strange shudder/clunking -front diff?

[kamineko]

starting to wonder if my front mech lsd is binding on me. would i feel it through the steering?

i'm getting clunking which sounds like a really naffed wheel bearing but i've just replaced both and issue has not changed

next thought is CV joint, i know what a clicking CV sounds like, but this is a clunk clunk clunk and you feel it through the steering wheel as it wobbles. it only happens while turning, at slow to med speed

could the steering rack be naffed? the bushes are nice and tight

so yeah. about 3 or 4k ago i changed gearbox oil to redline shockproof light - blue stuff.. is the answer as simple as a friction modifier to loosen up the front diff?

[DRFVDR]

What sort of mechanical LSD is it...

I know that the "detroit"type locker in one of my buses does this sort of thing and it is A OK as I just replaced it

[Tony]

If it is a proper plated mech LSD then that is totally normal. You can feel it through the steering and the front of the car feels jumpy as you turn.

It is common to get this much noise when using Redline shockproof as it has no friction modifiers added. You can buy that small black bottle of the redline friction modifier to pour in.

I ran shockproof without the friction modifier under recommendation from my gearbox guy, as it makes the diff lock up better (which by the sounds of it, yours is doing). Works well at high speed, but you certainly get some looks if you are driving the car around town ;D

Another reason I was told to not use it was because it is apparently quite bad for the synchro material as well...

The friction modifier will quieten it down a bit, but at slow speeds you will still have some noise - its just a trait of plate front diffs.

[kamineko]

thanks for the reassuring reply. gut feeling was binding due to new oil but glad someone else has experienced it

[nicardy724]

Hi there, Ive got a 2000 B4 Legacy, normal 5 Spd box and mine is doing the exact same thing. I've managed to narrow a few things down. Its definitely not the CV's as I have had them checked etc and it doesn't make the clunking noise when I first drive the car, with CV it would be a constant noise.

So even stranger it is really noticeable after a reasonable drive up the motorway and when parking the noise is there, and you can not only hear it clearly but you can really feel it through the wheel, so I don't think it is completely normal. Ive had the car about 5 years now and it never used to do this so it hasn't been there the whole time. when it started happening intially I took it to a locally Subby mechanic and we drained and re-did all the diffs. Then I tried the loops in a car park trick, none of this has worked.

Ive been meaning to really get to the bottom of the issue, but worried what can of worms im going to open !!. My thoughts are it is most probably due to a gearbox issue, or like you suggested above a slipping front LSD. The gearbox is still smooth as new to change gears, and it doesn't happen in a straight line only when turning.

Would be interesting to hear from someone who has had this issue and solved it. Anyone have any other ideas.

Cheers

[Swindog]

sure its gearbox? what about wheel bearings?

[nicardy724]

Yea I thought wheel bearings at first but ive had wheel bearings go on other cars ive owned and they make a real noise when they let go, and I cant hear a thing in a straight line or when its cold? have you had these symptoms when wheels bearings go?

I thought it even may be an oil viscosity thing being to thin or something, just grasping at straws mate.

[Guest boostin]

Definitely centre diff binding.

[nicardy724]

Cheers mate, I just found this post

http://www.clubsub.org.nz/forum/index.php/topic,8752.15.html

The symptoms are all there huh!! so it looks like its gonna cost $1500.00 to fix bugger !! anyone know a good Sub mechanic on the north shore I can go to, reasonable rates.

Gotta love this forum though, fiqured out what it was in 1 day, gold !!

[nicardy724]

Sorry that was North Shore, Auckland.

[Swindog]

 nicardy724 said:

Yea I thought wheel bearings at first but ive had wheel bearings go on other cars ive owned and they make a real noise when they let go, and I cant hear a thing in a straight line or when its cold? have you had these symptoms when wheels bearings go?

I thought it even may be an oil viscosity thing being to thin or something, just grasping at straws mate.

Ok. although its not a wheel bearing wheel bearings do odd things when they start to fail. Pauls one never made a sound in a straight line but man when he turned it was horrendous...but mine was the other way round. Straight line it was horrible, in a corner. no p robs at all.

Got mechanical insurance?

[Guest boostin]

 nicardy724 said:

Cheers mate, I just found this post

http://www.clubsub.org.nz/forum/index.php/topic,8752.15.html

The symptoms are all there huh!! so it looks like its gonna cost $1500.00 to fix bugger !! anyone know a good Sub mechanic on the north shore I can go to, reasonable rates.

Gotta love this forum though, fiqured out what it was in 1 day, gold !!

Yep, they're quite common for being fine when cold, but as the gearbox and oil heats up with driving, the centre diff starts to bind in turns. It doesn't operate in a straight line, so no shudder/vibration/knocking occurs.

[DRFVDR]

are these a viscous type centre diff ???

are your tyres the same type and wear front and rear

[Guest boostin]

They're more a clutch pack than viscous. See that link above for pics of one I pulled apart.

[nicardy724]

Hey Boostin, cheers for all your help mate really appreciate it. I just spoke to a mechanic and he said that if my model is the plate type differential then they can take it out, pull it apart and re-do it like you showed in your pics and then I dont have to replace it with a new part like the sealed ones.

Whats the easiest way to tell if mine the plate type? Ive tried googling the model and vin number but cant tell find anything any chance you can tell by the numbers below.

Subaru Legacy B4 year 2000, Manual 5spd

Model - BE5C48D

Vin - BE5 064025

Cheers again mate.

[nicardy724]

 DRFVDR said:

are these a viscous type centre diff ???

are your tyres the same type and wear front and rear

Just trying to figure that out mate, yea my tyres are the same ( Dunlop Direzza ) and they wearing evenly front and back.

[Guest boostin]

B4's are all plate type. Viscous is used in the earlier models, 89 to 98ish.

[nicardy724]

 boostin said:

B4's are all plate type. Viscous is used in the earlier models, 89 to 98ish.

Mate that is the best news ive heard all day !!! that has just saved over a grand !! stoked !! Im gonna get it all done next week, cant wait to be able to park without the street looking at me !! haha

Cheers mate