Drilling C30 dually hubs for 5 x 8" wheels

[LynnB]

Sorry for the long post.

I have this really cool 1949 Studebaker 1.5 ton farm truck. I use it regularly. I have posted a few times over the last 7 years in the “heavy haulers” section, mainly because I replaced (engine swap) the old flat head six (96 hp when new) with the engine and trans out of a 1972 C50.

Could not be more pleased with the swap.

The rear axle is a 6.66 gear. My five speed is NOT the OD model. That means, even with tall 235 80 17 tires I am spinning at 5200 RPM just to go 70 miles per hour. Low gear is virtually useless. I normally start out in 3rd without a load, and even with a load, unless I am going uphill.

I have a chance to purchase a 4:10 rear axle assy out of an 80s C30 dually.

If my calculations are correct, a 4:10 rear with the same tires would get me right at 3200 RPM at 70 mph. Quite the improvement. Getting ready to call the seller and get all the measurements to make certain I can make it work. I am adept at fabrication, so no worries there. Just need to make certain the flange to flange measurement is in the ball park. Doesn’t have to be exact, as it is a flat bed (actually a dump bed, and it still works, which is GREAT when I haul a load to the dump. Don’t even have to get out of the truck.

I REALLY want to keep my wheels. I know the easiest thing to do would be purchase four 17 inch dually wheels in the right size, which I BELIEVE is 8x6.5" Bolt Circle with 4.56" Center Bore. But then I have to carry TWO spares, one for the front and one for the rear. Also, finding that lug pattern in a 17 is a challenge. Most are 16s, and I can’t do that as I have six almost brand new Michelins (take offs from a 3500HD) on the vehicle right now.

Chevy bolt pattern: 8x6.5" Bolt Circle with 4.56" Center Bore

Studebaker bolt pattern: 5 X 8" Bolt Circle with 6.050 inch Center Bore


What I am wanting to know is if the hubs on the Chevy rear can be drilled for 5 x 8" bolt circle.
I am not worried about the difference in bore size, as I can have hub centric rings fabricated to make certain the wheels are centered.

Anyone have hubs bored for a larger bolt circle?

Is there even enough extra metal to go 8 inch?

Thanks in advance for any help.

[mongocanfly]

without pulling a wheel off, i dont think the C30 has enough hub for a 8in bc
also theres 2 diff widths of axles for a C30..theres true dually and the narrower cab&chassis
you might could pull it off with "custom" adapters...

[72c20customcamper]

My uncle had a 47 Studebaker tow truck . It had a two speed rear in it not sure if it was factory or if he did the swap . But since he was a Studebaker dealer I assume he ordered it that way

Do you belong to the Studebaker Drivers Club ? If not I would look into it as there is a wealth of info from them

[v30crewcab]

what about the 92-2000 3500hd setup? they ran a dana 80 with a 10lug in the rear and only used 5 lugs in the front. some motor home chassis used the same wheels.

[LynnB]

Originally Posted by v30crewcab

what about the 92-2000 3500hd setup? they ran a dana 80 with a 10lug in the rear and only used 5 lugs in the front. some motor home chassis used the same wheels.

Tried to find one of those rears, but seem to be really scarce. The bolt pattern is much larger, so may be a better candidate. I made a deal on one a few years ago, about 200 miles from me. Seller had already sold the work bed off of it.
It was a diesel with a five speed with O/D. That meant to trans would be a direct bolt in (one inch input shaft) for the five speed NP trans I currently run.

It had not run in 7 years but cosmetically was in outstanding condition. When they guy found out I was planning to part it out, using the trans and possibly the rear on my Studebaker he backed out. Couldn't stand the thought of his truck getting cannibalized.

[kwmech]

I'd be looking for the 2 speed rear and an over/under drive like a spicer unit

https://6066gmcguy.com/spicer-5831-b.html

or a brownie box of the same

https://www.bigmacktrucks.com/topic/...speed-brownie/

[LynnB]

Yes, I am on the Studebaker forum. Great folks on there always willing to help. Precious little info on the big trucks though. I have not been on the Studebaker truck forum in a few years. I can't get to it for some reason. Keep getting diverted to a talpatalk website.