Front Driveline Vibration Need Help

[DirtDonk]

My bronco doesn't really have a year. Everything is brand new, except the radius arms and the front end housing. It's titled as a 71, but it isn't. All Mod not much Resto.

Ah yes, I seem to remember a recent comment about a "Johnny Cash Cadillac" Bronco coming together.
That was you maybe?;D

Frame is Kincer

Stock height radius arm brackets? Or do they modify them (longer) to create some better geometry? Never heard that, but curious if that's part of their thing.

front end is the Dana 44 full set-up from Tom's, comes with disc brakes.

Ahh, custom brand new stuff, eh? I wonder if they build extra caster into them and have the pinion and radius arm bosses dialed in for lifts already?
I'm not familiar with their diff housings, but I'll go to their site and check it out for more details.

The 7 degree was suggested by WH precisely for tracking, I didn't have any input on that side as I don't know enough to have an opinion, though that rarely stops me.

Haha! Yep, understand. And yes for a mostly street Bronco more caster is good even with minimal height change, if any. But we can still run afoul of the pinion obviously. It's frankly not very often, but that does not help here unfortunately.

Might be time for a punt, or even a Plan-B.
We'll see how it goes with your tests, but I bet at least some of it comes back down to the angle.
Be nice to dial this aspect in for sure. But it pays to be certain. I remember how many NV3550's had to be replaced because they were "noisy" when it actually turned out to be a rear driveline misalignment (from the lifts) sending a harmonic right up the shaft, through the much tighter transfer case, and into the much looser 5-speed trans. Never had that issue with stock 3-speeds, but the NV was a real death-rattle trap when that vibration hit it.

Paul

 

[T-7ToNewOldB]

Paul,

Johnny Cash, that is what it turned into! Pretty sure you guys got a really large amount of that! . So pretty I don't want to drive it!! Need to hit a tree after skidding into a mud pit to get over this. Or drive through a salt filled Chicago winter. .

Kincer builds in the body lift to the frame so everything lines up. (I know that isn't an issue here). I don't believe they change the radius arm mounts at all, if I remember correctly. I believe the TBP is stock angles. They don't mention any changes.

Should I try the 4 first? Only a 3 degree difference. Will confirm angles with the protractor today.

 

[T-7ToNewOldB]

Paul,

They just rebuild stock ones see below.


Hugh



This is a Complete Dana 44 Differential for Early Ford Bronco. Dana 44 was stock in 1972-77 Classic Broncos, will fit 1966-71 as well.
This Complete Differntial Includes:

Reconditioned housings - checked for straightness, weld defects & excessive rust.
Rebuilt knuckles
New Chrome Moly Inner & Outer Axles w/Heavy Duty 760x U-joints
New OEM Open Carrier
New TBP Chrome Premium Hubs
New Motive Gear Ring & Pinion (Select Ratio from Drop-Down)
New Bearings, Seals & Shims for Center Section
New Wheel Bearings & Races, Inner & Outer
This kit also includes a Complete Disc Brake Conversion w/ALL NEW PARTS. Disc Kit includes:
New Hub & Rotors w/Studs
New Spindles
New Loaded Calipers w/New Pads
New Stainless Braided Brake Hoses
New Banjo Bolts
New Brake Hardware
New Caliper Bracket w/Dust Shield
New Hub Seals

 

[T-7ToNewOldB]

Measured with an electronic protractor.

15 degrees at diff
22 degrees at transfer case

These are both differential measurements not relative to any plane. A little hard to be as accurate as I would like but these are within a degree probably, 2 at the most off.

 

[DirtDonk]

While you're at it, grab an angle on the driveshaft itself. That's really one of the key components in this angle thing.

And as for which bushing, well the angle readings will tell us, but so will a caster angle if you can get one to add to the data bank.
Maybe you have a local place that will give you a quick readout for minimal cost, or a tire shop you've dealt with over the years that might cut you a deal. But knowing what caster you have now will let you know if going all the way down to 2 degree bushings will hurt your street manners or not.
Personally I think your pinion angle could use a bigger change in angle, but camera angles don't always sing true. That's where your angle finder will come in. But if losing 5 degrees of caster will put you at a deficit, then we definitely need a plan-B.

On the axle information, thanks for getting that. It's good that someone is refurbishing them. But that also means that we still fall prey to the inconsistencies that came right out of the Dana/Spicer manufacturing process. And not all 44's will have the same relationship between the pinion and the steering yokes.
Another reason that getting a caster reading will help out here.

With your angle finder you might be able to get an approx. caster angle. Maybe take a wheel off, lay a straight-edge over the top of the yoke right next to the upper ball joint, then take your reading off of that?
Maybe not as precise as a computer, but might work pretty decently.

Paul

 

[T-7ToNewOldB]

Fixed a typo in the previous post. They measurements are "not" relative to any plane. Just angle difference between pinion and driveshaft and then driveshaft and transfer case.

Shop will give me caster measurements on Monday. I'll get the angle of the driveshaft as well.

 

[DirtDonk]

Ok, so while it's still nice to have, there's not really any need for the driveshaft angle if that's what you were taking the other measurements from.
And I think I had forgotten that in the previous angle measurement you had said they were relative to the shaft. I remember because I was thinking those were relatively high offsets. Especially the 15 degrees at the diff. Zero to four would be better to my way of thinking. But 5 to 8 would still be acceptable I believe.
Even at that lower level though, at 8 degrees you might still have a vibration at relatively high speeds. Hard to say, again because every situation is as different (even when it shouldn't be!) as every Bronco.

Paul

 

[T-7ToNewOldB]

I'll get the caster on Monday and post when I do. Thanks for the help Paul.

 

[T-7ToNewOldB]

I didn't notice it being worse at higher speeds, didn't take it above 50.

 

[T-7ToNewOldB]

Current measurements in degrees
Left Camber 1, Caster 6.8, Toe -0.14
Right Camber 1.3, Caster 6.5, Toe -0.19

 

[Broncobowsher]

The first picture of the pinion U-joint angle, problem found.

As for 7° bushings, yes a bit much for that little lift. But I bet it drives NICE on the road.
The ~22° at the CV, sounds a bit steep for that little lift. Atlas you say, where do you have it clocked at? You might just fix this (or just make it a bit better) if you clock it down a little. If it is clocked to be really flat that will put the front driveshaft at a bad angle. Flat clocking is great for wheeling ground clearance, not great for front driveshaft angles.

 

[T-7ToNewOldB]

Atlas

Does track very well! Need that front end to work though. I've been pretty concerned on the angle since the original install. Atlas is not clocked flat. Here is a repost of the angle.

 

[T-7ToNewOldB]

If not for that cutout it would be about as low as you can get it with the Advanced Adapters AX15 trans mount. Clearance issues on the bolts if I clock it lower. This mount was made by Kincer specifically to make it work as is. Those guys do nice work.

 

[DirtDonk]

Thanks for getting the numbers for us to look at. Sweet caster angles!
Too bad they're not higher though, as this pretty much limits you to experimenting with 4 degree c-bushings to see if they're enough to get rid of the vibration.
Because if you went all the way to 2 degree bushings so your pinion angle would be much nicer, you'd literally lose 5 degrees of caster, leaving you with not enough.

So unless you're ready to cut-n-turn the steering yokes, start with the 4 degree bushings and cross your fingers.

And let's see if anyone here watching the discussion as ever cut and turned the yokes on a '78 or '79 Dana 44 and how much of a hassle it was.

Paul

 

[T-7ToNewOldB]

I could do either. Cut the steering yolk or try 4 degrees. One is more work for sure. Thoughts?

 

[blubuckaroo]

I could do either. Cut the steering yolk or try 4 degrees. One is more work for sure. Thoughts?

If you don't plan on using the 4WD on the street, try the 4 degree "C" bushings. You'll be in the same boat as many on this site. There was a trend started a few years back to use 7 degree bushings on everything.
Mall cruisers.?:?

 

[DirtDonk]

I could do either. Cut the steering yolk or try 4 degrees. One is more work for sure. Thoughts?

There is no either/or. There is only are you able to do a cut-n-turn or not.
The ONLY way to create both adequate caster AND a neutral pinion angle is to cut-n-turn. Most use bushings because they're easier and work in most cases.
The 7 degree bushings were a necessity for getting caster and most Bronco axles will tolerate it. But many won't as well. As you found out...
So it does come down to whether or not an owner needs to use 4-High or not, and what they want to get away with.

Still crossing fingers that losing just 3 degrees will eliminate the vibration.
But if not, we know what the bottom line is.

Paul

 

[Broncobowsher]

Paul is right on that one. You have caster number most of us can only dream of.

Your 7° bushing are probably causing 9° of your driveshaft angle. It's evil in that rotating the axle moves the U-joint further and creates even more angle than the bushings offset for.

If you want the best of both worlds, flip one bushing on each side to make the bushings 0° and cut/turn the outer Cs.

Easy way out, try the 4° bushings and hope that is a good balance between tracking and driveshaft angle. Sometimes the easy way is the hard way since it doesn't work. Other times you get lucky.

 

[T-7ToNewOldB]

Use this in Chicago in the snow so having 4WD is a must. I’ll give 4 a shot and see what I think. Can I do the cut and turn, sure. Would I have preferred to do it first, yes. But here I am. Will try 4 and do the cut and turn as needed.

Thanks for the input. I’ll post when I have more info.

 

[blubuckaroo]

Use this in Chicago in the snow so having 4WD is a must.

If you plan to drive on icy/snowy roads, open differentials is best. You might get away with a rear locker, but whatever you do, leave the front open.