View Full Version : Basic question for AWD newbie how to get gears smooth

2009.08.16, 03:10 PM

I got my MA-010 on Friday and first I did a testdrive with the car that came out of the box. Fantastic on my small RCP 50 track that fitted my hobby room. But for all, it was very smooth and "nearly" loudless, compared to my now tuned car.

Then I picked all my hop up parts and made a tuning night on the MA-010. The result was that I got more and more angry, and the car more and more noisy.

I took these parts:
TAR diffs from Atomic in front and rear
SAS Pro on rear with 98mm
Atomic spur gear
Atomic titanium 98mm main shaft

After two hours of testing I removed the Ti Shaft again and took the original one from the kit, so the front diff and main shaft went smooth again. But I still have trouble with the back transmission and the connection to the rear diff.

Do you have ideas, that could help me, getting the car smoother? I always read about shiming the diifs? How does that work on the TAR diffs?

2009.08.16, 09:32 PM
Have you used shims on the diffs to get a better gear mesh?

Both of my AWD's are pretty quiet. I have rear Kyosho ball diff with front Atomic (standard, not TAR). driveshaft is stock on one and Reflex Alu on the other (front pinion is stock on both), rear gear is Reflex 96mm on one and ATM white delrin on the other. Both of my cars are more quiet than most 2wd cars at the track...

To shim the diffs, you want to put the shims between the bearings and the diff. If the mesh is too tight (whining) then shim the spur away from the pinion. If the diff is clicking, then shim the spur closer to the pinion. Be sure not to add too many shims, this will bind up the drivetrain.

Hope this info helps...

2009.08.16, 09:55 PM
Also depends what gears you use. For one, 3racing ones SUCK! I don't know how mixing and matching of others goes, but mine's always fairly loud.

2009.08.17, 12:25 AM
I recently had a problem with my motor. The output shaft was bent. Which caused this oscillating, whining noise. Took me forever to find the problem. Kind of weird to have a new motor, let alone a Stock R, with a bent pinion shaft. Anyway it could be that. Definitely check the gear mesh on the rear diff.

2009.08.17, 04:59 AM
i run the atm 98mm ti shaft and tar diffs,what colour chassis do you have,smoke or blue/grey?
i could tell you what shims i have in mine

2009.08.17, 05:05 AM
Hi Mk2compressor,

I have the stock smoke grey chassis, that is delivered with the 2k4 chassis set. Were there shims with the TAR Diffs?

2009.08.17, 06:44 AM
there should be shims,spare 0-rings,spare diff nuts and an adjusting tool.
i think most of your problem will be coming from the front diff to centre shaft gear,the centre shaft gear wears to a cone shape after a few hours use and does become quiet.
start with the front and add 4x .1 mm shims to the non gear side of the diff, then drop down to 3 after a few hours use.
the rear is a little more difficult with the older sas kit as it can flex out of position when you tighten the screws down to the chassis,try 2x .1mm shims on each side of the diff then move one over to the gear side if it still slips

2009.08.18, 09:06 AM

thanks for your help. I use the SAS Pro and there the alloy bearing blocks limits the wide off the diff. I took two shims, and pressed the diff in the blocks. Now the gear mesh was perfect and the car rolled perfectly on the desk without motor gear. BUT: Due to the side pressure on the rear bearings the diff was blocked nearly and the behaviour of the car was completely different from before.
So I took a file and widened the holes on both of the SAS cfk plates, so the bearing blocks could go more (.2-.3mm) to the outside when assembling the wider diff. Now everything is perfet on my car. All diffs work perfectly and the car rolls more than smooth.

Sorry for the grammar, I am from Germany, and my English rusted a little the last years of not being used ;-)


Henning Piez

2009.08.18, 10:17 AM
no problem,glad to help:)
are you near the crc?

2009.08.18, 02:07 PM
Around 100km away from CRC. But I know Microsash from there. I live in Stuttgart. So Fellbach with it's yearly Masters is only 10km away

2009.08.18, 02:15 PM
cool,we did the 12hr race at crc last year:D
im coming to germany next month to enter the pnwc qualifier too:)