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Time to Change the Oils! - Hobby Letter #27/21


Hey folks, it is Heikki and my message for today is to remind you about servicing your RC cars! Racing with your RC cars is a sweet thing to do. Nothing beats the feeling when you let some steams out with good old bashing! I am sure that everybody cleans and oils their car all around after the intensive driving session, right? Right?

Regular service should be anyhow carried out about twice a year even if you are not racing every week. Now remember that our hobby may be a "toy" hobby but these toys tend to cost a bit more than Barbies. Please keep good care about your investment! Today we take a little look about something more tricky but rewarding, we open up the differentials, clean them up and change the oils.

Differential what

For those who are new to this hobby this is a very relevant question. It is one of those mystery things that you do not even dare to ask about because "everyone should know". But how do they work? I'd love to explain but ain't nobody got time for that! This old education film from year 1937 from Chrysler is the best explanation about this issue I've ever come upon, please check even if you are the master of differentials! To the YouTube, Robin!

Around The Corner - How Differential Steering Works (1937)

These are the basics. In RC hobby we take the full advantage of this technology and basically every RC has a differential of somekind. There may be just one or there may be more. Gear type of differential is pretty much stock in RTR cars. Many professional and competition level kits use ball differentials for offroad racing. RC Crawlers traditionally use "locked diffs" as it would be pretty hard to move anywhere in the rougher terrain if the other wheel spins freely and other one not. This is the reason why many crawlers tend to turn pretty horrible. Traxxas TRX-4 makes an exemption as it has differentials that can be opened or locked from the remote.

Wrench until it hurts and then wrench more

Now, you change oils in your real life full sized car regulary. Atleast you should! Like all the other equipment that have rotating parts, RC cars make no difference. Oils get old and dirty and loses its viscosity. If you have never opened the diffs of your car, good change is that there is no oil at all left! Differential in the pic above shows what happens when it has a meltdown after too heated driving session. RIP diff.

Depending what car you have, the access to differentials may be smooth as a summer breeze or a nightmare that does not end. Usually if the car has some racing DNA in it, the access should be pretty easy. It is recommended to service one differential at the time so that you dont mess with the parts. Also, take a photo or mark somehow the right position of the diff as they can be installed both ways. If your wheels rotate to opposite directions, there will be lots of spinning but not much movement. Don't ask why I know this!

Our Expert Guru team of Masters and Legends have made this sweet guide how to carry the service work for your diffs. Very hot read and very recommended!

RC Information - How to Change Differential Oil

When in doubt, lubricate!

Like said, we take a full advantage of differential magic here in the hobby of radio control. Simple and straight - using different thickness of oils can be used to improve your cars behavior. There is a wide variety of differential oils available and while you should be able to find from the manual what should be used, you can really fiddle here using different oils in front, center or rear. While this may be a bit confusing, these things really make the difference for your RC. Having these things right will seriously make your car much better. Trust me. Here are some guidelines:

Visco City

What is thin and what is thick? Once again this depends a lot about your car. Use the chart above more as a relative guideline and the right balance for your car and surface can be sourced out with a little Google-Fu. Thumb rule is that the more powerful and bigger the car and its wheels are, more thicker are the used fluids.

Here are some basic recommendantions per our Team of Immortals:

For 2WD buggies and truck outdoor use 2000-10000 cSt oil. Everyday Joe picks up the big bottle of Hudy 7000cSt. For indoor racing 10K is ok. High power brushless setups may benefit from thicker, up to 30K oils.

For 1:10 4WD Short Course trucks the basic set up we recommend is 5000 cSt in the front, 5000 cSt in the center and 3000 cSt in the rear.

For your everyday 1:8 Bashing trucks such as Corally or ARRMA, our team recommends 10000 cSt in the front, 7000 cSt in the center and 5000 cSt in the rear. If you want just to pop wheelies use this setup: 15000 cSt Front, 15000 cSt center and 10000 cSt rear.

For crawlers: Thick grease such as marine grease is good enough for your slow dirty rig.

What we also recommend is that you get to this century and use only oils that use standardized cSt system. Old WT -values are not standards by any means and may variate a lot between manufacturers.

Follow this link to our Differential Oil shelf and pick what you need. We sell only quality and tested oils from best manufacturers such as Hudy, Arrowmax, Team Corally and Team Associated.

Last Drops

Like it or not, some wrenching is always required if you want to keep your RC cars running. Most important thing in this wonderful world of differentials is anyhow that there should be always at least some oil or grease in the gears. Just never run them dry!

Servicing your diffs is not a biggie and once you get in to job it you often end up checking other places too, such as wear and damage in the outputs and all the other carnage. As simple as it is, more care you take of your hobby gear, more rewarding is the hobby! Now RIP and TEAR!!

Thanks for reading! Have a rotten good Halloween! :D

Heikki from EuroRC


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