# Tech Question of the Week



## celticpride311 (Jul 29, 2004)

Alright. For the sake of not having much to talk about on this board. As I was discussion with the almighty Biff earlier, in onroad to get the maximum traction control you need to take the rings in your diff and get a flat cut of glass and fine grit sand paper and file down a lil of the diff rings with the sand paper. To my understanding the reason you do this is because the rings need to have the right texture for the balls to rotate on (Adds grip to the balls). In doing so it becomes easy to the diff to counter act the the rotation of the opposite side. Given that titbit of diff know how, would there be any performance gain to do this in other applications such as offroad. Cuz although simplicity of a pan car diff the feel (in my opinion) is way smoother than anything Ive felt in offroad. Then again Ive never tried this in offroad. So I guess the question is "Is it necessary to do this with any other size in rc racing?"


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## madf1man (Jan 28, 2005)

I would say yes but only if you have nothing better to do! As far as the reason about the glass surface is to sand the ring flat.Sometimes they can be uneven,has nothing to do with creating a textured surface.That would be bad


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## KevinLRC (Jul 30, 2004)

It better be some really fine sandpaper.


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## celticpride311 (Jul 29, 2004)

I cant remember what grit it is that Joe used on mine.


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## Tol Thomas (Feb 18, 2005)

prolly either 1000 or 3000 wet paper. But in off-road the diff is not near as important as in on-road. Tire loose traction a lot easier in off-road so making sure that diff is smooth to keep tires from not loosing traction is not needed.


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## ruf4play (Mar 9, 2005)

madf1man said:


> I would say yes but only if you have nothing better to do! As far as the reason about the glass surface is to sand the ring flat.Sometimes they can be uneven,has nothing to do with creating a textured surface.That would be bad


Yes you are trying to sand out some of the grain and high spots on the rings, but TEXTURE IS GOOD. POLISH IS BAD. I use 600-1000 grit depending on what I have laying around. The texture gives the rings more grab on the balls and also make them easier to deform slightly to seat better. This allows you to run the diff looser without slipping since there is more static friction between the ring and balls. Rolling friction increases should be negligible. The looser setting allows for a much smoother diff action.


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## Gary (May 21, 2004)

*Yup!*

I learned that from a guy from Wisconsin at the BRCC2 running 1/12th scale. Now that I think about it, it works pretty good. Better than new rings. I used #600 and bushing oil for the wet sand effect insted of water. I forgot all about that untill Josh brought it up yesterday. If you dont have a piece of glass, a very flat smooth area, like a good formica counter top working the rings in a circular motion, works just fine.

Good idea bro! I would like to see more tech stuff around here. Its Groovy


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## KevinLRC (Jul 30, 2004)

Rod Payne (Matt Payne's dad) told me one time that he used sandpaper on their diff rings. His cars always had the smoothest diffs and they lasted a long time too.


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## celticpride311 (Jul 29, 2004)

Its scary to think about how many miles Ive driven my car and how fresh the diff still feels. When I get back into offroad I wanna try this out. Just for sheits and giggles.


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## Gary (May 21, 2004)

Had to clean up a bad word Josh. Sorry for the edit.


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## mongo88 (Aug 19, 2004)

A long time ago we used to start at 600 grit and steup to 2000 grit paper. Things looked like mirrors whe we were done and the diffs lasted forever! Now Im too lazy...lol


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## ruf4play (Mar 9, 2005)

2000 is too fine in my opinion. Puts a polish on the rings which makes them slicker, kind of defeating the purpose. The point of "roughing" the rings is to let you run the diff looser. It's an old 1/12 trick that works pretty much everywhere.


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## Gary (May 21, 2004)

Ill be shopping at Home Depot soon! 

I got a motor question. How do yall break them in?


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## ruf4play (Mar 9, 2005)

Biff - I just run the poop out of them. Water dipping works ok for these.

Kevin - you gonna be able to make it for the PN race? I'll be more than happy to help you get your rig setup if it gets another fast guy out there. Dunno if you're busy that weekend tho.


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## KevinLRC (Jul 30, 2004)

My car is in pieces right now and there's an offroad race that same weekend (my favorite class.) I'm not fast with the Mini-Zs anyway, I'd be looking like a rookie out on the track. I'll give you an e-mail before too long because I need to get my car going.


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## cjtamu (Sep 22, 2004)

Hey Josh, if you only rebuild your diffs after every 300 hrs of runtime does it really matter, LOL? I think what Tol said is right, it's just not as critical in off-road since your tires tend to break loose and not be in contact with the track so much anyway. It's sure not going to hurt anything, I'd already decided I was going to try it next time I rebuild an off-road diff. Kevin, get your car running after the K&M race and come play. The Open cars are screaming fast and a blast to drive.


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## ruf4play (Mar 9, 2005)

That's cool. Just get your butt back out there.


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## KevinLRC (Jul 30, 2004)

Yeah I've seen the open cars and they definitely look a lot more fun than stock.


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## Gary (May 21, 2004)

LOL at Chris.

I tried water dipping once and really didnt like it. What I did this time, with the new Speedy05 is use motor spray and 4 cells for about 5 minutes. Let it dry out good, lubed the bushings and ran it with 4 cells for about 10 minutes. Did the motor spray trick again and then, I used hootch on the comm for 5 minutes, cleaned it up and I think its gonna be pretty fast. 

Kevin. After the book race, lets get your Mini going again. Christians head is getting so big, he cant walk through the door anymore.


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## KevinLRC (Jul 30, 2004)

Yeah I have a feeling his head will just keep getting bigger because he is definitely fast. Now with an offroad car I could shrink it a bit. lol


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## ruf4play (Mar 9, 2005)

Hehehe!


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## Gary (May 21, 2004)




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## Gary (May 21, 2004)

This ones for you Joe. Or Trey, or Christian, or anyone. lol My car was definitly fast today, but Im having a hard time holding onto the rear end in both on and off power. I dont want to take too much steering out, but this what Im thinking of doing to the front. Lose the 20s and run the 18s. Change out the 1* knucks for the 1/2*. Maybe even stiffen up the front a little more. The front is softer on the bench than the rear. In the rear, Im just running basic. Tires, 8s. ATM dampner etc. I seem to have lost some traction since installing the dampner compared to the earplug set up. The earplug was definitly softer, and had more body roll. Got any suggestions?

Thanks.


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## madf1man (Jan 28, 2005)

If you,re running old tires lose em.I had some old ones and it was drivable but tuff.New tires fixed it to perfection for me.I think when the radials start to loose the grooves and become slicks its over


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## Gary (May 21, 2004)

Trey, nope. New tires. First time I ran them. It might just be a combination of things. Like the loose nut behind the wheel. lol. I havent driven for awhile plus I have never used that much HP before. I cant belive how fast that 05 is. The car felt like a slot car with the rear end jacked up high. Ill figure it out. These cars are pretty easy to set up.

Joe. The diff works.  Thanks bro!

Just noticed something else. Yesterday I got some PN "H" plates and notice that they are thicker than what I had. I dont know what brand I was using. lol. Ill try the medium first.


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## Gary (May 21, 2004)

Think I found a problem. The Atomic dampner and the PN rear pod. I installed the dampner per the instructions but it dosnt look like its spaced right. When I tighten down the dampner plate it compresses the under side spring ALOT more than the top spring, inhibiting travel. Ill try spacing the plate so its parrarel with the chassis and applies equal force to both springs.

Someone stop me if Im wrong. LOL


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## madf1man (Jan 28, 2005)

Some do some don,t have the spacer that goes under the dampner plate.I will use an o-rings to space it up.this should even it out pretty good


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## Gary (May 21, 2004)

LOL. Trey. I tried O rings. I eventually used the blue spacers and put them _UNDER _the plate. Seems to work alot better. Car seems fine now  See ya Saturday bro!


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## madf1man (Jan 28, 2005)

Just make sure the dampner plate itself is overlapping the post to keep it from moving.If the plate is above your just relying on the screws and they are moch smaller diameter than holes in plate and it will move around


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## Gary (May 21, 2004)

Thanks bro!

I feel stupid. I forgot I lowered the car which put the pod at a different elevation compared to the chassis. DoH!


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## Freshwaterman (May 21, 2004)

fun!!!!!!!!!!!!


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## celticpride311 (Jul 29, 2004)

Bored cam? lol

Im gunna start another tech thread here in a bit. Everyone can go post there.


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## RX21 (May 2, 2005)

You still think thats me, if you do then your stupid cause everyone else knows who it is.


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## celticpride311 (Jul 29, 2004)

Hi my name is Josh. I dont believe we have met. Atleased if I have then I will have to appauligize for not knowing who it is. But for the sake of playing mystery man why dont you just say what your name is? For the most part we are all friends here. so how bout some background racing info? If you dont want to thats cool too.


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## Tol Thomas (Feb 18, 2005)

Josh URDADDY is URDADDY or RONNIE for you who are clueless


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## celticpride311 (Jul 29, 2004)

Very interesting. Not to mention funny.


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## Gary (May 21, 2004)

Cameron just got "OWNED". LMAO!


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## RX21 (May 2, 2005)

How did I just get "owned"?


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## Gary (May 21, 2004)

Josh, we car pooling this weekend?


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## celticpride311 (Jul 29, 2004)

Sure thing man. Im waking up early though. The more practice the better.


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