irs leaking dime size puddles
- Thread starter rynocobra
- Start date
Your flimsy stock differential cover is flexing, and has probably caused a crack to develop and the problem will only to continue to get worse. Sell your IRS brace (it's more of a bandaid to prevent what already happened) and buy the updated Ford racing differential cover before you run your rear end dry. I posted a link below for the cover;
Ford Racing Mustang IRS Differential Cover - 8.8in (99-04 Cobra) M-4033-G3 - Free Shipping!
Ford Racing Mustang IRS Differential Cover - 8.8in (99-04 Cobra) M-4033-G3 - Free Shipping!
Make sure you replace the OEM rubber front and rear diff mount bushings with either the FTBR or MM polyurethane pieces. That will help isolate the diff and reduce flex which in turn will reduce leaking. The brace will not make a difference with the leaking, it's intended use is to add cover support. As said previously, look at the FRPP or the LPW covers and for a few dollars more than the brace end the headache.
this is a much better option:
1999-04 Mustang Ford Racing 8.8" Irs Rear Differential Girdle, M-4033-G3 at LRS - Free Shipping!
but if you still want to reuse your stock cover with the brace use Permatex Ultra-black or the Ultra-grey
here is the gear oil you will need:
ROYAL PURPLE 75W90 MAX-GEAR GEAR OIL KIT
let me know if you have any other questions. -tony
1999-04 Mustang Ford Racing 8.8" Irs Rear Differential Girdle, M-4033-G3 at LRS - Free Shipping!
but if you still want to reuse your stock cover with the brace use Permatex Ultra-black or the Ultra-grey
here is the gear oil you will need:
ROYAL PURPLE 75W90 MAX-GEAR GEAR OIL KIT
let me know if you have any other questions. -tony
i believe it's a supplement to the owners manual, a specific manual for your SVT vehicle.
You get the ford owners manual for mustang and then the SVT supplement in addition to it for some cobra specific info.
Factory uses 75w-140 gear oil and a bottle of friction modifier. I don't recall the volume amount of the modifier. you just get a bottle from ford and use the whole bottle. It is small though. 8oz maybe? You need 2 pints of gear fluid, but it will not take that much. I think the manual calls for 1.3x or something like that.
Do some searching for the leak issues and you will see plenty of info. I would not use the black permatex rtv. I only use the grey stuff from ford or the lube locker gasket. So far not one problem.
Factory uses 75w-140 gear oil and a bottle of friction modifier. I don't recall the volume amount of the modifier. you just get a bottle from ford and use the whole bottle. It is small though. 8oz maybe? You need 2 pints of gear fluid, but it will not take that much. I think the manual calls for 1.3x or something like that.
Do some searching for the leak issues and you will see plenty of info. I would not use the black permatex rtv. I only use the grey stuff from ford or the lube locker gasket. So far not one problem.
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You decide...manual says 75w140, other poster says 75/90. I personally go with what the manual says for gear oil and modifier on my cars and customers.
Not as easy as a solid axle. Search, it has been covered. To do it right, IMO, the pumpkin gets removed. That is the only way I will do it. Some people fight with it a little and leave the pumpkin in and shift it forward in order to drop the cover. IMO there is too much up there in the way to work around.
Use 75w140. If you change to the FRPP diff cover use the Lubelocker gasket or grey sealant from Ford. If you use the grey allow it to dry completely (about 24+ hours) before adding gear lube, ~1.9qts. Some gear lube like the RP already has the modifier in it others do not so you will have to add the modifier.
75w140 is what is recommended in the manual however if you live in a colder climate 75w90 might be a better choice. i noticed you live in illinois so thats why i suggested that weight but either one will work just fine. i have used permatex black plenty of times with zero issues, however, the ford black or grey (which i believe they use on trucks) is as mentioned probably the best option going, that stuff is heavy duty. not sure on the price, it's probably more expensive and you will have to go to the dealership to get it unlike permatex that can be bought just about anywhere for a few dollars. also, royal purple does add friction modifier to their gear lube but i always add about half the bottle of the ford friction modifier as well. this is just my personal experience and preference and has worked well for me.
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