Change Diff Fluid

Alright, my friend just bought a 87 ca20 hatch, this thing is beautiful. However it wouldnt move, the previous owner said it needed a clutch, but when we were looking at it the owner started it up and forgot to take it out of reverse or press in the clutch so the car shot backwards. so we lethim think it needed a clutch and then got him down to $500, brought it home slapped on a $20 slave cylinder and she drive great... sorta, it seem to have a knock in the rear end and i think it may either be the trans mount, a bushing in the rear, or something else.

so i wanted to change the diff fluid... and i have no idea how, anyone have any pics to explain to me how. it may not be the problem but it wont hurt to change it.

theres a bolt with a slot for a 1/2 inch ratchet, loosen the bottom one to drain out all of the old fluid, when done draining, put it back on and tighten in. to fill it up, take off the top fill bolt, about on the middle of the diff and fill it up with fluid until it starts dripping out. when it starts dripping out you are set

if your hearing a bad clunk from the rear check the u joints/carrier bearing on the driveline.

if you suspect the noise is from the differential than popping the cover off and inspecting the condition of the gears/bearings wouldnt be a bad idea.

one of the back calipers could be making noise to...when you put the car up in the air turn the wheels and if it sounds like it is coming from one of the back sides it is prolly a caliper...

i have yet to jack the car up adn check out all the mounts, but its not like a noise its just a clunk when you hit the gas, idk i havent driven the car yet so ill have to get him to let me take it for a spin and ill see when it happens.

Probably a good chance it is the sub frame bushings. Fairly common on s12's for the sub frame bushings to wear out. I have already replaced them on my ka-de s12 since when I got the car they were already worn out and making the "thud" noise every time I hit the gas.

yea that was my first guess, so were probably ganna put in some solid rear subframe bushings, but he has to deal with it until he has the cash and can get some time off work

MSA (Motorsports Auto) has a good price for a set of rear bushings.  I bought some from there, havent had a chance to put em in yet, but that may be coming this week finally!

http://www.thezstore.com/page/TZS/PROD/PSDC06D/23-4148

39.95 for em.

When do you hear the noise?  If it's between shifts in 2nd and 3rd gears it's the input shaft bearing.  Theres a TSB on them.  I'll look it up when I get to work in the morning and post the info.

Okay heres what I found:

According to ASSIST tsb TS88-117, the main shaft bearing in 86.5 to 87 FS5W71C Transmissions have a small amount of movement which can cause a clunk sound between 1500-2000rpm, going from cruise to deceleration to light acceleration, from cruise condition to light acceleration to deceleration.  This is normally heard when shifting into 3rd and 4th gears.
There is a countermeasure mainshaft:  Nissan PN 32241-50L80 although I am not sure if it is still available.