Adam, TD, Can You Help Me?!

[HyperFX]

I purchased a used DEX410. I was told by the previous owner, the diff oils were 20K/10K. I drove the car for a few weekends, making only minor adjustments, because the setup was very good "as is".

OK, time for fresh fluids. I open the diffs to find...very little, and very dirty oil, or grease, in both diffs. No leakage at all, just under filled diffs, or small amount of grease. BUT, the car handled very well this way, although there was a little understeer in medium to tight turns.

I wanted to get rid of a little rear traction to increase my corner speed, so, based on the 20K/10K info I received, I went to 15K/ 7K. This produced very little rear traction. Now, I'm thinking increasing the rear diff to 10K or reducing the front diff oil to 10K, to regain rear stability. Is this correct, or is my logic "we todd did"? LOL! (Say it out loud several times!)
(edit: Now, I'm thinking thinner oil will increase traction/stability?)

I believe, now, that the 20K/10K info is wrong, and the car was handling well with low filled/grease only diffs.
SO...
How do I duplicate the good handling when the diffs were low? Thinner oil? Grease only? Help from the TD pro's?!

I don't have previous experience with oil diffs, (yes, it shows. duh!) and I'm in need of experienced racers help with this, please. I really need to know the basics of how diff oil viscosity affects the handling of the 410, both front and rear.

The track surface is medium to loose traction. Clay mix, partially packed, with loose, moist, soil on the surface. Moist during all heats and mains.

Adam, TD, or anyone, do you have a minute to educate an "oil diff noob" before I race in the morning?!

Much Thanks, in advance!

[samd]

Hi I think the general rule is less grip lower weight oil, high grip higher weiht oil. I wouldn't worry too much about your diffs looking underfilled, mine do when i change the oil and if they had 20wt/10wt this will look a bit like light grease when you come to change the oil.
It's a personal think but I have my base set up 12.5wt/7wt going to 15wt/10wt high grip or 5wt/10wt low grip.
Hope this help, I'm sure others will chip in with some better info.
Sam

[mark christopher]

Originally Posted by samd

Hi I think the general rule is less grip lower weight oil, high grip higher weiht oil. I wouldn't worry too much about your diffs looking underfilled, mine do when i change the oil and if they had 20wt/10wt this will look a bit like light grease when you come to change the oil.
It's a personal think but I have my base set up 12.5wt/7wt going to 15wt/10wt high grip or 5wt/10wt low grip.
Hope this help, I'm sure others will chip in with some better info.
Sam

i hope your not running those oils or you mean 12.5K?

the diffs do not want to be "full" or they will leak oil out

[samd]

My mistake typo, 12.5k wt/7k wt etc.

I make sure my diffs are 'full' just not pressured - i fill them to the top of the axels which makes the diff full when the top is put on, i didnt think having any air in was a good idea, maybe im wrong?? This is how ive always built them.

[annonymous]

hello

i want to try to achieve something like a spool affect, so what front oil? 20k, 30k? what? what oil do i need in the rear to still allow the rear to rotate and not push?

I run at the same track HyperFX does, so you have some basis on how the car reacts to the track

thanks

[mark christopher]

put 100,000 or500,000 oil in the front and 5000 or 7000 in the rear

[HyperFX]

Originally Posted by mark christopher

put 100,000 or500,000 oil in the front and 5000 or 7000 in the rear

Mark, could this cause handling on the straights to be a bit twitchy? (moist, hard-pack clay)
How would it affect handling on jumps and bumpy sections?

Hello Annon! You race at MHS, I believe? I think we met there a few weeks ago. How's the 410 coming along? If the weather is bad here, we'll be road trippin' to MHS this weekend. Hope to see you there!
Tony

[annonymous]

Originally Posted by HyperFX

Mark, could this cause handling on the straights to be a bit twitchy? (moist, hard-pack clay)
How would it affect handling on jumps and bumpy sections?

Hello Annon! You race at MHS, I believe? I think we met there a few weeks ago. How's the 410 coming along? If the weather is bad here, we'll be road trippin' to MHS this weekend. Hope to see you there!
Tony

yup. . . . i was a few weeks ago now, but seeing your Durango inspired me..... . . .so i joined the bandwagon - - - nothing but awesomeness

i hope the "spool-effect" want make the car twitchy - or at least any more than one would expect - got used to the spool-feel running touring car and now i want it back! i don't thing anything can make this car squirrely on the jumps - its a tank!

[Adam Skelding]

Sorry about the late reply, been pretty busy this week.
Replicating low diff oil is a hard job, if the oil is sticking to the gears it's doing 75% of the job. The remaining oil just flows round to make sure your diff teeth are always covered during rotation.
I try to keep on top of my diffs by checking them at the end of every meeting. That way if your car is running good, there's less chance of altering something you can't replicate.

Spool, like Mark said, put really thick oil in the front and thin the back out. Try not to go too thin on the back as you won't get much drive from the back of the car.
I've never had to go this far yet with the car, I've only ever run spools off road on super high grip carpet tracks to calm the steering down.

[offroadrc]

i had 4000 rear and 7000 front now i have 7000 rear and 7000 back for loose dirt, that works great. why, because i had much oversteering now it's more balanced.

[MP9]

Hi Guys
Im just as confused as ever I have tried thinner diff oils and thicker oils and mixed it up front to rear and rear to front...

The result is the same I cant seem to get enough rear traction I run on clay which is slippery as we run at night pretty much used diff oil numbers listed here...

What I need to know is what would be a suitable diff oil to give me rear traction without loosing steering also what diff oil numbers should there between front and rear as i have seen differences that are quite varied some even extreme...

Can you guys shed a bit of light on this the Dex 410 is a fantastic buggy im just not much good with working out what is best using fluid diffs...

So I would like a starting point if possible or better still I would like some rear traction which is something that has been lacking for quite some time I have tried also using the 1 degree hubs which has helped a little there are lots of other questions that I would like to ask but at this stage I will work on the diff oils at this stage...

[wacattack]

Try a shorter wheelbase, thicker front shock oil and stiffer springs, lower the rear camber link position to the lowest point and keep realtively long, thinner rear diff oil, thicker front diff oil

[t8rtot]

What tires arte u running? That's about 90% of your setup right there

[MP9]

Hi T8rtot

That maybe the case but tyres being used are JC Double Dees but I have used others and still have had the same problem even if it is a slightly different overall it still is the same with the rear end....

Also tried what wacattack has stated tried something similar and still have the problem with the rear end being loose..