1947 KB-5 Differential


The old and reliable.

Pile of Parts
Pile of Parts

Posts: 46

Joined: Tue Jun 21, 2016 9:43 pm

Post Mon Apr 09, 2018 11:00 am

1947 KB-5 Differential

I’m not exactly sure what kind of differential it is that I’m talking about here but obviously it’s IHC. On the KB-5 the differential is quite large, had the triple diamond logo on the back plate and is set up with the dual Dayton rims. I have no clue about the internals but Info on this would be great. What kind of horsepower/torque can this diff handle? How low is the ratio exactly? I’ve got a feeling that it’s not a 2 speed but I’ve also got a feeling that it can handle a lot of power just being on a KB-5. Probably geared for torque? Any info helps, thanks.
1947 IH KB5
1951 GMC Pickup
1956 IH S110
1968 Chevrolet Chevelle

Site Admin
Site Admin

Posts: 4519

Joined: Thu Nov 29, 2012 9:10 am

Location: Nampa, Idaho

Post Mon Apr 09, 2018 11:09 am

Re: 1947 KB-5 Differential

You will need any and all numbers you can find on it. Have you looked above the glove box to see if the Line setting ticket is there?

Pile of Parts
Pile of Parts

Posts: 46

Joined: Tue Jun 21, 2016 9:43 pm

Post Mon Apr 09, 2018 11:14 am

Re: 1947 KB-5 Differential

lbesq wrote:You will need any and all numbers you can find on it. Have you looked above the glove box to see if the Line setting ticket is there?


I’m not able to check the truck any time soon but a few references lead me to believe it’s a 2 speed vacuum shift rear axle? Maybe Eaton with a triple diamond cover plate?
1947 IH KB5
1951 GMC Pickup
1956 IH S110
1968 Chevrolet Chevelle

Golden Jubilee
Golden Jubilee

Posts: 3366

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Mon Apr 09, 2018 7:00 pm

Re: 1947 KB-5 Differential

As to what they can handle, I've heard of stock (233 flathead) snapping axles. It comes down to the driver, the load and the traction.
Since replacement ring and pinions are almost non-existent, Same for cross and spider gears, diddo again for axle shafts, I would tread lightly.
Having said that I have read of K-7's pulling semi trailers loaded to 40K back in the day, They can likely handle a fair bit if it done gently. I've pulled my semi tractor out of the mud, I have grossed 18,000 lbs and drove it over 500 miles.
If you are thinking of dropping a V-8 and doing 4 wheel burn-outs, no it will not stand up to that.
I have pulled 170,000 lbs thru a 14" double disk clutch ( rated @ 900 ft lbs) @ 1450 ft/lbs of torque and a trans rated at 1100 ft lbs and rears rated only for 120,000lbs gross. It all come down to being easy on stuff.
I'm still running the same today decades after I did those heavy hauls. It comes down to some people can break an anvil with a rubber hammer, and others can exceed the rated capacity of something by 2 or more times with little to no ill effects.
The splines in the 1/2 shafts are not cut deep, nor are the axles shafts that large, the gears they mate to aren't very beefy. The ratio is likely to be very low (lots of reduction) so it will be easy to over torque when the power is multiplied thru the deep reduction.
User avatar

Golden Jubilee
Golden Jubilee

Posts: 4349

Joined: Thu Nov 29, 2012 11:47 am

Location: Bothell, Washington

Post Mon Apr 09, 2018 8:02 pm

Re: 1947 KB-5 Differential

International generally didn't put line setting tickets in the K model, started in the 50s, MAY be an exception to this but generally they didn't
Gentle Men! you can't fight in here! This is the war room!

Pile of Parts
Pile of Parts

Posts: 46

Joined: Tue Jun 21, 2016 9:43 pm

Post Mon Apr 09, 2018 8:56 pm

Re: 1947 KB-5 Differential

Thank you for such a good reply. Yes I was a bit scared of dropping in the V8 and overworking that old diff. I’m pretty sure I’ll be turning the truck into sort of a rat rod-motor home to use for short camping commutes during the summer. The V8 I have is a 454 from a 1974 Chevy motorhome, which I’m sure is pretty good for the job. It’s got about 230 horsepower and about 385 ft/lbs of torque. Which clearly much more powerful than an old green diamond. (The GD is no good by the way) I’m thinking the homebuilt camper on the back will be about 2000-3500 pounds dry (complete estimate) so the diff should easily be able to handle the slow and steady acceleration with the 454 and a 4 speed standard. I’ll probably end up swapping the rear axle out sometime anyways just for added peace of mind. What do you all think?

seccond of all I got my brother to send a picture of the rear cover plate. It’s not exactly the best picture but bear with me he’s only 10. You can faintly see the Triple Diamond logo on the cover and the configuration of the bolts etc. It is a 2 speed axle (axle shifter in the cab) this may not tell too much about it but has anyone seen many of the triple diamond covers? I’m pretty interested on the rarity of that cover. (And of course the diamond logo is just a blurred spot in the picture, I can’t get it to be any better but it’s about 4 inches long or so, stamped from the inside) (THE “Example” PICTURE IS THE ONLY ONE I CAN FIND ONLINE OF AN IDENTICAL DIFFERENTIAL WITH DIAMOND LOGO)
Attachments
C2C5CE94-AC61-484D-A224-6FA2C3C67AB8.jpeg
Online example
FA3C31C7-CB88-4978-8C73-284BFB56D301.jpeg
My KB-5
1947 IH KB5
1951 GMC Pickup
1956 IH S110
1968 Chevrolet Chevelle

Golden Jubilee
Golden Jubilee

Posts: 3366

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Tue Apr 10, 2018 10:35 pm

Re: 1947 KB-5 Differential

As to the rear cover with the triple diamond, not rare at all, all of them from that era (on IHC's) had that.
Both my K-7's do.
Most two speeds of that era were vacuum shift, but linkage was an option I believe.
My order of preference for 2 spd axles are:
1) air shift with piston
2) air shift with diaphragm
3) vacuum shift
4) electric shift
5) mechanical linkage.
I find the vacuum shift works well when maintained. Both my K-7s have it.
I have air piston on my Marmon tandem 2spds, and it works great.

Pile of Parts
Pile of Parts

Posts: 46

Joined: Tue Jun 21, 2016 9:43 pm

Post Thu Apr 12, 2018 9:53 am

Re: 1947 KB-5 Differential

Thanks all. I’m pretty sure from memory that mine is an air piston shift axle.
1947 IH KB5
1951 GMC Pickup
1956 IH S110
1968 Chevrolet Chevelle

Golden Jubilee
Golden Jubilee

Posts: 3366

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Thu Apr 12, 2018 8:14 pm

Re: 1947 KB-5 Differential

doubt it, the truck would have to have air brakes or at least an air compressor, most had a vacuum chamber and vacuum shift.

Return to K and KB

Who is online

Users browsing this forum: No registered users and 0 guests

Powered by phpBB® Forum Software © phpBB Group
Designed by ST Software for PTF.