Thats the answer i was looking for.
What balls do you sugest and do u fill up all the holes in the spur with balls or just the outer.
Thanks for the help guys.

I will check that carefully so!

Diff made with CRC parts, AE diff balls (#6626) ans AE diff lube (#6591), use 600 sand paper with water and a right hub to avoid parallelism problem.




Other point: I'm looking for some setup sheets for 12L3 and 12L4, in fact AE 1:12th pan cars with 4 cells. I did look at AE website!
Could some of you could post some sheets? Obviously carpet track

Please copy and paste this into MS Word so you have saved locally

Building a Diff

I use plain chrome steel diff balls from BMI, IRS, anyone...they are all the same high grade 1/8" ball bearings.

I like to use Schumacher U1301 silicon diff grease or Associated silicon diff grease, the thick type in a plastic cup not the stealth grease in a squeeze tube. Stealth grease is too thin and gets flung out too easy.

The diff balls I buy come in a 100 pack for ~$8. I open the pack over a clean paper tower and dump them out. All diff balls have a coating of oil on them to protect them while they sit on a shelf. I use motor spray carefull to wet them and then roll them on the paper towel to dry them. I then dump them all into the cup of diff grease. I keep them there untill I use them.

When I build a diff I sand both sides of the diff rings with 600 grit wet-dry sandpaper lubricated with a little motor spray untill I see an even finish across the face of the rings. I then clean the rings with motor spray and dry them on a clean paper tower.

Be sure to clean your finger tips with motor spray before touching the diff balls or rings. If you get any bearing oil or traction compound on them from your fingers it will contaminate the diff and mess it up.

I then pluck the diff balls out of the diff grease cup with a small clean flat blade screwdriver and put them in the spur gear. They will carry all the diff grease they need with them. You do not need to put more on the rings. I put a ball in all 12 holes in the outer circle. The inner circle of holes is for the no longer used small diameter "Stealth" diff rings.

Assemble the diff normally but tighten it slowly until you just start to get diff action. If you overtighten it you can dimple the rings and flat spot the balls. Tighten it and check the gear for slipping. As soon as the gear starts to get hard to slip stop.

Mount some tires on the axle. Hold one tire and the gear locked and force the opposide side to turn a few turns. Repeat with the other side. This is called cutting the diff. Cutting the diff smooths out any imperfections in the rings and balls by burnishing them. The diff may have loosened a little from cutting it so readjust it so the gear is very hard to slip (this is tighter than the previous step).

Install a motor and put the car up so the wheel are not touching the table. Run it at meduim throttle and alternatly touch one tire then the other untill it just stops then let go. This will heat up and fling out excess diff grease as well as breaking in the diff. Do this a couple times per side.

Re adjust the diff a final time so it wil not slip and you are done. The diff should be glass smooth. It should spin very freely as if it were really loose but the diff gear should be almost impossible to slip.

If the diff is gritty with new rings and balls replace the outer right side hub bearing.

If the diff is slipping you have some petroleum oil contamination in the diff. Take everything apart and start over after cleaing everything with motor spray.

Thanks Adrian, That REALLY help. Printed it out and put it a binder

Has the Speed 8 body pretty much become the standard, or are there still a lot of people using the Speed 12????

The Speed 8 is THE high grip stock carpet body.

For asphalt or med to low grip carpet most prefer the Speed 8HD or Speed 12.

I run the Speed 12 mostly because its fast, looks the best.

Thanks Adrian, I'm calling Jeff over at Speedtech on Monday to get some sent over

I'm looking for some spring rates to build a spring chart and I can't find spring rates (lb/mm) for Corally (both 1/12 and TC) and the CRC side springs.

1294 - Side Spring-Orange Super Soft
1295 - Side Spring- Blue - Soft
1296 - Side Spring- White - Med
1297 - Side Spring- Red - firm
1298 - Side Spring- Green X-firm
1299 - Side Spring Purple XX-Firm

75564 - SP12X – Front Springs, Soft – 4.0 T / 1.5 mm
75565 - SP12X – Front Springs, Medium – 3.5 T / 1.5 mm
75566 - SP12X – Front Springs, Hard – 3.0 T / 1.5 mm

Other than that, I get the AE both front and center springs, the CRC center springs - just need confirmation about the rate of the silver stiff and silver super stiff.

Guest with that all spring for 1/12 are the same.

PS: I already search website manufacturer and parts lists

Sorry for asking again, but what is a good rollout for 19T racing? I made a complete rollout chart, so I don't need to know which tire diameter or pinion I should run, just which rollout is best for 19T-23T (Orion V2 and Tamiya RZ).

Adrian

thanks for the post on building the diff. Great post.

Just a quick question. you mentioned to be carefull with a thrust bearing. My car came with a thrust bearing. what would be needed to complete a read diff with out the thrust bearing in it.

Thanks in advance

I've got a few questions....

There is this sweeper (in the pic) which comes off the main straight, and you carry alot of speed through this corner, But 3/4 of the way through the sweeper my car starts understeering and i have to button off the make it around the sweeper, whilst some other 12th drivers carry more speed through there.

pic of the sweeper:


we don't use tyre additive

Chassis: corally sp12x (standard front)

What i've tried:
Soft and hard T-bars

Soft and hard fronts,(even the softest compound still 'pushes' / understeers mid corner on power.)

hard and soft side damper fluid

different shock fluids / tensions.

I'm using pink rears, but thinking of going slightly harder to see if i can get more front traction.

Or i'm actually thinking of putting some weights on the very front of my 12x front, as there seems to be alot of biased weight to the rear.

Any tips?

Also....

I'm still a bit clueless as to what levels you adjust the tweak screws on the tbar for what surfaces etc etc?

cheers for any help... there is always more to learn with 12th










We had a full heat of them at the Hobby Direct / Racing lines International in New Zealand the other week.

they sound very awesome when a few of them are screaming passed you.

But they didn't impress me that much (speed wise etc).

12ths electric are faster, and require alot less maintenance

drivingpro-

You might want to post this on the SP 12x thread as well, in case someone there misses your question here.

Not really familiar with low traction asphalt on the 12x, but a couple things you didn't mention:
-softer front springs
-front camber adjustment to make sure you have full contact of front tire to surface...this may need to be adjusted if you change springs, T-bars, etc...anything that changes the roll of the front end may require a camber adjustment. We run 1 to 1 1/4 degrees of camber on carpet with the WC front end.

drivingpro-

Another thing- when the rear pod droop was too much, the 12x would push mid-corner to exit on carpet. You might want to try this adjustment.

Understeer under power is often best cured by using a firmer center shock spring.

great, cheers for the responses

Larry Brown - I've used soft and hard front springs, didn't make a difference on this particular part of the track

I will post this in the 12x thread also thanks