pmr2000

Would this be an option to change out the diff fluid on my stock 75 coupe 4-speed instead of pumping it out?

mortgageguy

I don't think you can get the cover off with the diff in the car. At least on my 72. Pumping is too easy compared to removing the cover. I'm sure somebody has removed the cover and will chime in.

WESCH

Hi

Right, I don't think it's easy to remove the cover as the Cover mounts the diff to the crossmember and spring.
I saw modifications where a drain plug got installed into the diff's body by drilling a hole and tapping a thread . Not really recommendable as the oil needs replacement every only 50.000 miles or so only.

Rgds Günther

midigike

Too much screwing around removing the cover. Unless you have a real issues with grinding or chatting while turning and you want to inspect it. You can be also opening yourself up to a future gasket leak if you don't already have one. I have a four dollar pump from HF tools and it is so easy to just remove the fill nut and insert the tube to the bottom and start pumping out the fluid. I put it in a old lube bottle so I know how much I removed and fill accordingly. Don't forget a bottle of additive.

Grahamred70

I fitted a magnetic drain plug in to the body of my diff when I had it all down for a ratio change, I'll be dropping the oil after a bit of a break in period, as to a 50000 mile change the oil would die of old age before then unless it's a daily driver.
Just my 2c worth
Graham

pmr2000

Thanks I will pump it out, and do the trans also next.

jimvette999

It's really easy but messy to drill and tap the floor of the housing (not the cover)....the oil that comes out will keep particles of metal from staying in the housing as you tap it. Buy the drill and tap as a pair from Ace Hardware or make sure you buy the exact drill size the tap recommends. I used a 1/4" NPT drill and tap with an allen head plug so it sits flush. As others have stated...siphoning is quite adequate too.