Slow speed front end knocking - Not Bilsteins

[Curley5959]

Hi Guys,

My Spec-B wagon had a few knocks when I got it. Have fixed the majority of them:
-New Sway bar end links
-New Sway bar mounts
-New Strut Tops
-New Front Bilsteins

Now I am only left with one knock. The knocking occurs at low speed, and is brought upon by jerky movements - forwards and backwards (Can be replicated by letting the car run down in 2nd and then slowly touching the accelerator so the car becomes jerky - This jerkiness causes the car to knock). I can also replicate it by taking off slowly and quickly putting the clutch back in.

2004 Subaru Liberty Spec B Wagon - 6MT with 100k on the clock.

Few key things:
-Front end knock.
-Seems to get worse in the afternoons when the car is warmer but could be imagining it.
-Can replicate at slow speed with jerky movements.
-Can kind of replicate by very slightly moving forward then then putting clutch in.
-Definitely a forwards and backwards knock (No knocking on uneven surfaces, so not an up and down knocking - Nice and solid now that Struts + Strut Tops have been done).
-Not sure but seems to go away if I put the clutch in (But this does stop the jerkiness)? I had the clutch adjusted by Subaru a few months ago as it had been adjusted to sink to the floor - Not sure why? Possible Master or Slave Cylinder issue?
-Has nolathane bushes on front lower control arm rears.

I have listed a few things that I have read up on that seem to cause knocks:
-Steering Rack - Knock doesn't seem to be affected by turning
-Tie Rod Ends - Again knock doesn't seem to be affected by turning.
-Front Diff bushes? Is this a thing?
-Is it possible the clutch could be the cause? There does seem to be a reasonable whirring sound when the clutch is out and car is idling, and this disappears when the clutch is in. Can the clutch make knocking sounds?

I have been trying to replicate the issue under different circumstances but it is quite difficult.

Any input would be greatly appreciated.

Thanks,
Aaron

[HardwareBoB]

pitch stop mount? engine mounts?

[Curley5959]

pitch stop mount? engine mounts?

Tightened the Pitch Stop Mount the other week - Wasn't sure of the name but I know now

Engine Mounts - Now that it could be. Can these be tightened to fix the knock or do they need replaced?

[Robbks]

it's just driveline backlash, something you have to learn to drive around
you can help eliminate it by using stiffer engine/ gearbox and rear diff-cradle mounts. but they usually come at the expense of transferring more driveline noise into the cabin.

Get an ECU tune which smoothes out the throttle application at low revs, it pretty much cured all the jerking that they do,
you can still induce it by being on/ off the throttle violently at low speed, but it just makes day to day driving 10X better

[Curley5959]

I can replicate the noise by taking off slowly and hitting the brakes hard.. Same in reverse. A Suspension Specialist I have spoken with has advised it could be Control Arm bushes or possibly Engine Mounts.

I think Im going to need to have it looked at, but at least I have something to start with.

[Robbks]

ahh, ok, if you can make it do that then it's very likely the LCA bushes.
factory ones chew out very quickly

get them replaced with some Poly bushes (I used Superpro) anyway

[HardwareBoB]

ahh, ok, if you can make it do that then it's very likely the LCA bushes.
factory ones chew out very quickly

get them replaced with some Poly bushes (I used Superpro) anyway

replacing your LCA bushes with poly bushes is pretty much part of the mods starter kit anyway.

W0506 LCA bushes and KCA334 anti lift kit - should run you about $60 for the bushes and another $150 for the ALK, plus $100 or so to install them (don't bother doing it yourself unless you have a press).

[Curley5959]

ahh, ok, if you can make it do that then it's very likely the LCA bushes.
factory ones chew out very quickly

get them replaced with some Poly bushes (I used Superpro) anyway

replacing your LCA bushes with poly bushes is pretty much part of the mods starter kit anyway.

W0506 LCA bushes and KCA334 anti lift kit - should run you about $60 for the bushes and another $150 for the ALK, plus $100 or so to install them (don't bother doing it yourself unless you have a press).

ahh, ok, if you can make it do that then it's very likely the LCA bushes.
factory ones chew out very quickly

get them replaced with some Poly bushes (I used Superpro) anyway

The Lower Control Arm Rear, or the Anti Lift Kit as you mentioned, is currently nolathane. I am not sure what the front LCA bushing is.

I am thinking that it could be the front LCA bushing or the ball joint.

Its booked in for next Friday so hopefully it can get sorted.

If the front LCA needs replaced, and it is best to go with the Whiteline Front LCA bushes, would it be necessary to get the Whiteline anti-lift kit for the Rear LCA bushes also?

I am planning, in a few weeks/month, to get Whiteline Sway Bars Front and Rear.

I will wait and see what it is before purchasing anything

Thanks for the help btw. Much appreciated.

[HardwareBoB]

The Lower Control Arm Rear, or the Anti Lift Kit as you mentioned, is currently nolathane. I am not sure what the front LCA bushing is.

I am thinking that it could be the front LCA bushing or the ball joint.

Its booked in for next Friday so hopefully it can get sorted.

If the front LCA needs replaced, and it is best to go with the Whiteline Front LCA bushes, would it be necessary to get the Whiteline anti-lift kit for the Rear LCA bushes also?

I am planning, in a few weeks/month, to get Whiteline Sway Bars Front and Rear.

I will wait and see what it is before purchasing anything

Thanks for the help btw. Much appreciated.

The 'anti lift kit' is eccentric and adds some caster to stop the front lifting so much, up to you if you want to replace it - if it's nolathane already it might well be that type.

The front LCA bushes are generally not great and tend to die, whitelines front LCA bushes are a good idea regardless.

If your ball joints are on the way out (like mine were), you can also add a KCA313 bump steer/roll centre kit which has new ball joints and tie rod ends - but it is meant for lowered cars.

I went for shockworks coilovers ($2k - another shipment coming in march) and the three whiteline sets mentioned. That should basically replace all the front end suspension bits, and make it handle awesomely.

It adds up - you're looking at approx $2800 all up to do that (incl labour), but it should handle amazingly when done - note that if you use shockworks, you do not need to change the swaybays.

[Curley5959]

Got the knock checked out by my local suspension specialist, and it turns out it is a rear engine mount. Have ordered the part and will have it fitted next week some time.

[Curley5959]

The 'rear engine mount' that the specialist replaced was actually the pitch stop mount. The rubber had split right open. $160 later including fitting and there are no knocks.

Would have replaced myself if I knew it was pitch stop mount But all good. Its fixed now