78rd400 trans?

Stoked2smoke · October 28, 2022, 11:40:18 PM

Going through a new used transmission I received for my 78rd400 and only issue besides needing new bearings is that the Mainshaft 4th gear pinion (24t) spins but has drag. Is that normal. It's not like a bad bearing type of drag it just needs force to spin unlike the Mainshaft 6th gear pinion (27t) which I can spin with a push of a finger. The gear in question is #2 in the picture and using # 7 for a reference. Thanks in advance.

rodneya · October 29, 2022, 10:24:56 PM

Probably a good idea to take all the gears off the shaft and check whats going on in there.

Stoked2smoke · October 30, 2022, 04:31:36 PM

Will take apart and check all components. Tried uploading a vid of it but it's the wrong format and My YouTube account was high Jacked by my son. Any tips for uploading videos on here with a Apple phone.

Stoked2smoke · October 30, 2022, 10:04:08 PM

Took apart and inspected. Shafts and gears look fine. Thrust washers are in good condition. I see that the gear in question has oil grooves cut into it and has a tighter clearance fitting on the shaft. The RD bible doesn't talk about that gear specifically but I am saying it's normal until told differently.

rodneya · October 31, 2022, 02:11:25 AM

Clean everything up really well. There may have been some crap or old dirty oil in there.

Stoked2smoke · October 31, 2022, 04:29:38 AM

Quote from: rodneya on October 31, 2022, 02:11:25 AM
Clean everything up really well. There may have been some crap or old dirty oil in there.

Perfect preparation prevents poor performance

rodneya · October 31, 2022, 11:50:33 PM

I finally found the 400 trans I have in my parts stash. The 4th pinion gear definitely has more drag than the other gear. This trans has not been in a running engine in well over 20 years, but it is fairly clean and the other gears spin easily.

Stoked2smoke · November 03, 2022, 10:24:12 PM

Quote from: rodneya on October 31, 2022, 11:50:33 PM
I finally found the 400 trans I have in my parts stash. The 4th pinion gear definitely has more drag than the other gear. This trans has not been in a running engine in well over 20 years, but it is fairly clean and the other gears spin easily.

Good to hear. I am going to clean it all up and get new bearings on it. Should be good to go then. Thanks for looking into it for me.

Vintagetz · November 04, 2022, 05:05:42 PM

There are different thicknesses of thrust washers, I believe there is a spec. for the side clearance, you can feeler gauge it and make sure it is not under spec (I don't have the numbers)

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78rd400 trans?