1938 Buick Transmission problem

[JerryJ]

I rebuilt the transmission in my '38 special. Ninety five percent new parts including spacers, detent springs, reverse idler gear, counter gear, sliding gear, and the first and reverse gear, input and output clutch gear and mainshaft bearings. Pre-lubed everything on installation and checked freedom of movement into each position. Finally re installed the transmission in the car and filled it with 140 weight gear oil. Without running, I shifted all positions several times, then started engine and shifted all positions. Drove the car back and forth  15 or 20 feet several times. Drove easy for half a mile while slowly shifting all positions. All seemed fine. Smooth and no noise. However, when having to start from a standing position on a hill, naturally had to give it more gas/rpm as I started off. As I  started off I heard a loud whining. But upon shifting into second, all was fine, no noise, as was third.  I brought it to a stop, and started off again with foot heavy on gas. It again whined in first, I shifted into second and all was fine.  It was fine in third also. Just to recount; In starting off slow and easy I heard no whining. It whined when more power was used to start off. (I suspect whatever is creating the whine is there at all speeds while in first, but just not so prominent at very low speed to make noise.). Back in the shop, I drained the transmission oil. It was very dirty. The oil I had put in was new and clean, (Honey colored). The oil that came out was dark gray, appeared dirty.. No chips, no pieces, but certaintly it appeared dirty. I put a magnet in it, but nothing was attracted.  I pulled the shift lever and cover off the top, and could not see any damage. Nothing was loose. Nothing missing, and no scoring was seen. I was able to move both shift shafts and gears normally. My thoughts are that the oil should not be dirty with less than two hours running, and the noise,(I never had a whinning like this before), could the noise be from a gear getting pushed against another  object, or the housing when shifted into first ? Any comments or thoughts? 

Edited October 27, 2022 by JerryJ (see edit history)

[F&J]

1 hour ago, JerryJ said:

(I never had a whinning like this before), could the noise be from a gear getting pushed against another  object, or the housing when shifted into first ?

If the 1/R sliding gear was hitting something in the 1st position, you would think it should be a grinding sound, not a whine.  

 

"Whine under load", sounds like gear mesh noise. 1/R slider teeth are straighter cut so they will make much more noise under loads than 2nd which has way more tooth angle. ...But you said it was OK before replacing gears.

 

Can you find a safe place with no traffic  on some hill to try accelerating just as hard, but in reverse?  If it did make a similar noise in R, then you could assume the teeth machining on the 1/R sliding gear is the issue?   I have no idea if you have NOS Buick gears or old aftermarket gears that might not be as accurate as far as machining?  

 

I have done a few 37-38 Century transmissions, they are different, but I never had one get dirty oil.  I can't explain that dirt look unless a few parts did not get cleaned enough (which I doubt is true), or grabbing at straws here, if the gear faces for 1st were not ground correctly, could it be ultra fine metal residue that won't stick to a magnet?

[DonMicheletti]

A first gear whine is a very characteristic Buick sound.

I have experienced the issue you have when new parts are used. Especially when the first / reverse and clouster are replaced. It seems that somhow original gear setups were better - or maybe I am just crazy, but I have had this espereince with other cars than just Buicks.

 

My '38 Special has the same issue.

 

Why did you replace the gears?

 

I cant explain the dirt.

Edited October 27, 2022 by DonMicheletti (see edit history)

[JerryJ]

F&J and Don; So perhaps the noise I have, caught me by surprise since I never had it before. (The transmission before rebuild was probably acceptable. Just having a 'slight' noise in first and a loose shift lever.). So I felt since the gears were available, I would replace them before any problems since there was a noise. (But maybe I didn't need too. I might be paranoid. LOL.). As for the manufacturer of the gears and other parts, I don't know if everything was original Buick parts, or after-market. I can check on that though as I saved the packing that the replacement parts came in.  As mentioned the oil that came out was appeared dirty.  In looking at it a second time even with a magnifying glass, I could not find and filings, or what you would call specs of dirt. Just what appeared to be a gray color, making it look dirty at first glance. I intend to flush the transmission with a lighter oil, (Marvel mystery oil or a 5/10 wt gear oil. Then refill with  Lubriplate 140 weight gear oil. I did find one thing tonight which could have allowed the  side of first/reverse gear to rub on the second gear synchronizing drum cover and make the whine. The set screw which holds the yoke on the shift shaft for the 1st/R gear, was not fully tightened, allowing the yoke to wobble enough on the shift shaft to allow this rubbing.  I could not find where any gear teeth were involved. This was especially good. I was able to tighten set screw by almost one and a half turns. This set screw is very stiff and almost felt like it was fully tightened but the give-away was that the set screw for the other yoke was sitting further down. So I was able to get rid of .005 to .010 wobble.  I will fill trans tomorrow or Sat., and try out again. I will also try backing up hard. I might also have opportunity to get oil analysed for impurities regards to color change. Thanks both to F&J and Don.

Edited October 28, 2022 by JerryJ
Add thanks (see edit history)

[EmTee]

Could it be normal wear-in of new parts?  If so, I'd expect any noise to subside and the oil to stay clean after initial break-in.

[NailheadBob]

Maybe on the dirty oil, how well was the inside of the transmission case cleaned? could be as EmTee sated just needs initial break-in, and then change oil again if see if any change in oil discoloration and whine.

 

F & J stated with 1st sliding gear hitting if hitting/rubbing you will a distinct noise, not whine.

 

the best man on this transmission is "Super" Don Micheletti, SO what Don states is "GOLDEN" extremely knowledgeable.

 

Do you still have old parts to compare any wear patterns OR pitting on gears?

 

Just some thoughts,

 

Bob

[avgwarhawk]

My 54 gearbag is very similar to the 38 gearbag.  First is quite noisy.  Even with smooth teeth gears.  Second gear quieter.  Third is silent.  The manual states the first 2 gears will make noise Third will not.     Under heavy load my  first gear will sometimes sing.  

Edited October 28, 2022 by avgwarhawk (see edit history)

[DonMicheletti]

With the shift fork being loose on the shift rail, the gear might not be in full contact with its intended mate. That could cause excessive noise.

In tightening those fork screws, I will tap on the end of the screwdriver while using an additional tool (vice-gripe) to put additional torque on the screwdriver

[JerryJ]

 Thanks for input. It could be normal wear-in., and yes i agree new gears could add to noise level. This noise however seemed to be more than that. I also might have been too quick to judge the noise as being detrimental, and pulled the top off the trans. right away, without enough  inspection/consideration. On the other hand, I learned something about the oil today. I spoke with a technician at Lubriplate and described to him my concern in the difference in the appearance of the oil. He was not concerned about the oil's discoloration though. He added that the oil will change color as it picks up the contaminants from oxidized  metals in the gearbox; i.e. including  all the internals and also the inside of the box itself. (And so with some parts that sat on the shelf for 60 or 70 years, there would be oxidation even thought he parts appear to be clean.).  After learning this, and not finding anything, (except the shift shaft set screw not being turned in to 'bottom of recess in shaft ); I intend to put trans cover back on, and when oil is delivered, put that in, and drive with the "purpose" to insure noise is not a problem.

 

 

 

 

 

 

[NailheadBob]

Before you put cover back on use a screwdriver that on the shaft you can attach a wrench to give you a little more leverage to tighten screw (like a Snap-On screwdriver)

 

Bob

[JerryJ]

Don, Bob;  good points on tightening the set screws. When I found the one set screw could be turned in further, I chided myself because I tried to be extremely thorough during assembly. But I am not too surprised when realizing how much effort was required to turn it in further. I probably thought it was in all the way. In thinking about it, Buick had to make the screw tight going in so that it wouldn't back out with vibration. There is no way to lock it in place mechanically.,No room for cotter pin or any other means. Although today a loc-tite compount could  be used. But again, no clearance was left in the female thread, so it turns in tight and stays. I both tapped it as it was turning in, and tested it with a wrench on the screw driver shaft. No worry about stripping these if done with care. Further, I shifted into each gear to ensure nothing was rubbing or hitting something it should not. So now, when oil arrives, I will fill trans and try it out again.

[NailheadBob]

Glad to see you found something, after transmission filled, now for the road test and break in period.

 

 

Bob

[DonMicheletti]

Properly tightened, I have never heard of one of those screws coming loose. You'll be fine.