Started noticing this week that my rig is getting finicky about going into reverse and shifts from 1 to 2 are getting a little chunky. I'm guessing this is pointing to the clutch since I changed the transmission fluid in January. I also noticed that there's a coating of black shmutz on the transmission housing that may or may not have been there when I changed the fluid. Haven't noticed any slipping under normal driving. What other indicators should I look for?

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reverse? puh-lease . haha... these always hate going into reverse. maybe you got lucky and for years yours has done what you asked of it. i got a marlincrawler rebuilt transmission that shifts like a dream in all but one forward gears, and still fights me getting into reverse. i start to suspect that there's some design issue with the reverse shift arm, like it should have gotten more bolts or better leverage or heck idk.

concerning clunky, i'm guessing you may be experiencing what i call 'notchy' -- it does go into that gear, but it doesn't feel smooth or cushioned. my T4R has that issue to some degree, and replacing the clutch (another marlincrawler heavy-duty kit) did not do anything to solve the issue. i wasn't expecting it would, and it didn't. i have read that 'notchy' is due to wear in the transmission.

if you are wondering what happens with clutch going out, here are the symptoms i've personally experienced with clutch and clutch-related components going out:

pressure plate: sudden lack of all power, yet RPMs stay up, whizzzzzsh sound as the engine revs with no load whatsoever, then after a few panicked moments it's back

pilot and throwout bearings shot: horrid squeak like an oily or loose drive belt only when depressing the clutch pedal, and happens between any gears (for shifting reference). eventually the bearing dries out and starts to smoke as it burns up and fuses to the shaft

slave cylinder puked: depress pedal and there's no resistance, and it goes all the way to the floor and the doomed feeling occurs since murphy's law requires it to happen on the way to work or an interview

worn shift lever cup or shifter bushing cap: pops out of gear under any load, even slight. holding the shift lever in place solves.

hope this helps. i think what you're describing sounds like what i am noticing in my T4R, and unfortunately what fixed mine (same R150F transmission, different vehicle) was the marlincrawler rebuild.


edit: the layer of schmutz may or may not indicate anything of consequence. get a paper towel and wipe some of it off, and have a sniff. if it smells like gear oil, you can be pretty certain that at some point there was either a spill or a leak. that would be enough reason to clean all of it and then keep an eye on it for the next couple hundred miles. if you have more gear oil-scented gluck, it could well be a leak that deserves some investigating.

Second on reverse always being kind of tricky. Sometimes I find that if there’s a tiny bit of backwards momentum it’ll go in perfectly, but generally it ‘notches’.

it sounds like yours is behaving a bit like mine, though it seems more acute for you. there are some instances when one of these R150F MTs just will not go into reverse. just flat refuses ten ways from sunday when the vehicle is running. if the vehicle is off, it'll go into reverse just fine. i think that's just a delightful design feature. in my T4R, every gear feels kinda notchy, like it sorta scrapes a bit but does go into that gear. the one in my truck before the rebuild did exactly that, and after the rebuild, it is quite smooth though not like a really good transmission such as a subaru or honda where it's like buttah. for some reason 5th fights me a bit after the rebuild; the other forward gears are all great.

i've read that gear oil that's too thin can exaggerate this feeling, hence the adherence to GL-4. without really clarifying why, marlincrawler recommends dino for the first fill, then can go syn.

I’ve never had mine refuse to go into gear like that. It always goes in, but sometimes it ‘notches’ (I put in quotes because I feel like there’s a more accurate term that I can’t think of) and I have to completely stop. I think there’s a sweet spot somewhere in between stopped and barely moving where it slides right in. Same thing with first when you’re moving but you can still get it to slide right in. Seems like that’s just how they are, my truck was the same way.

These problems sound like the clutch is not properly disengaging. If you can easily put it in 1st and reverse with the engine off, then there should be no difference while parked with the engine running because the disengaged clutch takes the engine out of the equation. I'd check the hose going to the slave for leaks and make sure the slave is fully opening when the clutch pedal is pressed. Also make sure the pedal is adjusted properly. Just FYI, my 4runners and Tacoma shifts like butter when working properly, even in reverse. So none of what you're experiencing is normal.

I agree with the above. I have 270k on my original clutch and tranny and it has shifted fine going into reverse and going from 1 to 2. I did have an issue when down shifting from 4 to 3rd at high RPMs that it would grind a little bit. I put redline mt90 and surprisingly it took care of that issue . I do agree that it is kind of notchy.

OP: What oil did you u use in recent oil change? Have u ever changed the bushings in tranny shifter? I would also look at clutch adjustments at pedal. How many miles does clutch and tranny have on them?

My experience has been if clutch pedal has good resistance when pushing down and not spongy then the MC and slave are fine.

Good luck

MikeM

Reverse has been hit or miss since I bought the truck at 220k. Sometimes it goes right in, other times I have to let the clutch out while in neutral a couple times or let the truck drift a little to get it engaged. Just seems to be happening a little more lately.

The 1st to 2nd thing is new but also not very consistent.

Not sure if the history of the truck. Currently sitting at 227k and may be the original clutch.

I did the take off from 3rd thing today and it didn't slip at all so maybe it's nothing. I'm going to have it up on a lift next week so I could throw some mt90 in it. When I changed it in January I filled it with Amsoil GL4...not Severe Gear.

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I feel the reverse thing is just a quirks on manual trans. Mines does it 10% of the time. My munci 4 speed does it. My former chevy work truck does it.

I also have the notchy part on my 4r. I noticed that cooler outside temps played a major part in how notchy it gets being as bad as not being able to get into any drive gear including reverse. Lucky for me it doesn't get cold out for the most part.

I replaced my all my clutch components (when I pilot bearing when out) except for the arm and master. Ever since the clutch overhaul the notchy as gone away. I suspected either the slave was worn out or the hose was bulging too much under pressure.

Difficulty going into a particular gear is usually the synchronizers. Try doing what Sparky 97Runner said with shifting the transmission through the gears with the engine off and the truck stopped either completely with either e brake of foot on the brake. If the shifts improve then it could be a dragging clutch not fully disengaging, but if the shifts are still notchy/difficult then it's your synchronizers.

Make sure you put the correct gear oil in the transmission. I don't own a manual 4Runner so I'm not familiar with what fluid they require, but transmissions that require GL-4 gear oil do not like GL-5 gear oil and vice versa. The different additives/composition of the two fluids can cause synchronizer issues.

I'd at least investigate a weak or failing hydraulic system on the clutch. Reverse has no synchronizers, so it will show those issues first. Getting into 1st and the 1-2 shift will be next (hardest on synchronizers).

Last time something similar happened to me it was a leaky clutch master (on a different Toyota).

-Charlie