3 speed 3.03 grinding in 1st & 2nd; not 3rd???

[gearida]

My trans started grinding in 1st and 2nd, but smooth and quiet in 3rd. It also makes noise while coasting with the clutch in going down a hill in 1st. Before I take it apart, is there anything I can do before taking it apart? I did change the fluid a few weeks ago and checked level again. It is my daily driver and I hate to pull it if I don't have to... I know, nice thought... I don't understand why 3rd is perfect.
Thanks for any ideas.

 

[Yeller]

My trans started grinding in 1st and 2nd, but smooth and quiet in 3rd. It also makes noise while coasting with the clutch in going down a hill in 1st. Before I take it apart, is there anything I can do before taking it apart? I did change the fluid a few weeks ago and checked level again. It is my daily driver and I hate to pull it if I don't have to... I know, nice thought... I don't understand why 3rd is perfect.
Thanks for any ideas.

So it grinds when shifting or all the time? If it is between shifts the synchronizers are worn out. If it grinds all the time it’s far more serious, something else is failing. If it grinds when shifting It will run a long time fine, just be annoying. If it’s all the time it will leave you walking due to catastrophic failure.

 

[Broncobowsher]

Grinding going into gear?
Or grinding as you drive?

The as you drive, probably bad bearings in the trans. In 1st and 2nd the gears are loaded and that loads the bearings. 3rd is quiet as it is 1:1 pass through. None of the bearings have any real load on them.

 

[.94 OR]

I used to have that gearbox. It would pop out of 3rd when cresting a hill going from load to coast. Got annoying so I took it and my spare box to a transmission shop and had them put the best of both into one gear box (college budget limited). After installing, 3rd was fine, but would pop out of 1st when the load was reduced going downhill. Got exciting at times.

My local transmission guy said this condition was from the end bearings being worn and allowing the angled gears to put a side load on the bearings over time. In hindsight, the rebuilt kit with bearings for that gearbox is pretty inexpensive and I would likely have just put new parts in it. I went NP435 since I had one and wanted the granny low. Shifts like a truck now.

 

[gearida]

It grinds or growls only when driving, however depending on throttle pressure it will seems to disappear. This noise comes and goes in both first and second. It does not make any noise in third. If it is just a bearing issue, I think I will run it for a while longer and trade up to a NV3550. Thank you all.

 

[Broncobowsher]

I would expect it to bearing self destructing. The cages that hold the balls evenly spaced get ground up and the balls are no longer evenly spaced, and rattle as the fall down inside the races. Somewhere I have (had?) an old bearing that clinked and ticked as the balls rolled around. Made a nice fidget to play with.

 

[DirtDonk]

Also, check your rear u-joints. Maybe even replace them if they are very old.
It does sound like a bearing issue with the transmission, and that’s not unheard of after so many years and possibly miles. But a vibrating driveshaft from a bad joint will do it too.

You didn’t by any chance happen to add a lift kit, or change the lift height recently, did you?

 

[gearida]

First, I didn't realize if the trans gets shifted out of first while laying on the bench, that the roller pins would fall into the bottom of the case. My wife and I put it back together and it looked good. About the same time my cousin brought me another older trans. I say it is older because it doesn't have a drain plug and the bottom is round. I put the original trans back in and it didn't shift smoothly. So I installed the second trans I had received from my cousin. I feel the sift rods may have caused the shifting issues, as I had to make a few extra adjustments on this install too. This trans now is making noise. I actually just changed my drive belts and drained the trans fluid as a winter preventative maintenance only. I do have a lift of 5.5", but it's been this way for a number of years. I really think the trans is the worst part of driving my Bronco now, after many different upgrades (hydro-brakes made such a difference). I would like to change the trans to something else, 5 speed etc. I have a NP435, but don't want to change driveshafts and I am still stuck with a trans that isn't road friendly. I didn't build this to be a daily driver, but it has turned into one now. Looking at the NV3550 now, just can't afford the time down or the cost at this time. My back up car is a 1967 VW Karmann Ghia with a big motor and a lowered stance, so not something to drive in the winter. (No heat either) I think I am going to go through the first trans again and reinstall it. Question, if you are still reading this long post, can I shift it on the bench without worries? I believe it the shaft that moves rearward which allows the rollers to fall out. Correct?

 

[DirtDonk]

You can’t shift any of these without a penalty!
However, it’s easy to overcome by either leaving the transfer case attached, or simply bolting some sort of metal strap to the back of the case to keep Output Shaft and bearing from moving rearward.
That’s the key. Keeping the shaft from moving that extra eighth of an inch.
You can probably get as much as a quarter inch of movement before anything drops out, but more than that, and you’re living on borrowed time and will probably be hunting bearings at the bottom of the case again!

By the way, the transmissions with the drain plug are usually the older, lower strength versions. They strengthened the case by leaving that hole out I believe.
Or maybe they just wanted to save money.

 

[gearida]

Attempting to change the trans back to the one that came with my Bronco purchase. I hope the adjustments in the shifter rails will be enough to allow it to shift. I just don't have the energy to do it... The bearing noise of the current trans is audible in the bell housing and the back end of the oil pan. I don't hear it in the trans, using a stethoscope. I hate doing this job on the floor, by myself, at my old age of sixty two... wish me luck...

 

[DirtDonk]

Good luck! Hang in there…
Without a transmission hanging there, that is!

 

[Jdgephar]

The most wear and noise that I've seen has been from failing front or rear main bearings. Not very hard to replace, but the shift rails and springs are a little tricky. My last one had the rear bearing making noise because I neglected to get all of the metal shavings out of the intermediate shaft housing when it was rebuilt (doh!). Both times I rebuilt the 3 speed, the secondary shaft stayed in (no dummy shaft). Those needle bearings were smooth as butter.