2500HD deceleration vibration??????
 

Anyone ever had this on there 2500HD??? I have a 2001 8.1/allison.

I'm getting a vibration upon deceleration. It's most prominent when slowing down/braking from 20mph down to a stop, but you can feel it slightly at highway speeds when you let off the gas and are going down a slight grade.

At first I thought it was brakes. Had it checked out at local brake/undercar place. They are pretty good. Front's at 75%, backs at 25%. Rotors all looked good. I had them replace the backs. They also rotated the the tires from front to back. No change in the vibration. They were stumped with the vibration and when it occurred and couldn't find anything that would cause it. Really can't tell if its coming from the front or the rear. Don't feel any shimmy in the steering wheel or any pulsating on the brake pedal.

Did some driving/testing to try and pinpoint the problem or at least the location.

On the highway at 60mph, take foot off the gas to slow down on a slight downhill grade--slight vibration like you are on rough textured pavement.

Normal driving 40 mph down to a stop-- Increasing vibration from 20mph to a stop.

Coasting in neutral 40 mph down to a stop--same result.

Coasting in neutral 40 mph, turn off engine, brake to a stop--same result.

Downshift 1st, coast to almost a stop--still have vibration, but not as much.

Its strange because at normal highway speeds, there is no vibration whatsoever. No clunking and no other stange noises at any time. Just the strange vibration during deceleration.

Re: 2500HD deceleration vibration??????
 

griff you might check at the diesel place. www. dieselplace.com for some extra info. Did you check u joints? trying to think of the obvious, along with shocks?

Re: 2500HD deceleration vibration??????
 

How are your u joints?

Re: 2500HD deceleration vibration??????
 

Ditto on the U-joints. Have someone check out the driveshaft. You have a two piece driveshaft and it is real common for the center bearing where the two halves are connected to wear out. Crawl under there and see if you can see any play by the center bearing.

How many miles??? Another thing might be a pinion bearing. I forget if it's front or rear on decel. Check out the driveshaft/cntr bearing and let me know. I have a good friend who is a Chevy truck Master technician. I can ask him for you.

Re: 2500HD deceleration vibration??????
 

there is a re-call on the driveshaft. Because of vibration ,they are going with a 2 piece shaft.

Re: 2500HD deceleration vibration??????
 

I have 2001 2500 duramax crew cab short bed 4x4 that I got 11/3/2000. Truck came with 2 piece shaft & chev changed it out to 1 big one. I just thought I had vibration when taking off & stoping but after they put new 1 piece on the vibration went away when stoping, starting & even crusing.

Re: 2500HD deceleration vibration??????
 

Griff- 2wd or 4wd? How many miles on vehicle? When did problem start? After a service event or hitting curb/pothole? Sounds like problem occurs on smooth roads. Is it worse on irregular roads? No pulsing in brake pedal,rotors 'look good' (was runout checked?). Any irregular wear pattern on tires? Were tires dynamically balanced to see if belts shifted,etc.? When was front end alignment checked? How many miles on shocks? I assume standard wheels/tires? Wheel bearings tight and in good shape? No noises making turns? Briefly, it's been a long while but I,ve seen some weird things like this. Key is the fact that you say you get the vibration without applying the brakes. I'd want to be sure that the caster and toe are in spec and that the shocks are in good shape. Those items give you your straight line stability. If out you could get the wheel/tire bouncing slightly and not be able to dampen out the vibration. Don't know what kind of steering you've got (Saginaw kind of box or rack and pinion) but I once had a vehicle with power steering where the stud that attaches to the Pitman arm was controlled by two opposing spring mounted ball seats that went bad. Unlikely in your case but my point is that anything could be suspect. Higher road speeds can smooth out many kinds of imbalances. Most of us don't realize how heavy the wheel/tire/spindle/brake assembly are. The shock/suspension design has a lot to do. The way sounds/vibrations can be transmitted, it's tough to tell which end the vibration is coming from. I'm sure there are foks with a lot more experience than me who could help. I just wanted to offer some thought starters to get the ball rolling to hopefully help ya out. Keep us posted.

Re: 2500HD deceleration vibration??????
 

I had a strange vibration in mine that ended up being an idler gear/bearing in the transfer case. I never did anything about it until I needed a whole new transfer case.

Re: 2500HD deceleration vibration??????
 

I've been over there for about an hour looking for info. Most everything I'm finding has to do with higher speed vibrations while running. Can't really find anything on a vibration that increase as you decelerate or brake at low speeds.

Re: 2500HD deceleration vibration??????
 

Thanks for all the quick replies.

2001 Chevy CC, 4WD, 61k. No services or big potholes.

Everything mentioned, I have pretty much thought of. Its just the symptoms point to varying things. I noticed a slight vibration over the past month or so and it has gotten slowly worse. I would almost prefer it continue that way until it blatantly obvious what the problem is, so I don't have to throw $$$$ at new stuff that wasn't causing the problem.

I don't know if they checked runout, but this is one of the best brake places in town and all other work I've had done by them has been perfect. The Owner has been there for 35 years and he was at a loss. He pulled up TSB's and couldn't find anything specific to my problem.

They checked the tires and said the fronts had a strange wear pattern and they first thought this was the problem after the service manager took a ride with me, he said he did not think the tires would cause that much vib decelerating without causing some at high at higher speeds. There is no vib while under even the slightest acceleration.

As far as the alignment, I have not had it checked. I've had a very slight pull to the right for a while and probably need an alignment. After they rotated the tires from Front to Back, I 've got about the same amount of pull to the left ????

I'm still doing some brainstormin, but this thing just doesn't make sense. I have read a lot over on dieselplace.com, but nothing quite matches what I have. Also a lot of the problems there have been fixed.

I'll call the place that checked the brakes and ask them if they checked the runout. More than likely it will be going to the dealer.