I was told when I got my new driveshaft for the Bronco that the U-joint was just about bottoming out and that some shims would help change the angle a bit. I bought 4* shims from www.broncograveyard.com and had Jason help me install them. I tightened down the bolts for the leaf springs, and the U-bolts as much as I could, and somewhere in the process I broke my hard brakeline. I fixed that brakeline the other day, drove for about 5 miles and retightened all of the bolts.

I took it out yesterday and noticed two things, one good, one bad. First, my truck is no longer shaking when I come to a stop - good. Second, when I give the truck gas, I get a loud sound coming from the rear - not so good. The best way to describe it is like the sound of boggers on a road picking up speed. When I let off the gas, the sound lessens, when I stop, the sound is gone.

Its quite loud, yet bareable for me, however I know my fiance will have issues with it when she wants to talk to me while we're driving. What could I be dealing with here, and is it normal?

Photo shows the "death lift" complete, with shim being the shiney aluminum piece in between the block and the springs.

 

I just did the same thing to mine (shim is built into my 4" block) and it actually eliminated all my clunks, but I noticed the same thing...my tires got louder.

Since you said it is only when driving, it's probably either the driveshaft/ujoint/tires. My guess is on ujoint or tires. Check the angle again, you want as close to 0* as you can get, but 2* is acceptable (from currie enterprises).

Have you tried getting up to speed, then shutting the engine off? That will eliminate anything wiht the engine. Also, does it to it whenever your tires are turning? Reverse?

 

Also, you probably need more of a degree of a shim. IIRC the one that is on the superlift is close to 8*

It puts it at almost less than 1* on mine

 

it could be your gears.....when i had my rear gears installed, after a bit of wear in they got louder and louder.....i am taking it back to my uncle-in-law tonight to readjust the backlash to fix the noise.........

 

PS.....what is with the silver spot on the brake drums?

 

Well, it is definitely not the tires, because it goes up and down with my rpm's, not my speed. I was thining it is either the U-joint or driveshaft. I don't think it could be the gears, because I haven't changed them.

Think it will be alright if I leave it this way?

EDIT: the sound is only coming from the rear, so I know it doesn't have anything to do with the engine.

The silver spot on my brake drum is a spot I painted so it doesn't look like *** when I have my wheels on there. I decided not to use the old hub cabs, because they liked to get loose and rattle when I was on the trails.

 

SO they get put between the leaf and the block? Not the block and the axel? So this noise STARTED after the shims?

 

That's correct Pat, the bolt that you see coming up through the leaf pack goes through the shim first.

If I were to put it underneath the block, the block would have no way to stay in the perch on top of the axel.

And yes, this noise started after I put the shims in.

 

Are the u joints good on your shaft? Could they have been trashed from the heavy angles and now that things are in line (they are in line right?) they are blowing appart?
If the noise came after the shims it is obviouly related in some way... I would have thought improving the driveline angles would help to get rid of noise not create it.

 

My thinking on the shims would be they should be on the bottom. I am not doubting your mechanics and I am prob wrong, but with a huge block like that your are twisting the block and axle which I would think would put strain on the u bolts and their top plates since everything now in 'leaning" off of the normal 90 degrees. If could be noise from everything flexing.

 

If the noise varies with RPM's, that sounds like an engine thing. If it varied by speed, it would be ujoints/tires/rear end, etc. Bc all those parts move faster and slower with speed.

Have you concidered the transmission? If it is indeed the noise varying with RPM's I would definetly check that...

If it were me, and it varied by RPMs, transmission/engine are the first two things I woudl look at.

I think (to test this theory) you should get up to about 45-50, shut the engine off, and see if the sound is there...that will eliminate a lot of things.



Then again, it could be U-Joints, but unlikely if it is indeed varying with RPMs...

 

When I had the new driveshaft installed, the guy said that it was pretty good, however I've put on about 500 miles since then, so I have no idea if it is good anymore, I don't even know how to tell if it is... other than it being broken in two, I'd assume then it would be bad.

I agree. I'm not sure how close it may be to 0* angle, I have to figure out how to check that.

 

I thought the same thing. The shim kit I bought (6* shims) (I was going to use them but instead I got 4" lift blocks b/c I needed more height) had you REPLACE the center bolt that holds the leaf pack together. It's really weird.

Basically it would go like this

____________ <---leaf
--,-- <---Shim
^
The comma is the pin that the block sets into


Thats how they have it setup when you do pinion shims. I thought it was like how you were saying...but I guess I'm wrong

 

My thinking is since this doesn't happen when the truck is parked and reving, it is not the engine. With the rpms fluctuating, so is the rotation of the U-joint and driveshaft, so I'm exploring that option. Sound about right?

I'll probably try your theory just to be sure though.

 

X2 I was looking at it from the same viewpoint at first.

 

I would just eliminate what you can. That is the first thing I do when I hear a weird noise, turn off the engine while going at a decent speed (be sure it's a safe area )

It could be you have a worn out u-joint. That happens quite often, especially when you have a nasty driveshaft angle like you did.

If it isn't that, I would check the lugs (make sure tires are sitting flush against the drum), the ubolts, meausre distances to make sure you are not dog tracking, etc.

After all that, if you don't come to a conclusion, I would check the driveshaft itself. It's gotta be an easy fix!!

I wish I could see it, I could have it fixed for ya...I'm good with noises

 

Well then take a trip up to analyze the noise, its not too far. Then we could get a trip to Wharton in, and you could play in more water.

 

Haha, no more water for me...

Well, maybe...prolly a coupel more weeks. I'm not scared of it, i just don't want to see the bill. I have NO problem offroading/sinking the truck, I just hate damaging it. Right now it's perfect, no problems.

I need my vent extensions put on, now that I think of it!!!

 

Well stop waisting time reading my BS, and get on it then!

 

to diagnose universal joint failure, u need to jack the truck up at the axle. grab the driveshaft near the universal joint and watch for any play. do the same for the front. also, check out the pinion bearing, same method but watch the pinion at the yoke.

if it varies with engine RPM while in gear, it sounds like it is in-line somewhere from the trans to the rear end. placing the driveshaft at a new angle could very well cause things that were previously worn and set in grove to come out of place an cause new noise/vibrations.

 

Thanks for the info Kiel.

 

any update?