The Stovebolt Site Forums The Shop Area Engine Shop 2nd gear grinding

I have a 1940 1/2 ton p/u 216 w 3 speed trans. I will get a bit of grinding from 1st to 2nd gear.

If I hold the clutch down and hesitate a few seconds between shifts, I do not notice the slight grind. It seems to need a few seconds to "slow down" or sync or whatever it's doing in there. Also, if I push the clutch down quickly I do not notice it as often.

Are there any simple adjustments to rectify this? Thanks for your help.

Mark

You've got a worn synchronizer. If it's just started this problem, just replacing the brass "blocker" rings will fix it. If it's already damaged the synchro section of the gears, then it gets a little more difficult, and expensive. As the shift collar tries to engage the gear, the blocker ring grips the end of the gear, and matches the speed of the two parts. It will take a full teardown ot the tranny to replace the rings, so you might as well put in a "small parts kit" with new needle bearings, etc., while you're in there. A slightly draggy clutch will accelerate blocker ring wear, so be sure you've got a good clutch adjustment.
Jerry

As a temporary maybe permanent repair, remove the fill plug on the tranny and smell it,stink like hi sulfur gear oil?Have you changed the gear oil lately? If so,drain the oil, refill with straight 40 engine oil,use quality detergent oil.In some cases, modern GL5 gear oils impair synco action on tranny not designed for it.This assumes the torque tube seal is ok and the motor oil won't find it's way into the rear end.

A worn release bearing on the clutch will manifest itself this way too, make sure the clutch is in good shape before you start blaming the transmission.

It seemed to me that in some old trucks, over-filling a tranny with lube agravates worn syncros. Easy to over fill with a pnuematic pump and put the plug back before it drains to level.

Well, the tranny was too full of oil. I drained the excess from the upper plug and presto...No more grinding into 2nd gear.

Thank you for all that replied. This forum is great for newbies like myself. This is my first vintage truck/auto and I really appreciate the help. I am really enjoying working and learning about "Rose".

mark

You may want to check that the tranny doesn't have water in it. Gear oil floats on top of water so you may want to change the oil to make sure.

I drained and replaced. No H2O.

Thank you.

Mark

posted 06-18-2004 05:33 PM
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I drained and replaced. No H2O.

I've been wondering about my trans, a 4spd in a 46 1/2t. I thought my synchros were shot, but it appears that 31-47 4spds were not synchronized. I learned this from an old motors manual that didn't show synchro rings. Also, Carter shows a conversion kit to upgrade the non-synchro 31-47 trans to a 47 and later that is synchronized (p. 65). Yet, a couple of old timers remember them synchro'd. When I was a kid, I was told you had to double-clutch the 46, a knack I've yet to master....What are your thoughts on this?

I just got my truck on the road a month ago. My tranny kept grinding too. I figured out that I must not have synchro's either. I almost have the hang of it on double clutching. After you get used to it, it's really not that bad.