X10 One-Way Differential

[darren]

funny. I have just finishe adapting an NTC3 front one way to the X10. I have driven a BJ4WE with the one way and the centre shaft, and this is what I finfd the biggest difference to be, simply, that the one way shaft facilitates onn power exiting a turn, and that the diff. one way facilitates power off entering a turn, allowing the front wheels to spin at their own rate while the ackerman effect is in place. Using over big winding sweeps like we have in here in north america (more the US than Canada) it will only help through the whole thing, but we all know that the race isn't won on the sweeper...
Anyway, back to the NTC3 diff...I used the std gear from the NTC3, why? simple, the teeth count is the same, but the pitch is slightly bigger, and I have found that while the ratio remains the same, the larger gears allow for a very subtle amount of over drive, making the car really aggressive to drive, without driving aggressively (I hope you get that). Why is this good? because as we all know, you HAVE to drive this car aggressively for the performance to come out. I do go through a bit of the NTC3 front gears 4 all season (while none of the X10 gears have gone) but the $$$ are worth it. I haven't tried the ACADEMY one, as there are no ACADEMY dealers here. To do the mode, I also used the H-D front diff, as the larger bearings are good and I needed the reinforced outdrives as I had to remove some material to allow the X10 drive shafts to work. (I am never going back to CVD's after having pines come out and the X10 drive shafts are bitchin'). The H-D front one way fits in the X10 bearings no prob. I used 11 shims (have to be AE) on one side and 4 on the other. I also tried using "O" rings,but they wear over time). Using a file, you have to deeper the slots by about 4mm on each side, which DOES NOT interfere with performance. I have only had to do this once.

[Northy]

Do you use the standard front drive shafts?

G

[darren]

Hey Northy,
I am keeping EVERYTHING the same where I can. So, yes, the X10 front drives. So far, the only thing I have had to do is the "half-ass? machining of the outdrives.

[Northy]

And you've not snapped any driveshaft pins?

G

[darren]

nope, never. I have changed the way that it works though. When I am using the front one way, I use drive shafts without the BUD cup. If you remember a while ago, I had experimented with using IRS pin cushions, well, I gave up on that, realizing that I can cut the IRS cushion in 2 pcs, and using Ryan MAifields trick, I use A/W grease on the outdrives with tape to hold in the grease. I will take some photos when I get a chance for you.

[Northy]

Yeah that would be cool, I'd have thought the pind would break though.

G

[Northy]

Darren,

Can you explain why you think you get some overdrive on the front this way? Surely the drive is just the ratio of the teeth and nothing to do with the size of the gear? Very interested in your ideas.

G

[darren]

Okay, work with me on this, the X10 ring gear is 10 cm in diamter (hypothtically) and the ring gear is 30 cm in diameter (again, hypothetically) The gear ratio is 2.44:1. It takes (again, hypothetically) 1 second (hypothetically) to turn once to achieve the ratio of 2.44:1. You with me so far? ok....
The NTC3 gear also will yield a ratio of 2.44 :1 as the tooth count is the same, HOWEVER, the DIAMETER of the gear, due to its different pitch, is slightly larger, say, 33cm in diameter (again...yes, hypothetically) so, in actual fact, the front wheels will achieve its one FULL turn in not 1 second, but in 1.2 seconds, meaning the front wheels, while keeping the same overall ratio, work LESS to achieve a more aggressive result, in causing the FRONT to over drive the rears rollout by .2 seconds making the car turn faster and more aggressively.
I hope you got it.
Cheers!

[Northy]

Darren,

Been looking at this tonight.

The difference in diameter of the TC3 gear to the X10 is only 1mm, and that depends where you measure the X10 on as the edges are not 'square' to the centre.

I'm still not sure that the different diameter will make any difference.

This is the biggy, you counted wrong! lol. ;D The TC3 gear has 40 teeth, and the X10 gear 39 teeth. I think thats where your getting your overdrive from!

Still a very interesting idea.

G

[darren]

AHA!!
simple math - a concept beyond me. it is the 1 + 1 conept that happens every time!!
Yes, well thanks Northy, that certainly explains the amount of overdive, however, the 1mm difference also comes into play as well I think, but as the teeth count are different, we'll never know. But I can tell you it does work.

[chris burgess]

it is the tooth count that makes the biggest difference - i think the same number of teeth over a larger area would introduce "underdrive" on the front....

[Northy]

Does the pinion have 10 teeth?

If so we have 3.9:1 at the rear and 4:1 at the front, so the rear wheels turn once every 3.9 prop turns and the front every 4 prop turns.

Isn't that 'underdriving' the front? I know it will accelerate faster, but wouldn't it be better the other way round with the front 'pulling' the rear round? Not sure.

I remember using different sized pullies on my Procat but I wasn't good enough to tell the difference! lol

G

[Northy]

Any more thoughts Darren? I was really enjoying this chat! ;D

G

[alfonzo]

Procat..Ahh, now there's a trip down Nostalgia Avenue ;D

[darren]

sorry about that, had a tonne of work to do. How do I post the photos here of the 1 way?
Either way, I am going to try to modify a NTC3 ring gear to work with the X10, it feels more aggressive, you should try it (it is aroun 4 dollars and an hour work) and I think it is well worth it.