One Way Diffs! Help!

[Brooklyn Nights]

Hi

I keep seeing people mention one way diffs as a hop up but I dont really know what these are or what they do!

What are the advantages/disadvantages of using these? I'm not really a race kind of rc member just a basher and curious! Any info will be great!

Cheers

Rich

[OCD]

Hi

I keep seeing people mention one way diffs as a hop up but I dont really know what these are or what they do!

What are the advantages/disadvantages of using these? I'm not really a race kind of rc member just a basher and curious! Any info will be great!

Cheers

Rich

Here you go - It's an article from January of '97, but I think it will still be useful

[Brooklyn Nights]

Here you go - It's an article from January of '97, but I think it will still be useful

Ah thanks!

So basically it turns a 4wd into a 2wd most of the time and is only really of any use to pull the car faster out of the corners .... and only on certain surfaces!

Dont think it will be much use for my TA01 rally cars then that are off road 95% of the time!

Still useful info and good to know!

Cheers

Rich

[MadInventor]

Ah thanks!

So basically it turns a 4wd into a 2wd most of the time and is only really of any use to pull the car faster out of the corners .... and only on certain surfaces!

Dont think it will be much use for my TA01 rally cars then that are off road 95% of the time!

Still useful info and good to know!

Cheers

Rich

What it does is turn your car into 2wd under braking / reverse, but greatly improves grip under power from the front end. With a 4wd car, when cornering, the front wheels want to rotate faster than the rears, because they travel along a different arc. The one way allows the front wheels to rotate faster, taking the strain off the 4wd system, and potentially reducing wear on the front tyres. The other advantage with a one way is that power cannot 'spin out' through the front axle when one wheel is lifted off the ground (With a car with a normal diff, if one wheel is off the ground, all the power goes through that wheel and effectively turns your car into a 2wd as only the rear wheels are gripping). With one way bearings, even if one front wheel is lifted off the ground, power will still be applied to the other front wheel without slipping. (it's a bit like having a diff lock in the front, without scrubbing a front wheel when cornering).

I've just spent quite a lot of time modifying a TT01 one way to fit in the front of my TXT-1. I have tried it this morning and it gives far better grip over a conventional diff when climbing very steep banks, and has the advantage of not locking up the front wheels when using the brakes when going downhill, which might cause the car to flip over front axle. It also takes the strain off the front propshaft when cornering on tarmac,which can be quite significant with the size of the wheels. (Basically I'm well chuffed with it )

For a rally car, i would say it really depends on what surface you run on, and how you drive. If you use brakes a lot, I wouldn't bother with one, If you tend to coast to slow up, and then use power to corner, (especially drifting), then try one. I have to say I totally disagree with the article where it says one ways are only good on high grip surfaces. This might be true for on road cars, but for off roaders being used on loose surfaces, I found it greatly enhanced grip and stability in corners compared with a standard diff, as long as you keep the power on, as when one front wheel slips, the other one does not lose power.

As the artical says, when I tried using it in a TT-01, I found it useless for racing because of the lack of front braking which caused the back end to swing round, so gave up on it and put the standard diff back in. (I'm one of the drivers who is not smooth and likes to jam on the anchors at the last moment before diving into a bend )

Hope this doesn't add further confusion, but the article is biased towards on road racers, and doesn't actually explain how a one way unit works, just the effect that it has on an on road racer, and the effect on an off roader can be completely different, especially where quite often one front wheel may be off the ground. (Rock crawler guys use locked diffs for max traction, but you wouldn't do that for a 4wd on road car as it would ruin the handling, I guess a rally car is somewhere in the middle.)

So to summarize, gives worse handling under braking, but provides a lot more front end grip and control in bends.

Hope this helps,

MadInventor

[Brooklyn Nights]

What it does is turn your car into 2wd under braking / reverse, but greatly improves grip under power from the front end. With a 4wd car, when cornering, the front wheels want to rotate faster than the rears, because they travel along a different arc. The one way allows the front wheels to rotate faster, taking the strain off the 4wd system, and potentially reducing wear on the front tyres. The other advantage with a one way is that power cannot 'spin out' through the front axle when one wheel is lifted off the ground (With a car with a normal diff, if one wheel is off the ground, all the power goes through that wheel and effectively turns your car into a 2wd as only the rear wheels are gripping). With one way bearings, even if one front wheel is lifted off the ground, power will still be applied to the other front wheel without slipping. (it's a bit like having a diff lock in the front, without scrubbing a front wheel when cornering).

I've just spent quite a lot of time modifying a TT01 one way to fit in the front of my TXT-1. I have tried it this morning and it gives far better grip over a conventional diff when climbing very steep banks, and has the advantage of not locking up the front wheels when using the brakes when going downhill, which might cause the car to flip over front axle. It also takes the strain off the front propshaft when cornering on tarmac,which can be quite significant with the size of the wheels. (Basically I'm well chuffed with it )

For a rally car, i would say it really depends on what surface you run on, and how you drive. If you use brakes a lot, I wouldn't bother with one, If you tend to coast to slow up, and then use power to corner, (especially drifting), then try one. I have to say I totally disagree with the article where it says one ways are only good on high grip surfaces. This might be true for on road cars, but for off roaders being used on loose surfaces, I found it greatly enhanced grip and stability in corners compared with a standard diff, as long as you keep the power on, as when one front wheel slips, the other one does not lose power.

As the artical says, when I tried using it in a TT-01, I found it useless for racing because of the lack of front braking which caused the back end to swing round, so gave up on it and put the standard diff back in. (I'm one of the drivers who is not smooth and likes to jam on the anchors at the last moment before diving into a bend )

Hope this doesn't add further confusion, but the article is biased towards on road racers, and doesn't actually explain how a one way unit works, just the effect that it has on an on road racer, and the effect on an off roader can be completely different, especially where quite often one front wheel may be off the ground. (Rock crawler guys use locked diffs for max traction, but you wouldn't do that for a 4wd on road car as it would ruin the handling, I guess a rally car is somewhere in the middle.)

So to summarize, gives worse handling under braking, but provides a lot more front end grip and control in bends.

Hope this helps,

MadInventor

Ah I see! But as the article says it doesn't allow the car to travel backwards as it locks the fronts and that will flat spot the tyres. As I do drive in reverse a bit (j turns etc) then I dont think its going to be a lot of use to me! Thanks for the extra info though its most appreciated!

Cheers

Rich

[stu22]

Ah I see! But as the article says it doesn't allow the car to travel backwards as it locks the fronts and that will flat spot the tyres. As I do drive in reverse a bit (j turns etc) then I dont think its going to be a lot of use to me! Thanks for the extra info though its most appreciated!

Cheers

Rich

I'm running 1-ways in touring cars and buggies and they all back up fine. When going backwards the front wheels don't put down any power, but they are not locking up.

Although there are some basic rules on when a 1-way will work, I still believe it comes down to putting one in and seeing if you like it or not.

[Brooklyn Nights]

I'm running 1-ways in touring cars and buggies and they all back up fine. When going backwards the front wheels don't put down any power, but they are not locking up.

Although there are some basic rules on when a 1-way will work, I still believe it comes down to putting one in and seeing if you like it or not.

Thats probably the best idea to be honest, as now I'm getting confused by what the article said and people on here who have tried them and I trust the members on here more! So guess I may have to raid my bank account again....

Ah well nothing ventured nothing gained eh!

Cheers

Rich

[VinceVegaUK]

Thats probably the best idea to be honest, as now I'm getting confused by what the article said and people on here who have tried them and I trust the members on here more! So guess I may have to raid my bank account again....

Ah well nothing ventured nothing gained eh!

Cheers

Rich

I didn't read the article but it looks a bit old.

I bought and did use a front one way in my TT01.

How it works:

Note:- when referring to a locked diff this means both wheels act as if connected directly to each other an cannot rotate at different speeds especially when cornering it doesn't mean the wheels wont rotate at all

Power on

both front wheels rotate at the same speed even in a corner like a locked diff (rear wheels still act as a normal diff and have different rotation speeds though the corner (inside rear wheel rotates slower than the outside wheel) and all 4 wheels have power. this pulls the car harder and more directly out the corners as the fronts have more direct drive.

Power off/coasting

The front wheels effectively free wheel offering more turn in as its not limited by any diff ration and has the effect of not being connected to the drive train

Brake/revers

acts the same as power off or coast and continues to offer a fee wheel action this in turn gives you more turn in under braking, Hard braking will give a hand brake effect and can unstable the car if trying to turn when braking.

The main use for a front one way is to offer good power off turn in and good power on corner exit in a 4WD car

Hope this helps

Later

VV

P.s

you can also use/purchase what is called a spool which basically connects the two front wheels together with no diff effect forward or backwards

[Brooklyn Nights]

I didn't read the article but it looks a bit old.

Note:- when referring to a locked diff this means both wheels act as if connected directly to each other an cannot rotate at different speeds especially when cornering it doesn't mean the wheels wont rotate at all

Well in the article it states that using a one way diff locks the fronts on reverse and flat spots the tyres! I know what a locked diff is and I knew that this wasn't what the article is talking about. Maybe its an old article as you say, or maybe there are different types of one way diffs?

Think as I said the best thing will be to get one and try it!

Cheers

Rich

[dimblum]

I can confirm that One-Way's -do not- lock the wheels when you go in reverse. I have been using a Center One-Way on my DB-01 Durga for the past two years for club racing.. Front One-Way's operate in a similar fashion and also -will not- lock the wheels in reverse..

One Ways use two concentric rings to operate. The inner ring will lock into the outer ring while turning in one direction and not the other. The outer ring has the ability to continue turning in a forward direction even when the inner ring is no longer turning. Regardless of the design (pulley based or gear based), your wheels will always be able to roll in both directions.

Hope this helps.

[Origineelreclamebord]

I have a one-way in my TB01... Here is how it works:

If the front wheels rotate faster than the rear ones, the wheels spin freely. However, if the rear wheels rotate faster than the front ones, the power will be also put on the front wheels through the one-way bearing, acting as a locked front diff.

In practice, this means that when accelerating, you have 4WD with a locked front diff (which works great for accelerating), and RWD when the car decelerates. So out of a corner, the car is very stable (locked front diff, loose rear diff, so the front wheels are pulling that bit extra on the car compared with a regular diff), and into a corner, the car is rather unstable (which means at high speeds you can spin out, but at lower speeds, turning into a corner can be done easier and quicker - and if you want, with oversteer).

My experience with the one-way in my TB01 is that my car is too unstable with the top speeds my EzRun can achieve. Offroad I haven't been able to test it out fully. I have to make a good soft suspension setup before I try that out, because the one time I did try it, it seemed to be rather a pain to keep in one line off the throttle (no wonder with onroad damping AND a one-way diff really - but I have to see what a good suspension setup does for the handling offroad).

PS: Reversing is no problem, but you have RWD only, so if you accelerate hard... Loads of wheelspin

[Brooklyn Nights]

Hmm so I'm guessing it will be quite unstable with my 15 turn in then!

Still I'll try one and see and if not.... well there is always the sales bit on here or ebay!

Cheers

Rich

[garry]

In basic terms:-

On power going forwards = 100% drive to both front wheels.

Off power going forwards = 0% drive to both front wheels.

On power going backwards = 0% drive to both front wheels.

Off power going backwards = 0% drive to both front wheels.

And how does that affect handling compared of a ball diff or gear diff?

One-way = more on-power steering, more off-power steering, but braking (trail braking or hard braking) will be like pulling the handbrake on a real car.

Its mainly a touring car racing option part, as you can carry more corner speed at the apex and get on the power to pull the car round. But, you can't brake ona track, so they are mainly used on huge open and flowing circuits. 4wd buggies use them to help balance the car in the air and set it up for landing (because when the front wheels are free-spinning, the car will fly ike a 2wd in the air and and is easiler to setup the landing angle). And compromise is a spool on the front axle, it gives the same effect as a one-way under power, it lets you use the brakes but you lose some entry-steering. Most people use spools in touring cars these days. It doesn't matter how quick the motor is, it'll give the same effect. In general on-road, if you need to use the brakes at any time, don't use a one-way.

If you're rallying, I'd use a one-way as a dab of the brakes will lock the rear wheels for a second and encourage the car to go sideways.