colsoncj

Does anyone make stronger inner axle shafts for the 86-95 IFS. On the last 3 wheeling trips I've managed to break 2 clean off at the side of the diff. (I've already developed a mod to help get the sucker out when you do break it, but thats another topic.)

What I'm looking for is a beefier or chrome moly shaft to buy me some time until I get around to SASing it. Apparently this is my weak link.

For clarification, the shaft is what slides into the diff, and the CV bolts too. Heres a pic of one I broke a couple months ago (before the one I broke today):

GenXr

Have you looked at Downey's porsche inner CVs? Not sure if you're looking for a cheap solution or something just beefier.....

colsoncj

I'm talking about the inner axle shaft, it is what the CVs would bolt to. the porsche CV's unfortunately wouldnt fix my problem...

In fact, in over 3 years of hard wheeling, I've never had a problem with breaking CVs... just these inner axle shafts.

MudHippy

Yeah...I make 'em. Sorta. Maybe.

I snapped one just like that one in the pics. I welded it back together, adding a small amount of metal to the weak area. On both sides, including filling in and around that hollow dimple on the shaft end with weld(more there than it looks). If you look at the driver's side shafts they appear to have more metal in that area around the center of the outer end. I suspect that's why they "don't" break(knocking wood).

I don't know yet if it's gonna be stronger, as strong, or not as. I already had a spare on hand when it broke, so I need to twist that one apart first. Then I'll see how much the prototype can handle.


Wish me luck!


Oh...because somebody's bound to wonder. I had to cut the part above the splines off because, in a moment of shear brilliance, I decided to weld it to the side gear(to which was welded the pinion(spider)gears, pinion shaft, the other side gear, and the other axleshaft). That's what's left after getting fed up with the spool-o-matic. Still work(s)(ed) fine.

colsoncj

I plan on tryin something like what you got going on... welding it back together and filling it in a little more. I have the center on mine drilled and tapped out for a bolt for easier extraction after they break (you can see it in the second to last pic up top. How are you getting yours out?

MudHippy

The hard way, taking the axle housing apart and knocking it out from the inside.

I'm liking the drill & tap method you cooked up though. Probably doin' that next time.

colsoncj

It works really really well. And thus far, doesnt interefere with the strength. both have broken outside the drilled out area. Just drill it, and tap it. After it breaks use a steering wheel/harmonic balancer puller wedged behind the a-arm cam adjuster bracket tab and pop it out. took me about 1.5 minutes last time. easy to do on a trail too.

tc

Yeesh - never really heard of anyone breaking the stub shafts before...

What are you doing when they break? STOP IT!

colsoncj

I figure if ya wheel it smart you shouldnt break CV's, and this kinda shows they arent the weak part. (unless your at full lock and off camber, then I might see a problem.) Recently, besided Mudhippy and myself, I've talked to about 3 other people who encounter the same problem...

Just wheelin..... this one was a hillclimb with a rock shelf, happened at the shelf.

Victor

Do you guys have front lockers? Maybe too much tire speed when a wheel is in the air and then touches the ground? I've never seen those shafts break like that - Mine always fail at the boots and I've had an inner joint fall apart but nothing like that.

colsoncj

Mine broke with relatively very little wheel speed, it is locked, and it wasnt bouncing around a whole lot. It just couldnt handle the torque.

EDIT: and its a 22RE with a stock trans, stock t-case, and 4.88s
I think the tire was just hung a little in a V and the torque required for it to crawl out was more than the shaft could handle.

MudHippy

I hear ya, and the other dozen or so people that said relatively the same thing to me about it.

I don't know what to say. I'm a glutton for punishment, both giving and recieving.

I posted pics of it on here when it happened. Then posted them again in colsoncj's other thread about 6 months ago for an example. Those 2(1 his, 1 mine)fractured in an identical manner to the severed shaft above by the way .

Here's the that other thread, https://www.yotatech.com/forums/f116...re-cvs-124847/

Yeah, 4low + the wheel "bouncing" or hopping that seems to occur more often in the front as it loses and attempts to regain traction. I'd like a better explaination as to why that happens and how to prevent it(I know...take my foot of the peddle..DUH!). All I know is everything(too many parts to list here )that has broken on my front axle has been due to it. It takes significantly less effort to start snapping stuff like that on grippy surfaces. For instance, I only remember the passenger side wheel hopping 3 or 4 times on dry dirt when I snapped the axle in the pic above. Then, CLUNK! And...well..ya either been there or you will be if you take your rig up into places it "shouldn't" go.

Victor, about lockers, nope don't got 'em in neither front nor rear. Yet...

colsoncj

I took my first broke shaft and had my TIG welder at work go to it. He really did a bang up job at welding it back together and adding some meat to it. I'm going to take it and put it in the truck, and have him do the one I just broke in a similar fashion. I plan on keeping the second one welded in the truck as a spare. Time will tell what happens.

I did speak briefly to a tool and die maker about CNCing me a new shaft out of 4340 with some revisions. Should have an idea pricewise before long.

The only thing that slightly worries me is once this becomes not the weak link, what will take its place.

tc

Lockers and gears are how you prevent it. Open, you have to hit stuff with some speed , and our suspensions are very bouncy, so you often bounce off. Lockers allow the tire to come in contact, ensure that it is spinning and crawl up. Lower gears help you apply a steady pressure to keep the bounce to a minimum.

I need to go back here and try it with the crawler to show the comparison:
[youtube]http://www.youtube.com/watch?v=bGt2ZwFZKPU[/youtube]

elripster

I can think of two things that might help change the bouncing characteristics. One is change the tire pressure, the other is stiffer shocks. Tire pressure is a free mod but the shocks might turn out to be the best way if it means you can run the best pressure for traction.

Frank

Cargun

Cory, can you tell if the shaft simply seperated from the flange or if the shaft broke in two, leaving part in the flange? From the pics, it looks like a ductile break, rather than a brittle one. But look up some fracture mechanics online or in a text book you didn't sell and figure out what the failure mode was, that's the first step to designing a beefier part.

CNC single piece flange/shaft sounds pimp... just watch out for corner radii. I'd make them as big as you have clearance for.

While the climb he busted it on looks gnarly, a locked/locked truck like his can usually get up without wheel spin. His IFS does lift front tires a lot on climbs, but being locked up I've never seen the tire come down 'spinning'. I didn't see him bust it either time, but I'm guessing it was as typical bound tire scenario, with the tire getting wedged in a slightly under cut V-notch. My 36's are just big enough to spin when I get them in there, the 33's are probably small enough to wedge. He used to be smart enough to not take that line... now he's trying to wheel like I do

Other factors - bracket lift kit, no ball joint spacers or cranked t-bars. And I think he even runs stock bump stops rather than low-profile ones. And on this climb the tires would be pointed straight ahead (or as straight ahead as the whimpy steering allows).

Were both breaks OEM shafts or was this last one 'Hecho en Mexico'? It looks aged, but whoe knows after a couple trail rides

colsoncj

Failure was ductile, torsion. However, it wasnt as ductile as a tranny output shaft. You can tell it twisted slightly before fracture, but it still fits together nicely like a brittle fracture. The fracture site was due to a reduced cross section as it transfers from the round shaft to a flat flange. From a cross section, imagine a round cylinder with a flat plate attached to it. Then take it and countersink a chamfered hole down into the cylinder, deeper than the thickness of the plate. What you'll wind up with is a cylindrical shaft turning into a thinner walled tube before flattening out to a flange. the fracture is occuring in that brief section where it can be cross sectioned as a tube.

the CNC single piece would alleviate the tube section and allow it to be more closely modeled as a flange affixed to a shaft. My hillbillyish solution thus far is similar to Mudhippy's welding, except I had my TIG welder add more material effectively increasing the thickness of the tube section. (confused yet?)

The climb is pretty much what Hans describes... It was straight on, crawling, no bouncing, and being locked, no spinning.

The factors are correct, but i do run low profile stops. However they only net me about 1/2" of more travel (1/4 up, 1/4 down).

Both shafts were OEM. First one was original to the truck (250K miles, ~1K of hard whelein). Second shaft is OEM, but unknown history.

Cargun

Got it

Another alternative would be to have stubs made and then spline/key them to modified stock flanges, then weld it all together and heat treat.

Wonder why they put that counterbore there in the first place?

I was thinking of this dilema on Sunday when I was back out in the woods alone doing 3500 RPM 1st gear clutch drops to get going on steep snow covered hills. Fortunately there was ice under the snow so there wasn't enough traction to break anything.

colsoncj

Well, part of the counterbore is to center the shaft for machining, but the main section of the counterbore which creates the "tube" section is actually casted that way.

I thought about your described method as well, splining the shaft and fitting it to a stock flange. Keeping it in place is where i had the problem.

MudHippy

First, thanks tc and elripster for the tips. They will be applied, in due time. I gotta quit breakin' and replacing stuff, and get on to enhancing my rig so that is a less frequent occurence. I'm getting there...slowly.

To tell you the truth, I might miss all the wheelspin. Not for long though, after realizing how much further up the trail I'd be without it. Surely.

...


Next, I just had a thought.

I wonder what could be done to mod the driver's side shaft to fit the passenger's side of the diff?

I had a chance to examine them both closely side-by-side when I had my front axle on the bench here recently. I remember thinking "I wish they were both as stout as this one(driver's side)". What I can't recall is having the notion I have at the moment. Or I would have guesstimated the odds of making the longer into the shorter. A beefier version of which though.

It would probably be more practical to make one out of an existing stronger forged piece. Than milling and joining 2 parts. You may be able to exceed the strength of both the stock parts by doing so, however. Which is an enterprising prospect.