I had gathered up pieces for years to do my A-V8 and knew it would have a 39 style Trans in it. I gathered up a shifter Top with the large (correct) Fork. I have a 37 tired Box and I bought a 41 Ford side shift Trans in good shape. The idea was to change over the 41 Gear set into the 37 Case with the 39 Shift Top. Easy enough. I have the Mack Van-pelt book to keep in line. Too much time goes by and my 41 Trans is M.I.A. I have 2 Good 49-50 Merc gear box's that could give up there Guts for the A-V8 project. So I go to the Van pelt book but it says nothing about cross over. I will not go back and change to Open Drive. So without shelling out the Merc box and trying to Un-Scramble Eggs, who knows if this is possible or exactly what it takes to make the Merc gears work in the basically 39 case? The Wizzard
As I recall it ain't gona happen,internal parts on those Merc boxes is the same as Ford cars for those years.The big pattern Merc case is giving you the wrong impression. And those parts are not close to the early stuff.
Actually Merc did not drop to the late Ford input size until mid 1951. Everything forward of the output shaft is still early Ford, 28 tooth style. My approach here would be to see what the part numbers are on the L-R slider and second. If those are early Ford numbers, you will still need to find the matching shaft to put them on but that should be all you'd need. I think I have a late Merc catalog so could probably dig out the info tonight. Also the great Don Francisco Zephyr gear article from HRM would explicate this...he covers the early into late type field very thoroughly in that.
Thanks Bruce; I had a feeling there would be a way to do this. I also have some loose parts and from looking I believe I have the correct shaft and sincro hub to get this done. I'll be getting on this very soon. I'll also hunt up the Zepher article you mentioned. You can never have to much information. The Wizzard
There are I think 2 different shafts for the ge****t. I will try to remember to look up the Merc gears tonight and see what they are. '49-50 Mercs have basically early Ford trans. '49-50 Fords had much smaller input shaft and bearing but were closely related to early...after that, gear teeth changed so nothing would match directly, even in the '51-2 pickup trans...which was still early Ford but suddenly got new gear tooth profiles! I do not remember the details, but back then Zephyr gears were still regarded as speed parts and were big sellers for the speed industry. From memory, the aftermarket came out with ways to stuff Z gears into Fomoco transmissions up to '54 or '55, when a much longer case was introduced. They started with the '49-50 Fords by producing Zephyrs manufactured with the smaller input shaft, after that the kits became much more complicated and required replacing nearly everything in the trans...but they still got those gears in there. The Don Francisco article covers the whole mess from 1932 to the end.
Sorry about the wrong info as I''m relying on my memory from selling trans gears better than 30 years ago. CRS for sure !
It looks like I may be lucky. I have 3 shafts, 2 look to be F-1 style to open drive shaft and 1 closed drive style. That shaft is drilled and taped for U-Joint. (2) R-1st sliders and a nice cluster and counter shaft. They are for side shift box having both forks in with the stuff. I have no memory where they came, seems to be a familuar Song lately. Both Merc trans I have are of Large pilot shaft fitting my 40 Ford clutch disc. I also have the 3 speed out of my 51 Vicky. It is a totally different unit. The Wizzard
'51 not only has the small input, it has the new gear tooth contour. I'll try to see what the Merc gears were, but looks like you may have found everything right in your toy box! Still worth checking, as it would be nice to keep the whole ge****t together. You'll need the Merc's type of thrust bearings, the Merc synchro was the last type of the '39 family and replaces all the previous ones...
As Bruce said, the 49-50 Merc gears are compatible with the 39-48 p***enger car trannies (whether top load or side load type). The key part for you is a closed drive type mainshaft of the 39-48 variety. I believe I see that in the picture you attached. ***uming it is ( and that its in decent condition) all you need to do is to match up the synchro hub to that mainshaft. Measure the length of the spiral splines.....either 2.9" or 3.1". That will guide you as to the correct hub. Double check the tooth count of the Merc gears. Cluster should be 28-24-18-14T. Main drive gear 16T, second gear 22T, slider gear 29T, and reverse idler gear 18T.
Fordyfordguy; So the way I read your info is that everything out of the 49-50 Merc case should do the job using a nice 39-48 closed drive main shaft. Is that correct? The shorter of the 3 in that photo appears in grate shape and the late sincro hub in the photo fits it. The Wizzard
Note my comment about the length of the splines....let me know what that is. Then e can figure which synchro hub gets used. Can you also post a close pic of the hub you have (pic showing its side view)?
The spiral spline is 2.9 long. The spline for the sincro hub is 1.5 from left of cut to Snap ring groove. The sincro hub is 1-3/16" wide. The bearing surface and over all condition of it looks outstanding. The Wizzard
Checked out the Merc book...all innards are indeed early Ford. Pretty sure, too lazy to cross reference, the merc is the common 28 tooth set...all you need is the output shaft. Unless there is an actual problem keep all the Merc stuff together...I believe in keeping used parts together. Merc 8M synchro became the service replacement for the '40-48 Fords I think. By the way, the overdrive Merc is also mainly early parts...the case and most OD parts are '40-48 Lincoln stuff!
Thanks Bruce; My plan is to use everything out of the Merc box as a set. I agree with not to mix and match worn parts if possible. They tend to make funny sounds at there best. The Wizzard
If the spiral splines on the short mainshaft are the 2.9" splines, you can use the synchro hub with the 3 pockets for the little balls & springs. You should see a small pin sticking out of the MS, just in front of the spiral splines. This is where you place the 81A-7071 washer. The slide on second gear. Then you fit the 81A-7069-A or -B br*** washer. Then the synchro, then the snap ring. Check the clearance and adjust as necessary.
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