Diff Halves, just seem not to be available anywhere ive tried atm.

At least not that i can find anyway, after a couple of hours e-mailing. And i did find 2 webshops with them on the net, but as soon as they were ordered i got an e-mail back saying they were unavailable. :confused:

37t pulley
http://cgi.ebay.com/Tamiya-54023-Opt...0|293:2|294:30

Rear white wheels
http://cgi.ebay.com/Tamiya-51321-Spa...1|293:2|294:30

Front white Wheels
http://cgi.ebay.com/Tamiya-RC-TRF501...1|293:1|294:50

501x Diff joints
http://cgi.ebay.com/Tamiya-TRF501X-D...3286.m20.l1116

Or you can go to Racing Factory (Finland) and buy all you need from them. (Amazing fast shipping).
http://www.racingfactory.fi/products...a-parts?page=1

Whoops didnt look on Ebay.com.. only .UK. - Lesson learnt !

Spot on, cheers :thumbsup:

Had a reply back from Brock Models today. Most of the parts i'm after ( 37t pullies, metal 501x diff joints, etc etc ) will be ordered in the next couple of days, and in stock, hopefully, in a couple of weeks. Worth contacting them to reserve a set or two if anyone needs those parts and don't want to order from abroad.