The Stovebolt Site Forums The Shop Area Driveline 1955.1 3 on tree transmission question

1955.1 straight 6 235 three on a tree.
This truck is new to me trying to straighten out my grinding up or downshifting second and third. It’s been suggested to me that my syncros are probably bad. I had an opportunity to pick up a complete drive train for 250 bucks complete with the bell housing starter and a three speed transmission that seemed to match all my casing numbers as follows.
- Shifter case 3845044
- Main case 3845122
- Tail housing very hard to read 3787186

The trans I just picked up had only the plastic gear on end of shaft 7/8” wide hanging in speedometer hole.
My original truck trans had the metal tab to swing to the side and then pull out the adapter the speedometer cable screws onto which has a steel gear on it about 5/8” wide.

Question I have is it seems I have to use the plastic one so it will engage when I spin the main shaft if I install my steel one into the adapter, it will not spin in the used trans I bought. I don’t really care if this speedometer is accurate it was not before. My question is more understanding how you can have two different diameter gears as the one of my original truck will not engage. Makes me wonder if I bought the wrong transmission?

Take a close look at the tapered steel adapter- - - -it should have more than one flat spot which allows it to rotate to engage different diameter cable drive gears. The hole in the middle is not on center with the outside diameter.
Jerry

Hi Jerry
My tapered steel adapter is on center so my steel cable drive will not make contact with the main shaft as my steel gear is not wide enough compared to the plastic one.

Speedo drive and driven gears have to be matched. You can't just swap in a driven gear willy-nilly and expect it to work, as you're finding out.
If you know what the transmission is (year and whether truck or car,) you can get a driven gear to match the drive gear that's in it. But you'd also need to know the rear end ratio that you have in order to get correct output from the speedometer.

See the bottom of this page and also a couple more following it (click on Next Page near the bottom.)

Okay that makes good sense. The tapered steel adapter that I have do they make different ones of those that are not drilled in the center like mine? If so, I get how all this works now.

Trucks of that era used a steel gear that matched the drive gear on the rear shaft.
Your replacement transmission is likely from a car which uses a larger plastic gear to match the
drive gear. The plastic gears are white 25 tooth, yellow 24 tooth, and green 22 tooth to match
the gear ratio of the rear end. The same speedometer "bullet" is used with both applications.

Note: There are some differences between car and truck transmissions.
The internal components are the same but there is a difference on the side cover shafts clock
position, the lower mount holes are threaded on the truck, and the speedometer gears.

Fred

I was told this transmission came from a 55 car so that explains the plastic gear I have. Will I not be able to use this car transmission in my truck because of the clock position and mount holes you mentioned ?

Use the side cover and levers from your existing truck transmission and use some longer
bolts with nuts for mounting. Be aware that the 2-3 shift fork is a high wear component and
based on your description of the problems it is likely worn.
You may be able to use one from the car transmission if it is good or pick up a new one.
Disassembly of the side cover is required to change the shift fork. Take a good look at the
gears and other components when you have the cover off. Hopefully the replacement
transmission is better than your current one.
Fred

Thank you very much for the explanation and my possible problem 2-3 shift fork. I will have to do some poking around online to see what that is. I am not familiar with the internals of the transmission, but not afraid to open it up and have a look and learn. Worst case I can bring it to a transmission shop but I want to give it the old College try first. I am going to try to spend all of next week on the truck. I will be removing the transmission bell housing clutch flywheel as I’m having problems cranking over (grinding occasionally starter just rebuilt) and I can see the teeth are chewed up on the flywheel in some places. Hopefully, my donor drivetrain will be a perfect match for most parts. Not a great start for this new to me truck have not been able to drive it much but I will get there.

Regarding your starter and its chewed up teeth; you'll need to verify whether you have a 12v starter or a 6v starter. You'll also need to verify the number of teeth on the flywheel.

12v starters need to be paired with flywheels built for 12v and 6v starters with 6v flywheels.

The number of teeth on each flywheel is different and the cut of the gear teeth on the starters is different.

I can't remember which is which but do a quick search on this forum to find numerous discussions on the subject and how many teeth each flywheel has.

Getting them mixed up will cause the grinding you describe.

Once this tech tip gets published you wont have to remember.

6V flywheels have 139 teeth- - - -12V has 168, if I'm remembering things correctly.
Jerry

Hello
Had some unexpected interruptions, but it was the kickoff to my retirement finally getting back to this project. I just removed the flywheel and clutch and bell housing from the used motor /trans that I picked up to try to salvage some parts from it to fix my truck. Likely from a 55 Chevy passenger car. This is definitely what appears to be a 12 V starter with the sticker on it said so and I have 168 teeth which is way more than what’s on mine. I think I counted 139 or 140 on my flywheel which uses a 6 volt starter.

I also noticed the bell housing from the used motor has a casting number on it. That is not present when I look in my engine bay on my truck at that specific spot. Picture attached.

Can I just swap the flywheel 168 tooth, 12 volt starter and clutch or do I need to swap bell housing? I’m concerned that maybe starter engagement could be an issue.

If your truck is a 6v system, 6v won't spin a 12v starter.

Have you figured out why your starter gear's teeth are chewed up? You said you have a 6v flywheel.

In 1954, the shape of the bellhousing changed where the motor mounts attach. 53 and earlier trucks have vertical mounting points and 54-up mounts are angled about 45 degrees. You would need to change the firewall crossmember to use the later model bellhousing.
Jerry

Hello
The truck as I bought it was converted from 6v to 12 volts. 12 volt battery is running a 6 volt starter I had rebuilt. I suspect the issue with grinding was caused by poor engagement of the bump floor starter rods to active the starter as it still grinds. Now that I have inspected my flywheel it’s chewed up and chew up slightly my new starter gear. So I have that issue and grinding on the transmission when shifting. I picked up this used engine and transmission hoping I could kill two birds with one stone, but apparently this may not work out too good other than hopefully the transmission is good.

Do I need to change my bell housing to use the 12 volt flywheel and starter ? I don’t want to swap out bell housing it would be better to buy a new flywheel and fix /rebuild my floor bump linkage or swap to solenoid mounted on starter.

You can use the 12V starter and flywheel with the original bellhousing. Your grinding might be a bad Bendix drive on the starter. You'll use the 12V one so that possible problem won't reoccur if caused by the Bendix. Don't mix them up. They look almost the same. If the starter is from a car you'll have a solenoid so you'll have to wire in a push button for the starter or get a truck starter up through 59.

That’s great news I didn’t want to swap bellhousing.
The starter in truck for floor starter is much different in shape than the solenoid mounted on top of starter from my used engine from a car. Did you mean fly wheel is easy to confuse and mix up?

Greg: Look here for info about 6v vs. 12v starters and flywheels.

Geg, the shiny new starter is a stomp starter. The old dirty one starts with a key.

Great info on different flywheels and how to identify. I marked everything that I took off my used engine. The flywheel seems to be in decent shape.
Getting ready to pull my bad flywheel and clutch down and do the swap out. First time using jackstands on a truck of this era with front springs. Typically I would place forward on each side of the frame but the springs are in the way. I would have to place the Jack stand as pictured right after the spring on the frame which is behind each front wheel right at the trans cross member. To me it seems like it’s to far towards the rear of the truck would prefer more forward. I will also add some big Wood blocks in a few key locations for added safety. Is that where people typically place Jack stands on these trucks while suspending the front end? The rest of the truck is fully intack nothing removed. Note also added a picture of the front leaf spring for reference.
-Need to research torque specs for flywheel and clutch.
-Research and buy a clutch alignment tool.

Thanks for all the support

Greg - Jack stands on these trucks are typically placed under the axle beam where the axle is bolted to the springs. Those are the best/safest support points. Resting the trucks weight on the springs themselves, other than where attached to the axles, can cause damage to the springs in addition to being a collapse hazard. Definitely block your rear wheels, both in front and behind, to prevent movement as well as setting the parking brake.

Torque specs for the flywheel and clutch pressure plate can be found in the 1954 Chevrolet Truck Shop Manual as they are the same as for your 1955.1 1st Series truck. Flywheel to crankshaft bolt torque should be 50-65 ft lbs with a torque wrench. Pressure plate mounting bolts should be torqued to 25-30 ft lbs. again with your handy torque wrench.

Okay and thanks for all the info. I was hesitant to put them under the axle beam where it just seemed if a spring broke the truck could collapse. I have a lot to learn like when I went to put a big socket on the crank to spin the engine and found out there is no big bolt on the crankshaft like most engines. Time for prybar for flywheel rotation.

Does anyone have a part number for clutch alignment tool? I found this one on amazon but when I check auto parts stores for fitment it says it doesn't fit my year truck.


Dorman 14522 Clutch Alignment Tool Compatible with Select Chevrolet / GMC Models
Technical Details
Manufacturer ‎Dorman Products
Brand ‎Dorman
Model ‎Dorman 14522: Clutch Alignment Tool Splines 10, Outer Diameter 1-1/8 In.
Item Weight ‎0.01 ounces
Product Dimensions ‎8.25 x 1.75 x 1.1 inches
Item model number ‎14522
Exterior ‎Machined
Manufacturer Part Number ‎14522
OEM Part Number ‎066-8127; 1202; 33-GM10; 5301; 69-5301; 73-350; T85; TAT-5301

I should thank you for posting, as I need to go find mine to reinstall my clutch when I get to that point.

Amazon also says that the Dorman 14522 Clutch Alignment Tool doesn't fit my '51, so it wouldn't fit your 55.1 either.

You can measure your transmission input shaft to see if it'll work. You'll need pilot diameter (and length, although that's not super critical), spline overall diameter, and number of splines.

My transmission is accessible and I could measure for you if you aren't able.

Amazon lists a universal clutch alignment tool for $10, but it looks like a POS to me.
I got mine with a LUK replacement clutch kit.

Here's the spline dimensions from the 55.1 Vehicle Info kit.
10 splines - 1.11-1.121 inches OD

Okay no good on that dorman 4522 choice above from the specs provided. I will try to get mine out this week, hot here and see what I have. I may even go with a new clutch which might give me the alignment tool ( at least last one I did came with it).

A couple of questions.
When checking what fits on automotive website because I have an odd year 1955.1 versus 1955.2 is the general procedure for me to enter in a 1954 pickup 3100 instead to avoid confusion with fitment?

I read up using the 1954 Chevrolet Truck Shop Manual link above. It says I will be lifting the 3 speed trans out thru the floor, I was expecting to lower it down from the bottom based on my past jobs although this is my first AD trans removal for me. Is that the correct way?

Sometime mid year '54 was when GMC changed from torque tube to open driveshaft and I assume Chevy did the same. So don't use the '54 1/2 ton when looking for any parts from the rear of the transmission to the rear axle.

The transmission is too long to fit thru the floor opening without tipping it on end. The best way is to use a hoist thru the door and lower it to the ground thru the floor opening. Second best is use a transmission jack to support it from below. Or just bench press it from below.

She is out and on the bench. It was easy drive shaft, shift rods and speedo cable. Used a quad jack which I made a wooden cradle for and lowered out from underneath plenty of room.

One thing was super odd, but don’t forget I’ve never really driven this truck yet. When we went to push it in the garage, I already had the starter out. We had four guys and it took everything we had to push it in the garage. Front wheel spin fine however with the driveshaft out, I jacked up the rear end and I can turn both your wheels clockwise but when I try to go counterclockwise, both sides are super hard to turn the driver side actually clunks when you try to go counterclockwise. Not sure what that’s all about but it sounds like something is messed up. I doubt it’s just the brake shoes hanging up.

Your rear axle issue should be a new thread to make it easier to discuss the new topic separately from the clutch/transmission we’ve been covering here.

Brake shoes will do that. Always remove/install a transmission from underneath. You did well.
IDK about the trouble of removing rubber mat or carpet ,unbolt the transmission cover,
move an engine hoist inside a cab to scratch all kinds of things. You guys work way too hard.

Clutch alignment tool: Clutch Alignment Tool
Samantha

Yes I will do that if need be thanks

I was wondering about those universal alignment tools. Looks like they don’t use splines just centering of disc via pilot bushing

I've had one that I got in the mid 70's and have used several times. It's always worked good.
Samantha

When I was about 17 years old, a friend and I were replacing the clutch on my old dodge and used a socket extension for an alignment tool We used electrical tape wrapped around the extension to get a fit. It wasn't high tech but it did work.

Anything will work as long as it fits in the pilot bushing and inside the disc splines and gets them reasonably concentric. Even the plastic ones can be a little off. Depressing the clutch as you insert the tranny can help it slide home into the pilot bushing if there's a little misalignment.

Greg... I've been messing with these transmissions for 50 years. Mostly 3100's.
Yours is a simple swap. You say the teeth on the "new" flywheel are good... most any automotive shop can flip the ring gear over to use the teeth on the other side if needed and I recommend having the flywheel resurfaced. Replace the pilot bushing in the end of the crankshaft, as a worn bushing will enhance its ability to jump out of high gear.

Your bad transmission has the perfect alignment tool... remove the input shaft and use it for alignment, bearing and all. I made two bolts with heads cut off into alignment studs, one 3" and one 4" long with a screwdriver slot cut into the end so you can screw them back out of the bell housing. I slide the shaft into the throw-out bearing, line up one stud to the trans, line up the short stud and slide the tranny on. Start the two lower bolts, remove one stud and start that one etc.