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IH Unistar

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Ok guys, first off this is not mine nor do I know the seller. I contacted him about the truck hoping I could pick up one of the rarest IH trucks built! unfortunately with my budget, shipping, and it missing the correct front axle, I am not going to be purchasing it. I wanted to share with the group in case someone has been looking for one of these. The book I have states only 19 were built. After a few email exchanges, sounds like he is somewhere around $4k. I know that this should probably go to the IH trucks category, but the rare stuff doesn't come up too often and would make one heck of a show stopper with some work and money!

 

https://inlandempire.craigslist.org/hvo/d/1971-international/6741162036.html

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Just curious what is unique about a unistar? What front axle should it have? Neat looking old truck.

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1 hour ago, iowaboy1965 said:

Just curious what is unique about a unistar? What front axle should it have? Neat looking old truck.

I'm pretty sure they were all wheel drive.

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Yes, the Unistar had a driving front axle, I don't know what one.  There was an overriding clutch in the front driveline so that the front didn't pull until the rear began slipping.  Its intended purpose was to pull freight in the mountains of the west in the winter and they appeared to do this well.  I heard that under some conditions, they were exempt from the chain laws that slowed other trucks.  Unistars were popular with some fleets such as PIE.

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Interseting!

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Yes.  In the front of the diff housing was a 31 tooth gear on the pinion shaft driving a 32 tooth gear connected to the yoke for the front driveline.  This gave a 3% difference in speed so the overrunning clutch, called the clicker, didn't engage until there was a 3% slippage of the rear wheels.  Here's a page from the brochure describing how it works.885523585_UnistarDriveline.thumb.JPG.0568a1a217dd7fae7560fd227516a302.JPG

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Here's an article touting the Unistar's capabilities at its introduction.

1704862398_Unistar1.thumb.JPG.2b98722474a0e5b7dceadbe880c0572b.JPG721114387_Unistar2.thumb.JPG.6d1e0ca14fe084a6fb6b0be593aff8ea.JPGI recall reading that some fleets stationed a Unistar at a pass to serve as a pusher to get their other trucks across the pass in the snow.

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Were they all single axle? Not counting the driven steering axle.

 

Dennis

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Should have read the article first.

Dennis

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It looks like the truck in the link does not have a “driving” front axle, but rather a straight or regular front axle where as the truck in the article clearly shows a driving ( pumpkin) axle. Am I missing something? Front axle been changed on the truck for sale? Buyer beware?

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11 hours ago, jingles1928 said:

Were they all single axle? Not counting the driven steering axle.

 

Dennis

Yes, and no.  There was not a tandem rear axle option for the Unistar.  There was something called a Jifflox Dolly which was a dolly for under a trailer that locked into the trucks frame making it into a tag axle.

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3 hours ago, Ihfan4life said:

It looks like the truck in the link does not have a “driving” front axle, but rather a straight or regular front axle where as the truck in the article clearly shows a driving ( pumpkin) axle. Am I missing something? Front axle been changed on the truck for sale? Buyer beware?

The first post points out it doesn't have the correct front axle.

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6 hours ago, R190 said:

The first post points out it doesn't have the correct front axle.

Guess I missed that...☹️

Whoops

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Wonder if a person could back track its history , might get lucky and find all or some of original parts somewhere? Doubtful but worth a shot. Hope somebody does save it and restore it. Would be pretty unusual. Maybe we can talk tonyinca or dirtboyz into it? If nothing else to preserve it till somebody else wants to tackle it....

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Sounds like it was pretty good innovation. Why didn't it catch on? Are there systems in big trucks now that perform a similar function?

Paul

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My guess is this is one of those things that got killed by changing market.  That rig came out just as trucks were changing from smaller rigs with less power, to the Interstate 10 wheeler seen everywhere today.   Singled trucks are limited in load capacity...and everybody has to carry max load allowed by the government, of course!   Also, the heavy front axle would have cut into maximum load.   Modern dual rear axles with lockers means the weight of the load is all over the driving wheels, unlike a single with 4x4 front axle.   Also, I would guess those overrunning clutches and front axle steering u-joints were a maintenance issue.   

A modern 6x6 truck with electronic engagement of all three axles would solve most of the problems....except weight.   Anything that adds extra weight and cuts into payload is rejected by the big fleets--unless government mandated.

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Not that to follow what happens in California is good for the country,but still a lot of every kind of freight is moved by double trailers and 2 axle tractors out here. Until you have them sliding on ice there are many advantages to double trailers. From my very limited experience a set of double flats is good  for several more tons than a 48 foot semi. There are a lot more big aluminum semis than 20 years ago when I was loading grape bins on them, so maybe not as much a issue today.  From what I know they don't worry about the traction and are running the same 400 to 600 hp the three axle tractors run. So maybe as good as they get around there is not much demand for a 4x4 tractor after all. LOL

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I've seen a lot more triple axle trailers in the last year or so,  not sure what they can legally haul,  maybe 40,000# on the 3 axles, maybe a bit more, with only the added weight of an axle and suspension. Single axle with duals is 20,000#, tandems is 32,000#, steering axle is 12,000#  Lot more tractors with a air lift tag axle too.  Company I used to work for regularly shipped a 68,000# rotor assembly, mostly to the east or west coast from right along the banks of the Mississippi.  Had to have those extra axles. We shipped a 40,000 to 45,000# assembly monthly, sometimes much more often, like three in one day plus the 68,000# monster in Feburary of 1989. We learned that aluminum trailers were not suitable for our shipments, too much weight in too short of length, bent the arch out of the trailers. Shipper actually took us to court to pay for a new aluminum trailer years before I started there,  we specified steel trailers after that, or they would load aluminum trailers at the carrier's risk.

The one article says a Unistar with 12,000# on the frt axle and 20,000# on the rear axle outpulled a tandem axle truck that could have up to 32,000#. With a power divider engaged, both axles driving I'm not sure I completely believe that.  Back when I drove I had a Summer 5th wheel setting and a winter 5th wheel setting, carried more weight on the tractor in winter, and an extra 1000-1500# on steering axle. With air latch on 5th wheel I could adjust in a minute or two. 

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From what I remember reading, it was a great idea but insurance and liability helped kill them off. If the roads were so bad you needed a 4wd tractor to pull trailers you probably need to keep the trucks off the road.

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45 minutes ago, Eason said:

From what I remember reading, it was a great idea but insurance and liability helped kill them off. If the roads were so bad you needed a 4wd tractor to pull trailers you probably need to keep the trucks off the road.

For sure.  and maybe the 4x4 helped keep you going up the hill...but sure wasn;t gonna stop the trailer coming around the tractor coming down the hill if it was that slick.

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2 hours ago, DOCTOR EVIL said:

I've seen a lot more triple axle trailers in the last year or so,  not sure what they can legally haul,  maybe 40,000# on the 3 axles, maybe a bit more, with only the added weight of an axle and suspension. Single axle with duals is 20,000#, tandems is 32,000#, steering axle is 12,000#  Lot more tractors with a air lift tag axle too.  Company I used to work for regularly shipped a 68,000# rotor assembly, mostly to the east or west coast from right along the banks of the Mississippi.  Had to have those extra axles. We shipped a 40,000 to 45,000# assembly monthly, sometimes much more often, like three in one day plus the 68,000# monster in Feburary of 1989. We learned that aluminum trailers were not suitable for our shipments, too much weight in too short of length, bent the arch out of the trailers. Shipper actually took us to court to pay for a new aluminum trailer years before I started there,  we specified steel trailers after that, or they would load aluminum trailers at the carrier's risk.

The one article says a Unistar with 12,000# on the frt axle and 20,000# on the rear axle outpulled a tandem axle truck that could have up to 32,000#. With a power divider engaged, both axles driving I'm not sure I completely believe that.  Back when I drove I had a Summer 5th wheel setting and a winter 5th wheel setting, carried more weight on the tractor in winter, and an extra 1000-1500# on steering axle. With air latch on 5th wheel I could adjust in a minute or two. 

12k on steer, 34k on tandems, 20k on single axle and if spread axle trailer 20k on each axle I believe. But you can’t exceed weight capacity on tire as stated on sidewall. Don’t remember much on bridge laws.

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On 11/17/2018 at 11:49 AM, Jeff-C-IL said:

For sure.  and maybe the 4x4 helped keep you going up the hill...but sure wasn;t gonna stop the trailer coming around the tractor coming down the hill if it was that slick.

 Based on what the design looks like there,  I don't think the front axle was capable of being engaged for holding back going down hill. 

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