Originally Posted by rnelias

Sure!

and it's not hard to visualize...

Imagine a very tight corner... The rear wheels will have to displace more than the front ones since they're in the outer radius of the car pivot -- the front wheels. By using a spool, you'll be forcing front and rear to have the same displacement and the car will probably loose the front.

In fact, front and rear diffs also play an important rule regarding cornering ability as the outer wheels must displace more than the inner ones. In the other hand, front diff is not an issue and some pilots like to replace the diff by a blocked spool. Front wheels are important to pull the car and keep forward traction while cornering. It explains why we use thinner diff oils in the rear diff