The Professor wrote: ↑Thu Nov 12, 2015 8:28 am
I finished swapping out the gear oil in my Tercel's transmission and rear axle with 80w/90. The old oil looked to be in pretty good condition, it was a dark amber and didn't smell as awful as black, ancient gear oil. Ditto on the rear axle.
Before, the trans would shift OK, but would nip the gears a little on the 1-2 and 2-3 upshifts. After the fluid swap 3rd gear will grind if you hustle the upshift. It's fine if you shift slowly and smoothly. I drove it a few miles and things didn't seem get any better. I'll have to go for a longer drive to see if higher temps help the shifting, but as for now, I'm considering draining out a quart or so and tossing in a quart of synthetic, as suggested.
Also, does anyone know the name of the engineer who designed this transmission? I have a few choice words for him. If you're familiar with Subarus, they have essentially the same engine/transmission layout as a Tercel. The difference is, the front diff is internal to the transmission case, there is only one drain plug, and, gasp, a dipstick and fill tube!
FHI>TMC on mid-80s transmission design...
The Professor wrote: ↑Wed Jun 08, 2016 1:53 pm
Once again I will state that I believe that Redline 75-90 NS is the best lube for the t4wd trans.
Cut and paste from the above link:
Improved copper corrosion protection to prolong synchro life
Redline themselves suggest a different fluid for the 6-speed Tercel: MT-90 75W-90 GL-4 gear oil
Offers quicker shifts, perfect synchronizer coefficient of friction
Safe for brass synchros
, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage
High performance gear protection and longer synchro life
Eliminates notchy shifting, even when cold
I'm about to order some and will check back in to let everyone know how it does. My main problem at this point is a crunchy 3rd gear syncro that was not present before I did a trans oil change.
I finally got around to changing out the transaxle fluid, since I was already poking around with the neutral return piston. As you can see from my prior posts, I started with some minor balking on upshifts when I originally bought the car. Swapped the fluid with generic 85W-90 dino-based gear oil and while the 1-2 upshift improved, the 2-3 upshift got worse. If I shifted any more quickly than "lazily" I would notice a bit of a grind going into third gear.
After doing some research, emailing different suppliers I settled on Redline MT-90. This is a GL-4 oil, the proper fluid for our transaxles. The reason this is important is that GL-5 oils will adhere to the brass synchros in our cars and as the oil and synchros do their speed-matching-dance, tiny pieces of brass are literally being ripped off the synchros. Modern GL-5s are even worse.
The gear oil I drained from the transaxle a few days ago had been in the car for a few years, but only had a few thousand miles on it. You can imagine my shock and utter disbelief when I saw how much brass dust was suspended in the old gear oil. I'm no talking about some flakes or shimmering tailings at the bottom of the pan, but spread throughout the entire 4.1 quarts, suspended, like a grey/green/gold flaked paint job. THIS is what GL-5 does to our transaxles! (Pics if I remember)
So here we are, transaxle drained, refilled with Redline MT-90 and WOW! This faintly pink fluid completely eliminated the 2-3 upshift grind. In fact, I couldn't get the transaxle to grind AT ALL upshifting or downshifting throughout the gears. I need to pump up the tires and take her up the grade of Snoqualmie Pass to get everything nice and hot before I'll officially sign off on the fluid, but there you have it. A pure, 100% ester-based GL-4 synthetic gear oil that IS NOT "too slippery" for our transaxles.