1LikesDiff Height Plunge
12-09-2009, 05:23 PM
#2
A higher diff will take away traction from that end of the car. Not sure why, but it does. I used to run the diff high in the rear and low in the front of my RDX. Haven't played with it in the Photon, because I don't have any rotation issues with this car.
12-09-2009, 05:32 PM
#3
I believe the theory is.. When you have more angle in the dogbones as they rotate they are trying to straighten back out. This pushes the tires into the track surface..
12-09-2009, 07:58 PM
#6
I don't buy any of this. My guess is that the possibility of having the diff up or down came about as a by-product of the eccentric belt tensioner adjusters and then the manufacturers had an idea and run with it without too much testing. Anything to boost sales. I will be convinced when I see a double blind experiment reproduced in controlled conditions by an independent institution and a peer reviewed paper published.
12-09-2009, 08:02 PM
#7
I don't buy any of this. My guess is that the possibility of having the diff up or down came about as a by-product of the eccentric belt tensioner adjusters and then the manufacturers had an idea and run with it without too much testing. Anything to boost sales. I will be convinced when I see a double blind experiment reproduced in controlled conditions by an independent institution and a peer reviewed paper published.
12-09-2009, 08:15 PM
#9
Mechanical dog bone plunge or "bind" does indeed change handling characteristics.
High Diff; The car will stay flatter and have more responsive feel.
Low Diff; The car will roll more and increase on power steering.
Basics are:
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
High Diff; The car will stay flatter and have more responsive feel.
Low Diff; The car will roll more and increase on power steering.
Basics are:
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
Last edited by Racecrafter; 12-09-2009 at 08:30 PM.
12-09-2009, 09:02 PM
#11
Mechanical dog bone plunge or "bind" does indeed change handling characteristics.
High Diff; The car will stay flatter and have more responsive feel.
Low Diff; The car will roll more and increase on power steering.
Basics are:
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
High Diff; The car will stay flatter and have more responsive feel.
Low Diff; The car will roll more and increase on power steering.
Basics are:
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
If lowering the diff makes the car roll more, would it not create more overall traction?
12-09-2009, 09:22 PM
#13
There are different things which have obvious reasons (or it is obvious they actually change something) whereas others are not that clear. The latter need to be properly studied and tested before a conclusion can be drawn.
A longer dogbone can actually bind in the diff joint or the outer CV joint as the suspension (and steering on the front wheels) work up and down and side to side, so there's an obvious benefit to choose one over the other. Beyond that there may be other benefits/changes in the car's handling but again, that needs to be demonstrated as I explained above. Unfortunately, I don't think anyone has the time, money and resources to do it, so I will reserve judgement until someone does. "Feel" is not a quantifiable measure and can not be reproduced therefore it doesn't allow any reliable conclusions.
Here's a quote from the Losi manual suggested above:
Originally Posted by Losi JRX-S type R manual
Diff Height: Caution! When adjusting the differential heights, rotate the eccentrics as to loosen the belts, rotating the belts in the
opposite direction, with the belts installed can severely damage the belts. Diff heights in the Type R are also adjustable by rotating the
eccentrics that position them. The diffs can be adjusted from a full low position to a full high position. The low position will allow the car to
roll more and keep the car in the turn longer, increasing on-power steering. The high position will give the car a fl atter and more responsive
feel. It is also possible to change the balance of the car quite drastically by offsetting the heights of the diffs from front to rear. On asphalt
tracks with rubber tires, testing has shown the best results with the rear diff in the low position and the front diff in the high position. On
carpet with foam tires running the diffs in the low position has yielded the best results.
opposite direction, with the belts installed can severely damage the belts. Diff heights in the Type R are also adjustable by rotating the
eccentrics that position them. The diffs can be adjusted from a full low position to a full high position. The low position will allow the car to
roll more and keep the car in the turn longer, increasing on-power steering. The high position will give the car a fl atter and more responsive
feel. It is also possible to change the balance of the car quite drastically by offsetting the heights of the diffs from front to rear. On asphalt
tracks with rubber tires, testing has shown the best results with the rear diff in the low position and the front diff in the high position. On
carpet with foam tires running the diffs in the low position has yielded the best results.
Last edited by niznai; 12-09-2009 at 09:55 PM.
12-09-2009, 09:51 PM
#14
Raising and lowering the diff is just changing that bind. Maybe i'm wrong though...