Bang bump bang bump from the front end...help!
 

On the way home from work yesterday, I slowed down to about 5mph because of traffic and from the front, right side of my truck, there was a loud BUMP BUMP BUMP and my hood was shaking. I thought I had a flat or ran over something, so I pulled over, but my tires were okay, and everything under my truck looked normal. I have an '85 GMC 1/2 ton 4x4 with 3.5" body lift. I got back in and proceeded to drive, and all was well. However, when I rolled the window down, I heard a constant ticking or grinding sound, similar to that of something rubbing on the rim or a gritty bearing. I put the tranny in neutral and it was still doing it, coming from the front right side. When I got off the highway by my exit and stopped, the truck made that loud bang sound again and I felt a jolt in the truck, and then that grinding sound went away and it hasn't done it since. What in the world is going on? Are my hubs going bad? No, I did not have the truck in 4x4. It has a 700r4 tranny and the 208 transfer case (gear driven). I believe it's the 208..lol Anyone got any input????

208 cases are chain driven, the 205 is gear driven.

I would take the front end up and put some jack stands under each end of the axle and spin the wheels and see if you can see anything not looking right. Possibly ball joint or bearings most likely.

just to piggy back on what Destructo

said, do you have auto hubs??
check the u-joints and spindle bearings also..

yeah, they are auto hubs. if i'm correct, they are still the original ones from '85 too. What's weird is that I no longer have this sound or this problem....What in the world would bang and make my truck bounce up and down like a flat tire or something stuck in my tire, and then cause the grinding sound, but now there is no sound at all. :confused:

I would check the hubs.If they are original and you have not serviced them,it might be time to chuck them and put a good set on.I prefer manual my self.Was it in 4wd recently?The one hub could have hung up and not released all the way.

Get that truck up on jackstands quick. No more driving. I vote for the hub being bad but it could be the wheel bearing. There's a lock ring that has a tendancy of spining out of the groove in the spindle. If this has come loose the wheel bearing will loosen or tighten up and toast the bearing/spindle assemby. That tire might just come flying off.

It has been in 4wd recently as we had some snow. Isn't my truck classified as "full time 4wd"? It's an '85 1/2 ton sierra with 350 engine, 700r4 tranny, and 205 t-case. I had thought the guy I bought it from said that it was a "full time 4wd" eventhough power wasn't going to the front wheels unless it was engaged in at the transfer case.

Anyways...back to the problem...the other day, on dry pavement, I turned really sharp to turn around, and i was in 2wd, and my front end was banging and jerking and banging and torquing kind of like it was engaged in 4wd. Then all of the sudden, later that day, it didn't do it again and was fine, but I still hear a tick tick tick when driving.

Who makes some good manual hubs? I keep seeing hubs and they list the year of my truck, but then they say "except full-time 4wd" which for some reason, I believe I have. Can someone clear this up????

You should have a np208 if stock.Even if someone put a 205 in,they are both part time.Warn,and milemarker make good hubs.Superwinch makes hubs,but I have never used theres'.Get the premium hubs whoever you buy from.When you take the hubs off you will need a special socket you can buy at any parts store for around $15.Take your wheel bearings out and clean,inspect and replace if needed.Buy a service manual,if you don't have one,it has how to do hubs and bearings.

Full time 4wd has power to both axles all the time without a kit in the transfer case.You have 4wd and 4wd lock.When in lock the differential in the 203 case is locked.

yeah,i don't have power to the front wheels all of the time, but my front driveshaft does spin constantly. whether it's in 4x4 or not. (that may sound dumb, but I'm a car guy and this is my first 4x4, so that's why i'm lookin' for the advice about hubs) When it initially messed up like that, I had figured it was the hubs, but wasn't sure. Since the truck steers fine and nothing binds when i turn, i'm sure it isn't anything in the steering. looks like i'll be buying some hubs for my own christmas gift. Just out of curiosity...how much are automatic hubs? I'm sure they are probably twice what manuals are. I don't do hardcore off roading..mainly around my buddy's 1,000 acre property on trails there, but no rocks or anything. With the way the weather is screwy here...it would be nice just to be able to grab 4x4 inside when needed. Just curious.

Check with napa,or another parts store.I have a few off road catologs,but they don't have auto hubs for sale.Manual hubs are not that big of a pain.When they call for snow or you know you are going off road,lock the hubs in.You will not be in 4wd till you shift the t-case.Are you sure the t-case is in 2wd?Put the t-case in neutral,then pull it back one notch.If you have power to the driveshaft it is in 4wd.

get manual hubs. Easier maintenance on them I think warn premiums are around 70-80bucks and are lifetime warranty, if they brake from normal wear, they replace free of charge.

Your transfercase should be aluminum with a slip yoke for the back driveshaft..If it is you have a NP208..

with auto hubs your front driveshaft may have a tendencie to turn. but is not engaged in your transfercase untill you shift it to 4hi or 4lo

if it is a 208 your shift pattern for it will be all the way forward 2hi
one back 4hi then pull it over a little to the right and pull all the way back to 4lo..

yup...that's my shift pattern. looks like the guy i bought it from lied about what kind of t-case it has in it. not surpising though. i've already put a new motor and tranny in. so, do you guys definitely think it's the hubs? I don't mind throwing some manual ones in there. it might even give me some better gas mileage. my 8mpg sucks...even 10-12 would be better.

First,check the condition of the hubs.Look at the wear or anything broke.They may just need a good cleaning and grease.While the hubs are off check and repack the bearings.I prefer manual hubs,they are stronger and you know when they are locked and unlocked.I would be willing to bet your one hub was still locked.My blazer and my 4x4 ford van both get 12-13mpg.Maybe needs a good tune-up,or your gears may be to high .

Well, my neighbor who's a big chevy guy tuned the truck for me. It has a stock gm crate 350 in it (190hp version), a 700r4 tranny and 33" BFG all-terrains with a 3" body lift. It has the edelbrock 1904 q-jet carb. I personally think it's way too big for the motor with it being 795cfm's, but from what I've researched, it's supposed to be a stock replacement. Unfortunately, it has 3.08 gears in the truck I have to give it so much throttle to keep a steady pace down the interstate that it's ridiculous. It will barely do 70mph down the highway without kicking into 3rd gear and then the 4-barrels open. Forget towing anything...to tow my ski boat which weighs about 2600lbs...I can barely do 60-65mph in 3rd gear at 1/2 throttle. And because of this, to tow my boat to and from the lake which is about a 70-75 mile round trip, my truck uses an ENTIRE tank of gas...all 16 gallons. Without towing anything, I can only drive about 100-115 miles on an entire tank of gas!!!! That's also with no a/c on. WTF???? :confused:

To run 33's and be around a a good ratio that is close to stock.
I believe you would have to run close to a 3.55 or 3.73 ratio to get back up into your power range for towing. that way your not always giving her throttle.:burnout:

I thought that the 208 was a gear driven aluminum case - 205 is the beefy gear driven iron case and the 203 is the full-time (unless you put a kit in it) chain driven iron case.

I would check your u-joints too. They can often send noises and vibrations throughout the truck making the sound appear to be coming from another part.

The 208 is part time, but it is chain driven.

sounds like i just need a new set of hubs. i'm sure they are most likely stock, and a little better driveability from manuals definitely wouldn't be a bad thing.

roller
 

Sounds like a piece of a wheel bearing roller broke off and got ground up rolling around in the rest of the bearing. That had me baffled for awhile too until I took the thing apart. 1 roller had disintegrated and got ground up going thru the other ones. Threw the front end all over the place. It fell out in pieces when I took it apart...Z

i vote for the lock ring.my 85 blazer did exactly that.i pulled the hub off,the lock ring was in there in 3 peices,i changed bearing and new lock ring,done deal

all I can add is that, on my truck, the front DS turns all the time, even in 2WD (NP205) with the front end unlocked.

They turn from friction, in the axle, because nothing is holding them still. Think about it, unlocked and in 2WD, can you not turn your front shaft with your hand??

BUT, it doesn't turn anywhere near as fast as the back one, or a locked in front one...

I observed this, when I was driving w/o my trans tunnel in the truck ;) -- I can still see it, because Ive been too lazy to find the screws for my shifter boots :(

-Marty