First Run of DB01 with Novak 6.5R and slipper

[wongy008]

i need help guys.

i think i found a related thread
http://www.oople.com/forums/showthread.php?t=19752

but i am seriously not impressed and thinking why i bothered. I'd always been a nitro guy but the brushless seemed fun at the time but seriously doubting why i wasted all the money now

basic set up. DB01. slipper clutch and Novak 6.5R system. Running this with a Reedy 5000 MAH 20C lipo pack. the car is purely for bashing

initially i though what the heck is that it. the speed and acceleration was crap. Im using the 23t pinon so firstly should i be using the 17T

after a few mintues up and down then Bang no drive to the rear when i inspected what was wrong

took the car home and took it apart for inspection and this is what i found










is it worth getting the damaged replacement parts or is there uprated items

i dont really have a clue and dont follow the scene. i just want a reliable car for bashing

with my current set up what kind of speeds should i be expecting in mph !!!!

i would say my car was running 24mph max

please help

[rowanp25]

looks like the rear diff was doing the slippers job! was the rear diff slipping at all?

[jimmy]

Not sure about mph - I clocked the fastest of the absolute fast cars on the main straight at Bury Metro (outdoors) at 28mph. But that's a race track.

Your problem isn't a big surprise - I fixed a diff like that the other week at bury indoors. The problem is because your diff is slipping / plates are slipping on the plastic (read, crap) holders. This is fine if you're running a mild motor - but a 6.5 isn't really a mild motor and I'd reccomend a 501X rear diff.

Looking at my review it's clear I broke the rear diff on the third race meeting - I only wrote up the first two races in the review. On the third one of the diff rings came loose and would have fried the rear diff like yours if I'd have carried on. I put a 501X diff in the back which I always ran after that. The front diff is NO problem.

Your centre pulley is worn becaue of the rear diff melting - these big pulleys are very good so that's not your problem. Having said that - if the teeth look worn then you have to replace it I'm afraid.

To sum up - 501X rear diff halves... straight swap and bullet proof.

This car is a racer - very strong and very good drivetrain for the most part. The rear diff is a weakness with hot motors but easy to upgrade really but you always need to be aware of the ball diffs and belts - and if it's not moving like you expect (slipping) always stop and check it out.

[i4n]

It looks to me as if you didn't have the diff tight enough (which would also account for the lack of acceleration as you were probably only FWD). I did something similar on my XXX-CR when I first got a brushless set-up (melted 3 diffs before I swallowed my pride and asked for help).

I ran my Durga with the standard diff and a Losi 6.5 in it for a few months before upgrading to the 501 diff halves with no problems (only did it to be safe during a rebuild when I also changed to ceramic balls). With the power you get from the 6.5 you want to do the diff up tight to stop it slipping (that's the job of the slipper) but as DCM points out in the other thread, not too tight that you 'crack' the glue holding the diff rings onto the outdrives.

It also looks like one of your belts was set too lose and slipping judging by the marks on the centre pulley (but that may be from where the diff destroyed itself).

I'd give it another go, when you adjust the diff it should be tight, but still smooth to turn when using the wheels when installed in the car. Bed it in by holding one wheel and running at 1/4 throttle for 30 seconds and repeating on the other side and then re-adjust and it should be fine. I also check that they haven't loosened by holding the front set of wheels between my knees and trying to turn both rear wheels in the same direction at the same time and then reversing to try the fronts.

I'm sure one of the other Tamiya guy's will offer some advice in not too long a time... (while I was writing my reply!)

[DCM]

I agree with Jimmy here.

Replace diff halves with 501X parts on the rear, new pulleys and balls, and whilst your at it, might as well do the belt and small pulley, make sure the belt tension is good. Run it for a couple of minutes, then check the rear diff, if all ok, should be fine, but you would need to just check that rear diff degular.

[wongy008]

firstly thanks for the quick responses guys

im really quite annoyed as this happened on its very first run and i was told by many people and reading lots of reviews the car is strong and bulletproof

there is lots of mention of diff slippage. what is this exactly?? the diffs seem pretty securely put together. can someome please describe this behaviour in more detail??

should i be running the 23t pinon or 17t pinon

there is mention of getting 501x rear diff and 501 diff halves i take it these are the same thing. where can i get these and has anyone got the part number so i dont order the wrong thing

how much should i be looking at in £

should nthe car be explosive as fast with 6.5 R, i would say after first run it is definatley slower than my mini inferno 09 which is stock !!

[DCM]

17-18t on a 6.5

The diff plates are glued in place on the DB-01, which is great when you have little load on them, but when you put a 6.5 in it, the loading on the rear diff is significantly higher, so the glue ends up cracking, the plates then start to slip, everything heats up, and then you got a molten mass in the rear pulley.

with a 6.5, it should be pretty rapid, but chances are, your rear diff was slipping at the start, so stunted acceleration due to it slipping.

[B44&501xRacerEX]

I suppose tungsten or ceramic diff balls might help also.
Doesnt the stock steel diff balls generate more heat?
My 501x diff did the same thing before, because it was loose like his.
I switched to tungsten and have not had any more issues.

[wongy008]

thanks for the response guys

i am having trouble getting a supplier for the 501 rear diff halves
can someone point me in the right direction

also whilst i am at which what other upgrades will be worthwhile for reliability
the car will be used purely for bashing

where do i order tungsten or ceramic diff balls?? and part numbers ??

cheers

[Eddie168]

Hi wongy you could get the 501x diff halves form Brock models but i don't think they are in stock at the moment
I got a set of ceramic diff balls from here http://demonpowerproducts.co.uk/prod...oducts_id=3157 they seems to be quite good hope this helps

[wongy008]

I am looking into the ceramic diff balls and they are very expensive

My main aim is to have a relaible DB01 for bashing. Will i really benefit from having them installed

also i have managed to get one 501 diff halve from a uk supplier and it was suggested to get a 36T front diff to take some additional load off the front

this a good or bad idea??

[jimmy]

You don't need any fancy balls (!) in the 37 tooth pulleys - I never did and never had a problem. The smaller 501X original diffs had a lot more strain and ceramic balls certainly helped there. So no - absolutely not needed.

[DCM]

they are not needed, they are nice to put in, but like Jimmy says, not needed.

[dimblum]

Not much else I can add that hasn't already been said. The Durga is an awesome car once it is dialed in correctly.

A decent inexpensive set of ceramic nitride diff balls can be bought from JAAD Racing (each set of 12 balls will replace the balls for one diff) - http://www.precisionrc.com/nv/car/product/...roduct_id=54309

Here is a link for the ceramic nitride thrust bearings as well - http://www.precisionrc.com/nv/car/product/...roduct_id=53980

These are the ones I have been using for months on the track. They have been bulletproof and are still perfect after a few diff inspections.

Hope this helps.

[wongy008]

right cheers guys

i think i will leave the diff balls for now

i have a 501 rear diff half waiting to go on the car. How tightly should this be done up. as tight as i can physically do it without breaking the diff pulley??

i have new centre pulleys too. just waiting for the 37t diff pulley from a different supplier

i will fit 501 rear diff halves to the front as a precaution when the supplier restocks them

talking of supplier. Daves Rc models is highly recommended by me. order yesterday and i received the items today. so fast and efficient

when i rebuild the db01 should the belts be set up as tight as possible too

would it not be easier for somone to release a locked diff or would this have a detrimentle effect on the handling

[DCM]

you tighten it up till, when holding the rear wheels still, and the slipper locked up, you can't turn the spur gear with your thumb.

[A.J. Gee]

Another way to tighten it to it's maximum potential, is to tighten the screw as tight as it will go and then back off about 1/8 of a turn. Maybe back off a bit more since you will be using steel balls for the pulleys. A half turn back from as tight as the screw will go. You will be good to go bro. Trust me man, i had the same problems until i switched to the 501 diff plates. I melted 2 or 3 of them. It didn't bother me to much, as i enjoy working on and doing repairs for my cars.

[wongy008]

i am about to install the diff halves. but what so different about these compared to the standard db01 ones?? besides being one piece

do i just use the diff halves or will i still need to use BG8 diff plate from the db01 with the install

sorry if these sound like stupid questions

[jimmy]

yes, you still use the diff plates. The difference is the proper support the metal provides - also the metal-on-metal contact stops the plates from spinning even without glue

[wongy008]

cheers for the advice guys, everything is here now

hopefully it will be ok. install will be tonight and hopefully ill have a reliable db01

otherwise ill put the lot for sale