Used Saginaw 4 Speed Trans Swap Rattling Noise

[Gregski]

So I installed a used Saginaw 4 speed I bought off of Craigslist into my 1974 1/2 ton 2WD short box GMC with a 350 enjin and sounds normal when stopped not moving and in reverse and in first gear but I swear it sounds like there is a loose bolt rattling around the trans case when I am in 2nd, 3rd, 4th or even rolling in neutral.

I am running 80W-90 gear oil in her, and she shifts fine nice and smooth, and it actually drives really well, it's just that annoying rattle sound. Is it the bearings? or could there actually be something broke loose in there.

oh the clutch is fairly new replaced it about 18 months ago got 15,000 miles on it, and old trans did not make this noise before I yanked it out (it made an entirely different noise, LOL)

I know it's hard to give noise advice on the forum I am just graspin' at straws here guys/gals.

[notsolo]

Not the expert, but driveshaft yoke sleeve that's in the rear of the trans?...U joints?...shifter linkage?. Pilot bearing?..clutch fork not seated?..just a couple things to consider.

[YoungPup1977]

On the good side of things you now have two used transmissions with different issues. Take both apart and make one good one. Than you would know exactly what you have going back into your truck instead of one you bought off of craigslist not knowing if it’s good or not.
Posted via Mobile Device

[Gregski]

Originally Posted by YoungPup1977

On the good side of things you now have two used transmissions with different issues. Take both apart and make one good one. Than you would know exactly what you have going back into your truck instead of one you bought off of craigslist not knowing if it’s good or not.
Posted via Mobile Device

copy that but they are two different models, I assume you meant make one good one out of the two, I am planning on running one whilst rebuilding the other, yes

[andyh1956]

The rattling of the Saginaw is a well documented problem. From the factory it has this alien looking sheetmetal thing with "Fingers" on it that's supposed to keep some preload on the countershaft but these failed & the fix was to use a small needle type thrust bearing in there after some machine work. Some also used "Wave Washers" to impart some preload but they fail also.
Also if the input shaft brg is worn there can be too much backlash between the input & front C/S drive gear & it can rattle.
Even yet the reverse idle will rattle!
I bet it's the countershaft rattling you hear if you don't have a gear missing a tooth.
Also use GL4 oil & not GL5.
You can spend a lot re-doing these transmissions & have the very same rattle when done you had to begin with. If there isn't any metal that drains out fill it up & drive it.
At $200-$250 each they are considered disposable transmissions so drive it!.

[Gregski]

Originally Posted by andyh1956

The rattling of the Saginaw is a well documented problem. From the factory it has this alien looking sheetmetal thing with "Fingers" on it that's supposed to keep some preload on the countershaft but these failed & the fix was to use a small needle type thrust bearing in there after some machine work. Some also used "Wave Washers" to impart some preload but they fail also.
Also if the input shaft brg is worn there can be too much backlash between the input & front C/S drive gear & it can rattle.
Even yet the reverse idle will rattle!
I bet it's the countershaft rattling you hear if you don't have a gear missing a tooth.
Also use GL4 oil & not GL5.
You can spend a lot re-doing these transmissions & have the very same rattle when done you had to begin with. If there isn't any metal that drains out fill it up & drive it.
At $200-$250 each they are considered disposable transmissions so drive it!.

shoot I just tore into it today

http://67-72chevytrucks.com/vboard/s...55#post8304255