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Driveshafts

m-35tom

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OK I have a 94 A0 that has driveshaft problems. So what I find is that these trucks came with the driveshafts not balanced at all. Seems stupid. Then there was a program to replace the shafts and stamp a D on the dash plate. My truck came with those shafts and 2000 miles. The rear shaft has .050" side play in the slip joint and .080 side play in the front shaft. This is WAY more than even remotely allowable. Spicer says max .003. I bought a new shaft but it did not have any balancing weights so I had it balanced and installed it. No side play in slip but it has not been driven. Is this shaft going to fail? It seems to me that there were simply defective shafts being used up to about 2000. Many large trucks go 300k and way more on the same driveshaft, Why can one of these trucks not even go 2000 miles? Yes I have read the published info about the shaft problem but I don't completely believe it. There had to be a serious problem with the manufacturing of the shafts for them to fail. Any insight into this appreciated.
Tom
 

coachgeo

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OEM NOS shaft replacements are a waste of time and money if one feels they can just slap them on and go. Also not so good shafts may get swapped onto trucks with little use or planned to be auctioned (drivable trucks are easier to move around even if they plan to just auction them.) Suspect the good shafts removed end up used for other rigs still motoring around troops? Sorry to hear you learned this stuff the hard way.

That being said NOS shafts from auctions etc... they get thrown into crates etc...... which can knock them out of balance.... and for all we know if someone bought a crate of them that had been sent to auction could well be they were decommissioned cause military found to be out of spec right from the manufacture??

Anyway... Parts they are made from are nothing that any driveline shop that does big rigs can't get or probably have on shelf. Just go to a competent driveline shop and have them made and balanced properly from the very get go.

Granted picking up low cost NOS shafts for parts when the price is right might work to your advantage... If you need to repair a shaft prior to balancing take the extra parts with you to see if swapping will save you any funds.
 
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simp5782

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Driveshafts do not always need to be balanced.

The shaft takes normal 1610 joints in a 3 or 3.25 tube nothing uncommon for any shop to get to make on the spot. Something else may be wearing it out if you have any increased temp in input bearings on the axles or outputs on the transfer case. Most of the time the shafts are just phased wrong with creates some chatter but not overwhelming enough to wear a slip yoke out
 

NDT

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How did you find that the factory drive shafts are unbalanced? They were removed in the field by Stewart and Stevenson employees and destroyed. The new driveshafts and bellhousing is better able to withstand the vibrations generated by the driveline angles.
In almost no cases do these trucks have 2000 miles or less, the speedometers were replaced due to failure.
Like Simp mentioned, for some reason the modern Army thinks that driveshaft phasing is optional, resulting in rapid spline wear, transmission wear, and wheel end spider gear wear.
 

m-35tom

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I bought a new rear shaft from Memphis, it had no weights on it, I took it to a shop to be balanced and it came back with substantial weights on each end. The problem is I don't trust this shop due to past experience, but they are one of the 2 places in Maryland.
 

simp5782

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Check with member John Appel. He may know someone in the area. I know of a good shop in Trenton, Pete's welding and driveline. Family has been in the driveline business for 60 years atleast.
 

m-35tom

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Right, like I said not reliable. I would not trust them after what they did to me. And there is a place in Baltimore, does crap work.
 

PiperSkyRat

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I have had great service from a place called Florig equipment in Conshohocken pa. They have been in business for more than 30 years and I have never had an issue. Highly recommend for drive shafts and spring re-arching.
 

simp5782

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Quality repair is never too far. Spend money on crap you are going to have to keep going back to have fixed.

Are you sure Memphis sold you a new shaft anyway? They do repurpose stuff and send it to their paint shop where they make it look like NOS when it's really a take off
 

tobyS

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Why don't you buy the components and build it with the help of a machine shop?

Did Wes say a 1610 u-joint?
 

simp5782

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Why don't you buy the components and build it with the help of a machine shop?

Did Wes say a 1610 u-joint?
1610 is the series of heavy joint for large trucks. 1610s are a 279x u joints. Same joint that the front driveshaft and the between tandem shafts on a 809/939 use. 1710s are a heavier wider joint that are the 280x part numbers. this is the transfer case to the front tandem on a 809/939 and on some of the 5 ton FMTVs. Then there are 1810s which are big big joints.
 

tobyS

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1610 is the series of heavy joint for large trucks. 1610s are a 279x u joints. Same joint that the front driveshaft and the between tandem shafts on a 809/939 use. 1710s are a heavier wider joint that are the 280x part numbers. this is the transfer case to the front tandem on a 809/939 and on some of the 5 ton FMTVs. Then there are 1810s which are big big joints.
All of the components are readily available for the 1610 u-joints including flange yokes, weld yokes, male and female slip yokes and tube. Tube seems to have different thickness, 3.5" dia.
 

Suprman

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From my experience, the slip joints wear out from highway driving. With the 2-1 hub reduction at 58mph those driveshafts are really humming away. Once you get play in the driveline you run the risk of throwing a driveshaft. This happens way more often than one would think. The manual has a hinging test it states .0015 inch of play is bad. The local unit that I know a few guys at say they cut that amount in half.
 
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