Gears grinding when cold

Jedediah

Jedediah

Junior Member
Ever since I topped off the (600w) oil in my transmission, I have a new odd problem:
I now cannot shift from 1st to 2nd, or from 2nd to 3rd, without grinding gears when it is cold. I can downshift (double clutching of course) perfectly. Once the car has run a few miles, the problem goes away and the transmission is very smooth. Why?
 
Dr Foot said:
Try shifting at lower speeds. Double clutch. D
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While I have tried that to no difference, I think it is safe to rule out operator error or oil type as I have driven this car 30,000 miles with the same 600w oil, and have not changed my technique, and never had a problem until yesterday morning.
 
I do the same as Bruce, trying to match the engine speed with the rear end. I also agree that lower speed helps.
 
Sounds like you got some 600W that is a little thicker than normal. I would start by draining out the old then refilling from a newly-ordered bottle.

I don't expect my A to drive normal for the first half mile. Two miles is too far. Put thinner lube in there until it drives the way it used to.

When upshifting, you double clutch to slow down the transmission intermediate shaft. When the trans is cold the viscosity of the lube is slowing down the intermediate shaft all by itself. You can skip the double clutching and quickly and gently snicker it right into second. Don't even try for third until it warms up a little.
 
Given your experience, do not think operator error is the problem. My 31 upshifts fine when cold without double clutching. Might investigate the clutch disc hanging up or a problem with the pilot bushing experiencing some friction causing the input shaft to rotate while cold. Be sure and share the fix with us when the problem is solved. Good Luck.
 
Has your idle speed increased for some reason ?! When it’s really cold I have driven in low gear a bit longer stirring up 600w steam cylinder oil .
 
When my transmission is cold I need to shift faster rather than slower. The colder it is the faster the shift needs to be.
As you drive and as the transmission begins to warm slow down your shifts.
 
The 600W oil that is sold today is not controlled like SAE graded oil. So some 600W oil is thicker than others. The 600W oil also does not have the wear reducing properties that modern gear oil does. My suggestion is to drain out the 600W and put in 85W-140 gear oil. The multi grade oil means that the viscosity does not change as much with temperature so that you should not have the shifting problems when the oil is cold. The 85W-140 oil has additives that reduces wear. Your transmission will thank you.
 
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nkaminar said:
The 600W oil that is sold today is not controlled like SAE graded oil. So some 600W oil is thicker than others. The 600W oil also does not have the wear reducing properties that modern gear oil does. My suggestion is to drain out the 600W and put in 85W-140 gear oil. The multi grade oil means that the viscosity does not change as much with temperature so that you should not have the shifting problems when the oil is cold. The 85W-140 oil has additives that reduces wear. Your transmission will thank you.
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Neil, have you seen any more or less leakage while using 85W-140 gear oil? Living in MN I would appreciate easier shifting on a cold morning.
 
30K on original trans fluid is 25K too far. What ever you had was worn out = thin.

Drain, replace, & relearn shifting while using fresh fluid. $.02
 
jb-ob said:
30K on original trans fluid is 25K too far. What ever you had was worn out = thin.

Drain, replace, & relearn shifting while using fresh fluid. $.02
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To clarify my previous comment, the trans fluid has been changed every 5,000 miles as per Ford. The point of my comment was not that it has driven 30k without changing fluid, but that it has run 30k with zero issues using the same kind of oil from the same barrel, and with the same driver, thus logically ruling out oil weight/kind or operator error.
 
B. I have not seen any additional leakage with the 85W-140 oil. Any additional leakage would come from a leak from a gasket or the ends of the shift fork shafts. Snyders sells a kit to fix the leak at the end of the shift fork shafts for later transmissions. See https://www.snydersantiqueauto.com/product.htm?pid=978999&cat=41756

600W is not SAE 600 weight oil. The original 600W probably had the same viscosity as modern SAE 140 weight oil. Steam oil may be equivalent to SAE 600.

In the early days of used Model A's, when they were just old cars, unscrupulous owners, and maybe used car dealers, would put saw dust in the transmissions to quiet down a worn one.
 
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First reference to S.A.E. oils I see appears in the November 1932 Service Bulletins and specifically gear oils.

Winter (any thing below freezing) S.A.E. 110 (90wt for 110 if unavailable)

Summer (anything above freezing) S.A.E. 250 (160 if 250 unavailable)


No mention from the poster if his 'topping off' was the same previous lube?

Sure the poster did, but check the clutch adjustment. While both had visual threads the trunnion would pull off the adjuster link under load. Interesting.

Purely personal, I wasn't comfortable with 'cushioning' of the gears with 85wt until it warmed to 140 wt.. Experimented with a lot of different gear oils and returned to 250wt. Only my $.02
 
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