Hard "downshifting" when hot H55 (1 Viewer)

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How new is the trans, what fluid, when was last change?

Setup the clutch adjustment per the FSM, once its setup correctly, that is it. If the slave and/or master aren't leaking and are pushing the clutch release arm (which they are since you can cycle all the gears) they are functioning as designed. They just push fluid, that is it.

Usually H55 is pretty notchy to start and takes time to break in. Trick is to drive it smooth and put the clutch all the way in and shift. It's taken about 5k for mine to break in with one fluid change around 1k. This trans isn't designed to be speedy or buttery smooth like a car or modern trans, but it does improve with time.
This kind of answers a similar issue I was wondering about.......I think. Upshifting into 2nd and 3rd when cool is suddenly not as smooth as it's been through the summer (I've put about 4K on it and IIRC it had about 5K on a @orangefj45 rebuild when it was swapped in, though it did sit in my shop for ten years and then had new GL4 oil put in when swapped in at Torfab in Everett, WA). After driving it for about 1K miles I drained and filled both the tranny and tcase with Redline MT-90 and it shifted buttery smooth up and down, both hot and cold. Now it feels like it catches slightly before getting it into 2nd and 3rd when cool (3rd catches until its actually been hot for a while). Not enough to be a problem shifting, but I was wondering if this is pretty common in H55Fs or par for the course. First thing I checked was fluid level, and both the tranny and tcase are still right on the money. My inexperience and lack of familiarity with the H5F is a big caveat here. The shifter seat and bushing (bushing came from Marlin Crawler) are brand new, though I haven't inspected them yet since noticing this. Wondering if it's something I should even be concerned about. I don't shift super gentle, but I don't bang through the gears either.
 
At this point I am going to send the vehicle back to Valley Hybrids for an expert opinion as soon as I can get in there. I drive the truck alot so I would prefer to have it solved properly before I create more problems with the inadequate shifting behavior.
 
The oil is key to smooth shifting. The trans requires a GL4 oil, and they can be hard to find. The best oil that I have used is Redline MT-90, as noted above.
 
Since I'm still chasing the catch when going into 2nd and 3rd when cool (pretty much exactly the reverse of the original post, but I suspect possibly the same or similar cause), I checked my shifter bushing and the shift housing bushing. Both are still in perfect shape, and as it turns out I have the OEM shift housing bushing installed and have the Marlin set aside as a spare if ever needed. But I noticed when fingering the shift housing (giggity), there was a second OEM shifter jammed down into the bottom of it! It had obvious wear and was pinched pretty good at some point. Very easy thing to miss since I didn't notice it until I had my finger in the housing feeling around for any damage I could find (no damage that I could tell). Visually, I couldn't even tell it was in there. Once it was removed I reinstalled my shifter and buttoned it all back up. Shifting felt the same, save the shifter was a lot easier to install this time. I imagine that much less stress on the shift housing will be a good thing in the long run. I also noticed that (pretty much from day one of installing new bushings) there's about 3/4" of side to side play when in gear when measured from the shifter knob. Is this typical of an H55F? With the shift housing bushing in place, fitment is snug in the housing, so that tells me the play is in the internal shift components. If it's normal, I'm not worried. I know it's still a truck transmission, but just want to make sure certain things I'm noticing are par for the course.
 
Since I'm still chasing the catch when going into 2nd and 3rd when cool (pretty much exactly the reverse of the original post, but I suspect possibly the same or similar cause), I checked my shifter bushing and the shift housing bushing. Both are still in perfect shape, and as it turns out I have the OEM shift housing bushing installed and have the Marlin set aside as a spare if ever needed. But I noticed when fingering the shift housing (giggity), there was a second OEM shifter jammed down into the bottom of it! It had obvious wear and was pinched pretty good at some point. Very easy thing to miss since I didn't notice it until I had my finger in the housing feeling around for any damage I could find (no damage that I could tell). Visually, I couldn't even tell it was in there. Once it was removed I reinstalled my shifter and buttoned it all back up. Shifting felt the same, save the shifter was a lot easier to install this time. I imagine that much less stress on the shift housing will be a good thing in the long run. I also noticed that (pretty much from day one of installing new bushings) there's about 3/4" of side to side play when in gear when measured from the shifter knob. Is this typical of an H55F? With the shift housing bushing in place, fitment is snug in the housing, so that tells me the play is in the internal shift components. If it's normal, I'm not worried. I know it's still a truck transmission, but just want to make sure certain things I'm noticing are par for the course.
My 4 speed has that shifter slop when it’s in gear. It’s a very worn transmission though.
 
My 4 speed has that shifter slop when it’s in gear. It’s a very worn transmission though.
Mine has less than 10K miles on a rebuild. I got it with 5K on a Valley Hybrids rebuild IIRC and finally installed it this last May and have been driving it since. I'll have to check with Georg and see if he remembers. Be good to have a for sure approximation of how much use is on it.

@orangefj45 do you remember how much was on this? You had pulled it out of a 60 that rolled shortly after you had rebuilt it before I bought it from you in 2010. I know it's a ways back, but maybe your memory is better than mine? 😂
 
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I went to Valley Hybrids on Friday... Georg drove the truck and we think it is the clutch hydraulics. I walked away with a new master and slave. Once I get the slave hose from the dealer and install, I will report back.
 
I went to Valley Hybrids on Friday... Georg drove the truck and we think it is the clutch hydraulics. I walked away with a new master and slave. Once I get the slave hose from the dealer and install, I will report back.
So likely clutch not releasing all the way in your case?
 
So likely clutch not releasing all the way in your case?
Correct. It releases fine when cold but when hot starts working intermittently. Interestingly, Georg gave me a history lesson on the clutch slave - on the early vehicles, in the 70s, it was actually located on the drivers side of the engine. Given that the exhaust pipe is there, the heat was causing problems with the clutch operation. In later vehicles, they moved it to the passenger side.

Given that the primary cause of the issue is heat, hence the suspicion that it is they hydraulic system. It is at least cheap enough to start there. It is not synchros and does not look to be the pilot bearing which is relatively new and not making any noise.
 
New clutch master / slave seems to have resolved the issue. I need to get a buddy to help me bleed it some more as it engages pretty quick off the floor (did it by myself).

The only frustrating part is that I ended up not changing the hose. I have a new one but where the old one meets the steel line it was completely frozen. I used kroil on it but did not want to damage the steel flare fitting / line. So I ran the old one. Hopefully it continues to last.
 
New clutch master / slave seems to have resolved the issue. I need to get a buddy to help me bleed it some more as it engages pretty quick off the floor (did it by myself).

The only frustrating part is that I ended up not changing the hose. I have a new one but where the old one meets the steel line it was completely frozen. I used kroil on it but did not want to damage the steel flare fitting / line. So I ran the old one. Hopefully it continues to last.
I wonder how much pressure the system operates at. Be interesting if a stainless steel braided line would make any difference in pedal feel the way SS braided brake lines do.
 
I wonder how much pressure the system operates at. Be interesting if a stainless steel braided line would make any difference in pedal feel the way SS braided brake lines do.

Not sure - quite a few folks like the SS lines so maybe someone can chime in. The factory rubber line was $61 from the stealership.
 
Not sure - quite a few folks like the SS lines so maybe someone can chime in. The factory rubber line was $61 from the stealership.
Ouch! Though frankly I'm not surprised. Dealer markup is atrocious.
 
New clutch master / slave seems to have resolved the issue. I need to get a buddy to help me bleed it some more as it engages pretty quick off the floor (did it by myself).

The only frustrating part is that I ended up not changing the hose. I have a new one but where the old one meets the steel line it was completely frozen. I used kroil on it but did not want to damage the steel flare fitting / line. So I ran the old one. Hopefully it continues to last.

The same thing happend to mine when I tried to replace the rubber hose. I ended up replacing the whole thing from the master to the slave with SS braided line. Got the line made up at the local hose and fitting place, works a treat.
The SS braided line does feel mildly more direct than the OEM setup, but not overly.
 
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How much damage is caused by grinding gears?
 
How new is the trans, what fluid, when was last change?

Setup the clutch adjustment per the FSM, once its setup correctly, that is it. If the slave and/or master aren't leaking and are pushing the clutch release arm (which they are since you can cycle all the gears) they are functioning as designed. They just push fluid, that is it.

Usually H55 is pretty notchy to start and takes time to break in. Trick is to drive it smooth and put the clutch all the way in and shift. It's taken about 5k for mine to break in with one fluid change around 1k. This trans isn't designed to be speedy or buttery smooth like a car or modern trans, but it does improve with time.
Which manual has the adjustment procedure? I didn't find it in the manuals I have but want to give mine a looksee and make sure it's still good from when it was installed. The dodgy sifting into 2nd and 3rd is bothering me still. Not a major thing, but the fact it ran smooth as butter through the summer tells me something changed.
 

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