Transmission or drivetrain problems 92 k1500 need your thoughts

Discussion in 'Chevy Truck Forum' started by Dustinc2650, Dec 8, 2012.

  1. Dustinc2650

    Dustinc2650 Member

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    I have a 92 Chevy standard transmission that has started driving like junk. New u joints 6 months ago, rebuilt rear driveshaft 3 weeks ago, and new rear end- axle, diff the whole thing 6 months ago. It has no engine problems or misfiring that I know of. The problems I'm having is that the whole truck shakes in 5th gear between 45-60 mph while your foot is on the gas, if you let off the gas or go in neutral at that speed the problem doesnt occur. Driving between 45-60mph in 4th gear the shaking does not occur. In 1,2, and 3rd gears there is an on and off grinding noise that speeds up while accelerating. 4th gear seems to be ok.

    I took it to a shop recently and had the driveshaft rebuilt, they told me everything was all better but the new driveshaft hardly had any effect on the driving problem. So I took it back to the shop and they suspected the input shaft bearing was damaged, but they could not tell me for certain and suggested a new tranny for $2k. But that was at a tire shop so I took it to a transmission shop. They were able to tell me it was not an engine problem or the front drivetrain- they removed the front drive shaft and the problem still remained. I believe he checked out the transmission sensors also. The transmission guy was not able to pinpoint the problem and gave the truck back to me and refunded all my diagnostic fees. He said the truck is old, and he didn't want to guess what the problem was and fix something that wasn't broke.

    I don't know what to do about it, thinking about buying a different truck or just using this one for parts. Any ideas? I'm not an excellent mechanic, just a welder so your help is very appreciated
     
  2. gpmorgan

    gpmorgan Auto Banned

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    welcome to the forum. the vibration(shaking) could be caused by a worn tranny mount. not sure about grinding noise. how many miles are on it?
     
  3. Dustinc2650

    Dustinc2650 Member

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    Thank you. Good thought I will look at that today. This truck has about 218,000 miles. I have only put around 15,000 on it myself since I bought it. It had some serious brake problems when I bought it but that was a simple fix, and soon after problems with a leaking rear diff.
     
  4. dirtrider73068

    dirtrider73068 Moderator Staff Member

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    Check your tires make sure they are not out of round or out of balance, is the driveshaft balanced? Does this truck have a carrier bearing if so check it.
     
  5. Dustinc2650

    Dustinc2650 Member

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    Well the transmission mount on the crossmember looks completely intact. I don't think this truck has a carrier bearing, just a plain shaft with the yoke ends. The wheels should be balanced. I got 4 new tires 8 months ago and were balanced and did an alighnment also. I thought there was a slight possibility that the mud stuck to the rims and may have been part of the problem. But after thoroughly washing the rims and under the front of the truck today the problem is unchanged.
    I would assume the driveshaft was balanced properly, it was sent to a shop to have new yoke ends welded on and be re balanced. But I had the same problems before it was rebuilt, the new shaft hasn't had any effect.

    Maybe I should pull off the diff cover and have a look. I was told I got a brand new rear end, it looked new, but maybe they gave me some **** from a junkyard?
     
  6. 88fivespd

    88fivespd Full Member

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    From the description you gave in your original post, it sounds like the problem is in your transmission. No problems in fourth gear and fourth gear is direct, basically just travels straight through the tranny on one shaft.

    Have you checked or changed the tranny fluid? I believe a '92 would take that synchro fluid.
     
  7. Dustinc2650

    Dustinc2650 Member

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    Well I will have a look at the trans fluid tomorrow. The tire shop said they checked it and it was slightly over filled so they drained it some. I have not looked at it myself.
    I read online to check exhaust and transmission mounts so I looked at them today- all that I found were intact except the two on rear dual tailpipes. The previous owner welded and bolted the tailpipes to the frame. Supposed to have a rubber isolater but its never been an issue being bolted to the frame.
    Tomorrow I may check out the rear differential.
    The trans shop did pull the front drive shaft because it was frozen up, would not extend and retract like it should from rust, dirt. I have not re installed it yet. I don't believe it was locked up like that until recently. Could it have damaged the transfer case and be the problem?
    Could it be the clutch disc or pressure plate is damaged and out of balance and causing the truck to lurch?
     
  8. Boudin

    Boudin Forum Moderator

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    I'm thinking that the problem is in the tranny too. Remember that the fact that this appears to only happen while the truck is trying to speed up (gas applied) and not when it is just rolling tells you a lot. These problems can be irritating and be very frustrating, but make sure to rule out the simple stuff first. Don't wish you hadn't. I learned that lesson on a vibration/noise from the rear of my truck. I went as far as replacing the carrier bearing and having a shop press on a new one before I realized it was something very simple. After all that effort, it ended up being that the lugs were loose on one of the rear wheels. I felt stupid, but was thankful I was only out a few bucks and a few hours. Rule it out now so you aren't cussing later.
     
  9. gpmorgan

    gpmorgan Auto Banned

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    did you just look at the tranny mount? might need to take a pry bar and make sure there is no movement. does it only vibrate in 5th gear?
     
  10. Dustinc2650

    Dustinc2650 Member

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    Good point Boudin. Been in this situation before, I thought I was having major engine problems and scratched my head for a week until I found out the truck needed some plug wires and a cap, rotor.
    Looked like all the trans mount bolts were secure. As I laid under the truck I did push upward on it with some good force but no movement. Prybar is a good idea though.
    Yes. Vibration in 1,2 and 3rd is negligible. The grinding type noise is consistant with the engine rpms; maybe I'd describe it sounding like the motor had a bunch of sand in it? In 5th it's a bounce, shake type of thing of the whole truck. Pretty sure it's not a bad tire, I've dealt with several lumpy tires and this shaking is worse than what a tire would cause I think.
    Thanks a bunch for the help
     

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