TB-02 diff
 

I race my TB-02 at my local track (a tight parking lot, so diffs front and rear), using an MVP motor with 58T Spur 20T Pinion on 26mm Pirelli D compound tires (with 2mm wheel spacers in the front to clear the ballcups). I have the alu.motor mount, SSG stiffener, TRF dampers (40wt, 2-hole teflon piston, tamiya gold springs on the rear with green (HPI?) medium in front), reinforced diff joints, and front medium swaybar on the car. It's on 1.5 deg negative camber all round, 10mm ground clearance f/r (the pirellis are high profile), and using Tamiya's Ferrari 360 body. But for some reasons I keep on blowing the cap screws in the diff. I blew 2 of the front diff's screws on last week's race meet (1 during practice, the other after 2x 4-min qualifiers, and 1x 5-min main), on the intersection between the threaded and non-threaded part. I assembled the diff the TB-02 way (with the spring+thrust bearing+screw on long outdrive, and the nut and the nut bucket on the short outdrive). And I do keep off the wall. I'm still a noob, so can anyone please pinpoint to me what I'm doing wrong and how do I stop from breaking the cap screws? :confused:

Re: TB-02 diff
 

i think you have it backwards. for tamiya diffs.. its usually screw head/ thrust bearing on the short side of the diff... spring/cap(nut bucket), nut on the long side of the diff.

also use the white delrin outdrives from the evoIII. work a lot better than the stock plastic ones that the TB-02 comes with.

The stock o/d's are set up different. On the long side you have bolt, bearing, spring. On the short side the ball sits in a permenant relief for the nut. The best thing I can say to not break the bolt is to take a pair of pliers, and compress the spring a couple times, before placing it into the diff!

Sounds like you may have tightened the cap screw too much to put that much stress on the cap screw...

I am using the delrin Evo3 joints..so I'm supposed to put the screw+thrust bearing on the short outdrive and the spring+bucket+nut on the long side? :confused:

yes you are right.

if you are using the stock TB-02 diff outdrives (black plastic) do what kevin said. (dsrbltoys)

TB-02 cap screws breaking
 

Hi,

I'm having the exact same problem.
The cap screws break just where the thread stops.
I'm using the standard (black) diff joints.
And the diff has been assembled according to the manual.

The reason for breaking is normally to much tention on the screw.
In my case it started after my diffs were starting to losen after a couple of runs.

I still haven't found a solution.
Although somebody told me that there were cap screws from associated that are stronger.

Any ideas are welcome.

Ok, update. The problem I have found to be the culprit is lack of or wrong grease on the thrust bearing. You should use a lithium greas (black) on the thrust. Tamiya's Anti Wear or AW grease also works well.

Good luck

Grease ????
 

dsrbltoys - Is the Tamiya king - He has seen it all and helped me fix this same problem 2 months ago - Since then I have not blown out one diff. I will offer up that HPI does have a screw that will work.

RacerX18,

Any change providing a partnumber for that HPI screw.
My local hobby-store has ran out of cap screws for the TB-02 (no joke).

They gave my a 2x30 cap screw that I will need to shorten.
So I might go for the HPI screws anyway.

I was also thinking that the diffjoints might touch.
In that case the tention on the screw would be to much because it would not only need to provide for the pressure on the balls in the diff, but also for the compression of the diff joint.

Would silicone grease or teflon grease be OK to lube the thrust bearing?

Wouldn't recoment those greases. Stick to something HEAVY. Associated black, tamiya black, tamiya AW. The black greases are made for heavy pressure. The grease that comes with the ball diff (clear) is made to allow things to slip once in a while. On a thrust bearing, you don't want it to slip !!! It must rotate freely. I have the hpi bolts in stock at Burien Toyota. Check sig for web addy. If nothing else, I can give you number for local dealer to use.

Good luck
Kevin

I just bought me a can of PTFE spray.
The idea is to coat the thrustbearing and the spring with a teflon layer.

Thanks for the link.
Unfortunately I live in Belgium (Europe) so having the screws shipped over from the US is way too expensive. Unless somebody could just put them in a letter and mail them with regular airmail. (chances are they won't clear customs)

Something a friend of mine experienced.
If you put the spring on the side of the head of the screw instead of the thrust bearing, then you will bend and break the screw.

In my case the assembly was correct.
Looking closer at the breaking surface of the screw, I could see that the screw had been torn apart. Pointing in the directing of the thrust bearing not rotating freely.
The thrust bearing was coated with the Tamiya diff grease that came with the kit.
It didn't clean the diff for a while, thinking that the eurathene bushing would keep the dirt out. But it didn't :rolleyes:

Reinforced diff
 

Hi

I'm trying to assemble the evoIII reinforced diff for my tb-02
But i'm a bit confused, if i follow the instructions for the standard black diff, there's no shaped hole for the nut to fit into on the short side of the diff.

From what i gather from this forum, the reinforced diff is the other way round. Is this correct? Also, what is the cap/nut bucket you guys refer to? I get the feeling i'm missing a part for the reinforced diff.

Just to be clear, according to the instructions for the standard black diff, it's bolt, thrust bearing, spring on the long side, then nut on the short side. What's the exact order for the reinforced one?

TIA
Fred

Yep, you need another part from your TB-02 box.

Unfortunately I'm in bed with the notebook now, so I don't have the Evo3 Surikarn Instructions with the instructions for the assembly of the white diff joints by hand.

Send me a PM to remind me, I will send you a part of the surikarn instructions tomorrow, this will make things cleaner.

greetings from franconia, germany,
N0Body

That would be great, thanx!