Gear diff vs ball diff
 

Is it possible to simulate a ball handling by putting a lower oil in a gear diff. I'm asking as the set ups for Worksop where the BWOC is on this year all the set ups show a ball diff. Now I do have one, but it's in my 4WD, I'll take it out if need but thought I would ask first.

Cheers
Ross

Not that I've seen mate..

Heard some stories about removing two of the gears but it's not the same so just chuck the ball diff in.

I ran a gear diff on medium grip carpet this week with 5000cst oil and 2 of the internal small gears removed in my KF. It felt similar in rotation characteristic and my lap times were very close with my ball diff performance. HTH. :thumbsup:

I'll take it out of the car I think and take it with me, but I may give what Dan has said about the small gear ago 👍


Thanks Dan 👍

I've taken the ball diff out of the K1, I think it's an SX or SX2 diff as it doesn't look like the K1/KF diff. The pulley is wider and it'd not offset.

Would this be Ok still?

I've run 1 and 2000cSt oil, that's fairly similar to balls.
I usually run on high grip, so have stuck with 7000.

No it wont mate.
The belt will be bent

Gaz

I've taken two gears out of the gear diff and put 4k oil in, it's feels good.





It sits straight as shown, but I think it will float around too much. Think I'll put he gear diff in.

When you take out 2 gears, do you still install both cross pins.

No mate, just take the gears, shaft and shims out :thumbsup:

Although I did end up running with just a coating of oil over the gear to lube them and it felt good. Not sure how it would compaired to a ball diff though.

I don't get this thread.

How are you guys comparing 2k and 4k oil in a gear diff to be a similar action to a ball diff?! Ball differentials have quite a heavy action, so surely by putting such a light weight oil in your gear diff is the exact opposite?

The 12,500 weight the KF2 comes with gives it a nice heavy action - similar to a ball diff. To me, if you wanted to make it feel more like a ball differential I think maybe 15,000 would be good.

Ball diffs and gear diffs will always handle slightly different though as they operate in quite a different manor.

This is my take on it also.

At Worksop we ran the ball diff tight due to low traction. For me this is the equivalent of about 10-15k oil for a very locked action.

Ball diffs are run loose on high grip to promote rotation, which is why you run 2-3k oil to mimic this.

This is just my personal take on things.

Too be honest Ross:yawn:

Never try to compare a Gear diff vs a ball diff, or even try to build a gear diff to replace your ball diff or the other way around.

Keep it simple. “Use it as a setup option”

Use a standard setup on your car and simply test it. Find out what is best for that track you are racing on. Use your gear diff and test some deferent oils you have (20k-15k-10k-7k aso…) And then try out a Standard ball diff. You will find that they act deferent.

You can never Force a “Gear diff” to be a “ball diff”…. If gear diff don’t work for you, simply just try out the ball diff. Some times its faster or slower.

Ok it looks like the post went a little of track to what I want it to be about.

So originally I thought I had a ball diff to put in the car, I didn't really want to take it out of the 4wd and thought I may be able to get a gear diff to be good on the slippy stuf (Worksop).

So my take on the difference was that a gear diff running low oil would be similar to a ball diff, coming from 1/8th nitro I don't really understand /like ball diffs, that's mainly because I don't really know how to adjust them correctly I suspose. Obiouvsly when I found out the diff I had in my K1 wasn't correct I had to stick with the gear diff.

Now reading the above it looks like my thought was wrong on the oil selection in gear diff's. My understand was that the thinner the oil the less drive I would get, hence going lower on oil, also taking a set of gears out out would make it smoother, less drive again.

So it looks like all my thoughts were incorrect, I didn't realise a ball diff would be run loose on high grip, if I had left my normal 15k oil in for Worksop it would have been better lol.

See, this is what threads are all about, learning :D:D

Thanks
Ross

Like 👍 😊

That's the problem with the gear diff v ball diff argument, many different opinions on the comparison. If you google it, you will see all sorts of different opinions.

You aren't completely wrong, with the thinner oil you will get less forward drive. With the thinner oil, the diff will try to put extra power to the wheel with the least traction. This can cause the car to be unstable under acceleration.

When it comes to cornering, thinner oil allows the variance in speed between the outside and inside wheel to be higher, allowing the car to rotate quicker. So for example on a 2wd, if you have 15k oil, the difference in speed of the wheels will be less, causing the car to push more in a corner, where as 1k oil will allow the car to rotate a lot quicker. That's why I compared it to a ball diff being tight or loose.

This however, is all my own opinion from lots of research done on the subject as there is so much false information all over the internet, the best thing you can do is try and get some track time. Stick 1k in the diff, do some laps. Stick 20k in the diff, do some laps and note the difference. :thumbsup:

Ross, the ball diff you tried is not from a K1 which should fit. I use the ball Diffs from my original K1 no problems.
I think some of the issues people will have in trying to get a gear diff to act like a ball diff is that they work in different ways so a gear diff can never really behave like a ball diff. Ok in some situations they can be made to feel similar but when the traction isn't there nothing beats a ball diff.

I've just removed my gear diffs from my K1 aero and fitted ball diffs. It's completely different to drive a lot more predictable and easy. Don't think a gear diff will ever act the same as the trusty ball diff no matter what you do. I was suffering with power on understeer it was really bad with the gear diff.
I remember when we bought Tamiya touring cars the gear diff would be thrown away straight away. That would be about 20 years ago!! ball diffs in my opinion are better.