H55F synchronizer rings (1 Viewer)

[Spook50]

After digging around and playing with my transmission lately; installing a stainless braided clutch line, properly bleeding, setting pedal height per the FSM, making sure everything else was in order, the mild stop/notch I hit when shifting into 2nd and 3rd (consistently into 3rd, upshift or downshift; sporadically into 2nd) remained. I finally determined that the synchro rings are worn just enough to still work, but not as well as they should be. The symptoms point to the inner surface being worn so they can't grip the "cone" portion of the synchro hub enough to allow for a good clean shift, but when the slightest pressure from the shift collar is applied, they line up and the collar is able to pop into place and complete the shift. On a few drives around town I experimented with double clutching and the shifts ended up smooth as silk. This further confirmed my deduction that the synchro rings are worn. Also of note: double clutching a truck transmission is a workout my left knee would rather pass on. Next summer, time allowing, I'd like to pull the tranny and install new synchro rings. It only has maybe 15K after a rebuild, but no idea how many miles it had on it by the time it was done, and the synchro rings are a reusable part that were obviously good at that time (they worked beautifully through all gears throughout this last summer since I had the swap done at the beginning of May; just started showing the wear maybe around late August IIRC). Plus I had bought the tranny back in 2010 and it sat in my shop until earlier this year when I could finally get the swap done.

That being said, I noticed that all three synchro rings are the same part number (33368-20012) from Toyota and are reasonably priced, so I plan to replace all three (no issues shifting into 5th gear, but figured I'd do it while I'm in there. The Land Cruiser mantra), and was curious if at only 15K miles I should even bother with the bearings. I know when the rebuild was done it got new bearings, so unless a particular bearing is a non-reusable part I'm assuming I shouldn't need to bother.

My other question is, are there upgraded longer-lasting synchro rings even available for the H55F? I've seen there are for many domestic manuals, but searching didn't land me with any results for the H55F. Found some non OEM that were cheaper, but if they're not an actual upgraded part, OEM all the way for me.

 

[RockDoc]

What oil are you running in it? I know oil choice makes a huge difference in shifting with my SM420.

 

[OSS]

So your tranny was a rebuilt unit?
That would explain the problems you're experiencing with it.
My H55F I bought new and it still shifted fine enough after 245,000 miles on it.

Try Mobil Delvac Synthetic Transmission Fluid 50. It's a mono grade 90 wt GL4 gear oil and my 5 speed shifted better and sounded quieter when using it.

 

[Spook50]

What oil are you running in it? I know oil choice makes a huge difference in shifting with my SM420.

I put in Red Line MT-90 shortly after I got it back to Spokane from Everett, WA. Ran that all summer and plan to change it annually (might be more than necessary, but will also allow me to track any potential leakage into the tcase if the seal begins to fail at all). When I change it I'll try the Delvac that OSS suggested and see if that makes shifting feel any different.

@OSS I'd be leery of the quality of rebuild, but in the case of this one, it was done by @orangefj45 and he's one of the few people I trust implicitly with anything Cruiser. But like I had said in the initial post, the synchros worked perfectly for me throughout the summer this year, so obviously they were still good when he did the rebuild 5K miles before I even got the transmission. I'll give the Delvac a shot though. Be worth finding out if it helps.

 

[RockDoc]

FWIW, MT90 is what I run. Shouldn't be a contributor to your issues, I wondered if it was full of GL5 "gear lube by the pail".

 

[Spook50]

FWIW, MT90 is what I run. Shouldn't be a contributor to your issues, I wondered if it was full of GL5 "gear lube by the pail".

I'm wondering if it was at some point too. I doubt Georg would've put GL5 in, and the guys at Torfab told me they serviced it with GL4 when they swapped it in, so I would imagine between that and then my filling it with MT90 it would've gotten all traces of GL5 out. Makes me wonder if it had been serviced with GL5 for a while before Georg rebuilt it though.

 

[cps432]

I'm wondering if it was at some point too. I doubt Georg would've put GL5 in, and the guys at Torfab told me they serviced it with GL4 when they swapped it in, so I would imagine between that and then my filling it with MT90 it would've gotten all traces of GL5 out. Makes me wonder if it had been serviced with GL5 for a while before Georg rebuilt it though.

I think it takes a really longe time for gl5 to destroy synchros. It’s not that it dissolves the brass... it’s that the molecules of the additive in gl5 bond to the brass molecules stronger than brass molecules bond to themselves. When the brass moves against something with enough friction it will pull a few molecules off with it. It will take a long time to wear them down like that. The Toyota FSM suggests using gl4 or gl5 in the transmission and transfer case. I would certainly opt for gl4 but I’ve run 5 in a pinch and have been fine. However I have a 4 speed with 276,000 miles on it.

 

[Spook50]

I think it takes a really longe time for gl5 to destroy synchros. It’s not that it dissolves the brass... it’s that the molecules of the additive in gl5 bond to the brass molecules stronger than brass molecules bond to themselves. When the brass moves against something with enough friction it will pull a few molecules off with it. It will take a long time to wear them down like that. The Toyota FSM suggests using gl4 or gl5 in the transmission and transfer case. I would certainly opt for gl4 but I’ve run 5 in a pinch and have been fine. However I have a 4 speed with 276,000 miles on it.

True. I could see it being the case if it ran for the majority of its life with GL5. If I get the chance to go ahead and change out the rings soon as I can, I'll keep it exclusively to GL4. I am curious to try the Delvac before I tear into it though to see if I notice any difference in shifting, whether better or worse, or no different.

 

[OSS]

While your shifting issue probably isn't oil related, I had used Mobil 1 75/90 synthetic gear lube in my tranny for two decades. That stuff is super slippery (and it was the only synthetic gear oil available way back then). It is so slippery that the synchros can't get a good grip on the cones and shifting with that stuff in the case was a little trickier. It's a GL-5 oil and it never harmed my transmission (270,000 miles) but when I switched over to the Delvac I instantly could tell the difference between the two oils
Mobil no longer recommends that gear oil for transmissions. I was their guinea pig for twenty years.