Diff oil?

[PaulC]

I bought some diff oil when I was ordering my new head button, cause I hadn't seen anywhere else selling it.

It's 100,000cps.

I want to stiffen up the centre diff in particular as there is far too much power being bled off on the inside front wheel, when I want more of it going to the back wheels for power slides.

Basically the problem at the moment with the buggies handling is on turn-in to a corner at speed the car rolls (need to sort anti-roll bars) and the inside front practically lifts off the ground. Too much of the power is allowed to bleed through that wheel preventing the back stepping out on the power and also the gyro effect of the spinning wheel seems to almost pull the car over more.

I was thinking the diff oil would stiffen up the centre (and possibly all the diffs) to help keep more power at the back?

Thing is, my front and rear diffs are not sealed. There is a hole at the bottom that gets covered only by the fact it sits on the chassis.

The oil looks very thick, but will it be thick enough that it won't just pour out?

Is this type of oil purely for viscous diffs? My centre diff might be viscous I haven't looked yet!

Thanks,

Paul

Oops, answering my own question: http://www.rc411.com/pages/howto.php?howto=24

Seems the actual diffs that take the oil are inside the casing and potentially sealed, will need to open them up to find out.

They are quoting figures for "weight" not CPS. I wonder if they are the same thing and I have bought 100,000wt diff oil!

 

[robmob]

Thing is, my front and rear diffs are not sealed. There is a hole at the bottom that gets covered only by the fact it sits on the chassis.

Sounds to me like you are referring to the diff housing.

Inside the diff cup is where you would put the diff fluid and if it's a buggy or truggy it should be sealed.

edit: I see now that you have seen the light.

 

[Scrogg]

100,000 cps is way too thick for any buggy or truggy.
7,000 weight is where you should be.
You can help fix your issue with other methods as well. Adjusting the droop screws and tightening the swaybars.

 

[PaulC]

Hmm, well it's in the center diff now. Doesn't feel too heavy. If I lift the back end up and wheel the front alone the rear turns almost as fast as the front, but there isn't that much resistance to stopping the rear wheels from turning.

I'm going to run it today and see.

Thing is the bottle came from the same manufacturer (or brand rather) as the buggy and the shop only had 30,000 and 100,000 cps. Also seen them elsewhere labeled "Medium" and "Extra thick"

Are we sure CPS = wt. ?

Droop screws. That's something I didn't consider. Will take a look, I thought they were just to be screwed down till they stopped the suspension hitting the chassis, but I can see how limiting the end of travel would stop the unloaded spring pushing the unloaded side of the buggy up (and over).

Still the main problem was that I'd get it into a corner and from my driving experience I would pump the throttle aiming to slip the back end out into a power slide, but all the power would be lost into the inside from wheel, not leaving enough to break away the rear and only causing the bugger to tip.... not to mention spray and excessive amount of crud up under the body shell!

Tightening the sway bars? Hmmm. If I move the locking colars in at the end does that change anything? I thought I needed to get stiffer bars to change the anti-sway bars.???

EDIT: http://cgi.ebay.co.uk/Silicone-Diff...sGames_RadioControlled_JN?hash=item414b2ac51c
Seems they do 3,000 - 100,000 oils.

So with 100,000 in the center diff things should be interesting.

 

[Scrogg]

I'll link you to the X-Ray buggy/truggy tuning bible when i get home. It explains everything. Everyone who races uses it or has it memorized.
Tightening the preload on the rear sway bar gives more steering but less rear end stability. Tighening the front, I generally don't use much preload unless it is def. lifting the inside tire too easily in a high speed sweeper.

 

[PaulC]

Cool, cheers.

I ran the buggy with the 100k in the centre diff and wow what a difference. Actually I 'think' its more or less what I was after. Even at medium speed (15-20mph) on damp tarmac I could pump the throttle and get it to break out into a full four wheel drift. Much more power delivery in slow turns and no ballooning tyres

Did some engine tuning, managing to still get a head temp of 150*C on the box and had to richen the HSN and go back through the LSN and idle speed to get it to idle consistently and take full throttle from idle without heading too hot.

It's a shame I drove it into a wall after about 3/4 of a tank and broke the front suspension holder and front right hub carrier.... again!

Paul