39 Tranny troubles

[solidaxle]

I rebuilt the tranny 2000 miles ago. Replaced everything worn, new synchros, C-clips, trust washers, springs and inserts, coutershaft B-7111R, front grease seal. Rebuilt the shifter with new balls and springs. All under the guidance of Van Pelts book.


Filled with 90W GL-1 oil.


Everything was running smooth until now. On occasion it will grid while just driving along and is a little resistant at times to shift into 3rd.


I drained the tranny and the oil has a green tint, luckily no shaving or metal chunks were found. I discovered my universal housing is loosing the JD corn head grease and it is migrating into the tranny.



I'm suspect the contamination of grease is the problem. What do you guys think?

[marko39]

Just thinkin, if the corn head grease was leaking into tranny wouldn’t the tranny fluid be leaking out too?

[solidaxle]

The shield in the back bearing is designed to allow some tranny oil to enter the universal housing. The corn head grease is thick when cold and not being churned up, then liquefies once it is moving around.

[solidaxle]

I had the 90W GL-1 just under the fill plug. When I drained the oil, it was overfilled.

[19Fordy]

solidaxle: I use STALUBE GL 140 in my 1940 transmission. Give it a try.
O,Reilly's has it a the lowest price per gal.
https://www.oreillyauto.com/shop/b/c...3/754ba5cbea99

[Bored&Stroked]

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When you say it will "grind while just driving along" - what do you mean by that? Is this while shifting gears?

If it is hard to get into third, then that could easily be related to a synchro that is worn (as that is what slows the gear down to let it engage with the sift collar). What did you use for the three caged roller bearings (new or used) and what did you use for the main cluster countershaft rod?

[solidaxle]

B&S


I was driving along around 50-55 MPH in 3rd gear, no noise, all of a sudden there is a momentary grinding noise. Best described as a deflection, if that makes sense. Pushed in the clutch, shifted into neutral, then back into 3rd. The last 120 miles it's occurred four times at different speeds.


It doesn't happen when shifting.



Bearings and cluster were in good shape and didn't change them. Actually when I torn it down, the syncros were in great shape, but I changed them anyways. Everything came from Van Pelts.


Before the rebuild the only problem I had was popping out of 2nd.

[Ken/Alabama]

Original or repop universal joint ?

[solidaxle]

A good original u joint with an original special heavy washer. I ordered a repop washer and didn't like the looks of it and found an original one.

[Mart]

I had a buzzing noise from the newly assembled (from the best used parts I had) trans on the first longer drive in my 32 Sedan. I selected neutral, coasted a bit, re-engaged top and
carried on at a lower speed. It did not happen again. I suspect it might have been the second gear sort of shaking possibly due to a dry bush. Once I had more miles on it it did not happen again.
This is not related to the UJ problem I had recently.
From a visual inspection via your photos, all looks good.
What do you intend to do?

I might suggest just driving gently and hoping it might improve as things bed in.

But your statement that it is reluctant to select top gear makes me unsure.

Personally I would just try and get some gentle miles on it and reappraise depending on if it starts happening more frequently or less frequently.

I would tend to go for one of the thinner 85/90 grades of oil rather than thicker as I want to make sure the oil is getting into all the nooks and crannies.

Re the oil level could it be a classic case of rear axle oil migration?
Lowered front end, lowered rear and rubber rake can set that in motion.

The oil level issue might not be related to the grinding.
The grinding might not be related to the difficulty in selecting 3rd.

There may be one, two or three issues going on here.

Have you checked the axle oil?

Good luck with it.

Mart.

Edit: It might be that the top gear synchro needs changing. Maybe a good used one is better than a new one. A friend built a box lately and the trans would not turn freely. There were dimensional errors in the synchro ring. It was effectively too thick. I can't remember if he thinned it down or refitted a used one, but the new synchro ring did cause a problem.

[Tim Ayers]

Same trans case was used for the rebuild? How did the thrust surfaces look? Did you check the backlash of the cluster assembly after you rebuilt it?

I'm leaning towards B&S and thinking it's a synchro issue. I went through 4-5 different synchros before I was satisfied with their fit when I recently rebuilt my trans.

Two of them I sent to Charlie NY to make them totally round. Some of the repop synchros are too thick (as Mart stated) and out of round.

Not that this helps, but Ford used this synchro for a long time. I always look for them at swap meets to try to avoid using the repop ones.

[Terry,OH]

Sounds like the transmission may be backing out of 3rd gear. When it does this have you tried just shifting back into 3rd instead of going into neutral first. Do inspect the 3rd gear blocker ring for a hair line crack. Crack, if there, usually happen from one of the corners of the recesses in the ring. From your photo above the transmission is not in neutral and the 3rd gear blocker is not visible.

[solidaxle]

Originally Posted by Mart

I had a buzzing noise from the newly assembled (from the best used parts I had) trans on the first longer drive in my 32 Sedan. I selected neutral, coasted a bit, re-engaged top and
carried on at a lower speed. It did not happen again. I suspect it might have been the second gear sort of shaking possibly due to a dry bush. Once I had more miles on it it did not happen again.
This is not related to the UJ problem I had recently.
From a visual inspection via your photos, all looks good.
What do you intend to do?

I might suggest just driving gently and hoping it might improve as things bed in.

But your statement that it is reluctant to select top gear makes me unsure.

Personally I would just try and get some gentle miles on it and reappraise depending on if it starts happening more frequently or less frequently.

I would tend to go for one of the thinner 85/90 grades of oil rather than thicker as I want to make sure the oil is getting into all the nooks and crannies.

Re the oil level could it be a classic case of rear axle oil migration?
Lowered front end, lowered rear and rubber rake can set that in motion.

The oil level issue might not be related to the grinding.
The grinding might not be related to the difficulty in selecting 3rd.

There may be one, two or three issues going on here.

Have you checked the axle oil?

Good luck with it.

Mart.

Edit: It might be that the top gear synchro needs changing. Maybe a good used one is better than a new one. A friend built a box lately and the trans would not turn freely. There were dimensional errors in the synchro ring. It was effectively too thick. I can't remember if he thinned it down or refitted a used one, but the new synchro ring did cause a problem.

Mart,


I looked it over last night again. I strapped down the clutch pedal and disengaged the clutch and jacked up the rear tires so I can spin things freely. Everything looks intact and tight. With a screw driver I tried to move the lower cluster length wise to look for play, There's no play. The 1rst and reverse sliding gear is a little chewed. I would think that is common since it's not synchronized.


I clamped the shift tower into a vise and moved the shifter through the H - pattern, everything is tight.



The rake is not too radical. I do not have a dropped axle. The front spring is lowered, but so is the rear, I have Biggie/ little tires. It's definitely cornhead grease getting into the tranny. I had it filled last year to where I could see it from the speedometer hole in the torque tube. I pumped almost another tube in the u-joint housing this spring. So it's going somewhere.


I have not lost rear gear oil.


My plan at this point is to refill with fresh oil and try it. I'm skeptical that this will solve the grinding.

[solidaxle]

Originally Posted by Tim Ayers

Same trans case was used for the rebuild? How did the thrust surfaces look? Did you check the backlash of the cluster assembly after you rebuilt it?

I'm leaning towards B&S and thinking it's a synchro issue. I went through 4-5 different synchros before I was satisfied with their fit when I recently rebuilt my trans.

Two of them I sent to Charlie NY to make them totally round. Some of the repop synchros are too thick (as Mart stated) and out of round.

Not that this helps, but Ford used this synchro for a long time. I always look for them at swap meets to try to avoid using the repop ones.

Tim


It's the same case.


The trust washers were replaced and the backlash with in specs. I bought everything from Van Pelt so I pretty confident they are good but it's not quarantined.

[solidaxle]

Originally Posted by Terry,OH

Sounds like the transmission may be backing out of 3rd gear. When it does this have you tried just shifting back into 3rd instead of going into neutral first. Do inspect the 3rd gear blocker ring for a hair line crack. Crack, if there, usually happen from one of the corners of the recesses in the ring. From your photo above the transmission is not in neutral and the 3rd gear blocker is not visible.

I'll check that.

[solidaxle]

Can someone give me the minimum thickness on the shifter fork ends. They do not look worn, but I would like to make sure they are in spec.

[Planojc]

Grease got into the transmission because too much grease was pumped into the u-joint housing and with that thick grease, your synchros are not going to work as designed.

[Farley's34]

Rich, I have a 39 transmission available if you need it. Jeff

[solidaxle]

Originally Posted by Planojc

Grease got into the transmission because too much grease was pumped into the u-joint housing and with that thick grease, your synchros are not going to work as designed.

You could be right. I was thinking the JD corn grease do to it's design may also be to fluid once it is moving around, causing it to migrate into the tranny, adding to the problem of over greasing.



I have a couple of things to check before I refill with oil and road test.

[solidaxle]

Originally Posted by Farley's34

Rich, I have a 39 transmission available if you need it. Jeff

Thanks Jeff


Hopefully I don't need to go that route.