The Stovebolt Site Forums The Shop Area Engine Shop 37 pickup transmission grinds

I bought a restored 37 pickup in Datona Beech a few weeks ago. I had it delivered by truck to Maryland where I live. The first time I took it out of the drive way within about 2 miles the transmission started grinding whenever I tried to shift gears. I returned home but by the time I drove the 2 miles back it would not shift gears--I drove back in second. The clutch seems to disingage the engine ok but the gears don't synchronize. I checked the transmission oil level and found it very low. Adding oil at this point did not make the situation any better. My neighbor is a mechanic, I don't know how good, but he says he can rebuild these transmissions. Any guesses what I am in for? I have ordered a gasket set and a small parts kit for the transmission.

Ken, I have a 1937 1/2 ton pickup and based on my experience, here's what I think you have.

I'm assuming this is a stock truck with the original transmission.

Your transmission synchronizers are worn out. You can find out for sure by draining the transmission oil. Most likely you will see small particles of brass in the oil, especially at the bottom of the transmission. The reason the transmission oil is low is because it has drained back down the torque tube to the rear axle; caused by a worn out seal (called an "Okie Bushing" by some) at the top of the torque tube, behind the transmission, which is designed to stop the oil from draining down the torque tube to the rear axle housing.

If you pull the filler plug on the rear axle, my guess is that the oil will come gushing out. If all of this is true, your transmission does need to be rebuilt.

By the way, it ran nice and shifted good until the transmission oil got hot and thinned out. Up to that point, the synchronizers were being slowed down enough by the thicker, colder oil in the transmission case and thus acted like they were functioning as designed. When the oil got hot and thinned out the synchonizers no longer functioned correctly thus showing their wear.

Some people add "oil thickner" such as STP, or a like product, in hopes the thicker "blend" will slow the synchronizers down and cause the transmission to shift normally. I tried that and it didn't help me, so I would not do that if someone suggests it to you.

The transmission needs to be rebuilt and if you plan on keeping the truck and the stock transmission, I would rebuild it with the newest gears available. By this, I mean use cross cut gears instead of the strainght cut gears the transmission most likely has in it now if it is stock and has never been rebuilt. I would look for a good set, or put together a good set, of 1954 gears, which will be much better than the 1937 gears. The only difference is that you will have to use the 1937 transmission output shaft because the universal has a 10 spline on a 1937 truck and the output (and universal) on a 1954 transmission has a 17 spline shaft. This is not a problem, just be sure you do it or you will not be able to complete the installation of your rebuilt transmission. It will shift easier with the cross cut gears and the overall satisfaction/enjoyment rating of the transmission will be higher and, thus, better for you.

If your neighbor says he can rebuild it, suggest my ideas to him and see what he thinks. That might help you decide if he is a good canidate as a rebuilder.

Whatever you decide to do, you'll have to do something, because it isn't going to get any better.

I hope I have helped you! Good luck!

Joe

i would first check to see if the shift linkage has come loose. i had the same problem and was told the same thing crawled under and found the ubolts on the linkage had worked loose. also drove home in second. tighten them up and ok. now. ron

I don't mean to hijack the thread but can you really use 54 gears in a 37 tranny? If so how about the newer gears in a 46 tranny? When did they go the the cross cut gears and would this be an advantage for my spare 46 trans that's now sitting in a bunch of pieces just waiting to be rebuilt.

Inquiring minds want to know.

George

WE b OLD: A 37 has a top load floor shifter. It is possible for the forks to get "locked", but it is not like a column shifter where the levers get jambed up and malfunction. A floor shifter will lock up and not shift.

George: My 37 has 54 gears in it except for the out put shaft because it has ten splines and my truck drive train is basically a ten spline drive line. Your 46, I believe, has a 17 spline output.
It does help the drivability of the truck. The only thing I had trouble with when I did this was with bearings. I replaced all of the bearings in the transmission and I had trouble finding a few of them. I sold a new house to a guy that was a rep for some bearing company, though, and he ended getting what I needed. I think if you went to one of the larger bearing houses, you could get what you needed.
Another critical thing is the transmission case. Some of the bearings run in races machined into the case and if those are bad or worn, you will be looking at finding a new case. I was lucky and mine were OK and yours probably are too, but it's something to be aware of.

Now the final question: I don't know if the gears in your transmission are cross cut or straight cut. Maybe someone her can tell us, like wdfoftx or Barry Weeks. My guess is that they are crosscut and you have good gears already. That's not to say that a set of 54 gears wouldn't help your transmission.

Joe

I have the new gears for those transmissions to go back stock or convert to the later 1940-up. It sounds like a new synchronizer might solve most of the problems. As a rule the 1937-39 gears can be purchased new a little cheaper than the later ones.

The original 1937-39 transmission had straight cut gears on the reverse idler gear, the sliding low/reverse gear and the 15 tooth center gear on the counter shaft gear. These gears were bevel cut on the later 1940-54 transmissions

OK, first thing it is wdoftexas (I had his Stovebolt name wrong - sorry Warren).

This guy is a transmission man that spent his career with General Motors. He has forgotten more than anyone I know knows about transmissions!!

And that's the answer, George! Your transmission is as good as a 54 except it's a 46.

Ken, by the way, WELCOME to the Stovebolt site. I think it is the best site on the web for Chevrolet truck information. There are alot of people on this site that know the answers to all your questions. I know! I have found all of the ansewers here to my questions, so far!! People like wdoftexas are very knowledgable and seem very eager to help at any time!

Good luck on your transmission. By now I think you probably know what you have to do!

Joe

Hey George - I didn't men to sound so blunt about your transmission.

What I meant is that, you have a transmission as good as a 54 as far as structure and performance. The only thing is that it is older than a 54. If you decide to rebuild, I would go back with 54 gears. As I understand it, some of the gears were used even later than 54. wdoftexas knows all about that stuff!!

Good luck!!
Joe

Joe the cluster gears were used in pickups as late as 1966. 1940-1966 is a long run for a transmission that has it's roots in 1937 (1936 for GMC). It's a real mix/match situation on some of the gears.

Warren

Joe and Warren I really appreciate the information. Joe your explanation was extremely helpful. I think I have a good picture of what is going on in the transmission. I can't believe the response I got to my question. I had a 27 2-passenger Studebaker coupe for many years and the Studebaker people were great but there were very few of them so having a more common vehicle is a new experience to me. I have looked up the stovebolt parts sites but does anyone have sources of gears that I may not run across on my own? How about a rebuild service in case my neighbor isn't up to the task of rebuilding it? Thanks again everyone. Ken

Ken - I know we arent't supposed to sell here, but when you find someone to build a new transmission, I believe wdoftexas said in his post he has those gears or knows someone who does.

You wouldn't find anyone better to do business with!

Just trying to help!

Joe

Thanks guys. Alot of good information. I'll have to print this thread to add to my collection.

Wdoftexas, I'm glad to hear someone has access to gears for these old transmissions. Now I know who to call on if I have questions.

Keep up the good work
George

George, that is the reason most mechanics don't want to work on the old transmissions. It takes 5 hours to rebuild the transmissions and 5 days to find the parts if everything goes well.

WD

Ken does your truck have a 3 or 4 speed,if its a 4 speed non of the gears are syncronized. Does it have the original 216 or did someone put in a later 235,if someone put in a later 216 or 235 they might have put in a newer clutch systen which is very different then the 37 and if they used the original 37 bellhousing with a newer clutch fork there will be problems too. When I put my 37 togather I could only drive it a few miles and when everything got warm the clutch would not disengage so I know what you are going through and you will need to figure out what clutch system the truck has to determine what is wrong so email me and I will guide you through on what to do. Jeff

Here is an update on my transmission problem. When I opened the transmission case, 2nd gear had been replaced but other parts in bad shape so I replaced the synchronizer, first gear and main shaft, also used a new case since the shaft holes were wallowed out and leakng oil. I resurfaced the fly wheel. Put it back together--still won't shift, but we now know exactly what the problem is. Maybe someone can give some advice on how to solve it. The engine is a 1962 235 but everything else is original 1937. When the clutch mechanism pushes the clutch lever backward, the lever contacts the brake pedal mechanism. This causes the lever to be pushed off the pivot point in the bellhousing. Then the throwout bearing goes into the clutch mechanism at an angle and the clutch only partially disingages. If you take the inspection plate off the top of the bellhousing and use a small pry bar to push the throwout bearing straight in, the clutch disingages properly and the transmission shifts fine. We did notice that a different shaft had been welded on the fork. I probably should have tried to replace it while I had everything apart but didn't. Thinking of fabricating a new mechanism at the base of the clutch pedal or going hydrolic. I have adjusted the brake pedal as far as I can. I would appreciate any suggestions. Sorry for the long post. Ken

Ken- '37 bellhousing, fork and clutch? Original carbon throw-out bearing or '38 and newer with ball bearings? It may be as simple as making sure you have the correct bellhousing, fork and throw out bearing all together there and not a hodge podge of mismatched parts.

Thanks, Barry. Although I have assumed that the bell housing and fork were original to the '37 truck, I, in fact, don't know this. I have only had the truck for a couple months and don't know much about its history. I also don't know about the throw-out bearing. My neighbor is a truck mechanic and I have been helping him with work on my truck. I will ask him about the bearing. Is there a way to tell the year of the bellhousing?

Hi Ken -

If you can find the casting number on the bell housing, I, or any number of the others her can tell you which bell housing you have. Since the brake and clutch pedals mount on a bracket which houses the master cylinder on these trucks, its is most likely you have the correct bell housing.

It is a very important point Barry makes, however, that the throw out bearing is definitely different on a 37 and the clutch fork is also slightly different . You need to be sure you have the right combination, and don't go back to the old carbon throw out bearing. It is trouble!

Joe

'37 truck bellhousing casting number: 838533
'38-'46 truck bellhousing casting number: 839257
'37 fork: 364495
'38-'46 fork: 609953

A friend of mine had lots of trouble with an original '37 pickup with the carbon throwout bearing and ended up replacing the bellhousing, pivot ball, fork and throwout bearing with the '38-'46 ball bearing throwout parts and ended his troubles. Might help your problem? Let us know what parts you think you need to make this work Ken, we ain't letting you wuss out and go hydraulic just yet!

Here is an update on my transmission trouble (the final one, I hope). Checking the casting numbers supplied by Barry Weeks and Warren Foster (thanks guys) I was able to determine that my bellhousing was '37 and the fork was probably '37 but modified to accept the more recent throwout bearing that was in it. Faced with the prospect of replacing the 37 bellhousing, fork, etc with 38-46 and all the work and delay that entailed, my neighbor mechanic tried something they use in dump trucks and other large trucks. He created what he calls a clutch break by installing another bearing in front of my throw-out bearing. Don't ask me details, I am not a mechanic but I have test drove the truck and the clutch has a really nice feel and with the freshly rebuilt transmission, shifts beautifully. I am especially pleased that I was able to maintain more of the truck original '37 this way. Thanks to everyone for your help. Ken

Cool! How thick is the other bearing he put in front of the regular one? 1/4"-1/2" or something?

That is great, Ken! I had never heard of that, but I understand exactly what he did!

Two comments: You learn something new every day!!! and: Take good care of your neighbor. He sounds like someone you need to keep around!!!

Good luck, Ken, and I'm ready to help you if you need any help. Love those 37's!

Barry, I will ask for details of the bearing he used. I know at one point he was thinking he needed something to take up about an inch of space. I know he went to a parts store yesterday and spent some time back in the shelves going through bearings to find what might work. My wife and I drove it the dozen miles or so to church this morning (an act of faith) and it ran great. Ken