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-   -   Stock AWD Gear Diffs - Dry or with 15k grease? (http://mini-zracer.com/forums/showthread.php?t=31611)

Felix2010 2009.05.02 09:17 AM

Stock AWD Gear Diffs - Dry or with 15k grease?
 
I read about "packing" a Kyosho AWD gear diff using Kyosho 15k diff gear grease. I have always liked the stock AWD gear diffs but disliked how fragile they can be, especially for racing. One hard bump, or crash, and a gear diff's internals can get destroyed. I've read some guys though like using a gear diff up front and a Kyosho (Or other brand) Ball Diff in the rear.

>What does "packing" the AWD gear diff with say 15k Kyosho diff gear grease do for performance? Does doing this help "strengthen" the gear diff and/or prevent the internal gears breaking under aggressive driving, i.e. racing?

>What weight grease is optimal? Is 15K a good medium?

>How much grease is enough? I'm not familiar with "packing" a gear diff. I read back in the day that using gear diff grease was frowned upon by track owners because the diffs would eventually leak some, get on the track, and make a mess. Is lightly-packing a gear diff an option for leakage prevention?

Sometimes running gear diffs in the AWD is great and the performance is there. I remember someone on here who was a top racer ran front+rear gear diffs and had great success. If "packing" grease into gear diffs is a solid option I would like to hear more about this and from you guys who run gear diffs on their AWD's (Front/Rear/Both).

Thank you in advance for the help & info :)

MantisMMA 2009.05.02 09:44 AM

i run stock gears on my stock car and ball diffs on my mod car. mainly because the mod car breaks the rear diff i pack the rear diff with kyosho 5k grease and the front with 15k kyosho grease. thicker grease settles the car down more so running thicker grease in the front keeps the steering smooth and gives a little push on exit. one thing that i have not tried yet is too actually boil the diff in water for probably 5 or 6 minutes and i know from experience that that will soften the gears up a bit and maybe keep them from breaking. i just havent tried it yet on a mini z.


just coat the bevel gears on each side and that is enough, it will spin off the excess anyway

cowboysir 2009.05.02 09:47 AM

I'm sure there are better people to describe the effect but I'll give my impressions of how a gear diff affected my AWD:

I found that a dry gear diff in certain driving conditions (brake then accelerate out of tight corner for example) would sort of load up tension from the braking action and then release it all at once upon acceleration. Sometimes it would cause a the rear to step out or unload harshly.

Instead of going straight to a ball diff I used some light grease in the gears to soften the action...it made the diff actin a little more progressive in it's transfer of power.

I didn't have my AWD long enough to give you an opinion about front/rear or both diffs. Once I switched to SAS and had a rear ball diff I found myself getting confused as to what my tuning issue was because I couldn't make the car work well at all...I sold it and called it quits on AWD.:o

I don't think you could put enough grease in a Kyosho gear diff to ruin someones track.

eztuner12 2009.05.02 03:03 PM

Quote:

Originally Posted by MantisMMA (Post 345857)
i run stock gears on my stock car and ball diffs on my mod car. mainly because the mod car breaks the rear diff i pack the rear diff with kyosho 5k grease and the front with 15k kyosho grease. thicker grease settles the car down more so running thicker grease in the front keeps the steering smooth and gives a little push on exit. one thing that i have not tried yet is too actually boil the diff in water for probably 5 or 6 minutes and i know from experience that that will soften the gears up a bit and maybe keep them from breaking. i just havent tried it yet on a mini z.


just coat the bevel gears on each side and that is enough, it will spin off the excess anyway

Hi MantisMMA
In rank to soften diff grease or any petroleum-based grease it is better to go with purified linseed oil or any oil paint thinner than water, water will eventually separate. Mix them together to the consistency of your preference and then pack the diff about 75% to 85%.
Cheers

MantisMMA 2009.05.02 04:33 PM

you would never be able to do that consistently. just go with the kyosho diff grease. coat both of the bevel gears and that will be good enough. too many other variables come into play doing it that way

Slipstream 2009.05.02 09:57 PM

Shim the internal gears to avoid breaking them.

Tamiya Antiwear grease is good for keeping the the diff from unloading too fast when the inside wheel lifts off in a turn.

Cherub1m 2009.05.02 10:25 PM

Quote:

Originally Posted by Slipstream (Post 345935)
Shim the internal gears to avoid breaking them.

Tamiya Antiwear grease is good for keeping the the diff from unloading too fast when the inside wheel lifts off in a turn.

Hi Slipstream

You have any links or pictures on what is being shimmed in the gear diff for the AWD. Currently I run ball diff on two of my AWD but the bone stock one i am running the gear diff. I actually prefer the gear diff but I've broken so many already that I learned to run with the ball diff. I would like to keep my stock car with a gear diff set up and not worry about breaking them. Any pictures would help.

Thanks

Felix2010 2009.08.07 11:42 AM

Kind of an old thread, but some good info has been posted on here - Thank you to everyone for the help:D

@Mantis - I have some 15k Kyosho diff gear grease which is awesome. I also have seen some bottles of 1,000-30,000wtg silicone diff gear fluid (Not a grease but a thick silicone liquid) from various companies being sold. Is this also good to experiment with in your opinion?

@Slipstream - I also would like to hear more about how to shim the internal gears on the MA010 stock gear diffs please.:D

I also could have sworn that about 2-3 years ago a small/indie Mini-Z hop-up company made & sold metal internal gears for the stock MA010 gear diffs. At the time I wasn't interested in the gear diffs because everyone in the race scene was running ball diffs. Now I wish I could find a couple sets of these metal internal AWD gears...

color01 2009.08.07 03:57 PM

Shimming is a simple process, we've been doing this since the days of the Gen 1 Xmod. :) Simply put a thin 3mm shim (ATM and PN make good ones) on the diff outdrive, between the outer casing of the diff and the side gears.

Alternatively you can put the shim between the side gear and the middle of the diff casing. You should do this if putting the shims in the other way causes the diff to 'click' under normal usage.

Felix2010 2009.08.08 10:50 PM

Hey color0, how you doin?:D Are we talking about shimming the gear diffs the same way as we shim ball diffs for the MA010, by adding shims to either side of the diff between the chassis-diff 6x10x3mm bearings and the diff housing? If so my bad, I have been doing this for years also.:) Or am I just way confused about the use of shims with gear differentials?:o The way Slipstream wrote it I was thinking he meant there is a way to shim the 3 teeny-tiny gears inside of the gear diff main assembly?

color01 2009.08.09 07:29 PM

Quote:

The way Slipstream wrote it I was thinking he meant there is a way to shim the 3 teeny-tiny gears inside of the gear diff main assembly?
Precisely. :) We're not shimming to move the position of the diff inside the gearbox -- we're shimming to add pressure to the side gears inside the differential casing itself. ;) This pressure creates a bit of friction that can create an easily adjustable LSD effect and/or keep the gear teeth from getting too separated, reducing the chance of failure under power.

Felix2010 2009.08.09 07:51 PM

Ah-ha, gotcha:D Thank you for clarifying. I will have to try this out. What size shim do you recommend again? You wrote a thin 3mm shim - Can you tell me the entire shim specifications please?(Inside diameter-Outside diameter-Thickness):D I know Atomic offers many different shims now, I just want to make sure I buy the correct/best ones.

color01 2009.08.09 11:05 PM

ATM AWD079 will do just fine.

I used to be a bit more hardcore and cut myself the requisite shims out of scrap thin plastic (ASC packaging or Xmod packaging). That will also do too as long as you've got time. :)


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