Neriyah

Been trying to figure this out but maybe I'm just too thick...

Could someone please give me ballpark numbers for Diff grease & shock oil for gst 7.7.
I don't race at all just bash with it. Terrain is gravel,sand some asphalt, with some grassy steep slopes. (and snow atm)
I was thinking of changing the pistons to nr 2 (1 in atm as the car is as stock as it gets) since I feels the shocks arent hard enough. Would 20wt oil be good ?
I have no idea what to put in the diffs (have some 30000 grease but that was bought for totally another purpose).
And while I'm asking could someone please be patient with me and explain how does changing diff grease from thinner to thicker actually affect the way the car behaves ?
I know diffs job is to allow the wheels to spin at a different rate, but I honestly don't know what different weights of grease do.
Cheers

Neriyah

Finally figured out the diff grease (and what it does) If I understood this correctly and please correct me if I'm wrong but basically the thicker the grease is the more 4WD the car will be right ?

And was thinking of putting some 30k grease in the front, 50k in middle and 10k in the back.

I still have no idea what to use for shocks tho, any pointers would be much appreciated...

The Real Dogman

Neriyah, on the diff fluid..that pretty much it in a not shell, although there are more complicated applications!!In fact, thats a fairly good way to put it..mind if I use hat when trying to explain it to someone.

The shock set-up is a bit more complicated, but for the surfaces you intend to run on, I think(it's only my opinion) that #3 shock pistons and 35-40 wieght shock oil would yeild the proper dampening with the "white" springs. Again that's my opinion. Some experiementing with your driving style/skill and suspension set-up will tell the true story.

Hope this helps- And have fun tuning

Neriyah

Thanks TRD, this is just what I was looking for. I kinda knew no one can tell the exact figures to someone else cause it all depends on driving style, terrain, personal prefrence etc. Just needed some ballpark figures. And please feel free to use my very short explanation of diff fluid if you wish

NIdaho Mudder

Yea that was a GREAT explanation on the diff's. Mine is stock and im getting ready for winter work on it. Now i just need to see HOW to get it in the diff. I havent looked ya so dont laugh. I have to fix my tranny also i broke the shift lever

Neriyah

Getting the diffs out isn't hard, just takes some time to take the car apart. Getting the diffs open on the otherhand... Stripped the screws on the 1st one and ended up drilling the screws out (with my battery DeWalt, I do not recommend it) Next time I have to do it I was thinking of putting the diff in oven for 15 mins or so at 250 C to loosen the threadlock on em, dunno what the heat does to the rest of it tho, Anyone have any experience with this ?? And for the shift lever breaking,,, broke mine too when I reset (by accident) the endpoints on my 3PKS :P but as I had taken the car mostly apart to get the front diff out it wasn't really a big deal to take the tranny apart too.

The Real Dogman

Neriyah, I have had to do that. I also use my electric stove burners to heat the diff enough to get the screws out..

Neriyah

Found out that 5 mins at 250C and the screws come out with little resistance, 7 mins and no resistance at all. Got the car set up finally. Got 30wt oil in front shocks, 35 wt oil in rear shocks with #2 pistons. (Shocks feel much much firmer now). Also changed 30k diff in front 50k in the middle and 7k in the back. Unfortunately didn't get to test it. Was out with me bro yesterday and we decided to fly some rounds with helis before driving so we spun em around for about 30 mins (was cold weather around -6 celcius) Helis started on 1st or 2nd spin of the starter even when being out for 10 mins for gyros to cool down to outside temp (they tend to drift if turned on when they are not the same temp as the air is). But I'm rambling again... So we finished our flight session and packed the helis and got the cars out (they've been in our cars but had cooled down to close to outside temp. So I proceeded to start the engine and noticed that on 1st pull the pull start seemed "odd" kinda like heavy to pull and it was constant strength resistance not the one you feel when the crank is turning. Well I tried again and this time I deffo felt the crank turn but the odd feeling was still there. After a few pulls the pullstart suddenly had no resistance what so ever (spring was fine since it rewound it nice, but no resistance on pull) and on the next pull the whole string just shot out (no resistace again so it kinda flew out) and this ofcourse killed the spring. I know these things are hard to start when cold so I was prepared to have to pull it quite a few times but then the pull start dies. The only thing I can figure out was that it was so cold the oneway bearing didn't hold anymore and when I pulled it shot out the string all the way which killed the spring (I am very carefull not to pull too far) Also I noticed 2 bends on the string kinda like the string had fallen off the wheel which had caused the marks. Took it apart once I got home and ofc the part where the spring attaches to the wheel had broken off. Tried the oneway once it had warmed up and it held very well again. Oh well, ordered a rotostart to replace it, but as my engine is still new (1 gallon through it) IIRC I have to loosen the glowplug around ½ turn ?? when starting it ?? Anyone else have similar experiences btw ?

unlawfullactions

any more updates on how those weights diff oil worked?

Neriyah

Seems to be a very nice all around combo. The terrain I run on is very mixed (asphalt, concrete, gravel, snow, sand and grass) and it works nicely on all surfaces. If I had to change something it'd be heavier fluid in the center diff or even locking it, but it's not in any way big enough of a deal for me to take the car apart for. Maybe when I need to take it apart anyway... And the way I drive if I had locked center diff I'd most likely be snapping outdrives every time I go out (I still do break one every month or so)

air1kdf

I have Ofna 120k in the center. I can pull some amount of wheelies. but get the 1-2 shift in mid air. Racing MT's like between 300k (Associated), and 500k(Kyosho) in the center diff. Seems that the more powerful big blocks require thicker (than 300k) diff fluid. I have 500k on order. With my 120k in the center it did help a little, but leaving me wanting much less unloading. I hear that those that are running 500K never go back, I'll let you know.

.46NitroAddict

Hey air1kdf,

I couldn't agree more. I just removed the grease from my center diff, & replaced it with Mugen 100K Silicone oil (heaviest I could find in AUS so far), but it is a little less locked than the original grease[:@], so I am looking for some 300k or 500k. Don't want to run the lock block!

Can any one tell me if the ratings for the brands you have mentioned are the same from 1 brand to the next! Or is 1 brand thicker than the rest!

Regards, .46NitroAddict [>:]

air1kdf

Kyosho is the only company that I know of that has 500k diff fluid. Ofna stops at 120k, and I know that Associated stops at 300k. I think that Kyosho has a full line but I'm not sure. I have heard some want 400k, so they mix 300k and 500k together. As I understand, 300k is like a jell and comes in a spoonable container. I can only imagine how thick the 500k is.

I also a have strong thoughts on keeping the diff unlocked, but mainly because I know that jumping it is very hard on the drive train no matter how soft the ground is, that's one heck of a shock to the system. On my EK4 I put on a slipper clutch for this very reason. It helped keep diffs together.

The Real Dogman

OK fellas, I wasn't going to post but I thought it only fair that the other side of the coin be heard.

I love my center diff locked!!!!

It is soo much fun bashing AND on the local track. The extra power planted to the rear coming out of an onpower corner is an absolute blast. With my sway bars and shock setup this animal is so very precitable and hard launching due to the front wheels not unloading when the inside front wheel lifts(all the power is on tap to the rears), the trucks settles into the turn and growls out of the corners. I do have a very controlled agressive manner of driving(I dont care if I break Parts/ although I dont very often anymore). I Did break one of the rear out drives but that was because that CVD shaft broke one side of the pin(A fluke, think). I have launched this truck up to maybe 15 feet or so while testing a bashing cage I am/was developing(On the shelf at the moment) many times and still no broken drive train parts upon landing(other than breaking the old axles). The drive train(Out drive cups only) is due for a rebuild in about 3 more gallons, but this is only after about 5 or 6 maybe even 7 gallons of fuel thru it.(Not bad if you ask me). I love to punch the go fast trigger just before landing to pull up the front and land on the rear tires. It is so cool to see this monster of an engine power out under that kind of load.

The point is, locking the center diff CAN cause abit more wear on the drive train but when setup properly, it is soo worth the fun!!!! And thats what it is really all about, FUN!!!!!!!!!! Woohooo!!! let's kill 'em THEN rebuild 'em!!!!!!! Besides the wear is not THAT bad!!!!

just so you dont think its a story!!

.46NitroAddict

Hi Guys,

air1kdf you first, check this [link=http://www.rcuniverse.com/forum/m_5659095/anchors_5760662/mpage_2/anchor/tm.htm#]link[/link] by Blitzekriec (post #26). Apparently Racers Edge make 500k, but last time I checked they were out of stock.

Hey TRD, yeah I see both sides of this discussion, but am still undecided, as I have said I tried the mugen 100k. But it was slightly worse than the factory grease. I can't find any supplies of anything above 100k here, & every one I tried so far on the net (in your country) hasn't replied to any of my questions, if the can send it to me in the post! So If I can't source any thing in the 300-500k range, I guess the decision, has been already made by others than me! I haven't given up just yet, but am beginning to surrender to the fact I will probably soon be running the Locker, purely cause I can't get what I want[:'(]

Regards, .46NitroAddict [>:]

air1kdf

I didn't know that Racers Edge carried 500k, not sure who makes it, but it does still say out of stock. I'm sure that it would work great though.

Good post Dogman, it's great to hear that this thing can take the abuse.

All of my other MT's have a locked center without option for fluid. They (especially the LST) handle pretty good, and it is nice getting rid of the unloading. But I also have other stuff like a tricked out Hyper 7 Pro, which I had a lot of success with diff fluid in the center although I run a torsen diff in it now. But I have also had premature wear on other MT's center drive cups like the savage SS. I think that the 500k would give the best of both worlds if it can be obtained, if not I'm with you on just locking it. Seems that the 500k would be so close to a lock, which is why I have it on order with my LHS. I'll have to call them tomorrow to get an ETA.

Best option would be a torsen center diff. But I don't think that any of them would work due to the 2 outer gears. I looked at the Ofna, and it won't work. Duratrax also has one that won't work. Kyosho's is the same as the Ofna's. Maybe there is a newer model that has 2 gears that would work. I know that the center torsen on my Hyper 7 Pro is like cheating. It puts all the power to what has traction, I also have one in the front. Buggies can do wheelies. LOL That thing rips out of the Hole. Thinking about it, seems that a front Torsen from Ofna might just work in the front of the GST. Next time I have it apart, I will check. That would deffinetly put more power to the ground by not powering the tire in the air.

.46NitroAddict

Hey air1kdf ,

All sounds good, let us know how you go & what you find out / install.

Regards, .46NitroAddict [>:]

MONAROMAN

You think thats what you want...
Lock it and you won't turn back - will be like ordering a new truck - it will awaken the beast within, it has just been snoozing till now [sm=sleeping.gif][sm=tired.gif]

csa

Ok, if you lock the center, do you still need to use oil in the front/rear? If so, what wt to use, 10k/30k? What do the stock ones come with any? Sorry too many questions I know.

Craig.

.46NitroAddict

Hey CSA,

Welcome to the forum! Where abouts are you?

Okay, as I stated earlier in this post, all 3 diffs (front, center, rear, according to CEN Racing) come from the factory with the same grease, slightly thicker than Mugen 100K wt silicone Diff Oil. (How do I know? - I just put it in my center. Now I am tracking down some 500K for my center. From the states, I can't find it here in Aust.)

If you fit the center lock block, you can still run the factory grease in the front & rear diffs, & see how it handles. If you don't like it because it pushes into the corners (understeers), put something heavier in the front (or lighter in the rear). As others have said above. Even though the 3 diffs are meant to be the same I found my rear & center diffs to be like that, & the front was about 1/3 as stiff. So I swapped my front & rear diffs, achieving the same effect. Getting rid of the massive understeer problem I had. I will eventually replace both diffs' grease with silicone diff oil.

Hope this answers your questions,

.46NitroAddict [>:]

csa

Brisbane/Australia

Thanks. Your post cleared things up. I read the previous ones but some times its a bit hard to determine what exactly they tried or said something but no follow up with what effect it has. When changing assembling a diff or other parts the book has little picture of grease required on some parts. I'm not sure what kind of grease should I use? Should I use the diff grease?

Cheers.
Craig.

mycarisaser

What is the stock shock fluid weight?

.46NitroAddict

Hi mycarisaser,

In an email I made to CEN Racing Customer Support last year on the same subjuct, I recieved the following reply.
So there you have it straight from CEN,

Regards, .46NitroAddict [>:]