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wright11
Senior Member
Canada
159 Posts |
 Posted - 11/03/2007 : 06:30:32 AM
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hi all
maybe some one can help me
97 bluebird gm chassis front and back sway bars 366 engine 150000 km
here is the problem
check complete front end numerous times, every thing passes
driving down road intermittent front end shake sometimes noticable,sometimes severe, new f tires, goodyear g159
replace tires with mich xze problem dissaperes, and never comes back
put on any other new tires problem comes back. i have 9 of these units and they all act the same. are the mich masking a problem???
i'm sure other fleets must be having this same problem
3 mechanics and my self cannot find the reason why ,,,pls help
2 of these units started shaking at 4000 km's
kingpins tight, tierods tight, steering box ok, sway bushings ok,
all front end components are ok
any ideas????? alignment within specs
thnx all |
Edited by - wright11 on 11/24/2007 10:43:17 AM
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baptistbusman
Advanced Member
USA
301 Posts |
Posted - 11/03/2007 : 12:29:41 PM
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Ok, here's the issue. This is a known problem on these chassis. Basically what GM has done to fix it is add a steering stabilizer shock and there was an alteration to the king pins. A Medium Duty chevy dealer/parts guy will know immediately what to do to fix this.
But anything will set off the shake. The tires need to be balanced, and properly in round and your shocks must be good too.
I have had this problem numerous times through the years.
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1 Timothy 1:15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief. |
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IBTMech
Top Member
USA
973 Posts |
Posted - 11/03/2007 : 3:41:02 PM
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In the '70s and '80s I installed quite a few steering stabilizers on buses, fire trucks and public works trucks. We've had fewer shaking problems through the '90s and none in the last few years.
Better quality steering arrangements? Better tires? I don't know.
We use a lot of Michelins in recent years and there have been no complaints. |
If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Pullin' wrenches for 45 years. |
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wright11
Senior Member
Canada
159 Posts |
Posted - 11/03/2007 : 3:50:12 PM
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thnx guys
but why would michelins cure this |
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busgeek++
Advanced Member
United States
253 Posts |
Posted - 11/03/2007 : 5:10:14 PM
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| maybe they balance or sit in a way that masks or corrects the issue??? |
Buses are not a way of life, they are life |
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baptistbusman
Advanced Member
USA
301 Posts |
Posted - 11/03/2007 : 5:37:35 PM
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Yeah, they are probably riding smoother than the other tire.
The Goodyears are probably causing it to bounce a little, and then it is causing a chain affect causing it to shake.
The Chevy in my picture had the same problem. It had goodyears on it, then it started having a shaking problem. The problem lessened with new tires, but eventually became more predominate until I installed the steering stabilizer and new kingpins. |
1 Timothy 1:15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief. |
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wright11
Senior Member
Canada
159 Posts |
Posted - 11/03/2007 : 7:22:43 PM
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thnx again guys
i'll give it a try
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torque
Advanced Member
Canada
358 Posts |
Posted - 11/04/2007 : 2:50:04 PM
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We just got rid of our last 94 GMC 2 years ago and I was never so happy in my life to see a piece of equipment gone. We had several of these and could never find a permanent solution. Usaully new tires, even though nothing really wrong with the old ones, would do the trick for a while. Yes steering dampeners helped a bit too, but we sent them to several different places for alignment over the years with no real good results. I believe in the end it is steering geometry that is the problem. Sorry, but what a pathetic piece of machinery these things are (were)
Does anyone know of a permanent solution, other than like us and get rid of them. I don't care what anyone says, these things are unsafe at any speed when they act up. |
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wright11
Senior Member
Canada
159 Posts |
Posted - 11/04/2007 : 6:51:48 PM
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| has there been any recall on this problem, where is the safety board??? |
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baptistbusman
Advanced Member
USA
301 Posts |
Posted - 11/04/2007 : 8:19:48 PM
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Not a recall, but a "bulletin". I'll see if I can find it.
There is no permanent solution, however the kingpin fix from GM takes care of it for 40,000 miles usually. Actually, after that fix, I haven't really had a problem with the newer style kodiac style front ends.
Now dont go getting the king pins from napa, the fix includes a steering knuckle pre load adjustment. Basically i believe the shims had to be machined down to a certain degree.
I have found though that simple maintence keeps the problem from coming back.
In reality though, I've had this problem with Fords big time with the 1970's model. Any vehicle is going to do this with loose steering components. |
1 Timothy 1:15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief. |
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wright11
Senior Member
Canada
159 Posts |
Posted - 11/04/2007 : 8:27:39 PM
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thnx baptistbusman
any info on the gm bulletin would be helpfull
if possible could you give me the number |
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baptistbusman
Advanced Member
USA
301 Posts |
Posted - 11/04/2007 : 8:49:19 PM
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| ima have to do some searching. I found this fix from the school district that i bought these buses from. I know i have the bulletin somewhere. |
1 Timothy 1:15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief. |
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Wolf0r
Top Member
USA
2181 Posts |
Posted - 11/05/2007 : 3:24:16 PM
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Sorry about the formatting and no illustrations. This should help.
Subject: Side to Side Strg Wheel Movement/Bump steer (Install Leaf Spring Spacer/U-bolts) #00-02-34-001 - (03/15/2000)
Models: 1997-2000 Chevrolet and GMC B7 Medium Duty School Bus Models
With 10,000# Front Axle, 11,000# Front Suspension and Ross Power Steering (RPOs FM6, FNO, NXW)
Condition
Some drivers may comment about a back and forth rocking movement of the steering wheel. This condition is especially noticeable when the vehicle travels on an irregular road surface and/or when driving over dips in the road. This condition may also be known as bump steer.
Cause
The steering system geometry may contribute to this condition, resulting in a variance in ball height at the steering knuckle third arm (6).
As the vehicle travels over dips or irregularities in the road surface, the jouncing of the front leaf spring may cause a tug on the pitman arm. This may result in the side to side movement of the steering wheel.
CorrInstall a 20 mm (0.80 in) spacer between the front axle and both front leaf springs on vehicles that may exhibit this condition. This spacer moves the pitman arm and the steering knuckle ball (5) 20 mm (0.80 in) further apart. The relay rod (10) angle will also change as a result of the spacer installation. This spacer creates different steering geometry that should reduce the potential for a tug on the pitman arm (11).
The spacer installation will also require longer spring U-bolts. Use the following procedure and the part numbers listed below.
Set the parking brake.
Block the rear wheels.
Notice: Do not use the front crossmember to support the vehicle or the crossmember may buckle.
Place a jack under the front axle and raise the vehicle. Support the vehicle by placing suitable safety stands under the frame.
Remove the spring U-bolt nuts (6) and the washers (7).
Remove the spring U-bolts (1) from the vehicle.
Lower the axle (5) far enough to provide clearance between the axle and the lower shock mounting bracket (3).
Install the spacer (4) between the lower shock mounting bracket and the axle. Ensure that the spring stud seats securely into the spacer.
Install the new spring U-bolts.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the new spring U-bolt washers and the nuts.
Tighten
Tighten the nuts to 350 N·m (258 lb ft).
Remove the safety stands.
Lower the vehicle.
Parts Information
Part Number
Description
Qty
15153701
Spacer Asm. - Frt Spring Lwr (20 mm)
2
15983090
U-bolt - Frt Spring
4
11516202
Nut - U-bolt
4
15650968
Washer - U-bolt
4
Parts are currently available from GMSPO.
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“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson |
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wright11
Senior Member
Canada
159 Posts |
Posted - 11/06/2007 : 6:54:39 PM
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| thnx again guys |
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Topic |
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97 bird gm chassis 66 seat front shake
