XRAY - Model racing cars

I have the set-up manual for my t3'11 and it gives no guidance on the effect of diff height.

would anyone be kind enought to explain it for me please?

i think its about "hardnes" of the belt
but im not sure

taking from the t3 2011 manual ...


Front diff upper position is recommended for tight and technical
carpet tracks. The upper diff position improves handling in
chicanes as it provides more traction, increased steering and
makes the car easier to drive.

Front diff lower position is recommended for large open
asphalt tracks with long sweepers

Rear diff upper position is recommended for tight and technical carpet
tracks. The upper diff position improves handling in chicanes as it provides
more traction, increased steering and makes the car easier to drive

Rear diff lower position is recommended for large open asphalt tracks
with long sweepers.

but how does it work?

Alot of it is to do with the fact you are lowering the diff and its rotating mass. Also the driveshaft angle has a big part to play in how traction is gained/taken away. If you have a greater angle in the driveshaft then under power they are naturally wanting to try straighten back up which would in theory " push" the tyre's more into the track surface.

If u have a low diff, you can see the angle change on the shafts. so when they want to straighten back out. but the starting angle means the traction should be less as they are angled inwards more. Which supports Xray's theory when they say a lower diff provides less traction

Heres a good starting guide as to what 'should' happen

Low front / high rear = maximum steering
High front / low rear = least steering
Low front / low rear = decrease overall traction
High front / high rear = increase overall traction

I have found a low rear diff is great on large open carpet tracks like an ETS track. And Medium-Large outdoor tracks

Tip. Spec-r gear diff can't be used in low profile. it touch the chassis plate