another ZF5 roll over thread.... with excessive roll over noise.

hacked89

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just put a new clutch in, and its better, but still i feel somethings amiss

heres a video.

https://youtu.be/jVvtTcF6NOA
More stuff is eliminated than is left that it could be
Not the trans, tc, bearing/bushing, driveshaft.

The only time I’ve heard something similar with same circumstances is when Miatas need a “ppf alignment” cause the engine, to trans, to driveshaft is out of wack.

When you are decelerating, if you put light pressure on the clutch pedal, just enough to start to put pressure on the clutch fork but not disengage the clutch, does the noise change?
 

ROCK HARVEY

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What is your transmission crossmember/mount setup? I wonder if it’s slightly too high or low, or maybe not rigid enough, and is causing the alignment to be out of whack when you’re decelerating in gear and engine braking.
 

Black dawg

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Hard to tell with video for sure, but doesnt sound like any rollover noise I have heard. What does the t case oil (what t case??) look like? Have a picture of rear driveshaft angles?
 

IDIoit

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A LITTLE UPDATE.

theres a 4 degree difference in the diff to trans angle.
seems within spec, but i may drop the trans down a bit to compensate.

ive removed the driveshaft, and ran it through the gears, with no vibration.

next is to rotate tires from the back to the front, before changing rear diff's
already have another diff on hand
 

Black dawg

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do you have a picture from the side showing driveshaft angles? If this is a standard 2 joint shaft, 4 degrees is a huge difference.
 

IDIoit

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i dont have a pic of the diff vs. the trans, maybe tomorrow.

i rotated tires tonight. no go

diff swap tomorrow
 

Isaac Ristow

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That noise is totally F'ed up... I've only ever heard rollover noise idling or just off idle in 1st or second gear in my smf 7.3 zf5 and the noise mine makes is more of a grunt noise from the torque pulses going though the driveline. The noise in the video to me sounds like a trans that has popped out of gear and is grinding gears.
 

IDIoit

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That noise is totally F'ed up... I've only ever heard rollover noise idling or just off idle in 1st or second gear in my smf 7.3 zf5 and the noise mine makes is more of a grunt noise from the torque pulses going though the driveline. The noise in the video to me sounds like a trans that has popped out of gear and is grinding gears.
completely horrible, i hope the diff swap fixes this.
but the dif i have is open :(
 

Shadetreemechanic

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I was always told rollover noise was an out of balanced engine. The DMF provided a buffer between the crankshaft and the transmission to mute the sound of the vibration being amplified in the transmission.
Did you build the motor? Did you have the crank balanced?
 

franklin2

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I was always told rollover noise was an out of balanced engine. The DMF provided a buffer between the crankshaft and the transmission to mute the sound of the vibration being amplified in the transmission.
Did you build the motor? Did you have the crank balanced?
The noise is from the diesel engine hitting so hard when it fires, that it shakes the gears in the transmission. The zf being aluminum and using thin transmission fluid for fuel efficency makes it even worse. Ever wonder why the 460 never came with a DMF?
 

Shadetreemechanic

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The noise is from the diesel engine hitting so hard when it fires, that it shakes the gears in the transmission. The zf being aluminum and using thin transmission fluid for fuel efficency makes it even worse. Ever wonder why the 460 never came with a DMF?
Right. If the rotating assembly is not balanced it will hit unevenly and cause rollover noise. Unbalanced injectors can also cause it. I have never tried to fix rollover noise by swapping motors, but i have changed injectors and improved the issue.
 

IDIoit

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the rotating assembly was balanced when i built it it is a fresh build
but it does have a slight fuel tick when cold.
goes away after it warms up.
the engine does not miss, stumble, or perform in anyway other than its supposed to.
had family in town today so i didnt do any work.

i think im gonna change injectors tomorrow FTFOI. i got a set of stage 1's from R&D on the shelf.
 

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