Automatic Transmission Is Starting To Act Funny.

I've known about this for a while and now finally something is getting done. I have a grinding noise coming from the rear end. The car has always made that noise since I've had it about 3-4 months found out it was the rear end not sure where though.

The noise is the loudest when I let off of the gas at any speed in any gear and is starting to make the noise when on the gas.

not sure what it is I was kicking around the idea of changing the fluid (already checked and there is plenty in there) but there is also some slop in the rear when I give it some actual throttle not slow acceleration.

I'm not sure of the problem or if it is multiple things in the rear end has high miles about 253xxx

I'm just wondering if anyone has any suggestions cuz I honestly have no idea

could it be the shaft it's self that connects to the brake HALF SHAFT thats it, could it be that? although I doubt it check it anyway.

Check your the U Joints on your drive shaft for slop. Or jack the ass of the car up to where both tires are off the ground crank it up and have someone sit in the driver seat, put it in first and with no throttle quickly dump the clutch a couple times and look for the noise. If its coming from the differential I would just hit a junkyard and swap it out. If its a U-Joint its a really cheap / quick fix. To see if its a U joint just crawl under the car and jerk the driveshaft around in all directions.

The S12s don't have serviceable Ujoints tho, you have to replace the unit

200sxkitcarThe S12s don't have serviceable Ujoints tho, you have to replace the unit

No, unfortunately; I meant the entire driveshaft then needs to be replaced.

Wow. That really sucks.

Like I said on the phone earlier, drain the diff, take the rear cover off and inspect the inside of it. Get a new gasket, put the rear cover back on and fill it up with some new fluid..

sounds like ur tolerances in the rung and pinion gears are way out of whack more then likely you will either have to shim them or get new gears

im with bart on this one.  sounds like the backlash on your ring and pinion gears needs to be reset.

bartc_jsounds like ur tolerances in the rung and pinion gears are way out of whack more then likely you will either have to shim them or get new gears

Ring and pinion play won't cause that.

You probably have bad bushings- either control arm bushings or subframe bushings (both HIGHLY likely at 250k+)

Did you change the fluid in the rear end yet??  That might help a good deal....

200sxkitcarRing and pinion play won't cause that.

You probably have bad bushings- either control arm bushings or subframe bushings (both HIGHLY likely at 250k+)

Did you change the fluid in the rear end yet??  That might help a good deal....

J-mannope I am going to do that soon here I have do deposit my check first then I can buy some gear oil is GL5 ok to use?

Xanofor the rear you CAN use GL5, id suggest finding GL4 if you can though, since thats what our cars were made for.  I used the generic autozone brand 75W-90 in my diff and its treated me nicely.

J-manis it ok to use any heavier gear oil or will it not lube up as much? considering that I have a rear end with lots-o-miles

so an immediate tune-up after buying the car fixed my power loss issue. a month and a half later, it's time for round two!

the transmission won't shift out of 1st until it hits almost 4000 rpm, and it won't go into 2nd or 3rd until 4000, no matter how light i'm on the gas. when it does finally shift, it shifts VERY hard. the car like jumps, kinda. it's not SLIPPING though. it just shifts late and hard. and it won't even shift into final or the overdrive gear or whatever at all until the coolant temp gauge is about halfway up.

the car also idles high in park now. not while driving, just in park. and it shifts into reverse very hard when it's cold, and not as hard when it's warm but still harder than it did before.

this all started happening at the same time a few days ago. any help? this is my daily driver and i really need it to be running well when i need to go out of the city or move shit. especially since my bicycle is out of commission right now (the rear hub busted on my way to work the other day).

thanks in advance.

well since you have a automatic, check your auto trans fluid, it may be low or leaking. i had this problem before, not in a nissan, but still the same thing, the auto trans usealy has a cooler that is in the radiator, the lines to it leaked, and the auto trans didn't like to shift uphill, or it would act funny wile just cruseing

awesome. i was hoping it may have been something that simple. i have so much shit going on that i really don't have the time to mess with the thing. i have not noticed any puddles but maybe it's just too gradual. i'll check the fluid before i go to work today and i'll post the result later.

Check the throttle sensor, its the extra plug hanging out of the TPS, you will eed to use a Multi meter to check the Values, Refer to the FSM for correct values for idle and Wide open throttle as this sensor controls upshift and line pressure for the transmission.

Also, check to make sure that the vacuum line that goes down to the trans (large line coming off of the check valve on the firewall down to the trans) is not broken or cracked, slipped off, etc. because if it did, its automatically registering zero vacuum IE full throttle, hence your high rpm shifts.

The delayed shift up into overdrive until warm is typical, thats how the system usually functions.

ok right now I'm literally filling my rear diff how many quarts does it take I bought 3

hope this fixes it *fingers crossed*

J-manok right now I'm literally filling my rear diff how many quarts does it take I bought 3

hope this fixes it *fingers crossed*

In an automatic transmission, you need to check the fluid when its hot and running.  The fluid expands when its hot and the hashed marks on the dipstick are calculated fluid levels with the car running.  So to get an accurate reading, don't check it before you go to work.  Rather check it when you get home from work when the car is still hot.

Sounds like fluid is low. Autos need centrifugal force to shit, fluid is the weight that is spun to determine this. The lower the fluid the faster it has to spin to make the needed weight to tell the trans. what to do. If your level is normal flush the transmission and replace with the right fluid type. Autos can act funny with the wrong type of fluid.

shit = shift by the way. lol

Im with 200kitcar, check the governor on the tranny. that tranny is a mech. valve body. you should have a detent cable and a vacuum hose going to the tranny. I would check for vacuum on that hose. If you have vacuum, it may be the governor itself.

jsvob03 that is weird I'll have to check that    

I changed the fluid to no success does anybody know how hard it is to check the tolerances on the rear diff without a gauge I don't have one

I would also hold the axle bearings suspect. that sounds like my old scout just before my rear tire passed me on the interstate.