HONDA F1 ULTRA SHORT DIFFERENTIAL
HONDA F1 ULTRA SHORT DIFFERENTIAL
Before bowing out of Formula One with their full Formula One team, Honda has some very impressive engineering designs and one of them is their Ultra Short Differential or U.S.D.
Before bowing out of Formula One with their full Formula One team, Honda has some very impressive engineering designs and one of them is their Ultra Short Differential or U.S.D.
Their targets for this differential was low inertia. Honda claims they manage to reduce weight by 1.2kg for this differential update. The goal in losing this weight was mainly to target a reduction in center of gravity height. Technically with the reduction of weight in parts, the tradeoff would be to shift this mass. Since light weight is limited by the regulations, this shift would be added to parts of the car that is lowest to reduce overall center of gravity. Another aim was to move more weight further forward. With a lighter differential, compensation mass was to move forward now that the rear axle is lighter
Their targets for this differential was low inertia. Honda claims they manage to reduce weight by 1.2kg for this differential update. The goal in losing this weight was mainly to target a reduction in center of gravity height. Technically with the reduction of weight in parts, the tradeoff would be to shift this mass. Since light weight is limited by the regulations, this shift would be added to parts of the car that is lowest to reduce overall center of gravity. Another aim was to move more weight further forward. With a lighter differential, compensation mass was to move forward now that the rear axle is lighter
Initially Honda wanted to move weight forward by remounting their limited slip differential from the rear axle line to a remote unit that would be positioned where the transverse drive shaft was. This unit will replace the transverse drive shaft that sits in between the gearset and rear axle but this design did not come to fruition because it meant that an entirely new geaxbox casing was needed and it was going to be heavier which is counterproductive
Initially Honda wanted to move weight forward by remounting their limited slip differential from the rear axle line to a remote unit that would be positioned where the transverse drive shaft was. This unit will replace the transverse drive shaft that sits in between the gearset and rear axle but this design did not come to fruition because it meant that an entirely new geaxbox casing was needed and it was going to be heavier which is counterproductive
However, in isolation, its targets though were advantageous. Honda calculated that with this design, 2.5 kilograms would be shifted forward or 0.19% forward weight bias in total for the car while center of gravity is lower by 0.4 millimeter. In this configuration however, Honda did not claim any weight reduction but in fact a penalty which was not revealed by how much. This may be from doubling up on splitting the rear drive unit
However, in isolation, its targets though were advantageous. Honda calculated that with this design, 2.5 kilograms would be shifted forward or 0.19% forward weight bias in total for the car while center of gravity is lower by 0.4 millimeter. In this configuration however, Honda did not claim any weight reduction but in fact a penalty which was not revealed by how much. This may be from doubling up on splitting the rear drive unit
This was the differential design Honda was using which is a common spur gear planetary differential
This was the differential design Honda was using which is a common spur gear planetary differential
Due commitments on their set targets for their final drive layout, Honda continued developing it from their base design that they were already using. From here they develop the Ultra Short Differential. As it can be seen here is how much smaller it is. It came about with a very clever way of rearranging the planetary pinion gears by having them in-line but at an angle where one set would counter-rotate the other to ensure no torque interruption for forward drive motion.
Due commitments on their set targets for their final drive layout, Honda continued developing it from their base design that they were already using. From here they develop the Ultra Short Differential. As it can be seen here is how much smaller it is. It came about with a very clever way of rearranging the planetary pinion gears by having them in-line but at an angle where one set would counter-rotate the other to ensure no torque interruption for forward drive motion.
Unlike their conventional Spur gear differential arrangement, this design which Honda describe as double pinion planetary gears have the inner set of six pinions driving one output sun gear to one wheel while the other set of six pinion gears which is the outer pinion gears being driven by the ring gear, drives the other output drive through the planetary pinion gears Carrier, driving the other wheel. Forward drive comes from the ring gear to the planetary sets then distributed as aforementioned. Its rotational arrangement is what locks drive for forward torque
Unlike their conventional Spur gear differential arrangement, this design which Honda describe as double pinion planetary gears have the inner set of six pinions driving one output sun gear to one wheel while the other set of six pinion gears which is the outer pinion gears being driven by the ring gear, drives the other output drive through the planetary pinion gears Carrier, driving the other wheel. Forward drive comes from the ring gear to the planetary sets then distributed as aforementioned. Its rotational arrangement is what locks drive for forward torque
Usually epicyclic differential are known to be used to split power and one that is well known for this was on the Ferguson Formula four wheel drive system's central differential. Drive is sent to the planetary gear Carrier then split to the sun gear and the other to the ring gear. The smaller sun gear would drive the front axle with a reduced torque output while the larger ring gear provided the bulk of torque output to the rear axle. Torque split is 37% to the front axle and 63% to the rear axle
Usually epicyclic differential are known to be used to split power and one that is well known for this was on the Ferguson Formula four wheel drive system's central differential. Drive is sent to the planetary gear Carrier then split to the sun gear and the other to the ring gear. The smaller sun gear would drive the front axle with a reduced torque output while the larger ring gear provided the bulk of torque output to the rear axle. Torque split is 37% to the front axle and 63% to the rear axle
The Honda engineers have cleverly re-arranged this for a very compact differential and now power is split 50/50. On it own discounting the limited slip unit, it could be made as compact as a direct drive fixed final drive layout
The Honda engineers have cleverly re-arranged this for a very compact differential and now power is split 50/50. On it own discounting the limited slip unit, it could be made as compact as a direct drive fixed final drive layout
They manage to achieve a more compact package as well as weight reduction where the differentials center is 25 millimeter closer to the transverse drive shaft, from a distance of 125 millimeter to 100 millimeter. Honda also claims there were no reliability issues as their entire unit could cover the mandatory four race per gearset regulation then, however, width and limited slip performance remain unchanged
They manage to achieve a more compact package as well as weight reduction where the differentials center is 25 millimeter closer to the transverse drive shaft, from a distance of 125 millimeter to 100 millimeter. Honda also claims there were no reliability issues as their entire unit could cover the mandatory four race per gearset regulation then, however, width and limited slip performance remain unchanged
Remounting the limited slip unit from shrouding both output sun gears of their previous differential where it was required to have a larger planetary gear arrangement for housing the limited slip unit within to the side on the new differential layout did not make it wider as the double pinion planetary gear differential was narrow enough to compensate this space. This made the need for a larger diameter planetary gearset unnecessary contributing to a very small and lightweight differential
2/2/2024Remounting the limited slip unit from shrouding both output sun gears of their previous differential where it was required to have a larger planetary gear arrangement for housing the limited slip unit within to the side on the new differential layout did not make it wider as the double pinion planetary gear differential was narrow enough to compensate this space. This made the need for a larger diameter planetary gearset unnecessary contributing to a very small and lightweight differential
