Topped off trans -- now synchros are glitchy

[Detonator]

My '35 coupe has a '39 trans and a '40 banjo, both newly rebuilt. I've put somewhere between 50 and 100 miles on the car. Today I climbed underneath and topped off the trans. I'm running Lubriplate SPO 288 in both the trans and the rear end. I added oil it it until it just started to come put the fill hole.


Now...my 2nd gear synchros are glitchy. It'll only downshift to 2nd at walking speed. The synchros worked fine before topping off. I put a few miles on it to warm things up, but it didn't help much.



Is it the gear oil? I read in an earlier post that Lubriplate SPO 277 was a better oil for newly-rebuilt trans/banjos. Is this my problem?

[joe 1950]

In all my years working on old cars trucks whatever i have always kept the oil below the filler hole at least one inch you’ll still have plenty of lubricant ,to full causes foaming good luck

[joe 1950]

Just to add one more thing what’s wrong with using 80-90 gear oil with a little lucas oil supplement works great for me thank you

[Gene1949]

Certainly appears you have the right product.
I've had very good luck with CRC Sta-Lube API/GL-4 Multi-Purpose Gear Oil 85W90 in both the 49 Ford (T-10) and the Camaro (Muncie)
Neither liked the more modern oils and acted "glitchy" when shifted. That being said both transmissions using that oil were cranky until warmed a bit.

[alanwoodieman]

what number GL?

[Zeke3]

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The SAE grade of the Lubriplate SPO 288 is 250, which sounds way too viscous for an old Ford transmission. The SPO 277 with an SAE grade of 140 is more in the range of where you want to be.

[Detonator]

Originally Posted by Zeke3

The SAE grade of the Lubriplate SPO 288 is 250, which sounds way too viscous for an old Ford transmission. The SPO 277 with an SAE grade of 140 is more in the range of where you want to be.

I’m pretty sure that’s my issue. I picked up some GL4 140 yesterday and will drain and refill in the next day or two. I’ll report back. Thanks.

[Newc]

Napa sells GL-1 for old transmissions. GL-5 is supposed to attack brass? Newc

[Detonator]

Originally Posted by Newc

Napa sells GL-1 for old transmissions. GL-5 is supposed to attack brass? Newc

True. GL-4 doesn't attack yellow metal.

[Fritz]

I second Sta-lube 85-90. Gl-4. Good for yellow metals in your trans. My 2nd gear likes that a whole lot better than the 85-140 I had in it. Second gear holds and doesn’t pop out anymore. The Sta-Lube is good trans oil. Don’t use bud light.

[Detonator]

I swapped out the Lubriplate for a GL-4 140W. It gets warm here so I didn’t go for the 85-90. The difference in shifting is remarkable. Lots smoother. Thanks.

[Ward]

600 wt gear lube works well . Stock

[Andy]

I put Tractor Supply Gl-1 in my 32. The improvement was tremendous. It says for Ford transmissions.