Differential fluid

Lawrence Godson · Post by **Lawrence Godson** » Wed May 28, 2008 9:44 pm

I'm wondering if anyone has satisfactorily adjusted the viscosity of the various differentials to get good performance cross country?
Thanks

Allan Richards · Post by **Allan Richards** » Wed May 28, 2008 9:48 pm

Lawrence,

There was a thread on this some time ago but I don't know if anyone came up with a satisfactory fluid to prevent loss of grip when one of the wheels looses traction. I think that the general concensus was to lock out the centre diff.

Yves Maurice · Post by **Yves Maurice** » Thu May 29, 2008 1:00 am

Hello gentlemens!
I have a question concerning the back wheels on the 222..the both are tilting and I want to know if it ' s right?

Thank you...
Yves

Lawrence Godson · Post by **Lawrence Godson** » Thu May 29, 2008 3:13 am

Yes I followed that thread. What I just completed was to replace the fluid/grease in the center Dif. with "Mugen" Super Silicone for Diff.. The viscosity rating was actually 100000 which I believe was much thicker than discussed in the thread. Unfortunately preliminary tests seem to indicate no difference in performance. If I lift either the front or rear end off the ground I loose all power transfer to all of the wheels. How was it again that a differential can be correctly "locked up"?

Adrian Harris · Post by **Adrian Harris** » Thu May 29, 2008 5:36 am

> How was it again that a differential can be correctly "locked up"?

I believe the usual method is to fill in some of the teeth of the crown gear so as to jam the planet gears and efectively create a locked system.

Adrian.

Allan Richards · Post by **Allan Richards** » Thu May 29, 2008 9:49 am

Lawrence,

I believe that the thicker oil only starts to become a factor when the vehicle is running fast, like a racing car. These vehicles trundle along compared to the racing cars so the higher viscosity oil make little or no difference. As has been suggested locking the centre diff means that at least two wheels have to loose traction to stop the vehicle. I have a 1/12th DUKW which had diffs fitted but in the end I had to lock all of them to ensure good traction, and it made no difference to steering or drivability, as has been suggested in the other thread.

Ad Wouterse · Post by **Ad Wouterse** » Thu May 29, 2008 1:14 pm

Hi guys,

I have filled the centre diff with 100.000 weight diff grease from FG and it works for me. I think it is as close to a locked diff as you can get.
The diff locking method used in the 1:1 world (filling in the gears by welding) will not work on the white metal gears. What would you use to fill in the crown gears ? Stuff like JB Weld does not work.
If you want to go all the way, take out all the gears and make a steel bushing that will fit tightly over the outgoing shafts. Secure it with the pins that normally hold the crown gears.

@Yves,
What exactly do you mean by "tilting" ? Use french if need be

Yves Maurice · Post by **Yves Maurice** » Thu May 29, 2008 5:40 pm

Sorry for my poor english Ad....The wheels are "penchÃ©es" in french...And not normal like the front ones...
Yves

Ad Wouterse · Post by **Ad Wouterse** » Thu May 29, 2008 9:08 pm

Hello Yves,

There is nothing wrong with your English mon ami.
So your rear wheels are leaning over, probably towards each other.
I checked on my 222 and it is the same there. When I measure the distance between the top of the wheels and that on the bottom, there is a difference of about 1,5 mm. When you put some weight on the chassis you will notice that the wheels are more squared then. In short, nothing to worry about.

Yves Maurice · Post by **Yves Maurice** » Fri May 30, 2008 4:41 pm

Same for me!.. Thanks Ad....
Yves

Ad Wouterse · Post by **Ad Wouterse** » Fri May 30, 2008 5:13 pm

Hello Yves,

We will handle every problem when we come to it

.
When you start driving your 222 you will want to change more things. The little suspension item that we discussed just now can/will be resolved at that moment too.

Lawrence Godson · Post by **Lawrence Godson** » Sat May 31, 2008 2:04 am

Hello Ad,

So you actually are satisfied with the performance after filling the center Diff. with the same weight fluid that I used? I, of course, now wonder what I'm doing wrong. Did you really stuff it full of fluid? I put more in than I took out but did not completely fill the open spaces. Could that be the problem?

Also since I consider differentials the next thing to magic in operation I'm not sure that my test was correct. Should the rear wheels force the motor to turn even if the front wheels are lifted and the car is dragged along? Is that a good test or not?

Lawrence Godson · Post by **Lawrence Godson** » Sat May 31, 2008 6:41 am

To add to the last post for clarification:

The rear wheels were "free wheeling" when I lifted the front end and moved the car. Same if I lifted the rear and pushed it along--the front wheels were free wheeling in that case. I need to charge the batteries so I have not yet run it since I changed the center Diff. fluid to the #100000 type.

Ad Wouterse · Post by **Ad Wouterse** » Sat May 31, 2008 12:26 pm

Hi Lawrence,

Wow, a lot of questions

The diff grease I used, FG # 6512, is no fluid but more grease-like although it will flow very very slowly when you turn the container upside down.
It is imperative to take the diff apart and to clean all internal parts very thoroughly. Make sure to remember where each part belongs.

The new fluid/grease should fill all free space in the diff. Start by pouring a thin layer on the bottom of the now empty diff case. Then mount the bottom crown gear and turn it a few times to ensure that there is no air trapped between the back of the gear and the bottom of the diff case. Add some more fluid/grease and mount the small gears. Turn each individual gear a few times. Now fill up the diff to its maximum. Finally put some fluid/grease between the top crown gear and the diff top cover and mount this.
An illustrated instruction can be seen here http://www.twf8.ws/new/tech/car/hobao/h ... step2.html .

Your "method" of testing should show the lifted wheels turning in the opposite direction and the motor kind of turning along (all be it reluctantly). This is a forced test, nothing you will ever experience on the battlefield.

Lawrence Godson · Post by **Lawrence Godson** » Sun Jun 01, 2008 4:36 am

Thanks Ad. I'm going to open her up again tomorrow and ad more fluid.