Front Driveline Vibration Need Help

[T-7ToNewOldB]

All new build.

Dana 44 from TBPs, 4.09:1
Ford 9” Rear from Wild Horses 4.11:1
(Both WHs and TBPs were ok with this difference)
Atlas 2 speed
1” Body Lift
1.5” suspension lift
7degree bushings

So have only put about 500 miles on the truck. Rear wheel only, though I had done a quick test of the front.

A little snow here today so put her in 4wd. Could feel a bit of vibration at any speed. Didn’t seem to change a ton with RPM or speed.

Most pronounced during engine braking. Doesn’t go away with clutch it.

Goes away if I put front back to neutral.
Goes away if hubs are disengaged even with Atlas in gear.

Definitely shouldn’t be there.

Haven’t run in just front wheel drive, will try that shortly. That would eliminate the interaction with the front and rear ratios or something else.

Thoughts? Questions?

 

[T-7ToNewOldB]

For reference the front end is from Tom’s bronco (full front end, open, with discs)

The rear end was components from WHs, Yukon Duragrip.

Hugh

 

[jim3326]

How do the driveshaft ends line up relative to the axle and transfer case? I ask because the 7* bushing may be to much for a 1.5" lift.

 

[DirtDonk]

Exactly.
Could be a few things, but the first thing to check is your front pinion angle. How far off is it from the centerline of the driveshaft? Can you post pictures of it from the side?
To be certain though, you should verify exact degrees with an angle-finder.

Dana 44 from TBPs, 4.09:1
Ford 9” Rear from Wild Horses 4.11:1
(Both WHs and TBPs were ok with this difference)

We have to be ok with it because that's how they work.
The front is a Dana axle and the rear is a Ford axle of completely different designs. So one has a tooth count that's a slight variation from the other, but even though we want to "match" the front and rear, that matching has some tolerance. And .02 is negligible.
Only a few combinations work out exactly the same, mostly with the same brand and model axles front and rear. Sometimes even that doesn't work out, as a Dana 30, Dana 44 and Dana 60 models also have slight variations sometimes.

Yes, it's enough of a difference that you don't really want to drive with the hubs locked and it in 4wd when on hard dry (high traction) surfaces for very long. But it's workable in most other conditions.

When everyone says they must match, they're talking about not having a 3.50 in one end and a 4.11 in the other.

Paul

 

[T-7ToNewOldB]

I’ll look at the angles on the driveshaft. 7 degrees was what WH recommended with this set-up but I get that there are a lot of variables. Seems like the most likely cause. But I’ll check figment on the driveshaft as well.

 

[T-7ToNewOldB]

Looks like about a 11degree difference on the differential and a 15 on the transfer case. I have an electronic level but finding flat reference points, that I trust, on the diff is not straight forward. I'll check with a protractor later to get angle difference.

Will post pics shortly.

 

[T-7ToNewOldB]

Photos

Here are photos of the front.

 

[T-7ToNewOldB]

One option

I could always clock the transfer case down farther, but that is a goofy way to fix it (ok but not low labor way to test it). Dropping it down will expose it as it is protected by the mount to some degree now.

 

[T-7ToNewOldB]

And that will mess with my already adjusted and mounted twin sticks.

 

[blubuckaroo]

Some could get away with a pinion angle like that if they only use 4X4 off road.
We use our Bronco year round and leave the hubs locked in all winter. That pinion angle wouldn't work for us.
Ford used different pinion angles, depending on year model, so it's impossible to tell what you have without measuring.
Our '77 is runs straight down the road with 2 degree "C" bushings.

 

[T-7ToNewOldB]

That is what I’m worried about. This is predominately a street rig and designed as such.

It doesn’t vibrate with the hubs engaged unless I engage the transfer case as well. Just like it doesn’t vibrate with just the transfer case engaged and not the hubs. Neutral or not on trans has no effect.

 

[MonsterBIlly]

Also check the wheel bearings. I had replaced mine and thought everything was great. U ended up with a vibration that would not go away. It ended up being the drivers side inner wheel bearing which was not seated correctly when installed

 

[T-7ToNewOldB]

Can’t find the alignment to say what the caster is right now. The shop will put it on the rig and let me know Monday. If this is the problem, probably is, then 2 degree or 4 is the question? Transfer case is really at the normal height, just looks higher as I have a cut out drop support to allow for clearance of the bolts and the driveshaft.

 

[blubuckaroo]

It doesn’t vibrate with the hubs engaged unless I engage the transfer case as well. Just like it doesn’t vibrate with just the transfer case engaged and not the hubs. Neutral or not on trans has no effect.

I'm no expert and depend alot on this group, but maybe the pinion angle isn't a problem without a load?

 

[Timmy390]

Remove drive shaft.......Lock hubs in and T-case in 4x4.......Give it run down the road and see where things stand.....

IMO it's about what angle works for you vs. what the angle should be.

I looked at your pics and went out and looked at my rig. I run 7 degree bushings....my front diff is pointed up where your's appears to be pointed level. MAYBE the bushings are on backwards/upside down. Easy to do and has happen to many a Bronco Brother. No way that diff should be level with 7 degree bushings.....

Tim

 

[DirtDonk]

I'm going to say that 7 degrees was too much for yours. Just by the look (and the fact that you do actually have a vibration) it's too steep for road-going 4wd as blubuckaroo said.
I think we're seeing the variations between diffs too. I've used 7° bushings on my '71 with 1, 2, 2.5 and 3.5" lifts without the pinion angle being too extreme. Nowhere near yours in fact. Used in 4wd often over the years, in both low and high ranges.
With yours though, it seems that it puts you out of the u-joint's comfort zone.

What year is your Bronco? Or what year front end if it's been changed?
Normally 7° C-bushings would NOT be the go-to for 1.5" of lift unless you already had a low caster reading, or were just trying to maximize caster for better road manners.
With power steering and the fact that we try to get as much caster out of our rigs as possible, it's not unheard of to use 7 degrees of offset on just about anything either. Even with stock height trucks! But it's a crap-shoot no matter what height, and it's basically why you don't see bushings with more offset than that even available.

I think what happened here too though, is the combination of both angles being a little too much off of the sweet spot. The upper is not out of it's design range, but it's close. Raising the front pinion back up will not only lessen the angle on the front joint, but also lessen the angle of the double-cardan setup at the same time.
You might be able to totally fix it with a 4° bushing, but let's look into it more first.

Depending on the year of the rig as well, the normal go-to for that level of lift is only 2 degrees, or at most 4 degrees. Perhaps something during the conversation led to the recommendation? Do you already know your caster reading? Were we hoping to just maximize caster for better road manners and knowing you had power steering figured it would not be a burden?
Sorry whoever you talked to didn't at least bring up potential pinion angle issues during the conversation.

Is that a new shaft as well? Have all the Zerk fittings been greased, including the female fitting in the double-cardan joint?

Post up a few more details when you get a chance please. I'll look into it a little deeper as well.
And do you know what the caster angle is currently? If you have not already had it checked, maybe that's something you can do in the meantime so we can see just what you can get away with. It really does help to know what you have, in order to know what you can do.

Thanks

Paul

 

[DirtDonk]

Good advice to try different modes, like removing the driveshaft. But even if it is load related, that's perfectly normal. Without the additional load of the front being fully locked in, most shafts don't cause a vibration when they're just borderline. Which might be where yours is.
But borderline or not, you definitely want to track it down and toss it out!

Paul

 

[T-7ToNewOldB]

Paul,

I'll double check the grease fittings.

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.

Frame is Kincer, your 1.5" suspension, front end is the Dana 44 full set-up from Tom's, comes with disc brakes. LAL body, new drivetrain etc. .

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. Did on this one.

 

[blubuckaroo]

I could always clock the transfer case down farther, but that is a goofy way to fix it (ok but not low labor way to test it). Dropping it down will expose it as it is protected by the mount to some degree now.

View attachment 514353

That chassis and underside are too pretty to put to use.

 

[T-7ToNewOldB]

That’s what my friend Brian said! Chicago area and will be my daily driver. Seems like sacrilege to drive in salt but I built it to be used!! Plus my wife let me build it but when I mentioned having a second ride for salt days that did not go well!!!

Have about 500 miles on it right now. It will age.