So why did my CV Break? Details:

Considering that I am still very much inexperienced and still learning this was not exactly a bunny hill to me, however I am very much interested in exploring the cause of the failure and appreciate your help.

At the end of this video, where he goes up the last small hill, I lost momentum and got stopped just before cresting the top of the little hill.



This pic was taken after I broke and tried a few times to make it up in 2wd. Hence, not truely depicting my position where the CV broke. You can see some disturbance on the top of the little hill were the left tire was sitting and the rear wheels were trying to make it up the hill when I broke.



I was further up the hill than indicated in this pic and my backend was further to our right, down hill (more in line with the road).




I had the wheel turned hard to the right and was spinning the wheels trying to make it up the hill on my second attempt after losing momentum on my first attempt when the break happened.

Overall, I am disappointed the break happened since I know this is nowhere near as hardcore as many members here use their rigs.

Some thoughts I had in referance to why this happened are:
1. Driver error - too much gas with the wheel cut hard and all the weight of the front on one wheel
2. CV age/mileage - with 86K they were due to be replaced
3. Toytech top plate spacer - I hope not since I like the level lift and have trimmed quite a bit already to fit these tires without rubbing, diff drop is installed, I saw no leaking from the CV boots after lift install, to my knowledge the wheel was not at extension when the break occured

Please share your thoughts, but keep in mind that I am admittedly a noob driver so please keep it constructive.

Trip report here: https://www.yotatech.com/forums/f100...7-08-a-137839/

 

"I had the wheel turned hard to the right and was spinning the wheels "


thats the problem if i had to guess. where the wheels "bouncing" as you were tring to get out? looking at the pictures i'd bet it was the passenger side that broke.

 

Actually it was the driver side that broke and there was some bouncing. It was slick so there was more spin than bouncing.

 

Was there any clicking from the CV joint prior to this event which would indicate that it was on its way out? And did you ever do a "boot job" on the CV boots?

 

ill bite, too much pressure on the driver side, too much gas, bad angle and too much weight.. be easy on her. its possilbe that you had a crack in the boot before hand making it weaker (assuming water and grit got in there). i would investigate that first

 

A little off topic: Did you fix it on the trail or did you get it home ok even with the broken CV? Just wondering what you did to limp it home if so.

John

 

Great Thread... not in the sense that you broke something but that you are asking for info. I myself am learning the ropes and its good info for me and others to know what situation could cause damage and how to avoid it.

 

time to upgrade to a solid axle!

 

driver error I reckon.

these are general rock crawling guidelines:

never steer it, unless you are moving

you hit some rocks, let it steer itself...you just 'guide it'
let the wheel go this way and that, don't fight it too hard

never let the wheels spin while trying to go over rocks
the sudden grabbing and turning is hard on tie rod ends
and CV assembly

 

This is EXACTLY why you broke. Turning hard and giving a lot of gas, especially while spinning the wheels is about the FASTEST way to break an axle.

Unless you are mudding, when wheeling, the skinny pedal is not your friend. Every now and then, more gas will get you up, but not always, and you break stuff much more quickly.

A couple of things to keep in mind: When climbing, avoid going fully right or left, unless it is completely necessary. A good rule is, while stopped, go full over on the wheel, then come back one to one and a half turns. That will bring your CV back to a good angle. Then try to climb whatever it is that you are trying to get up.

If you have to give it gas, try to turn as little as possible. Slight movements right and left are fine, but hard turns will hurt, as you now know.

 

good info edzo.. i dont do much rock stuff here, just a lot of mud and some creeks

 

can you explain that a little better? excuse me if i dont know the lingo. my apologies.

 

Sorry for the confusion.

My point was to never try to climb or give the truck a lot of gas with the wheels fully turned. If you have to make a tight turn, turn the steering wheel back one revolution. That will bring your wheels back from an angle that is bad for the CV's.

Obviously, this isn't always possible, and sometimes you have to turn the wheels fully. In the OP's case, there wasn't any need.

 

Man, I've been doing it all wrong!

 

ya! don't you remember... just let physics do its thing!

 

I always thought control was over rated anyways

 

Thats pretty much how i busted my first CV but I had slight binding issues w/ my pass CV due to the (then) bent frame the truck was on. Any wheel bounce would compress the bumpstops just enough to put the CV axle at an angle where it'd bind even w/ diff drop. However... You can still snap them the same way without any binding whatsoever.

Fully cranked wheels, gas, slippery conditions puts the most stress you can on your front end. Any axle setup, IFS or solid. (it's most common cause of birf and ujoint failure on front axles anyways)

To avoid this happening again? Well, as others have mentioned try to avoid fully turning in every situation. IF you have to get, get out and assess the terrain and figure out a way you can get through it with as minimal steering as possible. Easier said than done. And when your in a situation where its tight really caress that gas pedal.

a Full front locker would create less stress in your type of situation because your front wheels wouldnt be fighting each other for power. The torque transfer between wheels would be considerably less. Think of it as you taking a sledge hammer full swing to a pane of glass compared to just just letting it sit ont he glass. The glass is strong enough to hold the sledge hammer but not if it has momentum behind it.

 

Its been a LONG time since that was posted. Too long. Thank you sir, for bringing that back!!!

Oh man, gotta go clean the monitor now.

 

it all depends on what you have installed. if you got beefy parts you can do whatever the hell you want. I drive every weekend on 1800x2 feet of nasty rock and boulders to get to the cabin. most 4wd cannot make it up. plenty have broken on the way. I just creep up. maybe I described it wrong. I dunno. I just never steer unless I am moving, and I let the truck tell me what it wants. works great and I ain't busting the good bits, just sway bar links

 

Man this thread took off since I got busy at work. Thanks to everyone, there is a lot of great info here that is really going to help me. Sorry if I do not reply to everyone. Here is some more info to hopefully keep this thread going.

No prior work on CV. No indication the CV was on it's way out, sounds or binding in any way. There was no leakage after lift and I was watching closely since I expected some. The boots had no damage that I ever saw till this.


Good advise, that sums up what I thought I could have done better. As far as the boot goes, see above.

Excuse the lack of technical terms here. After quite a bit of fusing to get over the first obsticle, including putting it into 4wd again for a very short time, the broke end of the CV was resting on the top of the part of the CV that attaches to the hub. It didn't really seem to want to move anywhere else. So I drove it out in 2wd all the way home. I have noticed that where the broke part of the CV was resting on the part attached to the hub, some grooves were worn into that part of the CV. I have not investigated further as I plan on taking on the replacement project this weekend and it is a mess under there. I will see if I can get some pics this weekend.

I wish! 2001 not as easy.

I do think there was a sudden grab and as you mention, that is probably what got me.


Thanks for the pointers!