Found source for 760 U-joints with bushings

I was looking for a source of bushings for 760 joints since I tend to crush needles in my u-joints and thought I found a source at S&N Fab (http://www.sn-fab.com/images/retail/ujoint.html), but they told me they are using Longfields now, so it looked like that was my only choice (other than Jantz, OX, and CTM's.) However, a fellow lister on the mad xj yahoogroups pointed me to Smokey Mountain Off road, near Tellico 1-828-837-7707 who turns out to sell brass bushings that fit in 760 joints for $25 for a set of eight. I ordered a set installed in a set of 760's with a set of snap rings. I guess we'll see how they hold up in my D44 front end running 35" MTR's or 33" TSL's. Jeff

Do they press in or drop in?

I can't think of a good response to your question. Have you ever taken apart a u-joint? It has the center piece, called the trunnion (sp?) I believe, and four caps. In between the trunnion and the center caps there are needle bearings and grease. Needle bearings can crush under high torque loads. A brash bushing will allow the cap to rotate like the needle bearings but will withstand higher torque loads. You just put them in by hand, no special tools required.

On a separate note, are there any issues using brash bushings in a DD? Increased heat generated from long highway use, etc?

bbaker80 said:

Do they press in or drop in?

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Good question, Jeff will have to tell us. They couldn't be too tight since the brass won't be hard enough to put much pressure on. But, they need to fit pretty snug so they don't turn in the cups.

As far as using axle joints with bushings on a daily driver, it sure depends on whether you have hubs or not, obviously with the hubs unlocked it makes no difference. Without hubs, they will still probably last a long time IF they are lubricated regularly. A u-joint only rotates in the cups when the wheels are turned, and then they don't go round and round, only back and forth slightly. When going straight down the road they do nothing. Also, when in 2wd, even if the axles are spinning there isn't any load on them, so if there is grease in the joint they may not wear at all. I doubt they would last as long as a regular u-joint that uses needle bearings, but those can last 100k+ miles. If the bushing u-joints last 30% of that it's probably acceptable, since they can be rebuilt, or even replaced if they're cheap ones based on the 760x u-joint. They are going to wear when in 4wd, so that could easily have more to do with how long they last than how many street miles are driven.

There isn't enough history with these things yet to really know, so time will tell.

Any idea of what size these bushing need to be(ID, OD, height)?

I don't know and probably won't know how the bushings install since when I had Jeff on the phone, he said he would install the bushings and drop the u-joints in the mail with a set of snap rings. Richard, why would it be bad for the bushings to rotate in the cups? The needle bearings do. I do wonder about the wearing of the bushings, but the CTM's and Longfields both use bushings with success. Jeff also mentioned a strength increase number compared to needle bearings, but I'm not that concerned about that number. I am tired of caps breaking around the c-clip area and spitting out needle bearings. This has happened to me a number of times and the bushings may reduce this problem. Also, if I want, I can weld the caps in my stock junk yard shafts when using bushings without melting any plastic internal pieces. I do plan to get some alloy shafts, but want to try a set of bushed joints in my soon to be spare shafts for now. By the way, these will be run in my D44 front end with lockout hubs, so extended use should be less than with a front end spinning all the time. Jeff

hmm, well after measureing my little 260 and browsing on Mcmaster I found some bushing the might more. Question I have is how much is too much for a press fit.

The measured values are OD .8", ID .66". I found some bushing that are .875" OD and .8125" with ID of .625. Are those OD too large for a press fit? They are either brass or Nylon bushings.

Having been a tool and die maker, I can say that anything over about .003 will be damned hard to press without distorting. Even that is pushing the limits with a good press and clean surfaces. Ideally you wouldn't want plain brass, you want sintered brass but either are better than rollers in extreme torque situations. Life on bushings depends on several things. The angle the joint has to flex through on any given rotation along with the quality of lubrication are the two most critical items. Lastly the clearance is a big factor. If the clearance is too little, then there will be no lubrication. If the clearance is too great, the trunion will wobble and eventually beat the brass to the point where the clearances open up drastically and cause premature failure. If you make your own bushings I recommend a groove running across the inner surface at about a 30 degree angle to allow the grease to penetrate the friction surface from side to side.

McMaster has quite a few different option that would be neat to try out. Plugged sleave bushing(bronze with graphite plugs), MDS Nylon, SAE 841 Bronze(oil drawn into porous bushing), and others. Looks like I will have to make my own though since the premade ones are not close enough.

Old_man, that seems to be what I found poking around. OD max of +.003 for press fit and ID max -.001 for a slip fit.

The sintered material I was refering to is actually the Bronze are referring to. I had a case of cranial rectumitus.

I am setting up to cryo treat the trunions on my 760's for added strength. I worked on some of this back in the 70's on a NASA contract. If done correctly, it should yield at least another 20% strength.

All of this brings up the underlying issue for debate......will I strengthen the u-joint to the point where I break the axle and not the u-joint????

Oh by the way, don't even think about using the nylon or freelon bushings. They won't last 5 minutes under the torque.

I've sourced many materials for replacement machine parts from mcmaster-carr countless times. I will tell you, that you shoudl NOT expect to "drop in" ANYTHING off-the-shelf like brass or bronze stock without having to do finish work on a lathe. Most bushing/bearing stocls are purposely undersized in the ID and oversized in the OD so one has the ability to sneak up on a precision fit for thier application.

If you find something that drops right in and is good to go without machining and fitment work, it will be in the rarest form of dumb luck.

Beezil said:

I've sourced many materials for replacement machine parts from mcmaster-carr countless times. I will tell you, that you shoudl NOT expect to "drop in" ANYTHING off-the-shelf like brass or bronze stock without having to do finish work on a lathe. Most bushing/bearing stocls are purposely undersized in the ID and oversized in the OD so one has the ability to sneak up on a precision fit for thier application.

If you find something that drops right in and is good to go without machining and fitment work, it will be in the rarest form of dumb luck.

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Thats pretty much what I figured.

As for the Nylon, we have ran nylon bushings where the control arms connect to the frame on our Mini Baja car for some years now. They wear great and most of them are practicaly brand new after a few years of hard hard abuse. Thats the only reason I had even considered the nylon. Of course our car only weighs 400lbs.

Maybe I'll just say screw it and run the needle bearings, not like they don't last for me.

Jeff 98XJ WI said:

I don't know and probably won't know how the bushings install since when I had Jeff on the phone, he said he would install the bushings and drop the u-joints in the mail with a set of snap rings. Richard, why would it be bad for the bushings to rotate in the cups? The needle bearings do. Jeff

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Well, the trunion rotates in the bushing with a film of grease. I'm thinking that if the bushing rotates in the cup there is no grease, so the bushing will wear quickly on the outside and become undersized, leading to premature failure.

Richard,
The longfeilds I have are a loose fit (drop in). They have grease grooves in the bushings on the cap side to allow grease on that wall as well as the trunion side.

Matt

IMHO the type of bronze that I believe would work is Alloy 954 Aluminum Bronze. I spec. it out for alot of high load applications for our machines at work. It has a much higher compressive strength and higher brinell hardness than both Alloy 932(SAE 660) bronze and Alloy 841(sintered/ oil-lite) Bronze. Both the trunnion and caps are hardened and can handle the higher hardness of the 954. In my past experiences the 932 will start to flow out at high loads. The 841 is too porous to handle any type of high loads, it will collapse.

Guy

okay Guy, how much would it cost for enough of this stuff to do 2 joints? i have access to a good lathe....

A foot of material should be more then enough. On the 260's they would have to be .5" tall so 4" total of used material. I would think it would be fairly simple to do with a lathe.

guy'sxj said:

IMHO the type of bronze that I believe would work is Alloy 954 Aluminum Bronze. I spec. it out for alot of high load applications for our machines at work. It has a much higher compressive strength and higher brinell hardness than both Alloy 932(SAE 660) bronze and Alloy 841(sintered/ oil-lite) Bronze. Both the trunnion and caps are hardened and can handle the higher hardness of the 954. In my past experiences the 932 will start to flow out at high loads. The 841 is too porous to handle any type of high loads, it will collapse.

Guy

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Is it self lubing or would groovesd be a good idea?

BrettM
www.mcmaster.com p/n 8915k26 Alloy 954 1" dia. x 13" = $14.18

Guy

weasle
It's not self lube(self lube=bad. pores that hold the lube offers less compressive strength). After you turn the bushing you have to take a small grinding wheel(3/32"mounted point) on perhaps a Dremel and put in small grease grooves and passageways like old man said.

Guy