Cabin Knocking Sound at 1500 RPM

[stillslow93]

I am trying to diagnose a sound that has baffled me for about 2 weeks, I recently installed a JDL turbo kit and all of my data logs and driving experience have been great. I can drive the car all day long with zero issues. the problem I am trying to diagnose is only present if the car is warm and I hold the rpm at 1500. If I am sitting in neutral with the clutch out its present, If I am driving around town and creeping off a stop the sound is present. It only appears at 1500 RPM and immediately stops when the car passes about 1900 RPM. The weird part is that you can only hear it from the cabin... I have even gone so far to put the car on my lift and hold rpm to listen for it. Under the hood, under the engine, under the transmission, you cannot hear it, but in the cabin its incredibly noticeable. Has anyone come across this? I am still on a stock flywheel/clutch (to be replaced soon) and it almost sounds like it is coming from the shifter/transmission - but again, with my ear next to the transmission underneath I couldn't hear a thing. With all the mods and new sounds could it be a resonant frequency vibrating something?



https://photos.app.goo.gl/koDaSYmZ9katjBvi9


Anyone got any ideas?

[Gloonge]

Originally Posted by stillslow93

I am trying to diagnose a sound that has baffled me for about 2 weeks, I recently installed a JDL turbo kit and all of my data logs and driving experience have been great. I can drive the car all day long with zero issues. the problem I am trying to diagnose is only present if the car is warm and I hold the rpm at 1500. If I am sitting in neutral with the clutch out its present, If I am driving around town and creeping off a stop the sound is present. It only appears at 1500 RPM and immediately stops when the car passes about 1900 RPM. The weird part is that you can only hear it from the cabin... I have even gone so far to put the car on my lift and hold rpm to listen for it. Under the hood, under the engine, under the transmission, you cannot hear it, but in the cabin its incredibly noticeable. Has anyone come across this? I am still on a stock flywheel/clutch (to be replaced soon) and it almost sounds like it is coming from the shifter/transmission - but again, with my ear next to the transmission underneath I couldn't hear a thing. With all the mods and new sounds could it be a resonant frequency vibrating something?



https://photos.app.goo.gl/koDaSYmZ9katjBvi9


Anyone got any ideas?

I have two actually. It kinda sounds like it comes and goes when your compressor kicks on. So..

Does it do it when the a/c is off. And does it do it if you have the clutch to the floor.

[ls1ac]

Have someone watch the belt tensioner.

[stillslow93]

Originally Posted by ls1ac

Have someone watch the belt tensioner.

I think it was my throwout bearing. late last week the noise stopped and then over the weekend my clutch started rubbing and squeaking aggressively. A stage 2 clutch was already in the build plan so shes going in earlier than expected.

[stillslow93]

Originally Posted by Gloonge

I have two actually. It kinda sounds like it comes and goes when your compressor kicks on. So..

Does it do it when the a/c is off. And does it do it if you have the clutch to the floor.

Neither of these had any impact on the sound, but then this weekend my throwout bearing went (along with the noise) but was replaced by some terrible squeaks and screams while the clutch is depressed. Good news is I think it is safe to say that was the source of the noise, bad news is the car is parked for the next two weeks until the clutch goes in