U-J tech

[ntsqd]

This probably should be in one of the more specific sub-forum tech sections, but I'm looking for input across the board and didn't see a better spot to put it.

CTM u-joints; who's run them long enough to know their good and bad? Seems like they're really made for crawling, but what about use at speeds under, let's say, 40 MPH for more than just a short hop. How well do they stand up to that? I've been trying to access their page for a couple of weeks and I keep getting "Page under Construction" notice with basic contact info. I'm hoping to hear of real world use before I call them with stupid questions.

Specifically I'm thinking about stronger U-J options for the Blanc-Oh's TTB. I did look at RCV's, but their tech guy is saying 3500 mile service interval and for the center CVJ that means removing it to lubricate. A feller at PartsMike is saying that's if always used hard, incidental use should go a lot further, but he's not RCV saying that and it still has to come out to do the service. Which got me to wondering about the CTM U-J's

 

[Dusty]

I had CTM's in my trail rig EB years ago. I just kept them greased and never had any problems. But that was a trail rig that got trailered everywhere. And in a straight axle D44 where the only u-joints are easy to get to. I can't recall ever seeing a critique of them for more sustained highway use.

Why such worry about u-joints in the front end though? Is it full time 4WD/AWD? Or are you anticipating some long stretches in 4-hi?

 

[ntsqd]

Longish stretches in 4-Hi are very possible. My biggest concern is that if that UJ fails and tears up some of the attached bits it will be a copper-plated SOB to remove. Don't really want to be working on it in BFE, Nevada/Utah/Idaho/Arizona/you get the idea.

Confirm that you have to grease each CTM cap individually? And thanks!!

 

[Dusty]

Longish stretches in 4-Hi are very possible. My biggest concern is that if that UJ fails and tears up some of the attached bits it will be a copper-plated SOB to remove. Don't really want to be working on it in BFE, Nevada/Utah/Idaho/Arizona/you get the idea.

Confirm that you have to grease each CTM cap individually? And thanks!!

10-4. Yeah the cross is solid. Grease each cap. On the TTB isn't that inner u-joint sort of exposed? Seems you should be able to get to it to lube it. Also what size tires are you going to be running, and will there be a hard locker? If the tires aren't ginormous and you're not spooled and bound up on rocks a lot, it seems the Spicer joints would be up to the task?

 

[ntsqd]

Thanks!
The center UJ is fairly exposed. Greasing a CTM there wouldn't be the end of the world. Could possibly even leave normal zerks in place. I'd have to check on that.

35-12.50R15's right now, moving to 315/70R17's as soon as I can get the rest of the 8 lug parts and suspension pieces (new Solo Motorsports Beams, OX-Locked rear D60) here and bolted together. Contemplating an ARB for the front diff once I've recovered from this work and the soon to be here 408ci.

BTW, news to me that Spicer is now offering a version of the 760 UJ that has a Blue polymer (?) coated UJ body. Supposedly a LOT more corrosion resistant than the std UJ. I didn't know that corrosion was a big problem, but maybe it is in other parts of the country.
5-760XC

[EDIT: Fixed that link]

 

[ntsqd]

hum, well, now I see why the center joint yoke needs to be clearanced to not bind with any kind of reasonable wheel travel. This shows the max angle that the unmodified parts will tolerate:

Curiously, the angle at 90° to that is far greater. Why the stub axle would get more clearance than the slip-yoke is baffling.
BTW, those three bolts mean that I can put an ARB in the front of this truck! Yea!

 

[Mark]

Servicing RCV’s is more of an issue for rigs with unit bearing, and no locking hubs. So those parts are always in motion, whether in use or not. I recently bought them for mine, and I’m now in the habit of unlocking my hubs more frequently. Axle shaft quality is why I went with RCV’s. It’s amazing that 90% of the torque steer is eliminated with these axles, while running around with only a front driveshaft. I only have a couple of trips on them, so no long term reports yet..

Mark.

 

[ntsqd]

No locking hubs would sure rack up the miles on those joints, even if they aren't under a load. The guy that I talked to at RCV knew exactly what axle I wanted them for because we had just finished figuring out which p/n my truck would use.

The steering RCV CVJ's wouldn't be too bad to access for lubrication. Might even be able to access them w/o disassembling the whole knuckle. In a TTB that center joint is exposed but there's not a lot of room around it. Greasing a serviceable UJ there in the center would be reasonable, but I suspect that a CVJ would have to come all of the way out to be able to lubricate it. Right now I'm not sure how all of that would even assemble.

For now I'm just running the 5-760's. We'll see how well those last. I'm a little disappointed that those that I have lack a hole for a grease zerk. I get why, but being able to grease them periodically and push out any contaminants would be nice.

 

[Mark]

To grease the RCV’s on a std. D44. The stub axle has an inverted zerk fitting on the outer end. You simply remove your locking hub and give the zerk 5-6 pumps of grease, that feeds into the CV joint. RCV has their own grease, and I assume there may be warranty issues if other grease is used. CV’s that have been run dry are not covered as well.

Mark.

 

[ntsqd]

The TTB's middle UJ can't be greased this way. The RCV tech told me it has to be removed from the vehicle. If this were the '70 Bronc-up then it would be a lot easier, but this is the '96 FSB Blanc-Oh!