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Dead differential

fragchild

New member
Location
Floriduh
So my differential decided to eat itself while doing highway speed. Good times. Since I'm stage 2 dealer is denying my warranty claim, no biggie, but they want to charge me $6200. So I've decided to source a used one and do it myself. I've been looking on ebay and it seems like a lot the of the Audi/VW stuff is compatible with each other but I've noticed some Audi differentials are listed as 0CQ525015 and VW is listed as 0CQ525010 They physically look the same but does anyone know the difference? Would I be safe getting the Audi part?

Also, while the haldex fluid info is everywhere on the internet, does anyone know the fluid type and capacity used in the differential itself?

Thank you in advance for any guidance on this.
 

Cliff p.

Go Kart Newbie
Location
El Paso, TX
Ride
'17 Golf R DSG
Quite a few rear diffs on ebay available for decent cost. You'd use Haldex fluid. I use Ravenol AWD-H fluid, only took one litre, and actually had a tiny bit left over.

Replace the fill and drain bolts too.

If I were you, I'd go to vwparts or another online vw parts website that provides you with part numbers and interchangeability, just to make sure you end up with a Gen5 and not a Gen4.
 

OBP

Ready to race!
Location
ChiRaq
The previous poster is wrong. The diff and haldex are separate mechanisms and use distinctly different fluids. Do not use haldex fluid for your rear diff.

I’m pretty sure the rear differential uses 75w/90 gl-5. Same as the transfer case. Can’t remember the capacity, but GL-5 fluid is pretty cheap. Just pick up 3 qts to be sure.
 

Cliff p.

Go Kart Newbie
Location
El Paso, TX
Ride
'17 Golf R DSG
The previous poster is wrong. The diff and haldex are separate mechanisms and use distinctly different fluids. Do not use haldex fluid for your rear diff.

I’m pretty sure the rear differential uses 75w/90 gl-5. Same as the transfer case. Can’t remember the capacity, but GL-5 fluid is pretty cheap. Just pick up 3 qts to be sure.
Apologies. Don't know what I was thinking. Still getting over this flu and my brain should have just told me not to respond. You're right. I was only thinking about the haldex portion of the rear, not the differential itself.
 

fragchild

New member
Location
Floriduh
So when I went to drain the fluids by differential was bone dry. Don't know why but it was. I plan on taking it apart so when I do I will post pics.

For future people searching.

To remove the differential this socket is a must have (or the cheap stubby kit from amazon)
Multi-Point Socket
Mfg Part # T10035

Differential uses
Synthetic Gear Oil 75w90
Mfg Part # G052145S2
Little more than 1 Liter, so get 2

Differential drain and fill use same bolt if you want to replace them.
Mfg Part #N90281802

Used the haldex kit from ECS for the haldex fill and of course cleaned the filter on the pump.
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Ride
MK7 Golf GT Estate
So when I went to drain the fluids by differential was bone dry. Don't know why but it was.
I know if instances on the Mk4 R32 where the dealer drained what they thought was the Haldex, but was in fact the diff...& then basically overfilled the Haldex….


Too many people still don't know that the Haldex unit is ONLY one input shaft & one output shaft & is in FRONT of the DIFF unit which has one input shaft & two output shafts & is the rear most section of the whole big "unit"...& that both items have separate oils to be drained & filled...

The VW books are quite clear..just they are too THICK to understand...
 

fragchild

New member
Location
Floriduh
No clue. I had the haldex done about 10,000 miles ago by a local VW/Audi shop. It's the same 3 techs for years so I trust them. Plus when I drained the haldex fluid it was nice and clean. I did talk to them though, and they were very adamant about knowing the difference between both drain plugs.
 
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