So I lucked out and scored a set of 5.43 gears on eBay. They weren’t out of a truck, they are NOS from a machine shop sitting on the shelf for decades. The only issue is that the pinion appears to be for an open driveline and I’ve got a torque tube on my 1940 1.5 ton.
So I’m still in need of pinion yoke, nut, u joints and long open driveshaft and carrier bearing to make this work. If anyone has these parts let me know and I’ll buy them. I fully understand that whatever driveshaft I start with will have to be modified.
I’m not posting this in the Driveline forum because people will clutter the thread with all kinds of posts about how they converted thier 1/2 ton to open driveshaft and a nova or S10 rear axle.... this thread is about the Eaton H110.
These gears will lower my RPM from 3k at 55 down to 2640. A taller tire will help reduce it even more. Since it looks like I’ll have to convert to open driveshaft, I might as well install an SM 420 with the open yoke at the same time. This is a change of plans but a welcome one.
Plagued with the same over revving problem....... could you share the part number or how you identified that particular item....? a part number maybe.....? I fear that my best chance will be from a junk yard so would appreciate knowing what to look for.
According to the 1940 GM parts manual....... part number 604424 is given as 7-38 ratio which translate to 5.4285xxxx etc. and this is for the two ton rear axle part number 604404 is given as 6-37 ratio which works out to 6.16666 etc again two ton rear axle.....
There is also different gearing for the HD Canadian Maple Leaf GM truck as 6-36 or 6.5 and the real buzzer at 6-43 or 7.16......... engine runs out of breath at around 44 mph screaming to all heavens...
Another GM parts list shows the 7-38 or 5.43 to be for VE and VF Utility cab over engine for 1937-38-39 ....part number being 603720.....
What to believe......... I would love to find the the gears for the one ton at 5.14 (1947) but not sure it would bolt on to the 1.5 or 2 ton rear axle cast housing.
Mine have some part numbers that I couldn’t find searching the web.
Ring gear part numberr:
SA IH H1815
Pinion:
53810
Ring gear diameter is 12.25 and has 38 teeth and pinion has 7. Math comes out to 5.4287, rounded up is 5.43.
I’ve found that searching for EatonH110 doesn’t come up with much. Searching for GM H110 seems to have a few more results. Mine were listed on EBay as GM H110 gears. Seller is a machine shop with great ratings and reviews.
Well I am going with the 5:43 gears so save on RPM........ HOWEVER........... my intentions were to convert the rear to an open drive shaft, mainly for ease of parts and familiarity, b...u...t... the more I read the more I realize that I am playing with the design geometry of the 1940 torque tube ...... changing to an open drive line seems easy until you read.....
Will my 1940 rear springs and in particular spring hangers handle the axle wrap up......? and I am not going to drag with the 235 engine I plan to install.
I could even change the whole axle open style from a similar era Chev that I have. From what I have read in the various GM parts manuals the axle casting number was the same for up to 3 tons onthe Canadian Military Pattern trucks....and by the way they were all open drive lines back to the early models designed from off the shelf parts in late 38-39. The early model were huge cast iron contraption with extra beefed up ribs but then they quickly adopted the more simple cast steel design and made millions of them.
At first I was hoping to use the 2 speed axle but the ration is low and lower with 8.1 for the low range.
I have seen in junk yards trucks with a second transmission and one model used an over or under drive bolted between the tranny and the bell housing.....simple lever hi neutral low...... then the GM 4 speed. They all looked dealer or after market installed and mainly on logging trucks used at low speed.
Has anybody done the drive line conversion only and what was the end results???? pitfalls to avoid????
Mine is a 1940 1.5 ton with torque tube. . I want to convert from crashbox to SM420 and from torque tube to open driveshaft. The 5.43 gears I got on eBay are for an open driveshaft, specifically the pinion gear is different.
Marvin and I have connected and I am getting the gears....... a lucky find in my book......... a big THANK YOU to Stovebolt for providing the opportunity............
Hello Tony 292, I just received the 5.43 gears from Marvin for an open driveshaft, if you're curious what they look like... The pinion is marked WX2285 A (9 45) September 1945, as well as 38-7 or 5.43... I am unable to find anything online about the part number. One curious thing is the letter W in a circle similar to a casting stamp found on Willy's parts... Also of interest is the fact that the mounting holes for the ring gear are threaded for installation...
Can you please post photos of your pinion shaft for an open driveshaft design? I would like to see the difference. Thank you.
Here is a photo of the W mark/stamp on the pinion... It would be nice to identify the manufacturer. There are also the letters C 3338 hand engraved on both items.
Thank you for the photos. Everything seems to be as it should, your set is for an open driveshaft and mine for a torque tube... Any part numbers or markings on your ring gear and pinion?
Got my gears from Marvin.....very pleased. Opened up a spare 1940 rear axle to practice before doing the real one....... should be fairly simple to do with many patient tries to set up clearances properly...... I still trust a piece of brown craft ( of known thickness) paper to set the free play. The gears had been previously mated and lapped by the manufacturer to a back lash of .008 to .012
