Groan on slow speed turn when cold

[RDS]

Hello all

I hear a groan when doing a slow 90deg turn immediately after start up when cold. I need to manoeuvre to get out of parking spot and it is noticeable when the car is cold. Does not happen when car or weather is warm but is audible BEFORE full lock on turn.

NB it is not wheels rubbing on mudflaps or wheel-arch; car totally standard. I'm wondering if it is power steering as sound seems to come from front of car, so I doubt if this is the differential. Any thoughts/ideas?

cheers

RDS

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[Benno2000]

Hiya,

Not sure of the term but cold tyres on near full lock often make a skiddy/juddering noise/feeling as if skipping accross the tarmac. Mine does it on it’s Michelins and was worse on it’s original Pirellis. One of my other cars is terrible for it.

could that be it?

Benno

 

[RDS]

good idea Benno and I hope so but it sounds more like a groan as i pull away slowly and turn. Same on 90deg in reverse too. No skid feeling.

 

[WD Pro]

Have you ever changed your diff oil ?

WD

 

[Paddles]

Does it make any noise just turning the steering wheel while the car is stationary?

 

[RDS]

ref Diff oil: no, I'm only on 17k miles so diff oil unlikely to need change. Are you thinking this is a usual LSD noise?

ref turning steering wheel stationary: I've never done that so that I do not stress the tyres, power steering and linkages.

 

[WD Pro]

I was interested if the oil had been replaced (even if Ford U.K. did it, even if it needed it as part of another job etc etc) as in my experience, the euro spec / track lock diff needs it.

The Ford U.K. procedures don’t call for it (the USDM market does) and without it, it does exactly as you are describing, under the conditions you are describing.

I posted my findings here :

https://www.mustang6g.com/forums/threads/euro-cars-diff-oil-change-advice-experiences.186902/

Post #3 has since been removed, which makes post #4 seem a little random

WD

 

[RDS]

many thanks WD although your preconditions are different to mine (eg when warm and over speed bumps, whereas mine is when cold and on a sloped "level" road) the fact that there is a whine is interesting. the photos and write up are especially good. I'll see if the modifier is available on ebay

Did you manage to take filler off and inject the fluid without using ramps?

Fill level is the bottom of the filler hole when level, yes?

 

[WD Pro]

I had the cold moan pulling off the drive with full lock on in the mornings …

Yes, you can creep under it (just about, if it’s still at full ride height - but it’s not a lot of fun … lol)

If I recall correctly, the fill level is 9mm below the bung hole (maybe up to level with it ?). I have the workshop manual for the diff on my work pc, but I’m at home at the moment getting the en-suite finished (I can check from Wednesday onwards).

I think level with the bung hole would be fine - I think I read that if you fill it that high and do any track work or get the diff really hot, it might just eject a little through the vent.

Probably not an issue for normal driving / fast road stuff though

WD

 

[RDS]

hello again thanks for the tip - I had better slim down.

yes, if you could check please that would be great. I need to track down the friction reducing fluid

 

[RDS]

just bought some Motorcraft friction modifier EST-M2C118-A now £18

 

[Gregs24]

Hello all

I hear a groan when doing a slow 90deg turn immediately after start up when cold. I need to manoeuvre to get out of parking spot and it is noticeable when the car is cold. Does not happen when car or weather is warm but is audible BEFORE full lock on turn.

NB it is not wheels rubbing on mudflaps or wheel-arch; car totally standard. I'm wondering if it is power steering as sound seems to come from front of car, so I doubt if this is the differential. Any thoughts/ideas?

cheers

RDS

It will be the limited slip diff. Both my S550 and S650 have done it as long as I have had them. It is especially noticeable in reverse and goes away after a very short period driving. The plates in the Trac Lok are making the noise and is normal for a mechanical LSD. The noise resonates down the propshaft which is why it doesn't always sound like it is coming from the back.

Other forums for other cars with mechanical LSD's often have the same question asked.

A friction modifier just reduces the effectiveness of the LSD by allowing more slip

 

[RDS]

Hello Greg

many thanks for your input. Yes the sound (if I can discern where it comes from at all) does seem to come from the front of the car. However, I accept that it can be transmitted along from the rear.

So it is "normal" and not needing attention from what you have read?

If putting the additive in reduces the effectiveness of the LSD or damages it then, I would prefer not to use. If it is beneficial then that is ok. I am just reminded that when "Slick50" came out, people used it in their Laycock Overdrive gearboxes (eg MG, Triumph etc) and it wrecked them as the friction surfaces were unable to gain a grip.

If you have any links, please do share.

cheers

RDS

 

[Gregs24]

Hello Greg

many thanks for your input. Yes the sound (if I can discern where it comes from at all) does seem to come from the front of the car. However, I accept that it can be transmitted along from the rear.

So it is "normal" and not needing attention from what you have read?

If putting the additive in reduces the effectiveness of the LSD or damages it then, I would prefer not to use. If it is beneficial then that is ok. I am just reminded that when "Slick50" came out, people used it in their Laycock Overdrive gearboxes (eg MG, Triumph etc) and it wrecked them as the friction surfaces were unable to gain a grip.

If you have any links, please do share.

cheers

RDS

My S550 did it for 35k miles without any ill effects and my S650 is now doing it after 2k miles.

The only other thing it could be is tyre scrub at the front because of the Ackerman steering geometry which means the front tyres judder or 'jump' on full lock. TBH on the Mustang it isn't that strong compared to some other cars.

 

[RDS]

Could be, i did note that my old Michelin (i think they were OEM) set were worn on the outside edges at the front, nothing out of the ordinary recorded on the steering geometry set up though.

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