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Dyno blog

4wd dynamometer with linked axles (axle synchronization) – is that good?

2019-08-16 10:06
Dyno rolls linked axles synchronization

All VtechDyno 4wd (4x4) dynos have front to rear synchronization links as standard. It means that front and rear rolls rotate with the same speed (of course, only if sync axles, so-called „synchronization”, are enabled). Such linked axles functionality is offered as an option by other dyno manufacturers. Sometimes it is not available at all. The question is: is such synchronization important for nowadays cars?

The answer is simple – yes. Even while having one powered axle, many modern cars monitor the second one for speed. Measuring them on one axle dyno causes ABS error and power loss or strange behaviour of traction control. Even if you switch off the traction control in many cars, it is not fully switched off – some functionalities remain, causing perfect power measurement impossible.

For 4x4 cars, the problem of measuring them without front to rear axle connection comes from active power management – many so-called 4wd cars are 2wd with the second axle connected occasionally with an electromagnetic clutch. Only rolls with synchronization make dyno test of such cars possible (especially with Haldex clutch or similar).

So if dyno synchronization is not needed, it can be switched off from the control software or control panel. But considering having a 4wd chassis dynamometer with synchronized rolls is a piece of important advice for car tuners – do not invest your money in tools that may not be used with nowadays cars – and for sure won’t be usable in the future.

Dyno rolls synchronization – how does it work

VtechDyno 4wd dynamometers are equipped with a belt interconnection with a self-tensioning system. It guarantees the same tension of belt at any dyno bench length setup. Belts from the front and rear axle meet in the middle, where a pneumatically controlled clutch is installed. The Clutch can be engaged via software or a button on the control panel. In that case, rolls are synchronized front to rear. Belts delivered by Gates are certified for up to 1000 HP power transfer. If the clutch is disengaged (open), front rolls are not connected to rear rolls. No particular maintenance procedure for belts and clutch is needed.

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