Understanding Differential Preload Setup | Performance Engineering Series - Ep. 4

[@OptimumG]

What other videos and analyses would you like to see on the channel? Leave your ideas below⬇

[@carlosmaldonado8600]

How to correct car speed, when the speed is taken from one wheel speed, and the wheel is blocked..No GPS data available. When that happens the graphs are out of phase, and is very difficult to analyze

[@MrGgaggori]

I want to know what is difference in damper stiffness by data

[@yuvarajbadiger700]

Great insights to new learners! Thank you!

[@Cmoredebris]

My experience with a locked differential (Porsche RSR) , I never felt the adverse yaw because the inside rear tire was unloaded as the car leaned through the corner. Great corner drive off outweighed any inside rear tire's drag. The car did have to be driven more aggressively with throttle.

[@IK47-d2l]

Excellent explanation! Thanks!

[@OptimumG]

Glad it was helpful!

[@matthewm.1598]

If using preload causes longitudinal force reactions on the rear wheels, then wouldn't that be reducing the amount of rear grip available for cornering? If the car is too oversteer, why not tune the roll bars to modify the roll couple instead of degrading rear lateral grip?

[@artemouse2007]

best ive heard it explained! thank you so much! have literally been doing completely 180 the wrong way so far :/ LoL

[@dunnock343]

I understand the purpose of the iRacing video wasn't to demonstrate proper corner entry, I still feel the need to point out how awful the entry line was. Love the video though! Thanks for the series!

[@laurence12361]

Muito esclarecedor o vídeo. Valew!!!

[@sheggy012]

The yaw moment in the image at 6:30 should point in the other direction. The left rear wheel is pushing forward, the right one is slowing down a bit. If you imagine the car driving in a straight line, it will move to the right and not to the left. A yaw to the left would not help the car in the right turn. According to the explanation, an open differential would have an advantage in the corner.

[@OptimumG]

Thanks for your message. In coasting, the forces and moments are as shown in the figure at 6:30. The inside tire tries to follow a shorter path (closer to the turn center), but due to the differential, it is sped up (equivalent to traction), generating a force forward. For the outside tire, it tries to follow a longer path, but due to the differential, it is slowed down (equivalent to braking), generating a force rearward. The resultant moment is against the corner, as shown. Differential preload does not help the car to rotate, it does the opposite, it reduces the car rotation (increasing car stability). When you are at the track, and you increase differential preload, the car will get more understeer (less rotation in the corner). In a traction situation at corner exit, then it will be more similar to what you described.

[@rayanamaral6112]

Amazing !! U r the best

[@mashtyxzockt7420]

I love your videos!

[@bertrandvallat2136]

The video is very good for basic understanding of the differential settings. The data analysis and simulator analysis would be good if it was not biased by the fact that in the low preload setup, we can see the start of a rear wheel locking causing the instability of the car. This video shows the phenomenon of wheel locking under cornering condition but should focus more on this particular point, because that's the root cause of this kind of instability. On top of that it does not describe one of the most important effect and adjustment in a LSD: the reaction time.

[@OptimumG]

Bertrand, thank you for your input. We will take it into account for future videos.

[@Fearlusitano]

Wait, that graphic u talking about is showing wheel speed DIFFERENCE, so when it goes 0 it means the wheels are spining at the same time. If i was WHEEL SPEED only than if it its 0 it means lock up. Or i am reading this wrong?

[@fujiki5507]

@@Fearlusitano I'm also confused. That graphic is showing wheel speed difference, it has nothing to do with a rear wheel locking, unless both the rear wheels are locking. But the preload definitely effects reaction time

[@mmcpecora]

Very good

[@teddyruxpin3811]

A higher preload value = more locking torque? or do I have that backwards?

[@chrise.400]

👍

[@asaventurasdolucasluquita9633]

Top, top,top!

[@claudionorcosta9238]

Muito bom!!

[@clubsport.m3]

I loved this video!

[@andreapecora6572]

Excelente