df-03 rear diff prob :(

mx0range · #1 06-12-2007

my buggy is fwd! power isnt being transfered to the rear wheels. took it apart and tried to tighten it as much as possible, and its had no effect. i can literally poke either rear wheel when at full speed and they'll both stop with no resistance

jimmy · #2 06-12-2007

new balls, reverse the plates and rebuild it ?

I built the latest DF03 with Kanzen ceramic balls - still it needed to be quite tight to not slip. I put that down to the fairly small diameter so there's less leverage from the balls on the plates??

Do you have a slipper? a slipper set properly should protect the diff - the more the diff slips the worse it will get and more it will slip.

mx0range · #3 06-12-2007

i do have a slipper, yes. should the rear wheels spin in opposite directions when you manually turn 1 of them? the front does, rear doesnt.. im sure it should

jimmy · #4 06-12-2007

if you hold the spur / centre shaft then yes it should. without holding the drivetrain still then no - it might not! depends how loose the diff / motor and rest of the drivetrain are.

DCM · #5 06-12-2007

if they are the stock rear diff parts, the plastic holders have commited suicide or just been devoured by a spnning diff ring, so you can tighten it all the way down with no joy.

mx0range · #6 06-12-2007

not plastic, they never went in. i got some 3racing metal ones

DCM · #7 06-12-2007

check to see the plate mounting, and also the plastic block the nut goes in, and the nut ans screw

Saintboy_RC · #8 08-02-2008

Hey guys, just bought a DF-03 4 xmas and i kinda stripped the rear diff. the teeth arent stripped- the piece of plastic inside the ball bearings has obviously melted and then broken off of the main gear. i presume this is because of overheating balls. to what tensin should the rear diffs be tightened???

Mutant · #9 08-02-2008

The balls would have got hot as a result of the diff slipping. The use of any mod or 19t motor will require the use of a slipper to avoid this issue with any confidence. If using the stock silver can then when you rebuild it do it up until you can feel resistance when turning the wheels, at this point they should not spin freely when you hold the spur. this should be tight enough. another check is to put the rear tyres on the ground and pull the throttle, any slipping noise should come from the slipper (if fitted) not the diff.

Saintboy_RC · #10 09-02-2008

thanks mate. this has 2 b da best forum ever!!!!!!!

gracoat · #11 17-02-2008

Quote:

Originally Posted by Mutant

The balls would have got hot as a result of the diff slipping. The use of any mod or 19t motor will require the use of a slipper to avoid this issue with any confidence. If using the stock silver can then when you rebuild it do it up until you can feel resistance when turning the wheels, at this point they should not spin freely when you hold the spur. this should be tight enough. another check is to put the rear tyres on the ground and pull the throttle, any slipping noise should come from the slipper (if fitted) not the diff.

Sadly I think this diff is a bit of a 'throw away part'. The kind of thing that you run till it pops, then just bite the bullet and buy replacement parts.
The two output shafts that come from tamiya, that are the bread that sandwiches together the 'ball diff' itself appears to be a weak point, along with the plates they attach to. Plus, the diff gear itself is nylon! I suppose you have to run it really hard for quite some some to melt it out, but it would appear that it's been done on more than one occasion. I've looked everywhere for a metal replacement gear specifically for the rear to no avail... 3racing seems to be the most popular choice for metal/graphite replacement parts for tamiya cars but they don't do gears apparently. As with any smart company, tamiya, in order to purchase a new stock rear diff gear, you gotta get it with the spur gear set. http://www3.towerhobbies.com/cgi-bin...?&I=LXMSD1&P=7
Of course you can't just get the 'one gear' by itself!
I've upgraded my Avante with a Trinity Co27 Monster Stock pro motor... ...love it! Not too quick that I can't drive the car comfortably in my back yard, and not so slow that it's boring setting up and drive around the track in the tennis court across the street!
Anyways, I've just started to notice that if I come hard into a corner and slide to a stop, then pin the throttle, I'm hearing some slip from the diff. I know I'm going to have to make a new purchase of some diff parts soon. I'll probably buy the who kit... plates, gears, balls etc at the same time so that I don't have to make 10 trips to the store saying, "Nope that didn't do it."
Thoughts on solutions to an obvious weak point?

Mutant · #12 17-02-2008

As long as the diff is still functional then you will not have melted the gear. They do not tend to wear out so you should not need a new one.

If slipping becomes excessive, 1 or 2 seconds of slip per thumb action not a chirp, then it will lead to heat and melted gear.

The stock diff is a little bit of a problem because the balls and diff plates are thermally insulated from everything else, leading to easy build up of heat.

i think it could make sense using the front metal diff outdrives in the back, this will draw heat away from the inside of the diff if there is a little slippage.

The use of ceramic balls will also help as the material will not get as hot as metal balls. Cheapish on ebay.

The 3 racing outdrives i purchased seemed to have missed out on any hardening process, severe wear occured relatively quickly.

Cheers