cusco diff LOUD clunk noise (found the problem FINALLY) now which oil to use ???

J

johnnygt

Member +
Hi guys

not been on here for a while been cracking on with my other GT

some of u may remember my previous posts i had a very loud clunk/knock noise when turning full lock both sides

found the problem - as i driver the car turn the wheels it clunks so loud BUT with the clutch down on full lock turns theres no noise at all which means its my LSD box which i have been told by my high perfomance car mechanic that this gearbox noise is normal

i have used limited slip diff oil = LS80/90 - GL5
BUT this is making my lsd clunk so loud

been told to try thinner oil which should i go for that is the next thiner oil to use ???

cheers! :)
 
J

johnnygt

Member +
I am currently using the synthetic oil atmo

Have heard/researched that cusco say you must use mineral oil & NOT synthetic oil
Is this why my clunk noise is so loud because i have used synthetic oil ??

The noise defo wasnt there before i did an oil change on the gear box

Anyone know which correct oil to use for my cusco mechanicsl diff ??
 
A

AdamB

Member +
There is no "correct" oil really, the way I see it though the more noise its making the more friction there is, meaning its going to wear out faster.
Redline, Fuchs, Motul are all good brands of oils you can use.
 
J

johnnygt

Member +
AdamB said:
There is no "correct" oil really, the way I see it though the more noise its making the more friction there is, meaning its going to wear out faster.
Redline, Fuchs, Motul are all good brands of oils you can use.
Click to expand...

Problem is i've never had the noise that bad since owning the car for 3 years
Till i changed the diff oil uptil now

Which grade oil would you or anyone else recommend me ??

I use "granville LSD oil gl5 LS 80/90"
Was from a local motor shop £8 a litre

Also can my problem be that i have over filled it with oil ? Because i'm sure i have

How many litres of oil is the diff meant to hold ??
 
A

AdamB

Member +
Is not physically possible to overfill the gearbox as the oil will just come back out again.

What oil was in it before? Or is this the first time you've changed it? How many miles has it done since its last oil change?
The oil should be replaced every engine oil change, especially on a clutch type LSD as it prevents wear and prolongs its life.

The problem is you changed it for some shit oil by the sounds of it, get some decent oil in there!
 
weeJohn

weeJohn

Lifer
AdamB said:
Is not physically possible to overfill the gearbox as the oil will just come back out again.
Click to expand...


You can if the front wheels are higher than the back when filling it, once its leveled out, the oil at the back runs forward above the fill level.
 
J

johnnygt

Member +
weeJohn said:
You can if the front wheels are higher than the back when filling it, once its leveled out, the oil at the back runs forward above the fill level.
Click to expand...

exactly^

beacuse i was told the gearbox take around 2.2 to 3 litres of oil but i've put like 4 litres & i some more can easily go in there too
 
J

johnnygt

Member +
AdamB said:
Is not physically possible to overfill the gearbox as the oil will just come back out again.

What oil was in it before? Or is this the first time you've changed it? How many miles has it done since its last oil change?
The oil should be replaced every engine oil change, especially on a clutch type LSD as it prevents wear and prolongs its life.

The problem is you changed it for some shit oil by the sounds of it, get some decent oil in there!
Click to expand...

lol your right mate sounds like i've used crap oil as in the 3 years i've owned the car never changed the cusco diff oil, so i went to my local parts shop & he said use LS 80/90 ( my mate who had the car before me said he used the same grade oil too) strange as i have this loud clunk sound like somethings about to break

ok guys cusco clutch type diff - which is the correct oil i should use ??

cheers :)
 
thefalls

thefalls

Member +
I have been reading a bit about Cusco lsd oil lately and it appears that they use mineral oil with friction modifier. I say the best thing you could do is use some good mineral oil and add lsd friction modifier [ small amount at a time] till the clunking stops. I remember Oil man mentioning that there is a clash of synthetic/mineral oil when selecting the right oil. Also some mention about brass synchros.

So,i have used some Redline friction modifier and mineral oil and the clunking has reduced Very much. It is still there though,only when cold.
 
J

johnnygt

Member +
thanks for the input & info guys much appreciated as always :)

found an old post on here from the previous owner who owned the car before me he used

millers LS90 semi-synthetic gear oil

so i think i will be buying the same as the diff never was as loud as it is before i changed the oil

:)
 
J

johnnygt

Member +
also my link above says on the description

''Not suitable for synchromesh or overdrive gearboxes'' < is this oil still ok to use for mine or NOT ???

need to buy some tomorrow but need to make sure its the right one :(
 
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