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Old 07-01-2006, 08:03 PM   #1036
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Thanks for the info, I am going to try the 4 gear diff configuration tomorrow at the racetrack tomorrow morning.
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Old 07-02-2006, 01:25 AM   #1037
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Quote:
Originally Posted by CurveTracer
I notice that the Pro RTR cars we have always seem to get al little more rear traction on dusty surfaces than my Pro Kit car. With the ride heights and suspension settings being close to the same, and the florscent yellow shocks installed on all models, the biggest difference I have is the differentials.
On my Pro Kit CD3 I am using 6 gear diffs on front and rear.
The Pro RTR's have 4 gear diffs on front and rear.
Is there a large difference between the performance of a 4 vs 6 gear diff?
The problem I am trying to solve is rear end traction. The rear tires break lose too easily. On a race track with high traction I can use the rear end to slide the car around. But this a bandaid for a bad handling situation.
I am tempted to remove 2 gears from my rear differential and see if my rear traction improves.
What do you guys think?
If both cars are running the exact same diff oils then yes it is very strong possibility this is the cause. Certainly worth a try anyway....

What is the go is the US with Ofna throwing it's weight behind the GPX4. Are parts in shops drying up etc?

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Old 07-02-2006, 02:23 AM   #1038
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Quote:
Originally Posted by au_Nightmare
BTW - Ive gone back to 50K & grease mix in rear diff, might try the 100k & grease mix diff next meet. The rear was just too lose on the initial application of power in corners with the 100k oil diff (was ok before it was refilled & reshimmed)
Mines running fine with the above 50k/grease mix (posted a few pages back). I am now only running 1.5 rear toe-in. I would not go removing gears, just reduce the oil thickness. I didn't end up trying the 100k/grease mix.

Also grease up the internal shims when building the diff to reduce wear. If u can fit them in, I fitted two shims each side when I built my last diff and it seems pretty smooth. (it was the 100k so not race tested)
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Old 07-02-2006, 09:53 PM   #1039
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Quote:
Originally Posted by brc358
I had the same problem with my CD3 pro. I was running 6 gears in the rear diff. and constantly losing traction.
The track where I go to is in So Ca. and this is where Jeffery Lin from Ofna races quite a lot.
He helped me set up my CD3 pro one day, and the first thing he did was remove the 6 gear set-up, and installed the 4 gears.
It made a huge difference.
He also helped me with my chassis set-up, and the car was dialed in great. He knows the Ofna cars inside and out.
Remove your 6 gear, and go back to 4.
It should help you quite a lot.
I ran the 4 gear diff at the track this morning and the it cured the problem with the rear losing traction. This was with no changes to suspension settings and racing at the same track as before. In fact I will change my front 6 gear diff to a 4 gear to see if it reduces the on power/acceleration understeer.
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Old 07-03-2006, 01:11 AM   #1040
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Little confused why anyone would run a 4 gear over a 6 gear instead of making the oil thinner.

Anyway from the hudy setup guide (have you downloaded it?):-

Front diff
Tighter (Thicker oil)
Decreased steering response.
More stability under braking, but less turn in.
Better on power steering at corner exit.
Looser (Thinner oil)
Increased steering response.
Less stable under braking but better turn in.
Car will understeer on power at corner exit.

Rear Diff
Tighter (Thicker Oil)
Car understeers slightly at corner entry, but makes the car more difficult to control at corner exit (powerslides).
Increased on-throttle steering.
Better on high-traction surfaces.
Looser (Thinner Oil)
More stability mid corner and corner exit.
Understeer on-throttle.
Better on low-traction surfaces.
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Old 07-03-2006, 07:52 AM   #1041
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The only thing I can think of with the 4 gear diff over the 6 is the setup and how much oil you have in the diff. I know when I ran my LD3 if I had the wrong amount of oil in there running the 6 gear it would lock up from time to time (usually in mid corner, making the car snap around and spin). I'd take it out and check it and it was not smooth at all. Even with just a little oil inside it had a tendency to lock if the pins were not seated exactly in the diff cup. I guess only running 4 gears would negate that, allowing the diff to run smoothly all around.

I may try it with the spare diff I have, since I'm getting used to that one way and haven't swapped that yet. However, my 6 gear hasn't given me any real problems yet. Maybe if I get a day for some good practice I'll give it a go.
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Old 07-03-2006, 01:38 PM   #1042
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spenzalii - I have put the locking up down to the shims. Recently (as in a number of months ago) I had a diff lock up on me - when I took it apart I noticed shims where worn (I guess this would allow the gears to move around a bit?). This one was built when I lubed them with silicon oil during assembly (apparently not a good lube though it was in service for a long time). When I replaced the shims I used real grease and also managed to fit two shims in each side! It seems smoother then previous ones I have built but this could also because the gears are worn in.

The oil level really should not matter, one diff I had used for a long long time was almost empty when I did the christmas "checks" last year.

(Note: the 6 gear and 4 gear internals are different size)

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Old 07-09-2006, 04:47 PM   #1043
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Hi Guys,

It's time to replace the stock Force 12 motor in my CD3. Any recommendations as to what I should put in it? By all accounts I think I am going to go with a 12 of some kind???
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Old 07-09-2006, 05:18 PM   #1044
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hi CDS70 engines i have used and like are os tz 12, novarossi nsr12, and sirio evo3(later model with fixed crank problem), with you having a force 12 originally i am thinking you had pull start, with all of these engines youll need a starter box, all of them have good power, the os probly has the least but pretty torquey and sirio the most power, but not much difference between the lot, all of them should at least double the power of a force 12.
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Old 07-10-2006, 01:45 AM   #1045
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I've just been down to the LHS and they are suggesting an RB 12 pull start. The reason for the pull start recommendation is because of the class that I'm racing in. They also suggested the RB V12, but that would change the class that I race in. Both are the same price $420 AU installed.

What do you guys think about price and the RB motors?

Any info would be helpful.
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Old 07-10-2006, 02:27 AM   #1046
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if your racing in pullstart class then yes that would elimenate all the engines ive mentioned, and ive never had an rb, but have herd they are good engines, hopfully someone else who races pullstart can shed some light on which engine to get
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Old 07-10-2006, 04:19 AM   #1047
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Hi

I have had a RB V12 3 Port Rody and was a very nice engine, i only ever touched the HSN needle from the factory and it never missed a beat. They have always seemed to be a hard engine to come by, and you never see any online stores selling them in HK for example. I bought mine from Radio Models in Perth when they had a sale on them.

Were are you guys in far north Qld getting your CD3 parts from? Mind you any thought i had about a return to R/C have been dashed with the news i have to move again before September

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Old 07-10-2006, 04:32 AM   #1048
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Thanks for the info. My LHS majority of the time sells RB's and their supplier actually races at the same track so service/part is not an issue. I would like to stay in pull start as I still consider myself to have a lot to learn.

Anyone else?????? Any thoughts on prices?????

Keep the ideas and opinions comin' I really appreciate it.
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Old 07-10-2006, 04:37 AM   #1049
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hi bundy, there is 2 places up here you can get parts for the cd3.
http://www.herchobbies.com.au/ and http://ultrahobbies.com.au/store/customer/home.php
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Old 07-10-2006, 04:23 PM   #1050
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Hmm. Power pullstart. The RB is a great choice, as is the NovaRossi or Top pull start versions. Choices are a little more limited, but if you want to keep a pullstart, you can't really go wrong with those. Check to make sure they come with a threaded crank, or you may have to do a little work with the clutch you have (at the very least you will need the sg clutch nut). Depending on the size of the pullstart mechanism, you may have to add a spacer or two between either the chasis and the motor mount or the mount and the engine. I had that problem when I had my pullstart OS. Can't really say what the price on any will be in AU (I'm in the US).

Going bump start does have it's advantages, though. You will have a more powerful engine, without question. And you won't have to worry about tugging that pull start cord to get it to fire up on the day the tune is just slightly off and it does not want to start. On the flipside, in addition to having to buy the starter box, most bump start motors are rear exhaust, meaning a new pipe as well.
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