Grinding in 1st and reverse

[Justinlb]

I have a 1940 super, when I got the car the 1st and reverse gears have always grinded slightly but It's getting worse. Sometimes it doesn't want to go into 1st or reverse either unless I give it some gas and get it spinning, even when the vehicle is parked.

Ive checked all the linkages and bushings, everything looks good.

I use GL-4 also.

Any ideas or pointers would be appreciated, thank you.

[MCHinson]

What GL-4 gear oil are you using? I found that some gear oils did not work as well in my 1937 Century. I switched to this oil and it works better for me:

https://www.oreillyauto.com/detail/c/masterpro-chemicals/chemicals---fluids/maintenance-chemicals/grease---lube/gear-oil---additives/gear-oil---140w/587d6374459f/masterpro-chemicals-conventional-gear-oil/mp03/80040 It resolved some minor grinding that I was having with another brand of gear oil. 

[meteor]

Try putting the gear shift in second before going to 1st.

[Justinlb]

16 minutes ago, MCHinson said:

What GL-4 gear oil are you using? I found that some gear oils did not work as well in my 1937 Century. I switched to this oil and it works better for me:

https://www.oreillyauto.com/detail/c/masterpro-chemicals/chemicals---fluids/maintenance-chemicals/grease---lube/gear-oil---additives/gear-oil---140w/587d6374459f/masterpro-chemicals-conventional-gear-oil/mp03/80040 It resolved some minor grinding that I was having with another brand of gear oil. 

I am currently using that gear oil.

[MCHinson]

If you are using that gear oil, and the gear oil level is full, and you are having significant grinding, it sounds like time for some transmission work. I would guess there is a problem that is beyond my level of expertise. 

[edinmass]

20 minutes ago, meteor said:

Try putting the gear shift in second before going to 1st.

 

Also, try taking your foot off the brake. Letting the car creep just an inch or two will often allow it to go right in gear. On a 1940 Buick, I would be suspicious it’s an adjustment issue. Big early crash boxes often suffer the problem you are having. By the mid 30’s almost all transmission issues were solved for problems like the one you have. I would have thought a high idle would be the first issue. When you tap the throttle, could you actually be slowing it down when it goes in? 

[Ben Bruce aka First Born]

First and reverse are not synchronized. Idle speed should be 475rpm or so.  Sitting still, depress the clutch, slip into third then with clutch still depressed, go to first , or reverse. If this does not work, I would suspect clutch is dragging.  Try adjusting same.

 

  Ben

[Justinlb]

Thank you all for the responses, putting the car in 2nd or 3rd  before 1st or reverse works great and falls right into gear.

 

Is this an adjustment issue?

[hwellens]

Sounds like your clutch is not completely releasing.

[Ben Bruce aka First Born]

2 hours ago, Justinlb said:

Thank you all for the responses, putting the car in 2nd or 3rd  before 1st or reverse works great and falls right into gear.

 

Is this an adjustment issue?

 

Probably not.  Just the way transmissions worked before synchronized first gear in the modern era. My 1950 does the same.  If it did not work when doing this way, clutch would be suspect. 

  After doing it this way for awhile, it will be so automatic you will not even think about what you are doing.

 

  Ben

[edinmass]

I agree with Ben. It’s a standard technique we teach for people who are first time early car drivers. 

[Brooklyn Beer]

12 hours ago, meteor said:

Try putting the gear shift in second before going to 1st.

Some people say this is a GM thing but I do this all the time with my 31 Franklin when it won't find reverse. Also with my 39 Chrysler and 53 Plymouth

[edinmass]

23 minutes ago, Brooklyn Beer said:

Some people say this is a GM thing but I do this all the time with my 31 Franklin when it won't find reverse. Also with my 39 Chrysler and 53 Plymouth

Also works on Duesenberg, Stutz, Rolls, Cadillac, Packard ,and a bunch of others. 

[Bloo]

I think we may be talking about 2 different things in this thread. 1) being blocked from going in gear because the gears are stopped but not lined up, as in edinmass's post quoted below...

 

13 hours ago, edinmass said:

Also, try taking your foot off the brake. Letting the car creep just an inch or two will often allow it to go right in gear.

 

and 2) an unsynchronized first or reverse gear grinding because it is not stopped, either due to a dragging clutch, or due to the gears not having time to come to a stop after the clutch is disengaged.

 

The second gear trick is for gears that have not had time to stop moving after you disengage the clutch. It cant really compensate for a dragging clutch.

 

58 minutes ago, Brooklyn Beer said:

Some people say this is a GM thing but I do this all the time with my 31 Franklin when it won't find reverse. Also with my 39 Chrysler and 53 Plymouth

 

I don't know who says that but they missed the mark. The second gear trick is for anything with a combination of unsynchronized and synchronized gears in the same transmission.

 

A synchronizer is just a brake, a friction device. It stops one gear in relation to the other gear it wants to engage.

 

There are 3 things to consider. 1) the engine and flywheel, spinning at idle speed at a stoplight, 2) the output shaft of the transmission, stopped at a stoplight, and 3) the clutch disc, input gear, countergears, etc.

 

At a stoplight the clutch disc is spinning at idle speed, and the gears in the transmission are also spinning, first included. The other half of first gear and the output shaft and driveline are not spinning.

 

When you disengage the clutch, the clutch disc and gears slow down and will eventually stop, but probably not as quick as you would like at a stoplight.

 

If you try to engage your unsynchronized first too early, the gears will still be spinning, but the other half of first (connected to the output shaft and driveline) will not. There is no synchronizer to stop the rotating gears (remember, it is just a friction brake between the two halves of a gear!), so it grinds.

 

If you touch (or engage) second enough to get the braking action of the synchronizer, it will stop second in relation to the output shaft. Since the output shaft is at 0 rpm, and the gears are all connected, this brings the whole mess, including the clutch disc to 0 rpm. With both halves of first at 0 rpm, nothing will grind. You can touch ANY synchronized gear to do this, it does not have to be second. Third (or fourth or fifth if you have it) will work too.

 

The trick does not work if the car is moving, even a tiny bit. That is because the synchronizer (brake) only stops second in relation to the output shaft. If the output shaft is turning, second will match the output shaft, but first gear, having a different gear ratio, will be spinning at a different speed than the other half it wants to engage with.

 

All that applies to an unsynchronized reverse too, except that you probably wouldn't be engaging it at a stoplight.

 

 

 

Edited July 2, 2021 by Bloo (see edit history)

[edinmass]

Bloo is correct, I was just too lazy to type it all out. Try and drive a Rolls PII or my 1917 White. If you can shift gears without clashing, your an expert!

[Podster]

Sorry to join in late in this conversation, but have you tried double clutching from second into first? It's the process of stepping down on the clutch peddle twice and then shifting into first. It may take a few times to perfect the process but it is a lot quicker. Check it out on You tube  to get the general  idea.