1st and 2nd gear “chattering”

1950 - 1952, M38, questions, discussions, regarding anything related to the M38.
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wc56daveyboy
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1st and 2nd gear “chattering”

Post by wc56daveyboy » Thu Mar 25, 2021 6:03 pm

The best description I can come up with for the noise I hear... “chattering”

Recent rebuild / refurb
of a very clean T90/D18 in a 51 M38

Actually, all bearings, gears and even syncros in the transmission looked fantastic upon inspection so left the T90 alone. It just looked and felt darn near new.

Dana 18 transfer, however, after disassembly, noticed intermediate shaft “scoring” a bit so was replaced w/ a
Complete kit from Novak w/ specially hardened intermediate shaft, O-rings, thrust washers, bearings and snap ring.
All gears looked like new here too.

Upon initial drive after assembly, I did NOT notice anything crazy with noises or anything at all.
However, as I put a few miles on it around neighborhood, I’m noticing
What I’ll describe as low level “chattering” while in 1st or 2nd gear under driving load. I just drove it again/ I “think” I can hear the same noise, albeit a bit less pronounced, while coasting too

In 3rd gear, no noise at all. Perfect. under load or coasting or whatever: nothing in third.

What did I (we) miss in the tranny/transfer?

Oil level fine.

Using mineral oil 90 weight as found at tractor supply to maintain GL-1 rating
I live in a cold climate and these symptoms happening on cold days here


mdainsd
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Re: 1st and 2nd gear “chattering”

Post by mdainsd » Fri Mar 26, 2021 6:12 am

The fact that you hear the chattering in first and second, but not in third would have me looking into the transmission. First and second run through the counter shaft, third is direct through the transmission. Also the transfer case doesnt know what gear you are in so it doesnt seem like the culprit.
52 M38 2X, '52 M37, '44 WC51, '42 WC 56/57, '50 CJ-V35(U), '42 GPW, '44 M3A1 Scout Car, 2010 M-Gator

wc56daveyboy
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Re: 1st and 2nd gear “chattering”

Post by wc56daveyboy » Fri Mar 26, 2021 4:36 pm

Perfect analysis !

So., let’s say it IS the transmission. (And I agree)
What would cause “chattering” in those two gears?
And not in 3rd

mdainsd
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Re: 1st and 2nd gear “chattering”

Post by mdainsd » Sat Mar 27, 2021 7:50 am

Im not much of a transmission guru. But, my first one the list of likely culprits would be the bearing in the countershaft followed by the bearing between the input shaft and the output shaft. Finally the Main input and output bearings..
52 M38 2X, '52 M37, '44 WC51, '42 WC 56/57, '50 CJ-V35(U), '42 GPW, '44 M3A1 Scout Car, 2010 M-Gator


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