Diff. Ring Gear Failures

[dr_elvis]

Hey Racers..

After installing then new molded plastic chassis side plates and rear brace me and some of my race mates had often abmormal failures of the diff ring gear in the rear differential.

Has anybody else heard of this and found something to solve the issue? We are discussing if the increased flex is responsible for the damage. We have heard too that at the euros many diff ring gears were killed and most durango drivers used the plastic side plates too.

Thanks in advance

[dpackster1980]

That isn't possible as the gearbox casing would have to flex which can't happen.

Not using enough gear grease would cause it as the pinion gears seem to be a harder metal and you are running metal on metal.

I noticed that mine has a tight spot that I'm trying to solve other than that it's sweet as a nut.

I got a huge tub of molly grease for cheap as chips as I think you get no where near enough in the kit.

[JohnM]

I've been running the plastic side pods on my car for the last month or so, haven't had any problems at all with doing so, let alone the diff gears, and my car was one of the first ones, so the gears are a year old now, so seen plenty of use.

[dr_elvis]

Originally Posted by JohnM

I've been running the plastic side pods on my car for the last month or so, haven't had any problems at all with doing so, let alone the diff gears, and my car was one of the first ones, so the gears are a year old now, so seen plenty of use.

I'd ran my car for more then 10 month now aprox. 5 accu packs per week on expert level like most of my friends. the first failures came after installing plastic side plates.

de

[wacattack]

No problems for me and I've been running the plastic side plates all season (5-6 months)

[telboy]

No problems on mine either.

[BigBoyBigToy]

this has nothing to do with the plastic side plates imo!! i lost 3 teeth on my rear ring gear because of bad installation, u have to spread the 2 small bearing 2.8mm apart from each other and locktite the screw so it dont back off shim properly silver shim and copper shim till it feels just right with no slop at all!! and lots of grease always helps... been there and done that and havent had a prob since!....

[dr_elvis]

Originally Posted by BigBoyBigToy

this has nothing to do with the plastic side plates imo!! i lost 3 teeth on my rear ring gear because of bad installation, u have to spread the 2 small bearing 2.8mm apart from each other and locktite the screw so it dont back off shim properly silver shim and copper shim till it feels just right with no slop at all!! and lots of grease always helps... been there and done that and havent had a prob since!....

Thanks but as you can read i had about 200 runs with metal side plates and no confusions with the diff ring gears (motors from 5.5T up to 10.5T).

We found out that the newer gear boxes have problems near the outer ball bearing which can be solved using a single round of "tesa film" tape around the bearing. Installation of the bevel gear in the gearbox is def. not the cause for the issue. Shiming and gear grease are no problems at all.

[Gonzo]

Diff ring gears is the only thing I still brake often at this car, so good that you made this topic, I thought I was the only one seeing this... Every time a little chunk is missing at the outside corner of a tooth. Last week I even received a new one in a bag which was missing a corner at the inside of a tooth. It was replaced free of charge without a problem, but still weird…


Like probably most of you, first I’ve concentrated on shimming and meshing the diff sideways more carefully, but without success. Now I’m also focusing on the slop on the bevel gear. I noticed that one of my cases had no slop sideways, but some up/downwards. Also I believe that up/down movement of the bevel gear could explain more why I always loose the outer corners of teeth on the ring gear.

So I’ve put a tape longitudinally in the bottom of the case where the bevel-bearings go, so a 5 mm wide tape from just not touching the bevel gear till sticking out at the other side. This both in the up and down half of the case. That took care of the slop for me. Let’s see how this goes.

That the plastic sidepods have an effect is possible, if your rear axis touches your slipper (or hooks in a worn slipper outdrive) at extreme flex, and puts some stress on your bevel axis, shifting it up or down.

But don’t get me wrong, besides this, I’m verrrry happy with my DEX !!!



Maybe another option is that Durango designs a case with bevel bearings the size of the big wheel bearings?

[grapejuice]

I've been having a same issue....so is it better to put tape all the way around the diff bearing or just one side of the case where the bearing sits?

[Gonzo]

I've put a 5mm x 30mm tape in the same direction as the bevel axis, so longitudinally over the seatings of the bearings, both in upper and lower half.
Way easier than taping bearing per bearing, and the tape doesn't move because it makes some 90 degree turns once everything assembled.
If the slop would be sideways, different story...
Again, still testing this...

And what type of gear-grease would be best to use on the diff ring? A sort of type instead of a brand would be nice, so I could buy some non-RC quantities of it

[littlejohn]

Originally Posted by Gonzo

Diff ring gears is the only thing I still brake often at this car, so good that you made this topic, I thought I was the only one seeing this... Every time a little chunk is missing at the outside corner of a tooth. Last week I even received a new one in a bag which was missing a corner at the inside of a tooth. It was replaced free of charge without a problem, but still weird…


Like probably most of you, first I’ve concentrated on shimming and meshing the diff sideways more carefully, but without success. Now I’m also focusing on the slop on the bevel gear. I noticed that one of my cases had no slop sideways, but some up/downwards. Also I believe that up/down movement of the bevel gear could explain more why I always loose the outer corners of teeth on the ring gear.

So I’ve put a tape longitudinally in the bottom of the case where the bevel-bearings go, so a 5 mm wide tape from just not touching the bevel gear till sticking out at the other side. This both in the up and down half of the case. That took care of the slop for me. Let’s see how this goes.

That the plastic sidepods have an effect is possible, if your rear axis touches your slipper (or hooks in a worn slipper outdrive) at extreme flex, and puts some stress on your bevel axis, shifting it up or down.

But don’t get me wrong, besides this, I’m verrrry happy with my DEX !!!



Maybe another option is that Durango designs a case with bevel bearings the size of the big wheel bearings?

I have also noticed that if the CVDs aren't built with TLC, (ie. make sure not to use too much loctite and the whole joint moves without a single hint of binding at extreme angles), Then the pinon can be forced to wobble abit when eveything is put together.

I test my CVD builds but setting the joint at the most extreme angle and turing it to see if there is any binding. I also lube my CVDs with a wax lube.

[dr_elvis]

Will test the tape strips in the upper and lower half of the diff case

i use a standard grease including MoS2

[Hulk]

Also make sure your slipper is set correctly. I went through a few gears when i first got the car but since backing the slipper off ive had no problems at all.

When changing diff oils its a good idea to check theres no dirt between any teeth. I always clean them with a tooth brush then apply a small amount of grease whenever you change your oils.

As for your gears going after using the plastic side pods im sure this is just coincidence. Ive used the plastic side pods on many occasions without any issues. Yes they do give the car more flex, but there is plenty of room for the prop shaft to move in and out of the slipper outdrive before hitting anything.

Craig

[dpackster1980]

Originally Posted by dpackster1980

That isn't possible as the gearbox casing would have to flex which can't happen.

Not using enough gear grease would cause it as the pinion gears seem to be a harder metal and you are running metal on metal.

I noticed that mine has a tight spot that I'm trying to solve other than that it's sweet as a nut.

I got a huge tub of molly grease for cheap as chips as I think you get no where near enough in the kit.

Well the tight spot has gone but I've chipped the tops off 2 teeth and it wasn't due to plastic side pods.

It was either caused by the 2mm grub screw on the centre shaft working slightly loose causing the pinion gear moving backwards and forwards.

The second option is I was racing outdoors and the board for the loop wasn't pegged down so I didn't notice and hit it full speed and the cars stopped instantly.

Either way both my fault.

Still runs fine but slighly noisy from the front and it doesn't jump teeth so I'll change it later.

[Gonzo]

Originally Posted by Gonzo

So I’ve put a tape longitudinally in the bottom of the case where the bevel-bearings go, so a 5 mm wide tape from just not touching the bevel gear till sticking out at the other side. This both in the up and down half of the case. That took care of the slop for me. Let’s see how this goes.

Again 1 tooth damaged
It's not the top corner on 2 or 3 consecutive teeth anymore like the other times, but the complete side of one tooth . But I was already able to drive 15 packs with it, and no noise, I only saw the damage during maintenance.

So as expected, taking care of the slop with tape helps!!

I have to admit that my slipper is set tight, I hate a loose slipper (that's why I sold my BMax, with a slipper set to my taste, a set of gears of a BMax survived exactly 4 minutes...). With a DEX a couple of hours, so I can't complain.
I guess I'll have to loosen my DEX' slipper half a turn to get rid of the problem forever.
Or is there a way to loosen the slipper only a quarter turn?

[TKG26]

There are 2 durangos at my club... last night i was checkin them out. The R car wich was older had major bearing slop at the front tranny case, where the CVD enters the gear box and attaches to the pinion gear. IT there was a major amount of movement if you moved the cvd around. The other car a newer PRO car has similar slop in the bearings. i wonder if they too will be having gear failures soon? I pointed it out to both of them and hopefully they change the bearings asap

[grapejuice]

Originally Posted by TKG26

There are 2 durangos at my club... last night i was checkin them out. The R car wich was older had major bearing slop at the front tranny case, where the CVD enters the gear box and attaches to the pinion gear. IT there was a major amount of movement if you moved the cvd around. The other car a newer PRO car has similar slop in the bearings. i wonder if they too will be having gear failures soon? I pointed it out to both of them and hopefully they change the bearings asap

They probably don't have the bearings spaced correctly, there is a certain gap that needs to be between the bearings or else it will fit very loose in the case. But yes, running them like that will mess up the ring gear.

[dpackster1980]

Originally Posted by grapejuice

They probably don't have the bearings spaced correctly, there is a certain gap that needs to be between the bearings or else it will fit very loose in the case. But yes, running them like that will mess up the ring gear.

To space the bearings correctly if you don't have a vernier use a geabox casing half, squeeze the pinion and axle together so they nip the bearings against the bearing spacer on the gearbox moulding. Put the casings together and check to make sire it's not too tight.

Excessive vertical and latteral movement means the bearings aren't spaced correctly so you will damage ring gears.

I recommend using this method just incase there are variances in the case mouldings because if you space it at 2.8mm and the internally moulded was less than that them you'll have gear failiures.

[dpackster1980]

Rear crown gear is missing loads of teeth, slipper isn't too tight and bearing spacing is fine.

A question has anyone had this problem with the 2009 car?

If not then Durango seriously need to stop investing money in stupid big bore shocks and invest in a new gearbox mould!!!!

I bought a Durango to avoid crap like this from other manufactures!

Durango sort it out!