'99 Burb Vibration - I'm stumped!!!
 

1999 2500 Suburban, 454.
Can’t get rid of this annoying vibration! At 55mph or more, constant vibration. Under 50mph, smooth as can be. Truck has 80k on it now, vibration has been in it since I bought at 8,500 miles in 2000.

Here’s a run down of what I’ve done so far:
Multiple balances
New tires (two sets)
Had wheels checked for run-out, checked good
Alignment
New shocks
Rebuilt and balanced drive shaft (was not found out of balance)
New brakes all the way around including rotors AND drums
Full tune-ups (like four times)
Scanned with engine analyzer, no faults found.
New motor mounts
New tranny mount
New harmonic balancer
New flywheel

Vibration is coming from the back, or at least it’s manifesting itself in the rear. On car lift in gear at speed, axle bounces. Considered that maybe bearings or gears are bad in rear axle, but that would seem to be evident at all speeds. My only guess left is the torque converter, but I’m sick of throwing cash at this thing to no avail.

Any guesses/suggestions???

Re: '99 Burb Vibration - I'm stumped!!!
 

u-joints?

Re: '99 Burb Vibration - I'm stumped!!!
 

Done. Part of driveshaft rebuild. No change.

Re: '99 Burb Vibration - I'm stumped!!!
 

was the truck a wreck repair?

if it's not straight it'll rear it's head at higher vehicle speeds

and yes it would hop on the lift if the axle (frame) is side shifted.

been there since you bought it used with ...low miles... :rolleyes:

there isn't much left to consider Dave.

Re: '99 Burb Vibration - I'm stumped!!!
 

Don't know if it was whacked, doesn't show any signs of that. Alignment should have picked that up I would think.

Re: '99 Burb Vibration - I'm stumped!!!
 

cosmetic signs? you'd never know. Alignment? true 4 wheel?

was it off alot and they compensated as much as they could?

was it ANY better, or different after an alignment? I doubt it.

something's wrong in the back of the truck/driveline

just runnin' stuff by 'ya...

Re: '99 Burb Vibration - I'm stumped!!!
 

have somebody reputable put it on a frame rack and check it to rule that out.

I'd do that next.

if not before throwing all that money at other parts :p

Re: '99 Burb Vibration - I'm stumped!!!
 

Have the axles been checked for run out (with a micrometer, not eyeballs)?? Also lateral play while installed.

Re: '99 Burb Vibration - I'm stumped!!!
 

2 or 4wd??

Re: '99 Burb Vibration - I'm stumped!!!
 

4 wheel drive.

Haven't pulled the axles and checked for run-out, I don't have any v-blocks. It's a good suggestion and I've considered it. Pretty big job (not compared to everything else I've done) but, I need some blocks. Suppose I could make some.

I said "constant vibration" in my original post, I should qualify that; it's constant when it's doing it. Occasionally, it will fade to almost nil, not gone totally but almost. it's very infrequent that it fades and it will do that while driving at constant speed.
Very strange, almost like something finds an equilibrium or center point for few minutes then goes right back to vibrating it's ass of again. That's why I'm thinking torque converter. Does that sound reasonable?

Re: '99 Burb Vibration - I'm stumped!!!
 

Do you mean axial play? I have checked for that, it's tight. If you mean up/down, front/back by lateral, I've checked that also. By hand though, not with indicators.

How about pinion angle?? The angle of the differential to the drive shaft. It's supposed to be like 2 degrees offset or some such number. We've tried to measure that with all sorts of stuff like magnetic angle finders. Very hard to reference off anything flat and square. From what I;ve read, the drive shaft/u-joints at the the diff. and at the tranny need to be at a small angle (not straight) and opposite each other. Any knowledge of this weird angle spec? I'm not sure I understand it.

Re: '99 Burb Vibration - I'm stumped!!!
 

Pinion angle should not be an issue with a stock height truck and I'll assume the u-joints were checked for alignment when the driveshaft was worked on. Does the truck have an auto 4wd setting and do you drive with it like that? Have you tried to run the truck with the frt driveshaft out?

Re: '99 Burb Vibration - I'm stumped!!!
 

exactly

Re: '99 Burb Vibration - I'm stumped!!!
 

Truck is stock height. I don't know if Universal Joint checked the joints for alignment to the shaft. I told them to check everything and replace the joints. The truck does not have an auto 4wd setting, it's the old style lever on the floor. We did run the truck with the front shaft removed, no change.

If one of the rear axles was bent at all, wouldn't I feel that at all speeds? And why then would it fade to almost nothing sometimes?

I also don't think it's a pinion angle issue either. We ran the truck on the lift with axle hanging, effectively worsening the pinion angle. Axle hopped pretty good. Then we compared that by running another truck on the lift with it's axle hanging. That truck's axle ran smooth as can be at all RPMs.

One more tid-bit I forgot to mention, the vibration is less severe when the boat is trailed or when there is a heavy load in the back.

Re: '99 Burb Vibration - I'm stumped!!!
 

stop throwing in more tid-bits!!

though that is interesting...pondering...

it still points to chassis not driveline..

Re: '99 Burb Vibration - I'm stumped!!!
 

I'm thinking NOT chassis. The reason is that the vibration was evident while on the lift. Chassis alignment issues causing vibrations would only be evident while all four wheels are on the ground and "fighting" each other due to the misalignment. While hung in the air, the chassis misalignment would not have any resistance to any thing.

Re: '99 Burb Vibration - I'm stumped!!!
 

Ok smarty...

let me tell you if you have had a shuddering or out of balance convertor for the last 75K miles...it would have exploded along time ago.

and dont be so confident about chassis. it would still shake in the air if the axle was pushed to one side of the frame or cocked!

think about it!

Re: '99 Burb Vibration - I'm stumped!!!
 

:D :p

Appreciate your ideas Rip, but still not buying into the alignment thing. If it were an alignment issue, I'd have eaten these tires by now. The last set has about 15k on them, there should be some unusual wear evident from misalignment.

But, don't stop your input. It makes us think and analyze. There's got to be a culpret here someplace. After all, it's just nuts and bolts. :cool: And, by the way, when I get the chance to get it to a good body shop, I'll certainly have the frame checked.

Re: '99 Burb Vibration - I'm stumped!!!
 

touche' :p

though how much would cause a vibe (only at higher speeds) and how much would show in tire wear? especially rears? I think there is a thin line there.

Re: '99 Burb Vibration - I'm stumped!!!
 

BTW like my new avatar? :drink:

Re: '99 Burb Vibration - I'm stumped!!!
 

You're like a dog on a bone!! :D

Re: '99 Burb Vibration - I'm stumped!!!
 

No, it's creeping me out!!! :eek:

Actually, I don't know whats more embarrassing, Axa having to view himself in that get-up,,,,,,,,,, or you having a picture of another guy as your avatar.

:p :p

Re: '99 Burb Vibration - I'm stumped!!!
 

homophobe :rolleyes: :D :D

Re: '99 Burb Vibration - I'm stumped!!!
 

I have a bud going through the very same thing right now. I say t/c or xfer case , did the u joints . New tires . I'll see and report as we get there.

Re: '99 Burb Vibration - I'm stumped!!!
 

Thanks Hunster, appreciate knowing anything you guys find.

Re: '99 Burb Vibration - I'm stumped!!!
 

No,,,,,,,,,, I'm not afraid of you two homos at all. :p :p



Ok Randolph, we're devolving my serious vibration thread into another "Boathouse Ballbust".

I declaire a cease fire, right now. :drink:

Re: '99 Burb Vibration - I'm stumped!!!
 

OK but I still say any thing driveline out of whack enough to cause the vibe would've destructed itself in 75,000 miles

maybe it will tomorrow and you'll have your answer. :eek: :D

Re: '99 Burb Vibration - I'm stumped!!!
 

My 93 and my 99 both did the same thing

took me a year, 2 sets of tires and wheels, 4 tire balance shops, 1 set of drums, 2 axles, posi unit, just to figure it out on the 93, then found the cure by coincidence one day, with a real sharp friend of mine helping me do it myself...

fixed the 99 in 1 hour doing the same thing

it's the rear brake drums

the drums have to be balanced ON THE TRUCK using a strobe balancer, and using a drill with 5/16" drill bit, you drill multiple small holes 5/16 deep on the inside drum lip on the heavy side of the imbalance plane to zero balance the rotating ASSEMBLY, with the tires off, and ALL of the lug nuts in place, use the engine to get to the highest vibration point, and mark the strobe at that point. Have jackstands under the rear axle tubes to support the actual chassis weight under load

that'll fix it.

if it doesn't, it's the limited slip posi carrier out of balance, and there were a TON of them that were this way.. if your truck has the C6P option, it's one of those two scenarios, non C6P rear ends didn't do it.

Jim

Re: '99 Burb Vibration - I'm stumped!!!
 

Well now,,,, there's some intersting input!! I was on the right path by replacing the drums thinking they were out of balance. They are huge so I suppose they could be the source if out of whack. This strobe deal sounds like I need a specialized shop to do this. Is that right or can I go buy a stobe balancer?

How do I know if I have a C6P rear end? It is a posi unit. I'd be inclined to think it's the rear end since I did replace the drums and it made zero difference, same vibration, same speeds, same magnitude. I would think different drums would change the vibration if they were the cause. Agree?

Thanks for the input Jim.

Re: '99 Burb Vibration - I'm stumped!!!
 

look for C6P option code on the RPO sticker in the glovebox...

Re: '99 Burb Vibration - I'm stumped!!!
 

BTW, after you balance the drums, mark the drums using one specific lug stud so if you ever remove the drums they can be relocated using the specific stud for orientation. I stamped the drum with an X and stamped the end of the locating stud with an X as well. I pity the soul that gets the truck after you and doesn't know this.........

JH

Re: '99 Burb Vibration - I'm stumped!!!
 

Have you confirmed the balance weight is still on the flexplate? 454's of that vintage were externally balanced. Those weights can come off. The flexplate could be cracked as well.

Try your lifted/wheels-off vibration test with the rear axle on sturdy set of stands. If it still vibrates, get a big screwdriver (one that's at least 18" and hefty) Put the handle to your ear and start probing from the axle ends forward. Be VERY careful of the driveshaft- wear short sleeves and stay WAY AWAY. Try all over the axle & diff, TC and trans, then forward. The closer you get to the vibration, the louder it will be. You'll probably need an earplug for the other ear. The safest way to do this is on a lift with full-height stands.

I've also seen cracked driveshafts that vibrated and also popped and banged- you couldn't see anything externally. I have a 2-door Tahoe that my son drives now- goes thru a driveshaft every 60K.

Re: '99 Burb Vibration - I'm stumped!!!
 

Chris,
Flexplate?? Not sure what that is. If you're referring to the flywheel, I replaced that with a new GM unit. No change.

As for listening for vibrations, we actually hooked up a multi-channel accoustical meter. Several sensors (clips) were attached at the outer ends of the axle, inner by differential, pinion and back plate of differential. We noticed no appreciable sound difference, everything just "whirred" nicely and equally.

I appreciate the input, keep it coming please.

Dave

Re: '99 Burb Vibration - I'm stumped!!!
 

I thought I read something about a torque convertor- led me to assume it was an auto. Manuals use flywheels, autos use flexplates. Bolts to the crank, converter bolts to it. That year 454 was externally balanced- unlike any other Chev V8 of that year. Harmonic balancer had a bob weight in it and the flexplate had a weight tack welded out before the ring gear. If the balancer was wrong, thr motor would have shaken itself apart by now. If the flexplate weight was missing (or wrong flexplate) you could get a vibration. You'd thing it would be RPM-specific, not speed-specific. On the other hand, it could be small enough a vibration to be interacting with other harmonics in the driveline.

The brakedrum suggestion is a good one. You could pull the rear brake line and plug it, then remove the drums for a test drive. The rears don't do much braking anyway. Don't do it in rush-hour traffic, though.

Re: '99 Burb Vibration - I'm stumped!!!
 

Im Hunsters friend with the 97 Burb with the mystery Vibration. Mine is fine up to 60 and over 75 mph. In between it has a constant noise/vibration. New tires didnt matter. I explained it to a mechanic, left it for 2 weeks and just got it back with new ujoints. The vibration was actually worse and after 20 miles the rear ujoint came apart and the driveshaft came off. I had it flatbeded to a different shop, the owner fixed the ujoint. He is gona drive it and check it out further. I will definatly look into the axle code and the brake balance possibities. Keep me posted and good luck with your burbration.

Re: '99 Burb Vibration - I'm stumped!!!
 

:eek: :eek: :eek:
Exactly why I do as much of my own maintenance/repair work as possible. Mr GoofWrench does not impress me.

"burbration" :D

Will keep posting with progress reports.

Re: '99 Burb Vibration - I'm stumped!!!
 

I did replace the flexplate (I referred to it as a flywheel) and thought I'd discovered the problem when I removed it. There did appear to be a thrown wieght, there was a spot on the plate that looked like it had a weight welded to it at one time. Alas,,,,,,,,,,, new plate, no change.

Taking the drums off is a great suggestion!! I'll try that,,,,,,,,, in a low risk area of course.

Re: '99 Burb Vibration - I'm stumped!!!
 

i was gonna say shocks front and back the shocks gm is using are junk but when the rear brake drums were mentioned it reminded me i have a freind that had the same problem balanced the drums problem fixed i hope it is that easy for you

Re: '99 Burb Vibration - I'm stumped!!!
 

I also put KYB shocks on both my 93 and 99, made a great overall difference. Well worth the money spent.

JH

Re: '99 Burb Vibration - I'm stumped!!!
 

I think it is bent axle shafts in the rear, manifests as speed increases. Balance issues usually have certain specific speed ranges/frequencies they show up at , like 35, 52, 69 mph.

Wannabe