What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Vibration on decel with newly setup 14bff

C

ChuckMoney

Registered Member
Joined
Feb 19, 2005
Posts
41
Reaction score
0
Location
Oahu HI
Title says it. I set up a 14bff with 4.56 axles and I'm getting a lot of decel and low speed vibrations. The backlash was right in the money hole at .005 with a great pattern, did not require any shims.

Currently the truck doesn't have any rear shocks, the ones from ORD were too short. By the way, this is the largest 4" lift I've ever seen in my life, seriously, the 35's look small. Top height is over a hair over 7ft with 315/75/16. Shackle flip rear, 3" springs front, 1" body lift with new body mounts.

It almost feels like a bad U-joint, but only during decel under 15-20mph. Pinion angle looks decent, driveshaft looks fairly straight to the pinion, I would say about a 20* angle.

I'll shoot up some pics tomorrow of pinion angle and other pics ect.

Any ideas? I know this post is written as a 5th grader would, but 16hrs working on this from a completely stock truck and now about 5 drinks its expected.

Thanks ahead of time.
 
Is it possible that the pinion yoke isnt tight enough:dunno: . Or the ujoint like you mentioned. On a side note my front shocks were too short and my rears were too long from ORD. They work good enough for the driving I'm doing for now though
 
ChuckMoney said:
Title says it. I set up a 14bff with 4.56 axles and I'm getting a lot of decel and low speed vibrations. The backlash was right in the money hole at .005 with a great pattern, did not require any shims.
Click to expand...

Pictures of the pattern?

You also have to remember that now that you have deeper gears your driveshaft is spinning faster and any minor vibrations that you may not have noticed before are exaggerated. This is probably what's happening.

ChuckMoney said:
Currently the truck doesn't have any rear shocks, the ones from ORD were too short. By the way, this is the largest 4" lift I've ever seen in my life, seriously, the 35's look small. Top height is over a hair over 7ft with 315/75/16. Shackle flip rear, 3" springs front, 1" body lift with new body mounts.
Click to expand...

Lift from springs can be a little subjective, but the shackle flip is exactly 4". Give us a call Monday and we'll figure out what happened with your shocks.
 
38377k5 said:
Pictures of the pattern?

You also have to remember that now that you have deeper gears your driveshaft is spinning faster and any minor vibrations that you may not have noticed before are exaggerated. This is probably what's happening.



Lift from springs can be a little subjective, but the shackle flip is exactly 4". Give us a call Monday and we'll figure out what happened with your shocks.
Click to expand...

I'm hoping its all drive shaft vibes, as a pain in the ass as those are. I'll get a pic of the pattern and the pinion angle, I hope I took a good one when I was setting it up.

Oh yeah about the height, its probably just an optical illusion since I've seen the truck stock on 32"s for so long, but its looks pretty tall. I'll be having a little build thread soon with some pics to show off.



I'll give you guys a call on Monday. I'll measure the shock mount distance, while the truck is sitting flat, is there anything else you need?
 
Ok took her out for another drive this afternoon. Sounds like that rear isn't set up right, and I have a drive shaft issue. I'm hearing a chatter from the rear on decel from about 35-15mph, then it quiets down and shimmies like a bad U joint.

Been a while since I've set up a rear, so I probably effed this one. No pics of the pattern, kicking myself, but I'll have to pattern it soon again anyways, I'll get a before and after pattern pic. I'll upload a pic of the pinion angle in a bit.
 
"Whirring noise only while decelerating at any or all speeds is most likely caused by bad pinion bearings or loose pinion bearing preload, and almost never by bad ring and pinion gears." --Randy's Ring and Pinion FAQ

Well looks like I'll tighten her up a bit. I have no idea how the hell thats possible as it took around 400 ft/lb to get it set up for IIRC 20lb preload. I'll check that preload with another guage to be sure, but it "felt" right.
 
Drive shaft Angle:

2011-04-17_13-39-59_432.jpg
 
Did I post this in the wrong forum? Or is this site slow in general? I'm pretty here here (posting wise.)
 
you just have to be patient
I have a couple threads that have been dead since birth, o well.

Never mind the driveshaft angle, is the pinon parallel with the output angle of the Tcase? It should be within 2* IIRC. That's all that matters. If it is, then it's right. Then you get to move onto the shaft itself, joints, or gear set up.
 
K85 Octane said:
you just have to be patient
I have a couple threads that have been dead since birth, o well.

Never mind the driveshaft angle, is the pinon parallel with the output angle of the Tcase? It should be within 2* IIRC. That's all that matters. If it is, then it's right. Then you get to move onto the shaft itself, joints, or gear set up.
Click to expand...

Good call, I forgot about the Tcase angle. I'll check it tomorrow and post some pics.

Thanks
 
Ok so I shimmed the back DOWN to match the angle. Still a little bit of driveshaft vibration, going to get one made with the whatever joints they are called and lengthened a little.

The rear noise is driving me CRAZY. Me and two other guys tightened the living HELL out of that pinion angle today, did not sound any better. Preload felt the same (didn't measure it, but its not over, hell we could barely tell it changed.)

Tomorrow going to take that cover off, and recheck that backlash and re mark it. Son of a !!!!!!!!
 
You must log in or register to reply here.

Latest Posts

Top Bottom