Wrecker Broken CV Joint

[wcuhillbilly]

yes that double Ujoint was common in the 80s/early 90s GM too, Ford if I remember was the culprit behind the infamous Dana 61 axle that looked like a D60 but nothing interchanged with anything.,, and the cost to rebuild was astronomical, as in you could redo the axles under two trucks for the cost of that one front axle..
By my comment, I was refering to using Over The Road Truck PTO parts, not pickup or junkyard car parts, as the later will get me by jerry rigged, but where Im at I cant just hop down to O'reillys or the Zone and bring back a new whatever. This shaft turns at engine speed, 800-2000rpm and gobbs of torque thus Im a little skiddish of a joint from a Geo, or even pickup, that may be putting out 200ft lbs of torque where my 855 is putting out 800 compounded by gear reduction etc.
So,,,, lets not turn my lack of clarification into a GM vrs Ford.... even though my truck (sig) is a Johnny Cash Cadilac.

 

[Jakelc15]

I make PTO shafts at work with off the shelf parts from a local truck shop. Most are crank driven so they also run at engine speed. You just buy the yokes and joints you need and cut the shaft to length.

 

[saddamsnightmare]

November 1st, 2016


Any truck machine shop should be able to salvage and weld a new CV joint off of a large civilian truck to the end of your failed driveline. However, you will have to take said driveline components off the truck to haul them in. I had a Ford F250 that blew the rear U joints, we fitted two off of a 1-1/2 or 2 ton truck...never had that problem again!

 

[adamsoffroadperformance]

yes that double Ujoint was common in the 80s/early 90s GM too, Ford if I remember was the culprit behind the infamous Dana 61 axle that looked like a D60 but nothing interchanged with anything.,, and the cost to rebuild was astronomical, as in you could redo the axles under two trucks for the cost of that one front axle..
By my comment, I was refering to using Over The Road Truck PTO parts, not pickup or junkyard car parts, as the later will get me by jerry rigged, but where Im at I cant just hop down to O'reillys or the Zone and bring back a new whatever. This shaft turns at engine speed, 800-2000rpm and gobbs of torque thus Im a little skiddish of a joint from a Geo, or even pickup, that may be putting out 200ft lbs of torque where my 855 is putting out 800 compounded by gear reduction etc.
So,,,, lets not turn my lack of clarification into a GM vrs Ford.... even though my truck (sig) is a Johnny Cash Cadilac.

actually the Dana 61 was dodges front axle they used not Ford. and as per power through it. that little cv is most likely not as strong as the cv used on a pickup truck. just because the 855 makes a lot of torque it doesn't mean it's being applied to that little shaft. there is not much load on that shaft even if the wrecker is being used to its maximum. ifso you would see a driveshaft the size of whats on the axles going to the wrecker drive. before you say that cv wouldn't handle better look up the torque strength rating of each the cv and the spicer double cardian joint. I'm willing to bet they are almost equivalent. everyone is trying to make something so simple into a headache.

 

[Swamp Donkey]

the one in the pic comes up if you google 5ton m939 CV so it was used for something. I've come across them on other parts dealers websites so they got them surplus

It was used on the M936 wreckers. See screenshot below...

 

[adamsoffroadperformance]

so there's a good chance it could be retrofitted to work with an 816 wrecker without too much fight.

 

[Jakelc15]

The 936 system is immensely simpler than the 816. The 819 is actually a simpler system also but it doesn't rotate 360°.

On a side note. I've used portable electric power packs to cradle hydraulic booms and outriggers. One might get you out of the precarious boom position that you are in and then you could move the truck to an easier place to work on it. Tapping into the wet lines on another truck could work too.

 

[red]

Diagram of the crane side of the PTO shaft. Looks like the old CV joint and it's oval gear box can be removed, then take the input shaft out and have a more standard joint installed on it.

View attachment M816 crane gear case assembly.pdf

Question with that is, how much will the crossmember in the crane beds subframe need to be modified for clearance?

 

[wcuhillbilly]

Thanks guys for the diagrams, Been out trying to knock down an elk for the past week.... I looked for the diagrams but didnt have a day or two to dig through them all. Talked to Jeff Davis about retro fit of a 936 and ultimately that is the way to go if $$$$ wasnt a problem, but for now and living here in nowhere land, fabrication of an OTR or Agg style PTO shaft is going to be the solution. neighbor up the creek has a machine shop and worked in the Bakken oilfields for the last 20 years as well as driving OTR trucks, thus he has a good understanding of what is needed.
Plan is to eliminate the long extension housing and the oval box, remove the shaft associated with these two. Use the small extension housing, mill an end cap for it with a seal and bearing retainer, cut down the long shaft and fit it with a yoke. insert new modded shaft into milled end cap and fit to small housing. Cut CV shaft and attach a flange or slip joint for ease of install and route a couple double U joint up to the crane drive.

 

[Csm Davis]

Thanks guys for the diagrams, Been out trying to knock down an elk for the past week.... I looked for the diagrams but didnt have a day or two to dig through them all. Talked to Jeff Davis about retro fit of a 936 and ultimately that is the way to go if $$$$ wasnt a problem, but for now and living here in nowhere land, fabrication of an OTR or Agg style PTO shaft is going to be the solution. neighbor up the creek has a machine shop and worked in the Bakken oilfields for the last 20 years as well as driving OTR trucks, thus he has a good understanding of what is needed.
Plan is to eliminate the long extension housing and the oval box, remove the shaft associated with these two. Use the small extension housing, mill an end cap for it with a seal and bearing retainer, cut down the long shaft and fit it with a yoke. insert new modded shaft into milled end cap and fit to small housing. Cut CV shaft and attach a flange or slip joint for ease of install and route a couple double U joint up to the crane drive.

Looking forward to seeing this modification I don't think you will even need the double cardigan joints but maybe, the angle will tell. Take lots of pictures.

Sent from my SM-G900V using Tapatalk

 

[wcuhillbilly]

Looking forward to seeing this modification I don't think you will even need the double cardigan joints but maybe, the angle will tell. Take lots of pictures.

Sent from my SM-G900V using Tapatalk

Jeff did you ever look at that scrap 936, about the hydraulic system converting to mine.????? any prices??
Joe-307-282-0773

 

[wcuhillbilly]

Well I stumbled out of my beach chair and poured myself onto a 3rd world airport flight back to the frozen north,,,,, was -40 here while I was in Honduras, thus I was not looking forward to laying in the snow trying to put the wrecker back together.
Machinist neighbor of mine, called me the day I left Dec 7-(Remember Pearl Harbor) and told me the cap and shaft were ready for install.

(insert pics..... computor is screwing up again...)

When I took the extension housings off originally I did not find the allen key that allowed the stub shaft to be removed, Thus we designed the new output around having to use this female stub shaft.... I later found that there is an allen screw that keeps this stub held to a key way on a smaller stub shaft. If I had found this earlier Then we could have dropped the shorter extension housing too.

Basically, my machinist milled a cap with seal and bearing inset with a drain hole to return the oil back to the short extension housing. He milled a shaft to insert into this bearing housing and snap ringed the shaft and bearing so they dont move once inserted into the cap.








The flange ended up being pressed onto the shaft, I had hoped that it could be removed as it has a set screw as well. So as to re drill a new face pattern if need be.


IF you end up having to dissasemble your power divider down this far,,, watch the stub shaft from the power divider, once the little collar extension is removed, there is a small rubber bushing that likes to stick to one or the other and is easily lost. The key on this shaft is a woodruff, thus a half moon key, and likes to walk on re-assembly. IF it gets out to the rear, the collar will not seat, and the new shaft assembly will not mate up..

 

[red]

Without the short extension, do you think the crane PTO shaft would be able to go above the truck crossmember? Or have to stay below it? Crossmember right by the linkage in this pic




Oh and jealous of the beach trip. Granted my skin gets more red than my hair at the beach but still jealous hahaha.

 

[wcuhillbilly]

Without the short extension, do you think the crane PTO shaft would be able to go above the truck crossmember? Or have to stay below it? Crossmember right by the linkage in this pic

View attachment 659499


Oh and jealous of the beach trip. Granted my skin gets more red than my hair at the beach but still jealous hahaha.

I doubt the shaft could pass above crossmember, the pic does the actual config no justice. I need to get the CV mocked up and shoot an angle and lenght to start chopping the old shaft for extension. I will likely have to pass through or cut out a section of that crossmember

Tune in next time for more exciting fun wrestling a pig in the mud,,, or in this case---snow

 

[red]

That's what I was afraid of, not looking forward to doing this kinda mod when the time comes haha.

Did some parts searching for converting to a m936 type setup (pump on the truck instead of the crane) and found a few companies that make the hydraulic rotary union we would need. Link to one manufacturer http://www.dsti.com/products/rotary-unions/gp/2-pass/ A low pressure 2 passage rotary union attached to the base of the crane, 4 new hydraulic hoses rated for 2k psi, new mount for the pump, and build a new PTO shaft from the power divider to the pump would do it. The low pressure system saves us alot of money on hoses and the rotary at roughly 50% but it would still cost more than the PTO shaft setup you're going with.

 

[wcuhillbilly]

Thanks red, the ultimate fix is a hydraulic setup, I know I will have to convert sooner or later, but this will get me up and rolling for less than a grand hopefully, however I want to start making proactive tracks toward hydraulic so that I'm not stuck when the 10speed mod goes in.

 

[red]

before you say that cv wouldn't handle better look up the torque strength rating of each the cv and the spicer double cardian joint. I'm willing to bet they are almost equivalent. everyone is trying to make something so simple into a headache.

Wouldn't say the strength is the big concern, it's the angle. The stock m816 crane PTO shaft sits at about 35 degrees, it is a absurdly steep angle for a joint. Typical driveshaft CV joints are good for 30 degrees or less. Get rid of the extension housings and oil pans for the stock CV's and install a longer PTO shaft like wcuhillbilly is doing. Just have to figure out how to clear/modify the 2 crossmembers and other linkage. So not exactly a simple task.

 

[wcuhillbilly]

Ok, warm weather and off work early today, really sad when you call 35*f and sunny warm,,,, re-installed the old CV shaft on crane drive to check lenght and angle of the dangle. As feared the chassis crossmember was in the way. After much deliberation I came to the conclusion that it had to be cut, feeding the shaft in place via a hole was not doable, a carrier bearing on the crossmember would cause a steeper angle than the old CV config. And shimming the pwr divider lower would conclude with angle issues as well.
So cutting a hole alows the shaft to come within 6 1/8 of the flange with a 26* angle, this is doable with universal or cardan joints now. Iirc the CV shaft used to run at 33-37* of angle. Now when the 10spd goes in. I will be back at square one re-engineering everything I just did. Got cold so I pulled the shaft and will now go back to the drive line shop and find a slip for my old CV shaft splines








AAARRRRR!!!!! Computors hate me... I had these pics uploaded the other day, but today only one of them is actually here.... ok,,, now that that's fixed,,,,

The linkage shouldn't be a problem, it is very close, but there is enough wiggle room to raise it by re-drilling the mounting holes at the top of the drop bars and cutting off an inch or two. I will likely have to cut some more out of the crossmember, and likely come back and weld some plate around the cut out section for reinforcement as it really goes against my grain to torch out a chassis crossmember and not put some kind of structural integrity back in its place.

 

[red]

Haha I was wondering when those other pics would finally upload for ya. Don't know how much offroad driving you do but even our reinforced wrecker frames flex in that area. Figure 2-3" of clearance between that PTO shaft and the frame rail should be good.

Short video of mine for example.

https://www.youtube.com/watch?v=99jQOldO8oY

 

[wcuhillbilly]

Nice,
Machinist called about an hour ago, said he had a plan to finish it up. Basically taking the stock shaft and welding up the PTO side splines, turning it down and cutting 16 splines into it to fit my new high angle 1330 yoke, this yoke has extra long ears so it can run at 30* which gives me 5-6* to play with. This will also give me a slip yoke to ease re-assembly. Picks and part #s soon, as it's about 0*F outside so I have no desire to go lay in snowman poop and fight a sub zero pig