I got my first slant six vehicle last month and have been going through it to get it back to daily driver reliable ever since I picked it up. It's a 1974 Dodge D100 pickup.

I have the A250 transmission and I had to install a new clutch kit in there because the clutch disk kind of blew up. The pilot bushing was loose and sitting on the input shaft of the transmission. The input shaft was free to just kind of bang around inside of the crankshaft. Thankfully the new pilot bushing fit into place tightly as it should have and the flywheel was smooth as glass with no scoring.

The clutch installed fine and everything went well to remove and replace the transmission.

My question is about 1st gear not having synchro and the way the transmission makes noise at idle. Here's a link to a video showing how the transmission makes a slight whining noise at idle, but when you push the clutch pedal the sound stops.

https://www.youtube.com/watch?v=Fs2f7bZhPnE


First off, is that normal or typical? I notice that this noise also affects the success rate of shifting into 1st gear smoothly. You need that whining to have stopped in order to not grind gears getting it into first gear. I've owned old three speed cars (ford) in the past and have adopted the same trick I used on them. At a stop light I sit in neutral. When the light from the other direction turns yellow, I clutch in, shift into 2nd gear, and then quickly into 1st gear. This allows me to smoothly engage first gear. Otherwise it wants to grind.

Is that just how the A250 transmission works natively or do I have some sort of known problem going on? If you shift into neutral as you coast to a stop the transmission is quiet the whole time you're rolling. As soon as you come to a complete stop, that whining sound starts. It's almost as if some sort of shaft is turning that should just be sitting idle?

I completely drained the original red fluid from the transmission (I assume it was ATF) and replaced it with a full gallon of Mercon III ATF.

I noticed that the owners manual says the capacity for my transmission is 5.25 pints. So I'm about 40 ounces over that because the Haynes manual says to fill the transmission until the fill hole weeps fluid (which was a gallon.)

I'm just trying to understand what noises and behavior is normal and then asking if I over-filled the transmission with ATF?

Thanks for any info!

No, that doesn't sound right. By '74 the 3 speed transmission should have a syncrorized first gear. It should also be using 90w gear oil. You may want to check to see what you really have.

There were two options in 74, the A230 and A250. A230 has 1st gear syncrho and is a side loader. The A250 has no 1st gear syncrho and is a top loader and has a lock-out bar attached to the shifter that requires clutch pedal push to move the shifter.

It's mentioned in the owners manual as well as my Haynes manual as being an option for '74. And I'm certain it's what I've got even if it's not what was in there when it was new.

Mostly I'm trying to figure out what that noise might be. People suggested it was the throw-out bearing, but it's brand new (which I know means nothing.) But to me it feels like the noise is coming from inside the transmission itself, like an idler shaft that's supposed to spin free, but is 'locking up' at low speed due to being crusty from age or because I have over-filled with fluid potentially.

ATF Dexron is the original recommended fluid for the transmission. Seems weird to me too, but I poured red fluid out of it when I dropped the transmission and verified in three different service manuals that it uses ATF and not gear oil.

Here's a photo of my transmission (forgot to snap a pic after I had cleaned it up) for reference.

Most likely it's the input shaft bearing, it tends to whine when worn out, under load it tends side loads the bearing... eventually it will whine even while driving in gear....

That makes sense as that's where the damage would have probably occurred from not having the pilot bushing where it was supposed to be.

Is it normal to have to shift up into 2nd gear (clutch pushed in) and then into 1st gear in order to get a smooth engagement if you've been sitting at idle at a stop light?

It works. It's just tedious.

On non-synchro manual transmissions... and one synchro transmissions with worn out synchros...


If your truck was floor shift, I would recommend looking for a 1975-1987 A-833OD truck transmission, bellhousing, and shifter as a possible upgrade... not sure how many A-250 or 390 transmissions are left (currently none in my area....but there was a local a few miles south of me with a few NP-235/435 transmissions for sale a while back...)

I can live with what I've got. The idle noise is somewhat annoying. It's a column shifter and I'm not sure if there were differences between the A230 and A250 that way. In an ideal world I'd find a working T5 and a way to adapt it for cheap, but I know that's not happening. I have a 3.55 rear end in there and it seems to do OK running 55mph down the road. The engine doesn't seem to mind it even though it's higher RPM than I'd like to be spinning all the time.