Troubleshooting Transmission '47 pickup

[GB SISSON]

Last week while heading down our steep gravel road in first gear, the floor shift knob started vibrating badly and there was a loud clicking or ratcheting coming from the transmission area. There were no previous indications of this condition. This truck is the one I converted to a woodie wagon a few years back. I got us turned around and the noise/vibration was not evident going back up the hill. Later that day I pulled the driveshaft and checked the splines and u joints. Splines were perfect and showed almost 3" of engagement. The u joints were also in good shape. I finally got a chance to drive the vehicle quite aggresively today and the sound is very pronounced in decelleration and non existant in acceleration. Another important factor is this problem only exists in first gear. Second, third and reverse operate as before. While I have completely overhauled six or seven flathead V8s and all manner of other repairs on the V8 trucks, I have no experience with transmissions. Is it time to pull this 3 speed and open it up? (I have all winter). Could this be something more external? And lastly I have been considering a T-5 swap as my tall tires, hilly island environment, stock 221 engine and heavy vehicle have me longing for a lower first gear. With open driveline, maybe the T-5 swap is pretty straighforward? Thanks in advance, GB

[alanwoodieman]

countershaft thrust washer is worn out--these trans are not very "backdownable" very weak thrust washers on counter shaft. does not do it in reverse because the thrust is in the other direction on the counter shaft

[sidevalve8ba]

If you do decide to rebuild what you have I highly recommend Mac Van Pelt's book on rebuilding these transmissions. It was a big help to me when doing my first. He is also an excellent source for spare parts.

[Kube]

I tend to agree with Alan in regard to the most probable cause.
I agree with Sidevalve in regard to obtaining that book.
These transmissions are NOT tough to rebuild at all. With what I'd witnessed of your exploits, you'll soon be wondering why you may have had some hesitancy to tackle this.
You CAN handle this.

[svm99]

When you had the driveshaft out did you happen to check for end play in the mainshaft?
Regards, Paul

[GB SISSON]

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Thanks for the votes of confidence! Prior to this transmission situation I spent 3 days cleaning and organizing my narrow 'side shop' 14'x 28' into a sort of engine work space and am now looking into insulating and heating this room off the main garage. In the past it was used for an overflow area for the woodworking business, where we had a duplicate table saw and planer and some needed lumber storage. That was in the era of 3 or 4 employees. Now it's just me and the original woodshop is plenty. My thought was to build that long anticipated 255 8ba for the woodie this winter. I have most of what I need with the exception of pistons and rod bearings. My crank cleaned up at .010/.020. Would the added torque of this 255 over my 221 be enough to help me ease off nicely in first gear? Today I back out of the garage, point the rear downhill and start out cold up a rather steep incline. It requires some clutch slip which involves some serious and annoying 'judder'. Yes, I'm guilty of not having the flywheel machined, combined with the use of recycled engine mounts gleaned from a 3lb coffee can. I won't make these errors again. Moving in this direction I could rebuild my 3 speed, surface flywheel, new mounts (from where?) and spend the 2 grand on the engine parts and machine work instead of the T-5, adaptor/clutch/driveshaft mods. OOOH, maybe dual exhausts.....

[GB SISSON]

Originally Posted by svm99

When you had the driveshaft out did you happen to check for end play in the mainshaft?
Regards, Paul

No, I didn't. Just wiggled up and down and very little play if any.

[GB SISSON]

My 'new' mechanic shop.

[tubman]

I agree that you will have no trouble rebuilding your transmission. About 30 years ago when I was building my '36 3 window, I wanted a good reliable transmission to go behind the 276 ci flathead I was putting in it. I bought a '39 transmission off of Hemmings, a good '46-'48 transmission locally and all the NOS small parts (bearings, synchronizers, etc.) I could find. I also had an early Ford transmission book I got somewhere. After reading the book about three times, I got to work. I was careful and ended up with a transmission that was virtually perfect.

Long story short, I had almost no experience going in and got very good results. For a guy with your skills, it should be a "piece of cake".

[38 coupe]

You should have no problems rebuilding an old Ford transmission. I have to ask, if you are contemplating a transmission swap to get a lower first gear why not go with a 4 speed crashbox? They made half ton rear mounts for them and are usually free when you find one.

[petehoovie]

Originally Posted by GB SISSON

My 'new' mechanic shop.

[GB SISSON]

Originally Posted by 38 coupe

You should have no problems rebuilding an old Ford transmission. I have to ask, if you are contemplating a transmission swap to get a lower first gear why not go with a 4 speed crashbox? They made half ton rear mounts for them and are usually free when you find one.

When I got the pickup it had no engine or trans. I figured the 3 speed was what I would want in that vehicle. First time I drove it I knew it was geared too high in 1st. To remedy this I decided I'd one day swap in a T-9 crash box. Easiest route was to drive it 'as is' until I got around to swapping it. But every winter I just kept building something new instead. The diesel '47 tonner, the mongrel Foyota RPU, and last winter the almost stock '46 tonner with a T-9 and an H 226 six. I am very familiar with the T-9's operation and I like them but with the '46 I endeavored to build a smooth and quiet pickup, but the gear whine is very pronounced in the cab and not sure I want that in the woodie. Also my kids and grandkids enjoy the woodie so much I like to think they might make ice cream runs to town etc in the summer visits. All four of my kids drive a stick (2 boys, 2 girls) but not sure they are up to the crash box. Same for my wife. You couldn't pry the T-9 in the green tonner outa my hands, and if was just me, one would have been in the woodie in the first place. I Do have a good T-9 and a half ton mount, so I won;t say never, but for now it's most likely the 3 spd or the 5 speed. I tried ordering the book on Mac's site, but couldn't log in so I'll go old skool and call him in the morning. And Pete, good job once again with that picture!

[PeteVS]

Does your 3 speed have the 25 tooth cluster gear? If not, that might be a good option to get lower first and second gears.

My mistake!! Should have said 29 tooth cluster. (Thanks Tim!)

[GB SISSON]

Originally Posted by PeteVS

Does your 3 speed have the 25 tooth cluster gear? If not, that might be a good option to get lower first and second gears.

Sounds like something to look into for sure. Just the kind of thing I will be researching. Thanks much. Highest speed limit here is 40 on one of the few straightaways. We have taken the woodie to the mainland 3 times since building it, and only once on the interstate, so you can see my needs are different than most of today's drivers of early fords.

[RKS.PA]

Gary, I'm probably finished with my transmission rebuilding projects. If you can use a copy of Mac VP's book, send me a PM for your mailing address and I'll send it to you it off to you with my compliments....it was invaluable to me when I rebuilt my '47 side shifter!!

Regards....Dick

[GB SISSON]

Originally Posted by RKS.PA

Gary, I'm probably finished with my transmission rebuilding projects. If you can use a copy of Mac VP's book, send me a PM for your mailing address and I'll send it to you it off to you with my compliments....it was invaluable to me when I rebuilt my '47 side shifter!!

Regards....Dick

A generous offer I can't refuse. Hope I can make it up to Mac with parts purchases. Thank you ever so much!

[GB SISSON]

Does anyone have the specs on this 25 tooth cluster gear? I'm guessing I have the higher geared version. This could be a great solution. Edit: Looking at the VanPelt site, the chart seems to indicate the higher tooth (28) on first of the cluster results in a lower first and second. It also reminds me that there was a HD 3 speed for trucks with a low in the mid 3's, and a synchro 4 speed from '48-'64. These options could be very rare I'm thinking.

[Tim Ayers]

Maybe I missed something, but the 25 & 26 tooth clusters were found in Lincoln Zephyr transmissions. These were Ford's version of a wide ratio transmission and used to help move those heavy Lincolns down the road. Most of these LZ's had a 4.33 rears (I believe, not a LZ expert) with an O/D transmission and possibly a Columbia as well.

I'd doubt GB's transmission has a set of LZ gears in it, but you never know.

If this is going behind your 221 and your top speed is going to be 40 mph, I think you'd be much happier with a 28 tooth gear set with 3.78 rear end ratio.

Can't recommend Mac VP's book enough and agree you can handle this job without issue.

If you are going to give this trans a "refresh", I'd suggest going with the improved synchro set up found in mid to late '39-'48 Fords.

I've found 40-48 side shift transmissions to be excellent donors for good gears and other parts. You'll need a 81A double detent top with 91A forks to work with the larger synchro hub. This combo will provide endless miles of trouble free cog stirring.

[Zeke3]

There is a 29T cluster gear for the three speed transmissions that will give the lowest, most gear reduction, first gear ratio. I thought it was commonly used in truck transmissions.

[cadillac512]

The two ratios I'm familiar with for the three speed trans are 16/28 and 15/29 input gear/cluster.

A link to ratios courtesy MacVP-


http://www.vanpeltsales.com/FH_web/f...gearratios.htm