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Getting to know the Awesomatix A700L

Since owning my A700L a comment I get frequently, both online and at the track, is something along the lines of:  "It looks like a beau...

Since owning my A700L a comment I get frequently, both online and at the track, is something along the lines of:  "It looks like a beautiful car but it's too complicated for me."

In this article I aim to point out the major differences between the A700L and a conventional belt driven TC such as the Xray T4 or TRF417, which from now on I will refer to as a conventional TC.  I'll point out the difference these make in terms of car handling and I will run through all the settings and how to change them.

Hopefully this article will make the transition to the A700L a smoother and easier process for anyone who has just got one or is thinking of buying one.  I also hope to demonstrate how in many ways working on the A700L is in fact easier.


First of all a quick mention about the different kits Awesomatix has available.

A700L - This is the kit I have and will be using for this article.  It allows longitudinal motor placement only and uses the narrower L chassis.

A700EX - This is the base kit with everything needed for longitudinal and transverse motor mounting.

A700EXL - This kit is like the EX but only has the parts for longitudinal motor mounting, which is reflected in the price.

Since I am using the A700L for this article that is what we will focus on but everything should be relevant to the other kits too.

The Differences

Here is a quick list of all the major differences between the A700L and a conventional belt drive TC.  I will cover each point in detail.

  • Shaft drive
  • Longitudinal motor mounting
  • Suspension geometry and wishbone mounting
  • Rotary dampers 
  • Leaf springs
  • Double turnbuckle upper arms (camber/caster links)
  • Linear steering rack
  • Adjustable hubs
  • Battery locking system


Shaft Drive

Instead of belts we have shaft drive.  This gives more instant power delivery from the motor to wheels which in turn makes the throttle feel more sensitive and the acceleration more aggressive.  It also allows for a drivetrain which runs much more freely and efficiently.

Longitudinal Motor Mounting

Compared to a conventional TC the motor is rotated by 90 degrees.  This means the weight of our vehicle is more centralised.  This makes it is easier for the car to rotate through the corners.




Suspension Geometry and Wishbone Mounting

The wishbones do not use hinge pins to mount instead they utilise a trio of ball joints.  From what I have read Awesomatix found that with this arrangement inboard toe made little or no difference.  So the A700L has no inboard toe front or rear where most cars have rear inboard toe.  This means the rear of the car is more free to compress as inboard toe inhibits this.

The suspension geometry is the same front and rear.  On a conventional TC the rear shocks are mounted further out on the wishbones which has the effect of making them stiffer.  Since the shocks geometry is the same front and rear on the A700L we will, normally, need to use a softer spring rating on the front compared to the rear.

The same is true with regards to the anti roll bars (ARBs).  On a conventional TC even when using ARBs with the same thickness front and rear the geometry means the rear one is a bit softer.  This is not the case with the A700L, the same thickness ARBs front and rear means the same ARB effect front and rear.

Leaf Springs

Probably one of the most obvious differences are the shocks.  Instead of a coil spring we have a leaf spring.  This is basically a piece of hardened sheet steel which went bent acts like a spring, it's a bit like taking a ruler and holding it over the edge of a table if you press down on the end of the ruler it will spring back.

What this means is that we don't have to change springs to alter the spring stiffness instead we can change the pivot point for the leaf springs to do this.  This design also allows the shocks to be mounted on the chassis which lowers the centre of gravity.



Rotary Dampers

Instead of dashpot style dampers we have rotary dampers.  These are sealed units with an output, the rotation of the output is dampened by oil inside the damper.

This means to change the dampening we do not need to change the oil in the shock instead we can change the length of the lever working on the rotary damper.  Again this allows the shock to be mounted to the chassis for a lower centre of gravity.

A big benefit to this suspension set up is how quick and easy it is to alter spring stiffness and damping rate.  No need to change springs and oil just slide the shock and/or the spring adjuster to set them.  I will cover this in the how to setup section.

Double Turnbuckle Upper Arms (Camber/Caster Links)

The addition of a second turnbuckle to the upper arms allows for adjustment of both camber and caster.  On a conventional TC to change caster you need to change the C hubs, here we can alter the lengths of the upper arm turnbuckles to set caster.

This also allows for reactive caster (the amount caster changes under suspension action) by using different amounts of spacers under the front and rear links on either end of the car.



Linear Steering Rack

The linear steering rack replaces bell crank and double bell crank set ups.  The clue is in the name, it makes the steering inputs more linear as the rack moves along the same plane throughout the steering motion.

Adjustable Hubs

The hubs are made from multiple parts in aluminium and steel.  It's possible to fit spacers between the hub and lower ball joint.  This means we can change track width, king pin length and outer camber link height here.



Battery Locking System

No more battery tape!  The battery locking system allows fitting of the battery without tape.  This also allows the chassis to flex more freely and evenly as the battery is not fixed in place and is free to move a little.



How to Setup

The setup process is largely the same as a conventional TC with a few extra settings.  It's the way we change these settings that is different.

Weight Distribution

Setting the weight distribution is pretty much the same as a conventional TC.  We can place weights around the chassis and alter the position of the battery front to rear and side to side.

Something worth noting here is that changing pinion or spur size will alter the left to right weight distribution.  To minimize this change both spur and pinion at the same time to keep the total tooth count similar but alter FDR.  This will mean the motor will only move slightly left to right and the balance will be maintained.

Chassis Flex

There are a couple of options when it comes to setting chassis flex.  First is the number of screws you use in the top deck and how many of these screws have ST09 collars.  The ST09 collars are hardened steel collars which sit inside the top deck screw holes.  They are slightly taller than the top deck so when used the screw does not clamp the top deck down.  The centre hole in the top deck is the same diameter as ST09 so when used here it is still clamped somewhat.



The top deck also has a number of sections which can be cut out to increase the flex at the front, rear or middle of the chassis.

The third option is to use ST27 and ST28 chassis stiffener screws.  These go in the slots on the outer edges of the chassis and make the lower deck much stiffer.

Gearing

Changing the pinion is straight forwards, it is easy to access and is replaced in the usual way.

Changing the spur is also easy but a little different on the A700L.  First we need to remove the main shaft, just give it a firm tug to the rear of the chassis and it will come out.  Angle it over and pull it out the spur mount.  Now to remove the spur use a 12mm spanner to remove the spur nut and change the spur.  Reverse this to clamp the spur in place and refit the main shaft.

If you have the spur damper fitted like I do here then you don't need a 12mm spanner, instead use a 1.5mm hex driver to loosen the locking collar.



Note that there is no need to remove the top deck when changing spur making this change much quicker and easier.

Diff Setting

Just the same as a conventional TC.  Open the diff and change the oil.  Only difference here is that the diff's are easier to remove with just 4 screws on each.  No need to disconnect shocks or camber links.

Anti Roll Bars

The anti roll bars (ARBs) fit in a slightly different way.  They are mounted on the inside of the chassis and lower down.  Rather than a ball joint arrangement to attach to the wishbones they use what we call kidney beans (P05) which clip into the wishbone and hold the ARB in place.



The thing to note here is that there are no adjusters to help balance the ARB action.  Instead we need to make sure the ARB is flat and keep twisting it gently until the action is the same left and right.  Whilst this can be time consuming in general once an ARB is set it won't need doing again.

Spring Stiffness and Damping

As mentioned in the differences section there is no need for oil or spring changes here.

To change the spring stiffness loosen the spring rating screw (SRS) and use the feeler gauge to set distance from the damper body.  The closer to the inside of the chassis makes for a softer spring and vice versa.  It's also possible to swap the SRS and ride height screw to get a different range of adjustments.



To change damping release the screw which clamps the damper in place on the under side of the chassis and use the feeler gauge to set the distance for the damper.  Closer to the inside of the chassis makes for softer damping and vice versa.



These adjustments work by altering the lever length acting on the damper and altering the length of the effective leaf spring.  If you move the damper the spring goes with it so this alters both damping and spring rate.  You can then adjust the spring rate independently to effectively only alter one or the other.

The set up sheet available from Petit RC is very useful when setting the shocks.  You can put in the values for the spring and damper gaps and it will calculate the stiffness for you.  This means you can set the damper value as you desire and alter the numbers on the setup sheet until you get back to the original stiffness.  Putting these settings on the car will result in having altered the damping only and keeping the spring setting the same.

Ride Height

The ride height is very easy to adjust using the ride height screws.  Screwing these screws in is just the same as winding the collars down on a conventional TC.  It increases the preload and raises the ride height.  Adjust the screws on each corner of the car to obtain the desired ride height.

Droop

Droop is set in a similar way to a conventional TC but the droop screws are set into the chassis rather than the wishbones.  To adjust them you need to turn the chassis over and wind them in or out from the under side.



Set the same as you would on a conventional TC which is commonly either measuring using a droop gauge and blocks (or directly on setup board with ride height gauge) or taking an over ride height measurement.

Upstop

It is possible to set the upstop by winding in the upstop screws.  Personally I do not use this setting and so have not fitted the screws.



This is equivalent to fitting o-rings on the shock shaft (outside the shock body) on a conventional TC and will limit the amount of suspension travel.

Bumpsteer

Bumpsteer can be eliminated like usual.  Change the spacers either end of the steering rods to change the angle of the steering rod and alter the amount of bump steer.

Toe

On the front of the car it's just the same as a conventional TC.  The rear of the car is similar to the front.  The outboard toe can be changed by adjusting the toe links.



Roll Center and Camber Gain

These are set the same as a conventional TC.  Use spacers under the camber/caster links and wishbone mounts to obtain the desired roll centre and camber gain.  A roll centre calculator, such as RC Crew Chief, can be very useful here.

Camber and Caster

Camber and caster are coupled together on the A700L both are adjusted by altering the upper arm links.  On any corner of the car making both links shorter will increase camber at constant caster whilst making one link shorter and the other longer, by the same amount, will alter caster at constant camber.

I find the easiest way to do this is to put the car on the set up station and fit a pair of caster doodles, available from Awesomatix USA.  These make taking a caster measurement very quick and easy.  Now it's easy to see both camber and caster at once and adjust the links to obtain the desired values.



Wheelbase

Wheelbase can be altered by setting the rear caster.  Lean the wheels towards the front of the car for a shorter wheelbase and vice versa.  Be aware when altering wheelbase you are also changing the front/rear weight distribution.

Trackwidth

There are two ways to adjust the trackwidth, we can use spacers behind the wheels or add shims between the lower ball joint and the hub/upright.  When adding spacers to the hub/upright be aware that you are also changing the king pin length which will affect roll centre and camber gain.

Ackermann

Ackermann is set in two ways either at the hubs, like a conventional TC, or by moving the steering rack backwards or forwards.  Moving the steering rack is the same as adding spacers behind the steering links on a conventional TC.  This is easy to do due to the two access holes in the chassis.



Extra Settings


Reactive Rear Toe

Since we have toe links at the rear of the car we can angle these to get 'bump steer' but on the rear wheels.  This means it is possible to have a car which gains rear toe as the suspension is compressed.

Reactive Caster

By using a different amount of spacers under the front and rear of any of the camber/caster links gives reactive caster.  This means we can control how the caster changes as the suspension is compressed.
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