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I'm new to a driving a car with a 9 inch diff.

My XF has one fitted which is engineered and passed with all the other mods.

 

At low speeds when cornering I get a clunking sort of noise and bit of shake. Through the drive train which the missus freaked out over.

 

Driving straight its fine. Tiny bit of whine under load which goes when take foot off.

 

Unsure what it could be.

 

Diff is ford 9". Was told it had 3.55 ratio gears with tight LSD

 

Any help from the brains trust much appreciated

 

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The clunking would be the LSD clutch plates chattering (as you mentioned it's a tight LSD). Maybe try some fresh LSD oil and/or some additive to help with the issue?

Failing that, it could just be set up too tight. Unfortunately, that requires a full strip down to access the preload springs and shims, etc.

The noise is likely worn bearings which also could be putting the tooth contact out of whack when under load. This will need a full rebuild with new bearings, seals and an expert to assemble it all. Building diffs properly is a dark art that even most mechanics find hard to grasp.

If it's just a tooth contact issue in regards to carrier adjustment (ie poor assembly), this is fixable by adjusting the carrier bearing adjuster wheels (vs shims on a BW diff) so you'd be in luck somewhat there. You still need to pull the axles and remove the centre to do this.

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Having a "locked" diff can cause the wheels to chirp/shudder when going round corners, as both wheels are trying to turn t the same speed. Or as Gerg said, it might be real tight.

Ford made a special additive that used to stop the shudder in LSD diffs, not sure if it's still around, it was like 50ml or something. 

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Having a "locked" diff can cause the wheels to chirp/shudder when going round corners, as both wheels are trying to turn t the same speed. Or as Gerg said, it might be real tight.
Ford made a special additive that used to stop the shudder in LSD diffs, not sure if it's still around, it was like 50ml or something. 
Definitely not a chirp or scrub.
This is a clunk that shudders the whole car just about. Almost made me think it was steering before I listened a bit closer

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I'm going to jack it up tonight and check if it is lsd first.
Then drop the oil and get fresh stuff.

Previous owner has told me he didn't touch the diff and before he got it it was in storage for years.

But it public holiday today in WA so can't get anything

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In that case, the bearing noise might be from rust due to moisture buildup or the diff getting wet while being stored. I have a bad wheel bearing noise due to rain getting in to the bearing race as I was building it up outside.

You really have to make sure you get LSD oil. Normal 80W90 is not going to work. LSD oil is normally 85W140 unless it's synthetic.

The whirring noise when warm would just be the thinner oil not dampening everything like it does when it's cold and still as thick as honey.

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In that case, the bearing noise might be from rust due to moisture buildup or the diff getting wet while being stored. I have a bad wheel bearing noise due to rain getting in to the bearing race as I was building it up outside.

You really have to make sure you get LSD oil. Normal 80W90 is not going to work. LSD oil is normally 85W140 unless it's synthetic.

The whirring noise when warm would just be the thinner oil not dampening everything like it does when it's cold and still as thick as honey.

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So reckon 85W140 is the go then?
How much will I need?

I need to go to bigger town tomorrow to get windscreen replaced on my ranger so while I'm out I'll be able to swing by repco or similar

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So reckon 85W140 is the go then?
How much will I need?

I need to go to bigger town tomorrow to get windscreen replaced on my ranger so while I'm out I'll be able to swing by repco or similar

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Yeah they tell you on the bottle if it's LSD compatible. Generally 2 litres is enough for a Borg Warner, 9" probably takes slightly more so I reckon 3 litres would be needed, keep the rest for top-up later.

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Hey Ash, I use penrite full synthetic diff oil. Been real good, no noise at all.

8d87a072bab7642c8b25fc1ced647329.jpg

Go for a drive before you dump the diff oil, get it all thin.

Then just bung in the Penrite and never look back. Best diff oil ever.

I run an LSD and this stuff really lasts and has good colour even after a year.

Full Synthetic rules in diffs.

I use Penrite Semi Synth in the Gearbox and that's great as well.

 

Gary Neumann at Autopro should have some in Donny. Ask him to sing "Cars'.

Always funny....

 

 

 

 

 

 

 

 

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