Tamiya M-07 Chassis: Hard or Soft Anti-Roll Bars?

[kitefighter]

Hello,

I recently bought the recommended hop up option Tamiya 54757 - M-07 Concept Stabilizer Set (F, R). The kit gives you the option to fit hard or soft anti-roll bars front and rear.

So my question is what is recommended for what surface? The car runs on a carpet track.

Many thanks, H.

[TurnipJF]

It was explained to me that the anti-roll bar acts as a grip reduction device in corners, causing the inside wheel to want to lift as the car's weight transfers to the outside wheel. 

So for example if your car is grip rolling due to a front tyre grabbing in a corner, you might benefit from an anti roll bar up front. Conversely if your car is understeering due to the grip bias being too far to the rear, a rear anti roll bar might help. 

I found the former to be the case with my M-07, so I fitted a soft anti roll bar up front and left the rear bar-less. This has led to a nice reduction in grip roll.

(I also run on carpet.)

[kitefighter]

Hello,

Thanks for the reply and explanation. I also looked up some further interesting advice (please see below). I'm familiar with the understeer characteristics of a real front wheel drive car, particularly when lifting off power during cornering. Not something to worry about unless driving hard or cornering at speed in a real car. However, the Tamiya M-07 is clearly a designed as racing car and mine will be driven at speed on a carpet.

As as trial, I have fitted the soft anti-roll bar to the front and the hard to the back. Although I question in reality how similar in full size front wheel drive car (or any other drive) is compared to a 1/10 scale model of the same configuration. The physics of a RC car in miniature on a carpet at unscale speeds must have many differences from the dynamics of a different construction real car on road.

I must also add that the M-07 chassis is a great pleasure to work on as with all Tamiya models I've encountered, everything just seems to fit together like a well made watch whose movement you never see when the case (or in this case body) is fastened back on. (Please see picture at the bottom).

 

[nbTMM]

Sway bars allow you to adjust the roll stiffness independently of pitch/dive, whereas changing springs alone adjusts both at the same time. Moving to softer springs and a stiffer bar may achieve the same roll stiffness as harder springs and softer/no bar and therefore the same cornering performance when moving at a constant speed. Although softer springs will slow down weight shift between axles during acceleration and braking.

6 hours ago, kitefighter said:

The physics of a RC car in miniature on a carpet at unscale speeds must have many differences from the dynamics of a different construction real car on road.

1:1 handling physics is directly applicable to scale RC cars. What must be realised is that many suspension design decisions on 1:1 cars improve steering feel therefore the driver can tell when they are approaching the limits of the car and not push it too far causing a loss of control. A setup which results in sudden understeer or oversteer might be acceptable if there is enough communication through the steering wheel that the driver knows to back off before they push it too far.

In RC, we don't have any steering feel since we are just observing the car in the 3rd person, so suspension changes which improve 'steering feel' are moot and suspension changes which cause sudden loss of traction are less desirable.

[kitefighter]

Spot the difference (because I can't).

Without anti-roll bars:

With anti-roll bars:

 

[TurnipJF]

I can't see any significant difference, but then I couldn't tell much difference with mine until I picked up the pace, and you appear to be taking it quite easy in the videos. The faster you corner, the more noticeable the effect will be. 

[kitefighter]

Ah yes, well you have me there. The car is being driven by a novice under strict instruction not to crash and risk damage to the body shell.

[Juls1]

In basic terms you won’t see if the car needs a sway bar till you reach its limit. 

Often you’ll only use a sway bay if you want more weight transfer front to back (so you fit softer springs) but want to maintain or reduce your current body roll characteristics. 

Put simply. 

Oversteer = add sway bar front to fix

Understeer = add sway bar rear to fix

its unusual to need both unless your running very soft suspension. 

sway bars on rc cars tend to be pretty soft, it’s very important to install the bars so they are perfectly identical left to right, and that as much slop as possible is removed. 

Your not going to see the difference unless your able to find the limits of the existing setup. 

Having proper camber settings left to right is going to make the biggest noticeable handling difference. If your racing a setup station is a valuable asset.

Juls

[Fabia130vRS]

8 hours ago, Juls1 said:

In basic terms you won’t see if the car needs a sway bar till you reach its limit. 

Often you’ll only use a sway bay if you want more weight transfer front to back (so you fit softer springs) but want to maintain or reduce your current body roll characteristics. 

Put simply. 

Oversteer = sway bar front

Understeer = sway bar rear 

its unusual to need both unless your running very soft suspension. 

sway bars on rc cars tend to be pretty soft, it’s very important to install the bars so they are perfectly identical left to right, and that as much slop as possible is removed. 

Your not going to see the difference unless your able to find the limits of the existing setup. 

Having proper camber settings left to right is going to make the biggest noticeable handling difference. If your racing a setup station is a valuable asset.

Juls

My M03 does after steering tend to lean into one side, I guess probably due to slop in suspension. Has anybody tried sway bars on a M03?