fix that EVO diff.......

ph2t · Post by **ph2t** » Wed Oct 19, 2005 12:33 am

PART 1 - Fix a busted EVO diff

It's slowly becomming well known that the new differential in the EVO has a lot to be desired. I've put my EVO through it's paces by testing many hot, high torque and speed motors and eventually I made mincemeat out of my EVO diff.

The main issue with the EVO diff is that it uses a long pin to keep it assembled. This pin is not threaded so it just uses friction to hold the whole diff together. Over time the diff slowly starts to come apart. When this happens you will notice a clicking sound comming out of your EVO when you start moving from a stop or going forward after going in reverse.

The clicking sound is the small gears within the diff being stressed bigtime!

Keep it up for too long and this will happen.

Here's another pic showing what's left of the internal gears of the EVO diff.

This sucks! Having to find replacement internal diff gears sounds like a pain in the but.

So in the end I got an xmod gen 1 gear diff and busted it open.

The internal diff gears of the gen 1 diff are quite similar to the EVO ones. The main problem is that the shaft of these 3 small parts is too long on either side. So I had to cut them down to fit as shown below.

Also, the other issue is that the shaft of the gen 1 diff parts is WIDER than the evo diff. Due to this I had to widen the surounding are around where it sat in the diff. See below. I did this on all three notches for the internal gears. A small drill bit, aimed in at an angle, works perfectly!

Once I had done this I put the diff back together. It's all sweet! Everything turns well, those gen 1 diff internals were a god send.......

PART 2 - Secure the EVO diff

So now that it's fixed, what can be done to stop it from happening again? Let's face it, without some type of modification the diff will eventually loosen again and cause issues.

I wanted the find a way that I could modify the EVO diff so it would ALWAYS keep in constant pressue between the internal gears and still act as a gear diff should. I hate the whole concept of glueing/locking the diff, that's just turning a hobby car into a toy car, lol.......

Well I started playing around with bits and pieces and finally came up with this: I can use a kyosho mini-z mr02 front suspension shaft as the replacement shaft to the EVO xmod diff. I could also use a tiny E-clip to hold this suspensions shaft in place.

Here's what I mean about the replacement parts:

Notice by sheer luck that the mr02 front suspension shaft is pretty much the same in length as the stock shaft. It also has the indent to allow for the E-clip to be attached.

Installing the shaft side was a breeze. Once I had inserted the new shaft into the evo, I put the other side on and then slowly worked the e-clip onto the shaft. This is the triky bit, there's no EXTRA room on the inside of the drive cup that holds the e-clip. So you have to force it slightly to go in.

Once that was done it looked like this:

All done! This Diff now runs VERY smooth and I no longer need worry about it getting loose again, this baby is going nowhere!!!!!

Special thanks to LBRC who had supplied me with the crucial e-clip!!!

cheers,

ph2t.

Clint · Post by **Clint** » Wed Oct 26, 2005 11:29 pm

picked up a few pn racing mr02 kingpins in preparation for the fet mod. Still waiting on the e-clips, but i ordered a bag of 20 for 2 bucks. I obviously dont need them all, so if anyone needs a clip or two, let me know. i'll hopefully have them on monday.

Clint · Post by **Clint** » Fri Nov 04, 2005 2:13 am

Crap-monkeys. The 2mm e-clips I ordered were too big. I tried to compress the "e" with pliers and they still wont fit. I'm not about to
file one down to fit, although If I wasnt feeling so lazy it might work.

Do you guys happen to know the size of these things?

ph2t · Post by **ph2t** » Fri Nov 04, 2005 2:26 am

gotta link to where you got 'em? I'd hate for my towerhobbies link to be incorrect, since I had originally scored my e-clips from LBRC. the tower link was from somebody else.

ph2t.

Clint · Post by **Clint** » Fri Nov 04, 2005 11:49 am

The 2mm e-clips I ordered are:
http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXAMF5

Hmm, Tower also has 1.5mm clips, but I dont feel like guessing.
http://www2.towerhobbies.com/cgi-bin/wt ... LXJAG6&P=7

HACHI-RYOKU · Post by **HACHI-RYOKU** » Sun Feb 12, 2006 4:13 pm

I opened up my front and rear diffs to take a look at them. They were a little loose and it seemed to cause a little bit of binding. I don't have a MR-02 king pin yet (on order), but I decided to do a little preventive maintenance until they get here. I took a hammer and a screw driver and banged the stock pin in a little more so it wasn't quite so loose. The binding dissapeared. Popped the batteries back in and it had a little more speed and torque. Not much, but noticeable. It seemed to run a bit smoother too.

HACHI-RYOKU · Post by **HACHI-RYOKU** » Tue Apr 18, 2006 6:31 am

These work.

http://www2.towerhobbies.com/cgi-bin/wt ... LXJAG6&P=7

Same ones clint posted about above. 1.5mm

By the way, this was a pain in the arse! But now my diffs are nice and strong.

ph2t · Post by **ph2t** » Sun Apr 23, 2006 6:47 pm

lol, it IS a pain in the arse to do, but since day one my diffs hasve been fine. I've run some pretty crazy setups through the drivetrain as well.

7.4V Lipoly + Pn Anima
11.1C Lipoly + plasmatomic

Both these setups create crazy torque but the diffs are perfect, no issues at all....

ph2t,.