Knocking from rear of car on shift

frozen

1 AYC Bar
Lifetime Member
Location
Queensland
First Name
Josh
Drive
1990 Mitsubishi GTO
Formerly: 1996 Galant VR-4
Just been noticing it, a knocking coming from the rear of the car, sounds like the main drive shaft coming from the front taking up slack and knocking as it puts power to the back - thats the best description of how it sounds i can give..
Just when i drop the clutch into the next gear while applying power.. even if i just clutch in, rev a bit as i quickly take out the clutch it will do it.

You can REALLY hear it if i do a launch and spin all 4.. like a knock knock knock knock kinda sound, where as usually its just 1 knock, if the car judders its multiple..

Ill attach a recording i took on my phone. Save it rather than open it, then change it from .pdf to .wav to hear it (wouldnt let me upload a sound file..)

You'll notice one knock near the end, followed by 2-3 knocks when i do it again but a bit harder. The phone was sitting on the rear seat.

also note this is in 4th going around the speed limit.. so not really flogging it, just applying power as i take out the clutch.
 

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Can you feel any vibration at all coming through the car at any speed? I wonder if the rubbers in the driveshaft mounts are a bit tired.
 
theres always been vibration :P unless you mean a different kind? how would i check.
 
Get underneath the car and wiggle the driveshaft near the rubbers and inspect them for damage.
 
rear diff mount rubbers?

also cheak for play in the diff, how far does it spin before you fell the gears engage and turn the wheels?
 
the diff has just been rebuilt (as in had a couple new bearings etc before it went on the car) as it is a S-AYC from an evo 8..

Ill have a look over the next couple days for play and mount rubbers. where would i look for the mount rubbers?
 
the rubbers are in the in the the legs that connect the diff to the sub frame.
there a pain to change because afaik the sub-frame needs to be dropped to get the bolt out.

its on my list of things to do, and I'm yet to find a kit or suitible replacement bush
 
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