ok so i decided to throw a locker in my ifs front diff when i changed the gears to 4.88s. well one thing led to another and i threw some bj spacers in along with a home made diff drop. did a backyard alignment hit the trails. shortly there after both cv axles snapped.well then i did the usual scratch my head and drink a beer thing and gave it the once over and a new set of axles, n hit the trails again. two more axles are now in the junk pile. any one have any ideas as to where i went wrong? or are lockers in an ifs just a bad idea? to the best of my knowledge the t-bars have not been cranked, the spacers are 1 7/8" , i have not yet removed any bump stops. i run 33" tsls on a stock 93 p/u 22re 5spd and have confidence in my work. this is probally a case of to many changes at once and any advice would help to save me many hours of back tracking thru the entire front end one piece at a time. so i guess my question is, are lockers taboo in ifs or do i need to look at the geometry? specs: factory 4.88s in an add diff and manual hubs, 33" tsl @16 psi, diff dropped 1 1/2" at rear mounts. detriot e-z locker appears to work properly with ratcheting while holding one tire, axles snapped shaft off in hub right side & snapped cup out on left side.

 

I don't think the locker would hurt the CVs that badly.. If you didn't drop the diff enough, I can see there being an issue, but it's hard to diagnose. If you could post pictures, it would greatly help the case of somebody figuring it out. Good luck!

 

unfortunatly no camera at this time i know pics say a thousand words. id hate to just start the process of elimination and end up snapping more axles with trial and error type of approach. ive added more specs to my opening post. does any one know the max angle in degrees that a cv can operate?

 

Were you in a full lock turn when they broke? Probably just exceeding the limits of a stock axle.

If they broke going in a straight line I would think something else is up.

I had a Detroit Tru Trac in my IFS and never broke an axle but it wasn't much better than an open diff if I lifted a wheel.

I've seen a ton of posts saying 33's are the limit on stock birfs on a SFA and you still have to be conservative with your driving. So I'm thinking stock CV's just can't handle a locker and 33's.

 

That's a good point.. Even with the diff drop relieving the CV angle, I think if you reach that breaking point, it's over.

Did your truck have OEM CV's in it when they first broke? And did you replace them with OEM? If not on both accounts, that may be the answer.. There's been lots of criticism lately on aftermarket/non OEM suspension components not being able to handle a stock vehicle, let alone a lifted/modified vehicle.

 

actually idk the exact time of failure, or what i was doing when they let go. no noise or any thing like that. just came to a small obsticle and realized i didnt have 4wd drive anymore. the first set i believe were oem , second were cheapies from advanced auto ironicly called "tough one" lol!

 

im not convinced its a tire size issue. ive seen 36s on ifs with out failure provided proper gearing is used. 4.88s or 5.29s, how ever ive seen the 529s brake in a 7.5 diff, due to there thin teeth, but not the cv. and this is the reason ill only go to 488 in an ifs. im not saying ive never seen a cv brake because they do and thats part of 4wheelin. i will have to check my turning radius for binding at the cv.

 

I'm thinking along the lines of crappy CV's.. It's not crazy to think your OEM CVs went out after years and years of use and abuse, nor is it crazy to think the shelf brand crapped out soon after. If you haven't already, get new OEM CVs and have at it..they should handle it.

Of course, this is all based on the assumption that your fabricated diff drop does its job, your backyard alignment is straight "enough", and your spacers are properly installed. Not a jab at you or your build quality, but it's not outside of reason to suppose installation could've played a part in this.. Pictures would be PERFECT in this context!

I hope you're able to figure this one out! Good luck to you!

 

I'm running 35's on a lock'd IFS and the only time I break is in a locked hard turn or grabbing rock or something solid with the front tires spinning.
beef up or lengthen the steering bump stops ( limited steering radius but less chance of binding the CV's ). keepping to a steady crawl and not bouncing up stuff and I've had no IFS issues in a while.
I leave the slaming it up the hill to the solid axles ... but all thats gona change verry soon

The truggy is coming ...

 

Surprised nobody else has asked, but are you absolutely certain that you have the same gear ratios front and back? Any chance you swapped in a gearset that was not 4.88? Did you actually swap gears in both differentials?

It may be worth the effort to check that your driveshaft and wheels are turning at the correct ratios when you lift one of the wheels off the ground.

 

just did all BJ spaceser 1.5 inch, broke my Cv first time on the trail. you ever figur it out.
just ordered the diff drop and limiting straps

 

gear ratio is 488 front n rear and i am a crawler not a hold on tight n go for it guy. im 50 years old and wheel with my daughters. i leave the thrashing to them, i built there trucks better than mine, but i get in less trouble n go thru more. LOL! the steering radius is the first place im going to look at and go with some oems. as long as i hear from guys that run locked fronts in an ifs w/o fail im going to leave the locker in and spend my time working on the geometry. any more input from anyone?

 

any one else run a locker in an ifs with success?

 

I've just got one summer of wheeling on my front Aussie, but so far I like it a lot. It's a complete new truck in terms of dealing with uneven terrain where the suspension gets crossed up.

That being said, I don't have a lift or oversize tires, and I'm not into serious rock-crawling. I just want to be able to handle moderately difficult trails so I can get where I want to go for fishing and hiking and general backcountry exploration.

I replaced my CV shafts at the same time I installed the Aussie last spring, due to torn boots. I used reman units from NAPA, rather than new, on the theory that most remanufactured units are probably built on Toyota OEM cores, so the basic quality of the shafts is probably better than the new aftermarket stuff. I have no idea how much validity there is to that theory. Time will tell.

 

Keep in mind that Toyota designed the CV shafts to handle a max of 4.88 gearing (maximum available as stock, I believe) and assumed open differentials. An open diff by design splits the torque exactly 50-50 between the CV shafts, while a locker can send 100% to one side. That being the case, a locker can apply twice as much stress to a single CV axle as can an open diff. Factor in some 5.29 gears, and you've just increased the max load on the CV's by about 2.2X. If Toyota originally designed with a +50% safety margin, that margin has now gone to about -40%.

Basically, I think what that says is, use 1st gear gently. You probably have enough torque when geared all the way down to snap an axle if one wheel is doing all the work. And, if you've got a super low 4:1 transfer case, you can way overstress those shafts.

 

^ Good post. Math.

 

ok finally got time to get into my problem. it seems to have good geometry , stopping at the stops for the idler arm and steering arm as well as the stops on the lower control arms at each wheel. HOWEVER! the stop on the rear of the drivers side control arm has cracked and is bent 180*. checking by hand it all seemed fine but with the wieght of the truck and power from the motor being alot stronger than me im sure its being pushed past the stopping point and causing a problem at full left turn. im thinking this is breaking the cv on this side and then causing too much stress on the other side resulting in the actual shaft snapping. as did the previous shafts . any input on this? still would like to hear from people that have run a locker in an ifs and get thier thoughts on whether they think its a bad idea or not.

 

Right side stub shaft(side gear shaft) is weak. Nothing can be done to solve it(currently). Upgrading CV shafts only makes the problem worse. They can be as strong as they can possibly be. You will still snap the right side stub shaft off at(or rather just before) the diff. Lower gearing will not solve anything there either, and in reality just makes the problem worse(less torque required to turn the driveshaft = more torque applied to the axles...basic math). Lockers and LSDs will only make the problem worse yet. Smaller tires will help, but do nothing to strengthen the stub shaft(s). Most of which has already been said. I just added the crucial bit. It's not all about the CVs. It's just as much(if not more) about the right side stub shaft.

Lock the rear, leave the front open. Best possible solution for durability/reliability. You'll be able to steer 10x better too. Case closed.

For the record, IFS outer CVs are significantly stronger than SFA birfields. Even longfields...or whateverfields. None-the-less, operating them at extreme steering angles, with massive amounts of torque applied, and very large tires in contact with the ground resisting all that torque from translating into spin, will cause them to eventually fail(if the right side stub shaft doesn't fail first).

 

This is correct. CVs are usually made to fail before more expensive damage can be done to differentials, transfer case, transmission, etc. I've seen and heard of lockers being run in the front without problem. It's a pain in the ass to turn while locked, thus selectable lockers are a better idea. I would run one with no hesitation, and probably still will someday.

 

It's a good theory that. But I really have trouble subscribing to it totally. Based on my personal experiences.

So, to save saying/typing again exactly what I've already said in another thread, here's my views on it in fuller detail. And which all still holds true to this day(from where I sit atleast).
https://www.yotatech.com/forums/f116.../#post51369020