Diffs oil

[activeperception]

Hi Guys,

I want to put some oil in the diffs (ST) because it seems that I don't have enough turning radius. Our track is made of plastic and it has a medium-high slip (I don't know if they are the right words :)

What would help me to turn more? What about the settings (4 screws) to keep the car lower? Shall I touch them?

The diffs...shall I fill them with oil or just few drops? Is it complex to remove them?

I know a lot of questions but now that I solved my problem with the servo I really want to win (in two or three years considering my driving skills :)

Thx,
Raf

[pointcrossed]

Use grease, not oil. Almost any hobby grade grease is fine.

[activeperception]

Since the ST diffs are sealed it's not better to use OIL?

I have 5000 and 3000 and I thought to put it respectively in the from and on the rear.

Maybe I don't understand enough of diffs. Someone knows an article I can read about diffs in RC and maybe about setup in general?

Thx,
Raf

[FHM101]

The problem with using oil in the diffs is the volume, there's not enough room to get any real volume of oil. The lower the oil volume the higher oil weight you have to use to get the same action as you would out of say an 8th scale diff.

If you want more turn in from your ST, open the front diff and use just enough grease to make the gears shine, then run about a degree per side of front toe out and leave the 20 degree C hubs in the truck. It also helps to use a radio with EPA so you can get the full throw out of your steering. You may need to crank down the servo saver a turn or two, but only if it won't turn the tires when the truck is at rest.

For the rear diff, open it up and pack it as full of grease as you can get it, run the C toe block and about 1 to 1.5 degrees of negative camber. This will make your truck square up quickly off the corners as well as calming it down over the rough stuff. If it pushes too much at low speed, drop back to the B block and dial in camber until the rear end steps out where you want it to.

You will have to use the down stops to set your ride height. Set the front with bones level or slightly below depending on how rough your track is. If it's smooth run the front lower, higher if it's rough. Adjust the rear so there is a slight forward tilt to the chassis and you should be good to go.

[BitHed]

...FHM once again a fantastic post...I like the way you explain things so simply...It is refreshing :D I will mail you later on for more insider tips ;) Peace...

[FHM101]

Please Bit, you are making me blush. :o

To mangle a quote from pop culture

"Simple is as simple does." and that's all I've got to say about that.

[BiGRoB21]

i thought it was "stupid is as stupid does" from forest gump lol

[pointcrossed]

FHM that is a great explanation, but I am somewhat biased on your Diff setups. I know they are just litle tiny gear or ball diffs, but I have had faster cornering speed with less traction loss having a tight diff in the front and loose rear diff and pretty much a near locked center. I am using a ball center diff which does activate when it needs to. Of course this is a dirt setup I am talking about. On pavement I would reverse it but like you describe exactly.

In my tight Diff I use mugen Grease and near fill it up, but once you use that stuff the diff is done and you may not be able to remove all the grease, its like rubber glue that never dries.

[FHM101]

I've always prefered a loose front diff in an electric 4wd car, I'd love to have a front one way for the half 8.

I've been using a stiff silicone grease for my production MT diffs for several years with good results so that's what I used in the mini and so far I'm liking it pretty good. It has a very high droop point so it never gets hot enough to go soft and cause the diff action to change. It washes right out with dawn dishwashing liquid and warm water so maintenance is quick and easy.

[activeperception]

Hi FHM,

Thanks for your explaination. These things are very interesting, do you know where I can learn in details the effects of toe/camber/caster/diffs...? Maybe a good website/doc? (I know there are the forums but the info are usually scattered in multiple threads and sometimes not clear).

Anyway I'm trying to apply your setup and the first things I have done are:

C-hub on the rear and lower ride height.

Consider that the track is a plain plastic carpet quite slippery.

The effect I'm obtaining with all other things stock is that out of slow curve the car seems to push to the extern of the curve too much. Like the front doesn't grasp (is it called understeering?)

Another question, how do you change the front camber? I have the 20degree hub.

Unfortunately I cannot find grease to fill in the diffs in near shops. What about filling the rear with 20000 or 30000 oil?

Thanks a lot for your help,
Raf

[activeperception]

I forgot another detail:

On my axles (rear in particula) I had a lot of small movements due to the fact that the plastic arms are not very tight. So I have inserted some washers almost everywhere and not the wheels are very 'stable'. Have I done the right thing? or these movements where designed for a specific reason?

I hope you will understand me because I don't know the exact word in english (in Italian there is just one word to indicate it and is 'gioco' i.e. game)

Thanks again,
Raf

[BitHed]

...Raf you are doing great mate...We know exactly what you are talking about :D You call it 'game'; we call it 'play'...same thing brother ;)

...Putting in washers to keep the pins from moving is a good thing to do...You can actually move your lower-arm pins back or forwards using spacers and slightly change your wheelbase if you need to ;) Keep up the good work...You will have a great ride in no time :cool:

[FHM101]

do you know where I can learn in details the effects of toe/camber/caster/diffs...? Maybe a good website/doc?

Consider that the track is a plain plastic carpet quite slippery.
with all other things stock is that out of slow curve the car seems to push to the extern of the curve too much. Like the front doesn't grasp (is it called understeering?)

Another question, how do you change the front camber? I have the 20degree hub.

Unfortunately I cannot find grease to fill in the diffs in near shops. What about filling the rear with 20000 or 30000 oil?

Raf

Unfortunatly, I don't know of any single source on the web for these explainations. There are several books available that explain them as they apply to 1:1 cars, but not all of the information transfers to our models.

One good source of information on suspension tuning for rc race cars is a Losi assembly manual for one of their off road cars/trucks. These manuals contain an excellent tuning guide that takes each adjustment and explains how it is done and what effect it has on handling.

On the slow curves, try getting out of the throttle just before you turn the wheels, coast through the turn, then straighten your wheels and get back on the gas. If your track has a lot of this type of turn, lower your car all the way round, then raise your rear ride height a bit more than usual to put more weight on the front wheels. You may want to consider a rear sway bar. As a general rule, a sway bar will add steering to the oposite end of the car from which it is mounted.

Camber is the tilt of the wheels in or out, as viewed from the rear of the car. Camber is adjusted by lengthening or shortening the upper link. For the type of track you describe, try running your front tires with no camber at all.

Grease used in the diffs need not be hobby specific. I use a stiff silicone grease sold as a lubricant/protectant for heavy saltwater fishing reels. Automotive chassis or wheel bearing grease would work as well. You could try the oil as anything would be better than nothing.