Front One-Way

[CaptainChaos]

It seems that none of the current 4WD 1/10 cars have a front one-way any longer and are all full-time 4WD...

Is this the case and why has it gone that way??

[PaulRotheram]

Cas have enough grip / steering not to need them now - plus the added stability from a diff is great.

[CaptainChaos]

So none come with an option for a one-way at all?

I hear what you're saying, but I tried a BMAX4 a few years back and the thing was an understeery pig that wouldn't turn in... I know Tom Yardy managed to get his round at the usual warp speed, but it didn't suit my driving style at all

[PaulRotheram]

Nope - they are not produced anymore. Geared differentials are the preferred route to go.

The bmax 4 is also a good few generations old. The latest models are alot more refined and effective.

[CaptainChaos]

Why go back to gear diffs?

The ball diff was a HUGE leap forward...

[Navek668]

The Schumacher Cat K2 has an option for a FAB, front adjustable brake which will do a similar thing I believe, allows front wheels to continue to roll when brakes applied giving better turn in. ??

[CaptainChaos]

That's interesting information

I'll go download a manual and have a look, thanks!


Why have ball diffs gone again?
Tamiya Hornets had those in the 80s and then everything got better when Schumacher invented the ball diff...

[CaptainChaos]

Jut downloaded the CAT manual and both belt seem to slide onto the same gear on the layshaft


Correction:
OK, you're right, it's an option part :-)

[Welshy40]

Im the same, i can gain more laps with a oneway compared to permanent 4wd so stopped doing 4wd until i figure out how to fit one on my car and now sticking to 2 until then. A one way with a ball or gear diff is quicker in and out of corners for me.

[CaptainChaos]

Judging by your list of cars Welshy, I'd say we have the same issue because we grew up racing the same stuff

I might just have to build something retro and put lipos and brushless in it

Is there much difference with C ratings on lipos? I get the impression a lot of the power from high ratings and faster motors etc has to be turned down in the name of traction anyway?? For example, do 100C lipos have to be turned down, so why bother buying more than 35C?

[Bomberpilot]

i learnd to drive in the old days with optima and lazers, one ways always saved my corner entry....These days i have to do very odd things to get my 4wds to turn i how i like without loosing speed in the Corner...probably in the old days we learnd to drive the cars gently and not to to overdrive them or squeeze em out...

Greetings from the other side

[/tobys]

Originally Posted by CaptainChaos

Why go back to gear diffs?

The ball diff was a HUGE leap forward...

The combination of high grip and high power means that ball diffs tend to go crunchy very quickly. So gear diffs tend to last longer between rebuild and easier to set consistently.

Plus gear diffs seems to “drive” differently and this seems to suit current race surfaces, buggy layouts/setups and the generally more aggressive driving styles that are in use these days.

When I started racing again, the first few 4wd buggies I had were equipped with ball diffs and the constant maintenance was a pain (I even had to make rebuilds track side on occasions). I experienced my first gear diffs with a Durango and since then every 4wd of mine has had geardiffs. I prefer the way they drive and I don’t need to use the slipper as a diff protector any more either!

In 2wd, ball diffs are more common but even then, a gear diff can be a very useful thing to have if you run on carpet or very grippy Astro.

[mark christopher]

Originally Posted by CaptainChaos

Jut downloaded the CAT manual and both belt seem to slide onto the same gear on the layshaft


Correction:
OK, you're right, it's an option part :-)

Originally Posted by Welshy40

Im the same, i can gain more laps with a oneway compared to permanent 4wd so stopped doing 4wd until i figure out how to fit one on my car and now sticking to 2 until then. A one way with a ball or gear diff is quicker in and out of corners for me.

Try k2 with fab, but you do loose brakes the freer it is.

Simple fact is we have more power, more grip and gear diffs are know smaller and fully sealed units that can take the power and abuse while remaining consistent.

Many manufactures still offer ball diffs as options.

Some cars are now using centre diffs as 8th rally x

[steveproracing]

Jimmy will be smiling up there at this conversation. He was the eternal fan of the one way!! Infact when he worked for durango he had the only one way prototype they ever made as no one else liked it, but he loved it!!!

[mattr]

Another plus side of the gear diff is how flexible the tuning is. Rather than mucking around with an extra 1/16th of a turn on the ball diff, then brinelling the plates, you just change the oil viscosity, you can dial out understeer quite easily by playing with front and rear oils. Or running with two gears instead of 4, and so on. Just because the one you tried understeered, don't assume they all do.

And they don't slip. My first car after i came back to racing had a ball diff. If it drove well, it slipped under high power, if it was tight enough to not slip, it was too tight to drive. And that wasn't even with a silly motor.



And as for C ratings, i found it only really makes a difference when you get near to the end of the battery, so sort of 8-10 minutes in. Unless you have really cheap batteries. Gens Ace are the only "low C rated" batteries i've had any joy with. The Nanotechs have a far higher C-rating, but don't seem noticeably better than the gens ace, and a very similar price at the time.
(Also, bear in mind that there are many ways of measuring C rating, and lots of manufacturers pad their results, or lie.)

[adey]

I can’t use a 4wd without one. They just seem to understeer to me under braking without one. I wonder if we will see a return of the one way with the current 4wd cars.

[stuey]

Originally Posted by mattr

Another plus side of the gear diff is how flexible the tuning is. Rather than mucking around with an extra 1/16th of a turn on the ball diff, then brinelling the plates, you just change the oil viscosity, you can dial out understeer quite easily by playing with front and rear oils. Or running with two gears instead of 4, and so on. Just because the one you tried understeered, don't assume they all do.

And they don't slip. My first car after i came back to racing had a ball diff. If it drove well, it slipped under high power, if it was tight enough to not slip, it was too tight to drive. And that wasn't even with a silly motor.



And as for C ratings, i found it only really makes a difference when you get near to the end of the battery, so sort of 8-10 minutes in. Unless you have really cheap batteries. Gens Ace are the only "low C rated" batteries i've had any joy with. The Nanotechs have a far higher C-rating, but don't seem noticeably better than the gens ace, and a very similar price at the time.
(Also, bear in mind that there are many ways of measuring C rating, and lots of manufacturers pad their results, or lie.)

Hi, can you explain how you might change the diff oils to reduce understeer, especially when turning in to a corner? Thanks

[mattr]

Generally by lightening the oil up to allow the diff to move much more freely.
IIRC theres a bit on it in the Hudy set up book.

(Go too light and you get different issues!)

Also worth adding the suspension geometry tuning you can do on current cars is huge compared to what used to be possible.

[stuey]

Originally Posted by mattr

Generally by lightening the oil up to allow the diff to move much more freely.
IIRC theres a bit on it in the Hudy set up book.

(Go too light and you get different issues!)

Also worth adding the suspension geometry tuning you can do on current cars is huge compared to what used to be possible.

So a lighter rear oil will free up the rear end a bit? I know too light can lead to diffing out, especially in a 2wd car.

[Kev B]

In my Vintage class racing using the Cat 2000 and EC i run one ways and can back them into corners and direction change is great however against my Cat K2 on the same tyres and track last year it couldn't get near them on lap times. Both on brushless 6.5 set ups and wasn't in speed. just the modern Cat K2 could carry more corner speed and offer later braking. The main thing is you are on full attention for 5 mins with the modern stuff. The old stuff is just too chilled out and safe to drive.