SM465 L-2-3-4, can't shift into 2nd unless completely stopped (solved)

[discuspro]

1983 C30 2wd. To set my SM465 gearing naming I'm going with L-2-3-4. So, just completely rebuilt a SM465: all new bearings, synchros, rebuilt top cover. Also I replaced main shaft, input shaft, 2nd gear and slider, 3rd gear and slider, reverse idler gear.

I'm using Redline MT-90.

In addition I've put in a new flywheel, clutch and pressure plate, solid pilot bearing.

So, I don't recall the SM465 needing to be at a stop to get into 2nd because it has a syncro. L of course not syncro'd. Engine off I find I have to dance a little in 3rd and 4th and then try 2nd and sometimes it will go in, sometimes I have to do a couple rounds. Once I can get into 2nd, engine off, it will go in and out fine.

Engine on, I cant get into 2nd unless completely stopped. Going 2 to 3 no problem, 3 to 4th no problem. Sometimes engine on, completely stopped it wont go into 2nd and I'll try 3rd and or double clutch and it'll go in to 2nd after some effort. Engine on or off, easy going neutral-3, and neutral-4.

No grinding in gears at all. I have adjusted the clutch alot, definitely disengaging.

Is this a symptom of a syncro that is too tight and sticking to the gear, or the new 2nd slider catching on something? Replacing top cover springs has made things tighter, so not sure what's up.

 

[discuspro]

Want to add synchronizer hubs and associated springs and keys are the originals. I wonder if there are some wear features on the 2nd hub that's catching a nice fresh slider on...? I think I need to take the top cover off and take a look...

 

[Shorty81]

Every 465 I've ever had didn't like to shift into 2nd while moving. Down shifting entering my driveway the truck likes 5 mph or less. Does not grind just doesn't drop in.

 

[discuspro]

Shorty81, thanks for some reassurance. I've heard about that. I've tried crawling in my driveway too and I can't get it into 2nd. Only dead stop right now, and it still takes some fiddling. I've only put maybe 5 miles on all the new hardware too, so wasn't sure if it's tight stuff causing this...

Since I didn't replace the 2nd hub and keys but I have a new 2nd slider, I've really started wondering if the new slider is hanging up on the old hub or keys some reason. I remember seeing one of the hubs had keys with some really subtle wear marks. Hopefully taking a peak with top cover off can show me what I'm thinking of.


Does anyone know what's going on when a gear is sync'd, and wont go into gear, but also doesn't grind when trying. Syncro not stopping the gear, or something else??

 

[AuroraGirl]

How are you counting your shifter?

You must be registered for see images attach

you should only be using 1 2 3 for normal driving and you have synchronized gears doing this. L is not synchronzied. its also a hugeeeee shift ratio wise


what fluid you usibng

 

[discuspro]

I was using the naming L-2-3-4, and using Redline MT-90. Getting into the synchronized 2nd (or by your shifter pic 1st) is the tricky one after the full rebuild and clutch job. Until I take top cover off (tonight), I'm going to chalk it up to stuff is still tight, maybe the new solid pilot bearing is still seating to the new input shaft and so even with clutch fully disengaged, stuff is still moving... or new main shaft bushings, etc, are still seating and stuff is still not loosey goosey enough to get 2nd while rolling slowly.

 

[Shorty81]

I think after some miles it will loosen up some. We had a new 74 K20 with the 465 and it was a bear for a couple thousand miles

 

[hoagster]

Something to look forward to, rebuilt 465/205 combo attached to a 5.3L new clutch, pilot and throw out. Let me know how this turns out!!

 

[discuspro]

Tonight had top cover off. So nothing super obviously wrong initially. I did notice the 4th gear syncro ring seemed tight against the input shaft/ gear. Although it would still move left and right so not seized.

Had a helper rotate output yoke, and I noticed when I disengaged the clutch the input began to rotate with the mainshaft. Fortunately I could stop the input from rotating but not by hand, needed a screwdriver. Aka, it was a little tight with the mainshaft, but not seized to it.

So, looked at low gear, and found something... Low gear could move forward and back a little on the mainshaft, and looked like there was ~1mm gap between low gear and the syncronizer hub. So this to me meant the mainshaft may be a little too forward, even though I did my best to seat the rear mainshaft bearing on as bottomed out as possible.

So, took to tightening down on the yoke nut and I got the gap down to 0.635mm. After, I went back and rotated the output yoke, disengaged the clutch, this time I could stop the input shaft from spinning with the mainshaft much easier. I ended up stripping out the yoke nut, fortunately mainshaft is hardened and didn't strip at all. I have a spare nut fortunately.

Now waiting on test drive. If there is a notably better shift into 2nd, I think I'll leave it. If it's still a tiny bit better but still tricky, I'll tear it down and make absolutely sure the main shaft bearing is completely bottomed out to the full gear stack. I found Kent-Moore 22874-5 and 22874-1 on ebay, bonafide sm465 tools, and bought them just incase.

 

[pduffyd]

Hi Discuspro.
I have rebuilt my 465, with a full novak kit, and shift forks for good measure.
I watched this guy on youtube, I have a Chevy shop manual too. But thought hey watch someone else do it before I make their mistakes !!

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You obviously you know what you are doing, but a relaxed look at some one elses job may make you go ah ha!

 

[discuspro]

pduffyd, I totally watched all of his stuff, very helpful, got my phone all greasy pausing his video during my work.

So, update, I have learned the 2nd syncro hub and low gear can wear each other in normal operation. Both of which are original on mine, hence the gap, ah ha! The low gear thrust washer bottoms out directly on the mainshaft against the rear main bearing. So, I'm pretty sure I cinched up the rear main bearing some, and now I've learned i should expect a slight gap between 2nd syncro hub and low gear.

Anticipating test drive eagerly.

 

[pduffyd]

Sounds good ah ha! Lol.
Good luck

 

[discuspro]

Have been test driving past few days. Seems breaking it in, gently, and progressively longer trips has been making it shift into 2nd (L-2-3-4) much better. But, still can't shift into 2nd from neutral while rolling above 2mph. Might say I've now put 20 miles on the tranny. Planning to daily drive to work this week. About 13 miles round trip. I'll post an update how it goes.

 

[pduffyd]

Look forward to the update.
After I rebuilt mine all gears were easy to shift into, but that is with the engine not running as I havent got the engine running yet.

 

[WebMonkey]

my sm465 shifts into the 2nd forward gear pretty easy.
under load, up or down.
(i use the 1st forward gear to get going without stalling when stopped on a hill)

i'm sure you'll get it lined out.