Hi.I have just installed my new TA Performance rear girdle. I am in the process of filling but do not have instructions. Should I be filling to the top fill hole or the smaller middle one? So far I've put 3 Litres in and it's still not coming out of the top one!

Thanks in advance. Jay

 

You still have the factory 9bolt cover with the rubber plug right?
pull the rubber plug out, hold old cover over new cover and the bottom of the old hole should line up with your new full level hole. Definitely won't be the top fill hole or the bottom drain hole.

 

Doesn't the vehicle owner manual have a capacities table of data?

 

I was scrolling for instructions on T/As website (thought they had them posted) and saw all their covers add extra capacity.

 

Use the small middle plug for the correct level.

According to All-Data, the stock amount of differential fluid is 3.5 pt. (or 2.1 QT / 1.98 L) That cover should add a little to that, but not a lot. maybe 1/4-1/2 of a quart? So you should be around 2.5 quart capacity with that cover if I had to guess.
You likely will have a decent amount of fluid come out when you remove that middle plug if you have put 3 liters in already. You will likely get 1/2-3/4 liter out of that before it is at the correct level.

Another rule of thumb when filling differentials is that the fill level on a differential is usually right before the bottom of the axle tubes. Think about if you fill fluid above the bottom of the axle tubes, the fluid will have to fill both axle tubes to get to that higher level, and your differential will take like 4-6 quarts to fill to the top plug you are pointing at in your picture. Also, just like TTOP350 said, using the old stock cover is a great way to see which plug is the right one.

Hope that helps!

 

Bottom hole is the drain plug. Top hole is the fill port. Middle hole is the gear oil fluid level port.

The port you are pointing to in your picture is the gear oil fluid level port. With the car at normal ride height on flat level ground the gear oil should just dribble out the middle gear oil fluid level port when it is filled with the correct amount.

 

Thanks all, much appreciated. I knew this cover allowed for extra capacity but I will drain up to the centre hole. Unfortunately I no longer have my old diff cover to compare.

Cheers