Trouble Downshifting to First Gear?

[jfa.series1]

37 minutes ago, red67 said:

So today, with engine off went thru gears, with no problem. Weather would not permit a drive, so I didn’t start it. 

Thanks all for the help. How many quarts do I need. I know...search.

FSM says 1.5L.

[EuroDat]

8 hours ago, jfa.series1 said:

This is a highly recommended transmission oil, perhaps the same one referred to by @EuroDat

Yep. This is the one. Part nr 88900399.

I couldn't find that here in Europe, so I went with the Redline MT 75W-90. It works fine in these old transmissions.

[EuroDat]

10 hours ago, EuroDat said:

What can cause your problem:

1. The baulk ring is worm and under minimum tolerances. It can not synchronise the hub and the constant mesh gear. Result is grinding gears.

2. Poor quality oil makes the baulk ring inefficient. Oil does make a difference.

3. The teeth in the constant mesh gear and sleeve are blunt and rounded. That way the sleeve hits the blunt teeth and you require more force to engage the two. You have to force the gear a little left or right to get it home. Occasionally they will line up and it go in easily. 

One other problem I rthought I would mention here. It could be playing a roll in this problem.

4. When the springs behind the inserts get old and weaken they don't apply enough pressure for the insert in the sleeve. When this happens, the inserts don't apply enough force on the baulk ring to synchronise the hub and constant motion gear. The sleeve slips over the inserts and hits the gear before it reaches the same speed as the hub. Result is gringing into gear and rounding the pointy end of the teeth.

A good quality oil with help this a lot and extend the usable life of the transmission.

[Patcon]

Also loosen the fill plug before draining it!

They can be stubborn. Aweful to drain it then not be able to fill it.

[red67]

Will do, thanks guys! 

[cgsheen1]

On 10/3/2020 at 4:47 PM, Patcon said:

Also loosen the fill plug before draining it!

They can be stubborn. Aweful to drain it then not be able to fill it.

Let me chime in on the transmission FILL and DRAIN plugs...

(begin rant) I have no clue why people tighten these SO TIGHTLY! It's un-necessary. In my former life I was a licensed Journeyman Plumber (Ret.). Actually, I guess I still am a licensed Journeyman Plumber - just not employed as such... What in the crap does this have to do with transmissions you ask?? THOSE PLUGS ARE PIPE FITTINGS (well, they have pipe threads...)

So, now that you know that I am eminently qualified to speak on the subject: 

- Go the Home Depot. Plumbing Department. BUY an entire roll of TEFLON TAPE.

- Go home. Properly apply (ya, just wrap that sucker up with tape) the teflon tape following the manufacturers directions to the male threads of BOTH PLUGS - BEFORE you install them.

- Tighten the plugs (BOTH PLUGS) ONLY ENOUGH so that they don't leak! There is NO pressure inside the transmission (like there is in your Natural Gas line or your galvanized water pipe) SO THE PLUG DOESN'T NEED 80 FT/LBS OF TORQUE. Seriously, you can practically screw them in by hand if you use teflon tape or good pipe dope (just kidding (exaggerating really) you need to snug them up.) But you really, really can stop over tightening those plugs.  How do I know? Come and remove these plugs from MY transmission. Be a plumber - even if you don't want to - for me...

(end rant);

[red67]

@cgsheen1, consider it done! Thank you! Will report back with results. picking up fluid(AC) tonight. Hopefully change tomorrow!

[red67]

Changed trans lube today! What a difference! Used 2qts AC Delco 10-4014. No problem downshifting now. Thank you!

What I did discover, was the speedo cable connection appears to be leaking. How do I correct that issue? Or should I start a new 

thread?

[Zed Head]

Great news.  Curious...was it low?  Asking for future reference.  Your problem doesn't really fit fluid change but might fit low level.

Regardless, your transmission will be much happier with that fluid.

On to the next problem.  There are threads about the speedo connection O-rings.  Can't find them right now but they do exist.

[EuroDat]

Grats. Poor quality oil or low level can cause a lot of shifting issues. Yet another happy AC Delco/GM gear lube sucess story.

 

Speedo leak: Where exactly is the oil coming from? Leaking out the side of the adapter, then it's an o-ring seal between the adaptor and the transmission housing. If it is leaking through the cable itself, than it is a leaking lip-seal in the adaptor where the speedo pinion shaft goes through.

The speedo has an o-ring seal and a lip seal. It is easy to change both. They cost less than $10 for both seals. You will need to tap out a small roll pin, but with basic tools it's is not much work.

Simply unscrew the speedo cable and the 10mm hex (m6) bolt and locating tab. You can pry the adaptor out using a flat screwdriver in the locating tab slot. You will see the roll pin passing through to the side of the pinion shaft. It holds the pinion in place. You can tap it out with a small hammer and a blunt wood nail.

See tech article for the part numbers. You can also source the parts at a local (hydraulics) parts store. Make sure you ask for NBR, HNBR or Viton rubber. Don't use EPDM or Silicone.

 

[red67]

Blown away! Thank you, thank you! 

I think fluid was a bit low from speedo leak, and was quite nasty.

After leak fix, it’s on to Diff. Fluid change, what juice do you recommend ?

 Thank you, again!

[Zed Head]

I've never seen a sticker like the one on yours.  Might be a replacement or rebuilt.