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pm26

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Everything posted by pm26

  1. pm26
    I bet his dealer service department told him that they never heard of vibration problems with these trucks.
  2. pm26
    Why? Because they are balanced wrong that's why? If you take four improperly balanced tires and place them randomly on the truck, there is a good chance you do it in such a way that individual vibration cancel each other out to some extent. if you reposition such poorly balanced tires differently, you can cause significant vibration, and even amplify the overall effect. This looks like a logical explanation to me. Forget this road force crap already and go somewhere to an independent shop that has capability to properly balance your wheels. You may be pleasantly surprised. I have seen tires as much out as 1 ounce using state - of - the - art Hunter 9700 road force balancer because the guy was in a hurry and did nto bother to center the wheel properly on the machine and the machine was not recently calibrated. You think I am making this up? I have seen dealerships balance wheels completely wrong, so bad in fact it was sickening when they were finally balanced right and I saw how far off they were. My coworker had a Dodge Durango with a vibration problem. The local Dodge dealer did balancing three times and it was worse every time! Finally it was done right at an independent shop and every wheel was almost 1 ounce out on each side! That will surely cause very unpleasant vibration. Pathetic isn't it? And remember, tires with zero road force variation, i.e. completely round can still be balanced wrong, even though usually such perfect tires seldom require larger weights to balance.
  3. pm26
    Stick on weights do not come off easily and 5 ounce one piece weights are common only on large trucks and buses. 3.5 ounce (100 grams) per side is pretty much a practical limit for a light truck tire . If it needs more weight than that, the tire is probably of very poor quality. I have seen this on cheap imported trailer tires.
  4. pm26
    Are you checking the pinion shaft nut for proper torque? If not tightened properly, this will cause improper preload on the pinion shaft bearings, lateral movement of the shaft under load, and all kinds of issues with pinion and ring gears in your rear differential.
  5. pm26
    5 ounces too much from the factory on one wheel? Are you kidding me? Even 1 ounce out total will cause very noticeable vibration at high speeds. Who balances the wheels at that factory? Looks like someone just slapped on 3 oz worth of weights in the wrong position on the wheel to give it that much imbalance. But I wonder if they balanced those wheels right at the dealership too. If I saw that a passenger car/truck wheel is out by 5 ounces I would immediately suspect that the tire or the rim is junk or someone really just slapped on some weights to make it look like they balanced the wheels. Is this a chrome clad wheel? If yes, you should never cone the wheel in the front on the balancer, otherwise the cone will catch the cladding first and not center the wheel properly. Rear cone of collet, plus rubber protected pressure cup wing nut is the least acceptable. Rear mounted spacer, collet plus a flange plate in the front would give the best results. Collets are simply short centering sleeves with very low taper, and they are frequently used on high end cars like Mercedes and BNMW for proper balancing, together with Haweka flange plates that hold the wheel by the lug nut holes. Here is a COUPLE OF short videos showing use of Haweka flange plates to achieve the best balancing results: As you may have noticed, the balancers in the video do not have road force variation measurement capability. Zeroing on only on reducing road force variation numbers and using inferior mounting techniques will not produce good balancing results. On the other hands, using good quality tires and properly balancing them will more than likely produce very good results without measuring the road force variation. Unfortunately many techs out there simply think that there is some magic in measuring road force that will be a cure-all for all vibration problems. There is no substitute for proper mounting technique and high quality components used with the balancers. BTW, Haweka products are German made. I do not have any affiliation with that company and I do not sell any wheel balancing products. I am merely recommending what is the best on the market in my opinion. Because of high cost of high end products like these, not too many tire shops carry them. A set of adjustable Haweka plates alone costs about $ 3000. Then about $ 1000 for a decent set of collets. For comparison, a regular cone set is about $ 250 per set of four, plus about $ 250 for a good quality pressure cup wing nut and most tire shops will therefore use the traditional cones only.
  6. pm26
    I think that GM should delete the owner's manual and include this book with each new truck they sell http://www.amazon.com/Vibration-Analysis-Handbook-James-Taylor/dp/0964051729
  7. pm26
    This product also works very well: http://www.amazon.com/CRC-06026-Heavy-Corrosion-Inhibitor/dp/B0000AXYA0
  8. pm26
    I had the same problem with a 1995 Nissan hardbody pickup, 4X4, V6 extended cab, which I bought new. The rear differential developed a distinct whine at about 1500 miles that would disappear as the load was taken off the gears (i.e. taking your foot off gas). They swapped out the differential under warranty, all was quiet for about 1000 miles, then the whine started again, except this time it was there only while coasting (foot off the gas pedal). I just lived with that second differential because it did not affect anything else and the truck did not vibrate at all. That differential whine is definitely caused by improper backlash setting in gears.
  9. pm26
    I am doing something about this issue. I will not buy another new GM truck until I see definite confirmation that these issues have been corrected.
  10. pm26
    A few more things to watch out for when balancing wheels: Chrome clad wheels or any wheel with some cladding on it should never be balanced with a an outer cone centering the wheel. The reason for that is that the cone may catch on the cladding itself and not center the wheel itself properly. Outer coning is not good method at all, even for plain steel and aluminum wheels. Make sure they center the wheel with a cone on the inside of the wheel and use a rubber lined pressure cup speed nut on the outside. Ideally, flange plates that hold the wheel by the lug nut holes on outside should be used for even more accurate balancing. Sometimes it is necessary to use low taper centering cones, or even collets for centering the wheels. I still suspect that improper balancing accounts for at least some percentage of persistent problems here. Just because the balancer has road force measurement capability does not mean that the operator can get away with mounting the wheel improperly on the machine. If he does, you get improper balance and meaningless road force variation numbers. Things that can cause improper balancing results: 1. Machine not secured to the floor properly or mounted on porous surface. 2. Improperly calibrated balancer or machine not calibrated for a long time. 3. Use of improper wheel centering techniques and/or hardware 4. Entering wheel parameters wrong into the machine 5. Balancer flange or threaded shaft not secured properly to the main shaft 6. Bent main shaft, damaged flange, or damaged threaded shaft. 7. Motor drive belt (if not direct drive machine like Coats) excessively loose 8. Use of poor quality centering cones and other hardware. Yes, centering cones must be machined to very high tolerances and be properly hardened to work correctly. When in doubt, ask for Haweka brand. Most American or German made cones are good quality, stay away from Chinese junk.
  11. pm26
  12. pm26
    Sometimes stopping and moving the vehicle in opposite direction helps unlock the differential. That's what I did when I accidentally locked up my differential spinning rear tires on the wet lawn and then taking a hard right turn onto the street.
  13. pm26
    If the pressure in the system drops too low due to loss of refrigerant, the low pressure switch will disable the system and will not allow the compressor to operate.
  14. pm26
    Yes, that's definitely a lot and you will feel vibration from a wheel/tire that is so much out. Imbalance of up to 0.5 oz per wheel is the limit of tolerance on a light truck like yours. On a passenger car with firm sport suspension, imbalance of only up to .25 oz per wheel can be tolerated without annoying vibration.
  15. pm26
    The hose from the A/C compressor to the condenser is the high pressure side hose and sees around 350 psi pressure when the A/C is running. If the hose is not restrained properly, one of the crimped metal fittings on the hose ends may eventually start leaking due to constant flexing of the hose in that location. Restraining the hose should help, but this may not be the root cause of the problem. As I mentioned before, these bolted connections utilize O-rings, which must be properly compressed for the joints not to leak. if the fittings are improperly dimensioned for whatever reason and the O=ring does nto get fully compressed , the joint will have a slow leak.
  16. pm26
    That would describe just about any poorly maintained 15 year old car/truck with 250k miles.
  17. pm26
    Consider the source of these parts. Reassurance? As good as Chinese quality control.
  18. pm26
    New drivetrain? Perhaps you mean new drive shaft?
  19. pm26
    The irony is that even Timken makes many of their bearings in China now. It all comes down to sufficient quality spec and decent quality control. Both of which are a big question mark when it comes to Chinese made stuff. It seems to work rather well with more expensive electronic devices, not so well with most other things. The front hub bearings on my 2009 Impala failed at 70k miles. I never had front wheel bearings go out this fast on any car I have ever owned over the past 35 years.
  20. pm26
    It almost seems that the price and quality at GM are inversely proportional nowadays.
  21. pm26
    I remember at least one complaint by someone who had the max tow package with the 6.2 engine.
  22. pm26
    I had a set of OEM Goodyear Eagles on my '09 Impala LTZ and never had any vibration or flatspotting problems. Of course these tires were Z rated for speeds of up to 168 MPH, so there is no comparison to a SUV or truck tire that's just S rated for up to 110 MPH speeds.
  23. pm26
    You can buy a truck with creaking front suspension and various other noises for a lot less than $ 40k.
  24. pm26
    Sorry, I was describing my 2006 Silverado frame. A fully boxed frame is of course stiffer than a C channel frame, but most likely it also is a great contributor to vibration issues. A C channel frame has better ability to flex and to absorb road vibrations. Anyway, here is a frame rust video clip I found:
  25. pm26
    You mean the 3rd ATTEMPT at fix.
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