s13 rear end knock on accel

[di-devol]

Hi, I recently started to build my rear end and now have a knocking sound when accelerating.

No sound on decel, coasting, braking, just decel. The more load I put, the louder the knock. I honestly can't tell where the sound is coming from.

Rear end:

Brand new voodoo13 ruca, toe, traction and solid subframe bushings(I did raise the subframe).
Brand new Gktech drop knuckles
Brand new axles, also tried used known good axles
Brand new calipers and pads
Brand new ichiba 5-lug hubs
Carrier bearing is good

No rubbing or scuffing on any of the parts(as they are new).

The e-brake cables are in their brackets and not rubbing the driveshaft.

The sway bar is not hitting the driveshaft.

I raised the car on jack-stands(securely), and had someone run through gears and still couldn't find anything.

lol the only thing left, is the diff, but i've never heard a diff make this kind of noise nor found anyone mention it. Replacing the diff is the last thing I can change and will do that tomorrow, but anyone have any ideas?

[anti tyler]

Have you got it aligned yet

#1 make a video, someone can generally pin point it right away.

#2 when you say you couldn't find anything, did you at least hear the sound again?

[di-devol]

Have you got it aligned yet

#1 make a video, someone can generally pin point it right away.

#2 when you say you couldn't find anything, did you at least hear the sound again?

yes, got alignment 2 days ago.
0 toe, -.5 camber, traction set to 212mm.

I will try to make a video tonight. I still can't find a diff to try, looking for an open one as this one is welded.

Jacked up, i could not hear the sound at all, I tried jacking up the wheels to get proper load and still nothing.

[di-devol]

https://www.youtube.com/watch?v=oSa0T8r1ZVc

only video I took that picked up the sound. it's at the end of this clip. you can hear it go knock knock, faster as I go.

[91EfSi]

Pinion bearing going bad? My old tiff would only make noise on accel but decel nothing

[di-devol]

I've never had a diff make that sound, it does have terrible backlash. I'll put in a diff when I find one.

[anti tyler]

To me it definitely sounds differential related. You can't feel the noise in the drivetrain? Through the shifter?

[s13silvia123]

its the diff. i had that problem as well. fix it or it'll ruin your subframe.

[brndck]

are the toe arms "bent" style? or are they a straight rod?
you said you raised the subframe, make sure the toe arms are not contacting it. its not uncommon on lowered cars

[di-devol]

To me it definitely sounds differential related. You can't feel the noise in the drivetrain? Through the shifter?

Hmm I didn't notice any feeling through the shifter, I'll give that a try.

its the diff. i had that problem as well. fix it or it'll ruin your subframe.

Since it's really the only thing I haven't changed, I'm leaning towards that

are the toe arms "bent" style? or are they a straight rod?
you said you raised the subframe, make sure the toe arms are not contacting it. its not uncommon on lowered cars

Straight toe arms yea, no contact that I can identify, I don't see how if there was contact it would change with speed.


Thanks everyone, I'll change the diff and report back.

[di-devol]

Lots of shit happened since last post.

Still knocking

Things I tried and done:
New wheels bearings l/r
New AutoZone axles
2 sets of different oem axles
Swapped diffs
New 1 peice driveshaft
Raising subframe, lowering subframe, back at oem height.
Even tried different wheels.
We had it up on a lift twice, can't see anything interfering, one of the lifts was a drive on, so the weight was down.
Did it with and without exhaust

I'm out of ideas, what in the fuck is knocking.

Edit: we tried running the car in a life in gear, seems to be load dependant, and turning LEFT I can hear it.

[di-devol]

Final result:

Found a tear in the body on one of the rear subframe studs. This was flexing causing the knocking sound.

[jedi03]

wow ...what a find!