The Stovebolt Site Forums The Shop Area Driveline Transmission grinding in first

I get an intermittent slight grinding when going into first on my original 3 speed. Even when stopped it does it, and is worse if I try to go into first quickly. If I just ease it into gear, it usually does not grind at all. It has been doing it since I have owned the truck, and did not change any after I replaced the clutch. So my question is could rebuilding the transmission help the problem? It is the original transmission and to my knowledge, has not been opened or overhauled since new. Again, it is not a big deal, but since I do not know the condition of the transmission I thought I might go in and replace the bearings and such and thought it might help the grinding issue too.

Thanks, Lee.

I doubt that doing anything with the transmission will help. The issue has to be that the input shaft is turning when you try to shift into first, and the only way that will happen if the clutch is hanging up a bit. Did you check the fit of the disc on the input shaft splines when you replaced the clutch. If it doesn't slide freely, it can be held against the flywheel and tend to rotate with it.

Or the clutch is just not completely released. Try adjusting it for more release.

Ed

As you know there is no syncronizer in 1st gear on these older transmissions. When you are stopped, shift partway in to 2nd or 3rd gear first & then into 1st. That will stop the clutch disc & gears from turning. If you are still moving, you can double clutch to shift into first gear. Heavier grease in the trans. will help some.

George

Thanks for the replies. I have noticed that if I am just slowly creeping forward, it will go into first without grinding at all. I guess the rotating parts have matched speeds. I have tried adjusting for more release, but found that I was getting a noise from the clutch with the pedal depressed all the way. So I backed it off just enough for the noise to quit with full pedal. Like I said, it is a small issue that I can work around. About the only time I have any problems is when at a light and I try to hurry getting into first when the light changes (I don’t like sitting with the clutch in more than I have to). The drivers behind me can wait!

Lee.

Now might be a good time to change the transmission fluid into a clean container and see if you get of metal flakes or chunks in the process.

Mike B

When you replaced the clutch, did you replace or service the pilot bearing?

My truck sat for several years after I got it, before finally getting back on the road again. After that extended down time, it would grind while shifting into any gear from neutral when stopped. It was also a little trickier at times to shift into some gears when moving (trans is unsynchronized in all gears and yes, I was double clutching).

Cutch freeplay was fine. I could feel a fair amount of movement- so it was not like I wasn't getting enough travel.

The trans always had a noisy 5th gear, so when I pulled it to check into this issue, I also removed the clutch for inspection. The clutch driven disc and pressure plate were great, however the transmission input shaft had wear marks where it contacted the pilot bearing. I checked the bearing (ball) and the grease in it had turned into something extremely stiff and very un-grease like, making it almost impossible to turn the bearing. I think this caused the input shaft to turn inside the inner bearing race, which caused the wear and kept it spinning enough when the clutch was disengaged to cause problems.

Installed a new bearing, and no more issue.

Best Regards...

I did replace the pilot bushing when I did the clutch.
The fluid was changed when I got the truck, about 3 years ago (do not recall seeing anything in the fluid at that time); another check could tell me if I need to overhaul the transmission.

Lee.

As others say, who have paraphrased the carburetor guys that frequently contribute on this site: It's never the transmission, always the clutch (except when its the transmission)

Seriously, this does sound more like a clutch issue. As klhansen mentions above, the input shaft is still turning when you try to engage first gear which is why you hear grinding. And as you observed, when you are underway, the relative speed of the gears is closer, so they engage more easily.

Also, while the clutch was replaced, was it the correct one for this application - or just the same one that came out of the truck? The two might not be the same. What was the condition of the input shaft ? Any weird looking wear patterns on the splines or pilot bearing contact area? Could there possibly be an alignment issue between the engine and the transmission that is causing the clutch to hang up?

Maybe you could drop the inspection cover and with the engine off, and look up in there while someone operates the clutch. You should be able to see the plate inside the pressure plate assembly retract away from the driven disc.

BTW, Is this a diaphragm type pressure plate? Not sure about the ones specifically used on your truck, but in general, the diaphragm spring in some can be bent if the clutch linkage is adjusted to provide too much over travel.


Best Regards...

I ordered the clutch that was listed as correct one for my model, and it seemed to match the one I removed as best as I could tell. I don’t recall seeing any unusual wear on the input shaft or any other parts.
After installing the new clutch and adjusting the play, I did do as you suggested, watching the clutch movement while my wife pressed the clutch and it seemed okay. I’ll have to check it again.

Thanks, Lee.

When you replaced the trans, did you use a jack for support? Or just do a bench press of the trans? In the process of getting everything lined up if you let the trans hang in the splines while you rest your arms before the pilot snout is engaged with the bearing, the force can bend the clutch disc. The result is usually clutch drag as you describe or clutch chatter on take off or both. If it doesn't chatter you may be able to rectify the symptom with an adjustment. But you can only go so far until the throw-out bearing is always engaged. In that case, the bearing will eventually fail and/or the clutch will slip.

There is also the possibility that the rivets, on which the diafram spring pivots, are loose and moving slightly or the spring is distorted. I had this happen on a reman clutch a few years ago. It was replaced on warranty but I still had to do the job twice.

I used a regular floor jack to hold the weight, and headless bolts for alignment. No problems there.

Lee.

What lubricant are you running? A synthetic lube, or one that's thinner than the original won't have enough drag to make the gears stop turning quickly when the clutch pedal is pushed. Straight 90 weight mineral oil such as the "Ford tractor" gear lube that Tractor Supply sells is probably as good as it gets for stovebolt transmissions, both 3 and 4 speeds.
Jerry

When I changed the oil 2 years ago, I put in 80W-90 gear oil. I guess not as thick as the straight 90 weight.