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Discussion Starter · #1 ·
Does anyone have complaints about the rubbery driveline in the 540i 6 speed cars? All i can say is that shifting isn't quite the great experience i would have hoped it would be in "the ultimate driving machine". The driveline feels more akin to that of a 60's bus than that of a BMW sedan - there is just way too much on/off throttle play.
I know worn rubber components that have likely loosened up over time such as the guibo, transmission mounts and motor mounts are likely contributing in this issue but will replacing these get rid of the excess looseness or do I have to build some poly components to get rid of the slop? Has anyone got some insight into this? I have high expectations sadly and perhaps this car will never feel quite like my other souped up cars.
 

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Discussion Starter · #4 ·
CDV is deleted. I have even replaced all my suspension bushings, shocks, etc. as that can add to the boat-feeling of the car. Does the clutch have some give in it also?
 

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explain more:
sloppy on.off with the throttle feel or the shifting or the pedal feel?
 

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CDV is deleted. I have even replaced all my suspension bushings, shocks, etc. as that can add to the boat-feeling of the car. Does the clutch have some give in it also?
Yup... this is taken from the UUC website:

"Many owners of these cars [E46 and E39] have experienced mushy clutch feel, inconsistent engagement, and premature wear of the clutch in their manual-transmission cars. The reason is quite simple - the original BMW (LUK-manufactured) clutch has a new "SAC" (Self Adjusting Clutch) design. This new mechanism built into the pressure plate is supposed to keep the clutch pedal engagement point the same as the clutch wears... but in all reality, it's a case of "an answer to a question that nobody was asking." They have added a layer of complexity and feedback isolation, filling a need that didn't need filling - it is not too often that anybody notices that their clutch engagement point as moved 1/2" over 50K miles.

The SAC mechanism itself causes problems; it over- or under-adjusts the pressure plate and therefore causes the clutch to slip or burn out prematurely. They are also known to shift, causing the pressure plate release fingers to slip off the plate, keeping 1/3 of the pressure plate engaged at all times. Bottom line is that the only fix is a complete clutch job, and your dealer is likely to claim "driver abuse". We have seen it happen too many times.

The SAC mechanism may not give a clean release like a standard clutch. Instead of just two sets of springs, there is an adjuster mechanism that makes engagement feel mushy or slow.

All UUC Performance Clutches for these models use an all-new design pressure plate that does not have the SAC mechanism. The resulting improvement in feel is immediate - the clutch is easy to modulate and is consistent, regardless of temperature. Additionally, the reliability and lifespan of the clutch are enhanced. The UUC clutch eliminates the SAC mechanism and restores traditional clutch feel with predictable and crisp engagement."
 

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You Lick It, You Own It
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Yup... this is taken from the UUC website:

"Many owners of these cars [E46 and E39] have experienced mushy clutch feel, inconsistent engagement, and premature wear of the clutch in their manual-transmission cars. The reason is quite simple - the original BMW (LUK-manufactured) clutch has a new "SAC" (Self Adjusting Clutch) design. This new mechanism built into the pressure plate is supposed to keep the clutch pedal engagement point the same as the clutch wears... but in all reality, it's a case of "an answer to a question that nobody was asking." They have added a layer of complexity and feedback isolation, filling a need that didn't need filling - it is not too often that anybody notices that their clutch engagement point as moved 1/2" over 50K miles.

The SAC mechanism itself causes problems; it over- or under-adjusts the pressure plate and therefore causes the clutch to slip or burn out prematurely. They are also known to shift, causing the pressure plate release fingers to slip off the plate, keeping 1/3 of the pressure plate engaged at all times. Bottom line is that the only fix is a complete clutch job, and your dealer is likely to claim "driver abuse". We have seen it happen too many times.

The SAC mechanism may not give a clean release like a standard clutch. Instead of just two sets of springs, there is an adjuster mechanism that makes engagement feel mushy or slow.

All UUC Performance Clutches for these models use an all-new design pressure plate that does not have the SAC mechanism. The resulting improvement in feel is immediate - the clutch is easy to modulate and is consistent, regardless of temperature. Additionally, the reliability and lifespan of the clutch are enhanced. The UUC clutch eliminates the SAC mechanism and restores traditional clutch feel with predictable and crisp engagement."
it's not just BMW that does this. every other manufacture has SAC too.

any other aftermarket clutch also removes SAC from Clutchmaster to Centerforce
 

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Discussion Starter · #8 ·
Any input on the rubber bushings... guibo, motor mounts, transmission mounts? All these allow for play but has anyone seen improvement from replacing these parts with new ones?
 

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Have you replaced the stock shifter bushings, stock shifter, and transmission fluid? That should at least increase your happiness with the shifting experience.
 

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I'm sorry, not replace, I meant upgrade. Change the shifter to an e60 545i shifter, replace the shifter bushings with a stiffer bushing, and change the fluid to a good aftermarket synthetic.
 
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