Full Trans lub now clashing gears

JoeCB

JoeCB

Senior Member
I just topped off the trans lube with 600W, it had been a little low. Now I'm getting much more gear clashing when shifting up thru 2nd - 3rd. It does get better after warm up. Now, I had always thought that the heavy lube slowed down the spinning gears, making for less gear clashing when shifting. I guess maybe not! What's going on here?

Joe B
 
The 600W stuff I have seen in action aerates excessively, and I do not believe it meets the SAE GL4 or GL5 high pressure gear lube criteria. I suggest you that change the transmission oil to a GL4 or 5 SAE75W140.
 
RPM matching is a learned skill. It takes a while to learn. Double clutching can help but the input shaft & cluster gear still have to be turning at very near the same speed as the mainshaft is before attempting a shift. The fresh oil just helped the countershaft cluster to slow quicker but doesn't always help to match rpm with the gear to be selected.
 
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Thanks guys for the suggestions. To answer a few of the questions posed. The trans had 600W but the old style dark stuff, the new top - off was with Snyders 600W , a lighter colored oil. Yes double clutching going up does help. I'll look at my idle speed, yes could be an issue, now that I think about it, getting cooler here in MI , maybe had the idle up a bit.
As for driving the A, not a newbe, I have been driving this car for 58 years. And just thinking ,,, I'll double check for full clutch dis-engagement.
Joe B
 
The "600w" most vendors sell is closer to modern 140 w equivalent, not as thick as original period 600w, which usually slows down the gears. Suggest draining it all completely out and get some 1500 w from restoration specialties or others. That may slow the gears down and with other suggestions when shifting.
 
The 600W that a lot of sources sell is a blend of several products and not an actual 600W steam cylinder oil. The Society of Automotive Engineers made the viscosity standards after 600W had been in use for many years so it's not rated the same. SAE 140 would be fine in these old sliding gear type units but a person can still get SAE 250 if they want something thicker. 600 is available in multiple different viscosity levels from ISO 480 to ISO 1000 so it's not really a standard viscosity lubricant.

The 600W was more suited for steam powered locomotives than model A transmissions & gear boxes but that's all Ford had available in that time frame. That changed in the V8 era when they published manuals that listed SAE graded gear lubricants for their cars and trucks.
 
Having driven Model A's for over 60 years I shift by ear and don't use the clutch. Never an issue with grinding. I use the clutch for starting and stopping. This is something I learned as a teenager driving 1948 & 1949 Mack and Kenworth trucks with three sticks.
 
OP states the problem started when he added oil to transmission. I'd recommend draining the ****** lube, let it drain at least overnight to get as much slop/sludge out as possible, then fill with a good heavy lube. NOT 600W from the vendors. I tried 2 different suppliers and both were crud. I now have used Lucas Oil Stabilizer at 100% strength for 6 or so years. Made an amazing difference. OP states he's driven model As for 50+ years, I don't think its a know-how issue. I never double clutch unless I'm in a hurry downshifting for a corner on a hill or something like that. If everything is correct and you take your time between gears, keep the idle speed low, have heavy lube, it'll shift smooth as a baby's bottom.
 
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