Center diff question

[Error401]

Ok, I just got a lightning, and I have it up on the stand. This is the first triple diff car I've ever had and I'm kind of stupid in this area, but is it normal if you can turn the both front tires one way and at the same time both of the rear tires in the opposite direction and the center diff not turn? That's what mine is doing, and it just don't seem normal to me. Any help would be greatly appreciated.

Whitt...

 

[1meathead]

so you are turning the front 2 forward and the 2 rear backward at the same time? Is that what you are saying? If so when I turn my Pro that way the center diff wont turn because the front gears in the diff are going forward and the back gears go the other way.

 

[Error401]

Yeah, that's pretty much it. If I turn them like you said, and in the same ammount/speed, the center diff doesn't move. If I jold one set and turn the other, the center diff does move. I think I figured it out, but it's just kind of strange to me.

 

[HumboldtBlazer]

That is normal for the way I understand my diffs to work. First thing Error you want to open all 3 diffs and clean the grease out. Go buy some silicone diff oil. Fill the front with 5.000 Cs center with 7.000 Cs and rear with 1.000 Cs silicone oil.
TIP! Mark the front or rear dif with a small inscription in the dif case before filling it. You can play with different oil wt's but I really like the middle of the road setup on my Storm's. I would only stray from that formula if say I was driving a front biased diff car like the Mugen's

one more tip as you can over fill the diffs: Fill all diff's until the fluid is level with the connection point of the crossing pins. Let the fluid settle for a few minutes.

 

[RobH]

Hot Bodies Lightning comes with diff oil. not grease. I don't know what weight, but guessing from how stiff my was stock I would guess it's 5000/10000/1000. I don't know where the myth that the Lightning doesn't come with diff oil came from, but it's down right now true. I know because I had to dump and clean the stock diff oil from all my diffs when I upgraded to the MP 7.5 diff gears.

and yes that sounds very normal. if you put a more powerfull mill in it, you gonna need the diff gears i mentioned. The upgrade is only $22 assuming you have all the diff oils already.

 

[HumboldtBlazer]

Even in the RTR huh? Well my Storm RTR's had grease (very little at that) so I guessed (having no prior knowledge) that they had grease in them. Did you pull apart a RTR to see if there was grease or oil or were you assuming that it had oil because the pro did? Stop being so defensive, everybody already gave your buggy props.

 

[RobH]

someone is a little cranky today.

 

[Smokey]

The grease myth is my fault. My lack of experience led me to believe that when I took my diff apart that it had grease in it. After putting in lube, then taking the diff back out later, I now know that there was lube in from the beginning.

I just won an auction for the TCD diff upgrade for the MP7.5. I can't wait to see what difference it makes.

The diff gears from a Savage are a direct fit also, you have to order 2 sets though to get 4 spiders. They look beefy, we'll see how they hold up. I got 2 sets for $12.50.

 

[1meathead]

Originally posted by RobH
Hot Bodies Lightning comes with diff oil. not grease. I don't know what weight, but guessing from how stiff my was stock I would guess it's 5000/10000/1000. I don't know where the myth that the Lightning doesn't come with diff oil came from, but it's down right now true. I know because I had to dump and clean the stock diff oil from all my diffs when I upgraded to the MP 7.5 diff gears.

and yes that sounds very normal. if you put a more powerfull mill in it, you gonna need the diff gears i mentioned. The upgrade is only $22 assuming you have all the diff oils already.

Hey Rob is this the diff set you got?http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXVD22&P=Z and do you think they hold up better than the HB ones?

 

[HumboldtBlazer]

Think what you want, but if you want my real opinion we would have to go to the lounge.:shhh:

 

[RobH]

this is the exact set I used front, center and rear:

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXVD22&P=7

The "old" hot bodies diff gears were light weight. The reduced weight in the gears was intended to increase performance. Instead it backfired and produces soft gears that can not stand up to high torque engines.

I say "old" because HB has release a new set that is hardened and supposidly better.

I skipped right to the proven design and bought the Kyosho MP 7.5 diff gears as they are a direct fit and are proven to stand up to the high powered engines. At $7 a set they are not expensive either.

If you ever feel like tuning your diffs with various silicone oils, pick up the set of diff gears because you gonna have the buggy torn apart anyway.

-Rob

PS if you ever see a "diff gasket" for the Lightning, dont' install it. You will mess up the mess in the diff and hence blow your gears right away. If you wrench down real tight on the screws that hold the diff together, they won't leak.

-Rob

 

[1meathead]

Hey rob one more ? did you have to shim it at all? and did the set come with shims? Or should I get this? http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXV109&P=Z

 

[RobH]

see the four skinny washers at the bottom of the pic? those are the only shims you need. I removed the stock HB gears and shims and replaced them with the respective Kyosho gears and shims. it was very easy.

Apparently, I did right because I've run another 8-10 tanks of gas thourgh the buggy now and the diffs are working perfectly.

 

[1meathead]

ok so I don't need to shim the big gears. I know the HB set came with one shim for that and didn't know if I need it for the 7.5 ones.

 

[RobH]

you thinking about this:

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXEPA8&P=C

INCLUDES: Two Large Bevel Planetary Gears
Four Small Bevel Planetary Gears
Four Black Metal Washers

it doesn't mention a shim and that because I'm 99% sure that big thing at the bottom is a diff gasket. The gasket you shouldn't put in.

when i took my diffs apart, I didn't find any shims. (EDIT: aside the the four thin "washers" you see above) I don't have a pair of callipers but the stock gears looked like they were the exact same shape and size as the kyosho replacement gears. my theory is if I just replace the gears and put it back together the way i found it, it shouldn't leak and the mesh should be perfect.

 

[1meathead]

good deal I think that is a shim to put on the big gears the gasket is not like that it is made of some kind of fiber I have a few that they sent me but I will do like you said thanks for all the help.:bling:

 

[Error401]

Thanks guys for all the input. I looked into the book and the diagrams say that there are gaskets in the diffs from the factory. I have yet to run a complete tank thru the thing so far (loose tire and no wrench monday night, and thunder storms this afternoon). I guess when I take it apart to change the diff oil, I'll remove the gasket and put your suggested weights in the diffs. Blazer, your weights are the same as the LHS guru's here, so I'll probably go with that, and the local guy races lightnings (pro's I think, not RTR). I'll probably end up beating the snot out of the chassis and towers, so they'll get changed eventually, as well as the factory front brace added. Anything else I need to worry about?

Also, Buggys ROCK! Man, I got the Hyper up to about 220 and it was ballistic.

Thanks again,
Whitt...

 

[1meathead]

I have the gaskets that came in my pro still in no prob. yet. Most people have prob. with the wing I broke my wing the first day out. Have fun when you get to run it.

 

[Çh®i§tiªñ]

Keep an eye on not using the gasket. Some diffs are made to take them for a reason. Leaking. If you plan on retaining fluid in the diff you may want to use them. I'm not saying you can get away with not using them, just keep an eye on fluid levels (a little work required here.....)

 

[Error401]

I was just working on the buggy (installing a fail safe since it's crazy fast), and noticed the feel of the diffs. The front one is looser than the rear, and the center feels really loose. By this I mean loose = weight of diff oil. The gear mesh feels fine. If I read Blazer and Rob right, the rear should be the lightest weight, then the front and the center the heaviest. Is this right, cause if it is HB got it all backwards.