need help on tranny fluid and differencial

[digitaldrifter91]

sorrie i spelt differencial wrong..well my dad has a 86 300zx n/a 3.0l v6. as far as i know the car is very well conditioned but i dont remember him changing his differential fluid at all....it has 107k miles on it right now. how do i do that, what type of fluid do i use?
thank you!

 

[sprintman]

Friend here is in the 300ZX club. He says Redline is what most hanker for if they can afford it.

 

[MolaKule]

I'm assuming a rear drive vehicle here and not a front-drive transaxle.

If it's an '86, it probably doesn't have the oil drain plug, so you will have to purchase a gasket
and remove the bolts from the back of the differential cover.

Loosen the bolts in a circular fashion (CW) starting with the ones on the bottom and go to
the top.

Tap the bottom of the cover so the GL starts flowing into drain pan. Remove cover and scrape gasket material from cover and diffy housing. Gasket may be a paper gasket or RTV (silicone rubber) gasket.

Take clean rag and rake out and dry out the bottom of the diffy and look for any large slivers of
metal. If there are none, good.

If the diffy cover had a paper or composite gasket, take RTV silicone and smear gasket on both sides with a thin film of the black RTV. If cover had no paper gasket, coat diffy cover face, sealing surface with the black RTV about 1/16" to 1/8" thickness. Place about four bolts thru cover mounting holes and place cover on housing as guides. Replace remaining bolts and torque all bolts to approx. 20 lf-ft of torque. Let set at least 4 hours before putting any fluid in it.

Remove threaded fill hole bolt on housing and pour in about 2.5 pints of GL4-GL5 gear lube.
Put finger in hole and see if fluid touches tip of finger just below fill hole. If it does, you have enough gear lube, if it doesn't add in 2 oz increments until it does. If fluid starts to come out as you're filling, stop and let new fluid drain into pan.

Most vehicles require 60,000 mile or less diffy lube changes for normal service operation.

You can use just about any dino or synthetic 80W90 or 75W90 GL4-GL5 gear lube.

 

[ex_MGB]

A great tool for getting fluids out where there is not a drain plug is a mini-vac hand held vacuum pump. I bought it for changing out brake fluid but that little suction hose is great for sucking out not only the brake reservoir, but power steering reservoirs and rear ends.

Tell your Dad to put some Redline power steering fluid in as well.

 

[UncleS2]

Mini vac? That'd be nice. But don't forget the plain old fashioned suction gun. Cheap, works great, lasts a *Long* time.

 

[OneQuartLow]

I'd start by finding the lubrication section in your owner's manual. What's the schedule for the diff? What type of GL do they recommend? Do they require some type of friction modifier? If so that can affect what you buy. Memory says some of those had a viscous limited slip device. It's probably closed but you should find out if it has special requirements.

Pumping out the diffs from the drain-plug is dubious. The worst wear particles will stay at the bottom and you'll have a tough time checking condition (metal/water content & pattern). Too blind of an operation for me. Not that lube shops don't do it to save time...

In most cases pre-formed gaskets are optional. Buy your lube, some RTV (I've used about every kind for diff covers with good results), possibly brake-clean to flush, and go to town. If you need novelty try TheRightStuff aerosol RTV. No waiting. For that matter, most RTV's have a short time-to-service.

On brake-clean, you'll find varied opinions. I've used it for years but I don't use it on LSD packs. The worst part is waiting for it to completely dry; closing it in to mix with fresh lube would be bad. It's not critical so do what you're comfortable with.

It's easy. Just do it.

David

 

[digitaldrifter91]

thanks guys

 

[Al]

I agree with OneQuartLow. Pull the end cover and do the job right. Its an easy job.