1941 Special 40 series

[Turbosl2]

Recently my 3 spd on the tree is hard to get into 3rd gear after the car gets warmed up. It grinds most of the time into 3rd but if i push the clutch in and wait a second or almost 2 it may fall in without grinding. When i first leave the driveway it goes into 3rd gear smooth. Seems to be attributed to things getting warm. I changed the fluid to SAE 140 2 years ago and this is when the problem started. Thoughts?

 

I used this fluid

https://www.amazon.com/Sta-Lube-SL24238-Multi-Purpose-SAE-Gallon-Fluid_Ounces/dp/B000M8IHI2/ref=asc_df_B000M8IHI2/?tag=hyprod-20&linkCode=df0&hvadid=312097317052&hvpos=&hvnetw=g&hvrand=14033158343216263725&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004605&hvtargid=pla-571170829858&psc=1&tag=&ref=&adgrpid=57631863970&hvpone=&hvptwo=&hvadid=312097317052&hvpos=&hvnetw=g&hvrand=14033158343216263725&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004605&hvtargid=pla-571170829858

[Bloo]

Most likely either your clutch is dragging or your 3rd gear synchro is shot. I have used that oil and I don't like it much, however if I remember correctly several Buick owners in here have posted that it works well for them so I am leaning towards it not being the oil.

 

If it was me I would adjust the clutch according to the manual and then drain the transmission and put some real synchromesh oil in there, like Redline 75W140NS (note the NS) or Redline MT-90 (and there are others). I am using the 75W140NS in my 36 Pontiac transmission, which is VERY closely related to the Buick Special transmission and it works great. These oils are kind of light, and may not slow down first very fast for you at stoplights, so touch second before going into first if you are in a hurry at a light.

 

Do I think it is going to help? Not really, but I'd try it before tearing the transmission down to put a synchro in. If you do have to take the transmission out, pull the clutch and have a good look at it at the same time. Maybe it's saturated with oil, or the disc is hanging up on the splines. Check the pilot bearing too.

 

 

Edited May 26, 2021 by Bloo (see edit history)

[Ben Bruce aka First Born]

My money is on the synchro. If so, they are available.    Do you drive a lot? Or just a couple hundred a year?  If the latter, it may not be worth the expense and work just to replace the synchro drum.  Just learn to double clutch if you don't already know how to do so.

  Ben

Edited May 25, 2021 by Ben Bruce aka First Born (see edit history)

[Turbosl2]

I drive about 500 miles a year with it. The thing is I don’t remember this problem until I switched to 140wt. The manual calls for 90 but everyone said 140 is what you want. If it was the synchro why would it work fine for the first 10miles or 15-20 mins and only rear it’s head when the driveline is warmed up? That’s what throws me off. It could be the clutch. I know it’s prob saturated with oil because it leaks out of the rear main, as well as every other area that holds fluids. Maybe I should try the 90wt first and see. It has always dragged when going back into first. Have to wait a second or 2 but I gotten good at double clutching and or timing the lights

[Rock10]

I'm no expert, but I would try the clutch adjustment first. Keep us posted.

[DonMicheletti]

Think about it. The problem started when you changed oils. Go back to the 90 wt. Cheap and easy test.

[neil morse]

I certainly agree with Don about going back to 90 wt. oil as a test.  However, I am using the exact same Sta-Lube 140 oil that you mentioned in your first post, and it works great.  So I seriously doubt that switching oil is going to completely eliminate this problem.

[Turbosl2]

Thanks guys. Clutch adjustment first since I have never done it then I will switch the oil back then if that doesn’t work I guess the trans needs to come out

[pont35cpe]

On the clutch.. say starting off in first gear, when releasing the pedal from being pressed to the floor, how far do you raise the pedal before clutch starts engaging.   If midway, or to the top of travel, needs adjustment. As the disc wears, the fingers rise. If it hasn`t ever been adjusted, the fingers of the pressure plate are probably riding continously against the throw-out bearing, even after complete release(BOO!). This could be the root of the grind. Once adjusted, the PP fingers and the throw-out bearing, should not be touching in the released position. Also check all your pedal linkage/pivots for slop/wear, and give the zerks a shot of grease. Good luck.

[Turbosl2]

Hmm I would say at least 2/3. It’s a long throw and release for sure