Crunchy shifting

I just changed my trans oil a week ago cause it was old (Mobil 1 full synth 75w90). Since then the shifting has been a bit rougher, especially into second gear, but second has always not been as smooth. I’m assuming this is cause it’s newer thicker oil so these symptoms are a bit more pronounced. I tried flushing the clutch fluid which seemed to help for a bit, but it seems to be back to how it was. When I’m at a dead stop it shifts fine, but when the axle starts turning is when it starts to get rough. If I rev higher before shifting, it seems to shift smoother. I got a couple ideas on what it might be and I’m looking for some input. It’s also cold as shit which is making all the shifts seem even stiffer.
150,000 miles btw and a w59 trans

1) slave or master cylinder starting to fail (slave is pretty crusty looking and the seals might be questionable)
2) worn clutch pressure plate (truck has oem clutch still and it’s engaging pretty high up)
3) worn synchro rings or some other internal issue (god I hope not)

 

I'd try double clutching. If it's just cold thickened oil the second clutch drop should spin the gears making engagement smoother. If it's synchros, rev. matching will make the shifter slide in gear like butter. Dirty/dark clutch fluid doesn't help.

 

I just put a new Aisin clutch package in my son's Tacoma we bought used with 235k miles. I did not like the shift as the pedal had to be buried and it still did not want to play all the time grinding on occasion or just flat out refusing to shift. The clutch removed was a less expensive Performance Clutch put in at 144k. I really like the Aisin as it actually feels like its a cammed throw meaning the disengagement before bottom of pedal throw but feels easier to hold once past disengagement. I sucked up and bought the Redline MT90 for the refill and it may be the real juice I'll have to get some time on it but on the initial test drive the Tacoma was shifting easier than my Honda Accord.

 

Check and see what kind of travel you are getting out of that slave cylinder. The previous owner had changed the slave cylinder to an off brand and it was jacked. We changed that out when we first got the truck and it helped a lot. You can get a new Aisin slave cylinder from RockAuto.com for about $40

 

Try Redline MT90 for a fluid change

 

How do I check for full travel on the slave cylinder?

 

Just dropped a bunch of money on Mobil 1 full synthetic

I’m a broke college kid

 

Check pedal linkage under dash as you press pedal with hand looking for any undue slop from worn yoke or after market hardware. 150k you may be getting to end of life depending on user history. Truck we bought, one owner, evidently had factory clutch changed out at 144k. I will let you know full opinion on MT90 after I get back in town and finish the project next week.

 

I have to check the manual but you may be able to reuse that Mobile in the differentials they don't care.

 

Ended up replacing the slave cylinder finally and flushed and bled it again. Definitely made it better. 1st 2nd still a bit tight but noticeably better

 

Try adjusting the pedal, mine was a little off after replacing the master and slave.

 

Pedal height is topped out all the way as far as I can tell, although I’m still a bit confused on how to adjust it

 

Loosen the lock nuts and thread the rod out or in to allow a small amount of pedal movement before rod contacts slave cylinder. 1/8 -3/16 should do. Then lock nuts and check again. Make sure the fork end has not collapsed or folded over.

 

Yeah I checked that and everything looks good. The free play is set fine which means that the pedal height is also topped out. I think it's just a very old clutch that's on it's last legs, engaging at the very top of the throw.

 

Could also be an old worn master cylinder that doesn't have the same travel as it used too. I might try and replace that, just worried about having trouble bleeding it...

 

3/8" clear poly hose attached to bleeder, other end in raised container covered by brake fluid.
Air bubbles out through fluid and can't go back in.

 

I just got a motive power bleeder too and holy shit is that thing amazing...I tried it on my brakes the other day and it was so much better than bleeding them with the gatorade bottle method. Much better pedal feel then I've ever been able to get and so much easier.