I been browsing the locker forums, I ended up going with a detroit locker in a 9" with 4:11 gears, I'm not happy with the noise and constantly breaking the u-joint at the pumpkin, I noticed there looks to be a bit of excessive play between the locker engaging and disengaging. I checked the clearence between the gears it is .008 and the gears are new. I have plenty of spare parts so i pulled the locker out and put in a factory posi unit and the u-joints are holding up fine.

Its a BB429 with a 3 speed auto trans, 35in tires and it was a full time locker in the rear, it isnt a daily driver more of an off road toy, but I drive up to 100miles to get to the play spots.

Has anyone had a similar situation? any solutions or suggestions? I love the performance of the locker just hate carring 2 extra u-joints with me everywhere.
I'm not the easiest driver on the truck too if that helps

-Robert

 

Welcome to the forum!
I'm assuming the truck is 4wd, b/c I don't see why you'd have 35s other than that.
35s on the stock 1/2 ton axles is close to the max tire size you want to run on them, and the heavy foot doesn't help either.

I wonder if there is any way it's getting in a bind to be breaking u joints like that? A locker will put more stress on your parts, but it shouldn't make that much of a difference.


I have 36s and a pretty heavy foot, and I've only had trouble with the u joints on the front driveshaft. My rear hasn't broke one yet.....

So what type of u joints are you useing?
Spicer joints work pretty good, but there's CTM, OX, ect...

 

It would seem the problems is related to axle wrap.
The bigger tires attributes to be related to more torque required for all rotating parts.
Adding detroit lockers into the rear creates additional traction and thus more axle wrap.
It would seem the truck has a lift kit has added more angle to the driveline too.

Adding some sort of traction accessory to the rear axle should help the u-joint problem.
A cardone u-joint will help too.

 

Meant to Cardan drive shaft.

 

Thank you for the input, As far as u-joints I had a set of spicers but lately I have been useing the autozone cheapies, before I swaped out rear ends I was changing them weekly granted once I noticed the problem I have been driving it a bit more lately trying to diganosis the problem.

But I might have made a mistake on removing the Cardan drive shaft and replacing it with a standard 2 ujoint shaft, i figured the less flex joints the stronger the shaft, I will re install it this week.

The truck is a 77 1/2 ton
78 bronco suspension and steering
429 motor
3 speed auto
2.5" in suspension lift 2" body lift
35" tires
Moser max axels with ox ujoints in the front with a detroit locker 4:11

and yet to beef up the rear end with the exception of (4:11 detroit locker)

 

Ladder bars work great on eliminating axle wrap.

BB429 engine have plenty of torque and horsepower.

A buddy of mine has a high performance 429 cid and he snapped the shaft on the rear axle pinon gears the other day in the mud boggs. He added ladder bars to eliminate axle wrap.

 

I had the same problem with an old bronco on 35's. Because it was lifted 3'' I had enough play in my slip yoke that I was able to add a knuckle down at the axle end of the shaft.This will split any pinion angle between 2 u-joints instead of 1. That ended the deadly ''clunk''for me.

 

I agree with 1975Ford, it's axlewrap. I never cared for ladder bars on my 4wds, just because they hang up on everything. I run 54" Goodyear tractor tires on my buggy, with a welded Dana 70 with 5:86 gears, and used to have the same problem. The solution:, we started using 3 point hitch bars (available at tractor supply stores) for traction bars. We weld a bracket to the top of the differential and another on a crossmember in front of the rear axle, and bolt the right length hitch bar in. We mount a single hitch bar per axle, parallel with the leaf springs to allow the axle to move up and down with the springs. They have 2 threaded rod ends so they can be adjusted 3 - 4 inches, you can even "pre-load" the hitch bar by tightening the adjusting sleeve. The nice thing about this set-up, is it's mounted directly over the ring and pinion (axle wrap is caused by your pinion gear trying to climb your ring gear), it's on top of the differential for clearance, and it allows your axle to pivot unlike ladder bars that restrict movement. The hitch bar setup is the norm for swamp buggies down south, I even run one on my 74 Hi Boy. My buddy's buggy runs a 513ci Ford, 66" Goodyears and the same hitch bar set-up, no more broken u-joints.

 

Look up driveline info here:
http://www.clubfte.com/users/torque1..._WebLinks.html

 

it's all in the pinion angle, you can't just lift a truck and not pay attention to the pinion angle.