HELP!!! OT: But I don't know where else to turn for intelligent answer........

[ts71281]

Hi Gang,

I know this doesn't belong here but I need help with my 2003 GMC Sonoma Pickup and I don't know of a better group of guys with intelligent answes than you so here it goes. The truck is a 2003 GMC Sonoma, reg cab, short wheel base 2wd truck with the SMOOTH ride suspension (standard) 2.2L 4 cyl and a 5 speed trans. Ever since the truck was brand new (Bought it with 68 miles on the odometer) it's had a little bit of a hop to it from 50-60 MPH. I had the tires balanced twice on it and no luck so I took the junky uniroyal tiger paws off the truck 205/75/15, and replaced them with Michelin LTX M/S tires 225/70/15. Drove around for a little while on those and it had a little bit of a hop but not like the tiger paws. Well after 3 months of those Michelins I brought them in to get a road force balance TWICE and the truck still hopped. I finally said "that's it!" and I had them replace all four tires with another set of Michelin's, this time the XW4's were put on. 235/70/15's. Now the hop is progressively getting worse. I swapped on tires from another Sonoma that were Yokohama's 225/70/15's and my truck seemed to be about %50 smoother but not entirely. What do you guys think the problem is? I watched them road force balance my new XW4's and they only required 4 lbs of road force to balance! Which is next to nothing. I'm so frusterated guys, I just want to be able to enjoy my new Sonoma and not have to drive it 75 everywhere I go to get the truck to smoothen out. Does there come a point where the tires are too large for the suspension system on my truck and maybe I'm in need of a larger or smaller shock to absorb the added weight of a bigger and stiffer tire? Drums or rotors out of balance? Suspension is tight, Maybe the pinion angle isn't set properly? I have no idea. I know they make an S10 with a ZR2 package that has STIFFER springs and heavier shocks and they run big tires on a 15" wheel with no problems. Remember I just have the smooth ride (standard) suspension. My truck also has one of those goofy harmonic balancers that go over the driveshaft, could that be the problem? I haven't modified this truck at all in any way other than a K&N FIPK kit and I installed a Zexel Torsen Posi in it but never did anything other than remove the axles and rear diffy cover. Besides, remember this truck hopped since day 1. My dad has the other Sonoma and his rides much smoother, same truck as mine other than the paint. He's running factory tires on the front and 225/70/15 Yoko's on the back. Do you think my shocks got hurt from the 2000 miles I put on it with the hopping factory tires? I'm just throwing ideas out here. Hopefully someone has some insight to this. I also heard overtightening the wheels down can warp rotors and drums on these trucks. Anyways I'm done here for now. I'll be checking back every 30 minutes. Thanks for your input guys, again I'm sorry I know it doesn't belong here but I don't want juvenile answers from the 16 year old kids in the S10 forums. Afterall, It's still a

Thanks!

Joe

[barn9]

http://forums.s-series.org/

[ts71281]

I said INTELLIGENT answer

[PR454SS]

While overtightening the wheels can warp the rotors, you'll feel that when you apply the brakes, I would check the shocks, factory shocks are not the greatest.

[doughby82]

have you checked the shocks,or leaf springs maybe one has a crack?is this just a rear end hop?

[67chevemall]

If you changed the tires that many times I would say the problem lies elsewhere!
Bearings? Ball Joints ? Drive shaft/line out of balance?

Does the whole truck hop or just the front/back?

Which side seems more active?

[ts71281]

It seems as though it comes from the back, (feel it more in my butt and the back of the seat) Steering wheel is smooth as glass. But then again it's got one of those fancy vibration dampening steering boxes in it. (whatever) Is it possible to have driveshafts from the factory that have excessive runout or out of balance? I should put a dial indicator on the shaft and see how much runout it has. What would make more sense? To use a stiffer shock or softer than factory to minimize wheel hop (assuming it's wheelhop)? I would think stiffer? (notsure) Also what's a better shock to look for? Oil filled or gas filled? (have no idea) Thanks for your input so far guys, this is all great stuff! Keep it coming


Joe

[krazy_texan]

could it be that your driveshaft is to far out of balance, i am as confused as you are just an idea for you to think about

[ts71281]

What's an acceptable amount of runout on a driveshaft? Also this truck has one of those harmonic balancers on the driveshaft to take any vibrations out. Not saying you're wrong, but I don't think it's likely to be the driveshaft. I can put my indicator on it and check for runout. As a last resort if the shocks don't do it, I'll bring the truck in and have the tires/wheels balanced while they're mounted on the truck! Anyone ever do that or have good / bad luck with it? Heard it works wonders in some cases.


Joe

[Vince M]

If you've got a dial indicator start with the wheels. Jack the truck up and dial everything. Check for concentricity (How round they are) and runout. I think you've eliminated the tires as being the issue. Take all the wheels off after you are done and visually inspect the mounting hubs etc. for flatness etc. Making sure that each wheel is bolting up flat to the hub. Check the inside of each rim and see if you see even wear marks where they bolt to the hubs.

I'm sure you'll find it..sometime it just takes a while. Since you have swapped tires and wheels and the problem still exists I think it's going to be something with the rear axles. Could be a driveshaft but It wouldn't make the truck hop..just vibrate. My vote is the axle is bent....

What is GM saying about this? I'm assuming it's under some kind of warrranty.

[Jason71k10]

Did you take it to a GM dealer? If it's still under warranty, i'd let them worry about ......especially since it's done it since new. just my $.02

Jason

[racedvl]

Bent rim?

[stllookn]

Have one of your buddies drive next to you and behind you just to check to see if you are getting any wheel hop or side to side movement. Get them on a cell phone so that you can communicate. Actually have two friends help you so they don't run off the road trying to look and talk at one time. It is never worth an accident.

[Longhorn Man]

I'll have to say go back to teh dealer.
I'm also willing to bet it is the drive shaft.

[chevyforever]

if its still under warranty i would take take it to a GM dealer and have them worry bout it, they will get it fixed for ya.

[ts71281]

The vibration that I'm getting goes with the rythem of the tires turning, wouldn't a driveshaft vibrate 3.73 (ratio) times faster than the rotation of the tires? The vibration definatly feels like it's at the same speed as the tires. Wouldn't a driveshaft vibration be a "finer" vibration and not so "coarse" like a wheel that hops? Just thinking........ I'm going to play with it one last time this weekend I think and if everything checks out visually I'm going to bring it into the dealership. I just don't like being without my truck, and I'm sure you can all agree with me, it's just an incomfortable feeling knowing someone else is working on their truck.

Joe

[Jason71k10]

yeah, i know what you mean ts71281, but on the other hand, you already paid alot of money for a NEW truck....if it left the dealership with something wrong with it, it's their responsibility to fix it, not your's......stick it to them!!

[LudwigTheMad]

just had a issue like that with one of our work truck....

steering smooth but the damn thing was doing just what you described...

turned out to be a bent drive shaft...was hard to see anything while driving behind....

check your rims also..

but I would take it back to the dealer....make a Mech ride in it with you...then let them deal with it....This is def. a manufactures defect.......

oh and demand (request) a loaner truck...if they don't want to give you one...call around and see what dealer will.....

[Longhorn Man]

You said you took the tires from another truck, I'll asume you also borrowed the wheels, this would exclude any rim/tire issuewhat so ever. The drums or discs would have to be pretty fubared to make the truck shake, and you would HAVE to feel it in braking.
The diveshaft shake would increase the same as a wheel problem. The increase in speed is the exact same % of increase of the wheels.

[ts71281]

Yeah, I took a known good set of tires/wheels off my dad Sonoma and put them on my Sonoma and mine still shakes so I know the problem lies within the truck itself and not the tires/wheels. Which leaves me with the chassis. What is the general rule of thumb for a driveshaft being out of round? How many thousands? Even if the driveshaft appears to spin perfectly true, it could still remain un-balanced right? Just how effective are those harmonic balancers they put on the driveshafts anyways? They slip them on right over the pinion yoke.... Going to try playing with it a little bit this weekend otherwise the truck is going into the shop. No more of this BS or something else is going to get hurt on it. All that hopping isn't good. We'll just see how long it takes for me to get my truck back from the dealership........... I can't wait to hear them hollar about my K&N FIPK....

[Longhorn Man]

We always send our drive shafts out if we even suspect it being out of ballance, so I have no idea what is OK, and what is not. Does it happen to shake more once you go into overdrive? If so, then I'll garuntee it to be the drive shaft. (In OD the shaft is going faster than the engine, and this causes problems on poorly ballanced shafts)
If it is in fact the shaft, the more you drive it, the more damage you ill do to boh th tranny and the rear end...nothing that will show up now, but rather once your warranty is long expired.

[68speedalert]

Don't forget the brake drums. They have a balance on them as well. If you dad's has the same size drums, try them.

An unscientific method to check for drive shaft run our is to take a piece of chaulk and, while the drive shaft is turning, slowly move the chaulk to the shaft and stop when it just hits at the high point. Stop the shaft and put on hose clamps with the screws OPPOSITE of the chaulk mark.

Of course do this with the wheels on jack stands!

[doughby82]

you say you feel it in the seat,usually (i think when you feel it in the seat it could be tranny mount,maybe its loose or????????just tryin to throw more ideas.i would assume if the tranny mount is loose you would have driveshaft wobbles

[68LSS1]

I agree with those that said ujoint/driveshaft. I'd pull the shaft and have it checked (should be 20-40 dollars to check). Most dealerships can't do this themselves and will send it out anyway if they suspect one. Replace the ujoints as the shaft will be out and that will eliminate them. Then you'll be down to the rearend/axles. I don't think changing shocks will do anything for you.

[ts71281]

Speed alert, you have a great idea, I should swap on his drums as well. Do the drums have to be in a certain position on the axle? The factory puts all these pretty pink and blue stripes over the axle and drum I don't know if they mean anything by if it has to line up or not??? Should the weight on the drum line up with the notch on the end of the axle? Tomorrow's the big day and I get to play with it some more.

Longhorn Man, The vibration is the same at a given speed regardless of the gear I'm in. If I take it up to 60 in 3rd it has the same pulse rate as 4th and 5th. That's why I'm thinking the problem lies in the suspension or differential. Still, driveshafts I suppose can be deceiving. If I don't figure out what's wrong with it myself, I'm going to bring it in Monday. Shakes are not good and tend to hurt mechanical pieces.

On another note, this morning when I was driving to work (65 degrees outside and 15 mile highway drive) the shake was there but not so bad as when it was colder. Maybe just a fluke, I don't know! Maybe there's something binding like a bad u-joint that loosens up when it's warm because the grease is thinner??? I don't get home 'til later at night so it's hard for me to work on my truck. I have weekends off so tonight and into tomorrow I'm going to look at it deeper. Time to get some chalk as speedalert says, and break out the dial indicator for the rims (just to doublecheck) and then axle flanges. If I find nothing then it goes to the dealer.


Joe