r154 tranny issues

jeph_tsi · 09-28-2011, 12:07 AM

I'm having some odd troubles with my r154 transmission, it came from a mk3 supra turbo and I'm not sure of the mileage. It shifts great with no grinds and makes no wierd noises, very nice and smooth. Unfortunately downshifting from 5th is very difficult. this only happens when shifting out of 5th, so from 4th to 3rd is easy, but 5th to 3rd or 4th is impossible. the shifter just won't go into the gear, even if you try to force it, unless you do one of two things, 1: slow down to around 40, or 2: once you get out of 5th, just shift back into 5th enough that you feel the synchro starting to engage and then pull out and then it will downshift like butter. Once you've left 5th, trying to shift back into 5th will grind the synchro's. the transmission is full of redline mt-90 fluid and the clutch works and engages as it should.

Wheelin · 09-28-2011, 12:14 AM

synchro sounds fucked up.....

meatmarket · 09-28-2011, 12:20 AM

bleed slave cyl, if no improvement torch car, if torching car isn't option, swap in lsx and t56, if you cant afford said swap, bullet to brain is only resolution....

jeph_tsi · 09-28-2011, 12:25 AM

Quote:

Originally Posted by Wheelin

synchro sounds fucked up.....

5th synchro? Its wierd because 4th to 5th is great at any speed/rpm, it only grinds 5th when you take it out of 5 and try to shift back in (usually after trying to hit 3rd or 4th).

SloRice · 09-28-2011, 08:32 AM

Bent shift fork?

jeph_tsi · 09-28-2011, 11:03 PM

i have no clue... I'm just going to drive it and see if it gets any worse, now that I know how to downshift it, it isn't too bad. I am planning on swapping this into another conquest at some point this winter hopefully, so I'll probably just get another r154 or have this one rebuilt at that time.

Mista Bone · 09-28-2011, 11:43 PM

sounds like 5th has been ran dry and the synchro not full disengaging, basing on my Honda knowledge.

Oh yeah, I don't like the Honda MT-90 or MTL in Honda trannys, might be just as bad on your Toy tranny.

Mista Bone · 09-28-2011, 11:52 PM

5th is outside the main case area....

also has a reverse synchro, has reverse been giving you any issues?

http://www.turbosupras.com/pages/pag...nical/R154.htm

jeph_tsi · 09-29-2011, 07:23 PM

Quote:

Originally Posted by Mista Bone

sounds like 5th has been ran dry and the synchro not full disengaging, basing on my Honda knowledge.

Oh yeah, I don't like the Honda MT-90 or MTL in Honda trannys, might be just as bad on your Toy tranny.

wow, thanks for the help, this is making some sense now if it isn't disengaging. today I actually couldn't get into 1st after shifting outta 5th and coasting to a stop. I bumped the 5 synchro and then it went right into first. The reverse isn't great in this trans either, but usually if it doesn't want to go in I hit 2nd and then it goes in easier but it is easy to grind the synchro. Are these easy to rebuild? I kinda leaningt toward that rather that getting another used tranny that could also suck. In the meantime what kind of oil do you think would be best considering my situation?

Mista Bone · 09-30-2011, 12:54 AM

I've never messed with one, just did a quick google search.

Was even able to find the FSM for it, 5th gear tabs look like a PITA....

DEL SLW · 09-30-2011, 04:26 AM

2nd gear issues are very common with those trans... Never really heard much about your issues.

Fluids: I used Redline MT90, never once had a single issue with my used R154, and 500whp+