Strange noise in the Sherman

Hey guys, need some of your knowledge. When
my 8N sits and idles there is a knocking
noise coming from (I'm 95% sure) the
Sherman transmission. But it's not
constant, it goes knock...... knock.....
knock.............. Knock..... Knock.....
Knock, etc. Faster engine speed, faster set
of three knocks. Shift the Sherman to high
range and the knocks speed up. This just
started doing this last fall just before I
put it in the shop and I wasn't doing
anything except backing up. I also had the
drivetrain lock up twice, simply would not
move until I put the tractor in a forward
gear and let the clutch out, and the engine
lugged down considerably before it "broke
free". Ideas?

If you are pretty sure it's the Sherman split the tractor and open up the Sherman for a look see/possible rebuild. If you have or could get a standard input shaft you could switch them if you really need the tractor and will also tell you if it truly was the Sherman. Most of the time knocking is from engine or hydraulics.
Does the knocking still happen with the hydraulic lever disengaged?
Before doing a split I would pop the top cover on the tranny and check for any broken/chipped gears. Also check under your top cover to make sure your spring is in one piece and you shifter gates are not worn and shifter operates properly.

Agreed, Kirk.

Sounds like broken/chipped gears in the main transmission to me.

Should stop with clutch disengaged.

Dean

Thanks guys, appreciate the advice. The reason I suspect the Sherman is because it "sounds" like that's where the noise is coming from when putting my ear up to that area then the main transmission. Yes, the noise stops when the clutch is pressed, and speeds up when the Sherman is shifted into high. As you suggested, I will take the top off the main trans and see what I can see, and will check the spring under the cover (not sure what that is but I'll take a look at the manual). Never been in a trans before but there's gotta be a first time The engine is back together and running great after a major overhaul so I guess I did that right! I did not try turning off the hyd pump, will disengage the PTO and see what happens. I agree with you that knocking is a strange sound from a trans but that's what I'm hearing. Three knocks then a pause then three knocks and a pause, etc. I'm thinking it's a damaged gear as you said Dean. But why is a mystery. It was working fine and all I was doing was backing up a slight incline. I suppose it could have broken a tooth that was ready to go already and then the tooth got jammed and broke more teeth??? Who knows. Time to start looking inside.

One other thought. If the main trans is in neutral, isn't the only thing turning inside just the input shaft? And if so, isn't it more likely that the noise is in the Sherman since in either high or low range there are gears turning? Just thinking out loud.

Last question. Where can I get a Sherman manual? Don't believe I have ever seen one.

Thanks guys!

Norm

If your tractor is 8N or newer, the main transmission is a constant mesh design. All gears turn in a constant mesh transmission whenever the input shaft turns.

Dean

Which Sherman do you have? They made a step-up, step-down, & a combination. Here is a link for the combination. www.oldfordtractors.com/screbuild.htm

Ahhh, thanks Dean!

I didn't know it until I found oldfordtractore.com the other night, I have a combo. I've been associated with this tractor since my teans and I always thought there was just a low range and a high range. I never knew you pulled the handle out to get to "standard"! But thanks for the link, I did find that a few nights ago.

Norm

My Father bought a 51 8N with a Sherman combination transmission in 1974.

I used it a lot with a 5' cutter in the 1970s and 1980s and always thought that the low was too slow and the high was too fast.

It wasn't until I overhauled it in, IIRC, 1989 that I discovered the much needed direct.

Dean