truck shakes in third gear

[CecilDunn]

start off by saying i have this 62' c20 from the farm today i pulled out of the gas station and when i did i thought i heard something but didn't pay it no attention due to all the commotion at store once i pulled of and down the road shifted into 3rd gear and it started shaking horribly thought it might have just been bad onramp to highway i shifted into 4th and went on my way and it quit later down the road noticed it again shaking horribly once again in 3rd and goes away once ur above 2000 rpm in 4th never feel it in 2nd still new to the old farm truck and need to learn what this could be going to check plugs and spark to make sure its not a misfire idk what to do really any help would b greatly appreciated

[aerotruk63]

Does the steering wheel shake or do you feel it in the seat?

[CecilDunn]

no i thought it might of been drive shaft or universal joint cause it has 2 piece but all looked fine only other thing i could thing of was misfire, clutch or tranny (knocks on truck bed)

[Clyde65]

look fine?

go under and move each u-joint side to side and see if you get any movement. if you do, replace them all!

[aerotruk63]

My buddy's Blazer had a bad tire that caused the vibration. Only between certain speeds. Replaced the tire and problem was solved. We found it by rotating the tires and the vibration was felt through the steering.

[padresag]

and it shakes more in third under throttle pressure?
ron

[Brad54]

Had this problem with the Suburban in my avatar... Turned out to be the front shocks were slap-ass worn out.

It'd vibrate bad at a certain speed, I'd lift the gas pedal and drop RPM (and unload the chassis from the drive forces) and it'd go away. Ease back into the throttle, and it'd stay gone... for a while.

Once a cadence gets set at a certain rpm, it'd cause the wheels to bounce.

Replaced the shocks, problem went away.

Could be the problem with an old farm truck.

-Brad

[padresag]

petty tough for shock absorbers to cause a driveline vibration i think. they might rattle ,bang,clang or let you bounce
ron

[CecilDunn]

after chasing my tail all afternoon and checking everything i could think of, went back and looked over 2 piece driveshaft found that the driveshaft support & bearing were wore slap out with quite bit of play and also cracked and loose u joint right beside it $100 later 3 new u joints and bearing support which looks like they have never been changed due to rust and way there stuck together any sugestions on best way to free them up to replace thanks for all the replies also

[CecilDunn]

i dont know how i missed that smh

[padresag]

Originally Posted by CecilDunn

i dont know how i missed that smh

you will know if i happens again. it is easier to spot with an a/trans as you will usually feel a shudder when you first start out and again when it shifts if your foot is in it a little. when you apply throttle it transmits torque and will thrust it sideways until the pressure eases off and will centre itself unless the rubber cushion is really gone. then you will know for sure. that is why I asked if it happened in 3rd as you will usually apply more throttle in 3rd and 4th you hold steady
ron

[CecilDunn]

alright this might sound dumb but i cannot get the broken support bearing off the damn spline once unbolted the thing fell apart and the rubber with bearing is stuck and will not budge any suggestions please im still kicking myself in the rear end chasing my tail...

[padresag]

you can use a press or a puller or a good cold chisel and a hammer. give us a picture of what you have
ron

[CecilDunn]

unbolted it and metal frame fell off now the bushing and rubber is only thing stuck on driveshaft and i have tried beating prying sraying with cleaner and greaser

[padresag]

you should be able to pull the rubber off. if not cut it off so that you can get to the bearing
take the d/shaft out of the truck so that it is easier to work on
Clean all the crap off the splines
ron

[padresag]

don't put the d/shaft tube in the vise either and squeeze the poop out of the tube. clamp where the weld is
ron

[CecilDunn]

alright i have pried beat cussed smoked even tried to get a puller but its not working either the shield is in the way i dont want to mess anything up but the new bearing support comes with new dust shields can i bend the old one and break it off i really dont know what to do at this point im stumped cant think of anything else seems tried everything....

[Palf70Step]

I cut one off with a dremel tool. Slow an easy.once the bearing was split it releved the pressure and came off

[CecilDunn]

what about the big dust cover on the back does it come off also to b replaced or did u just cut the bearing and small dust cover on the front?

[padresag]

if I can remember that 1st cover(slinger) comes off(1/2 donut shape) by sliding down the shaft and goes back on. the big back cover stays. the dust covers should pop off. don't worry about damaging them as they are being replaced. if you are good with a cutting torch, cut it off the shields and outer race of the bearing. you can heat up the innner race and it should expand and slide off. you do not want to heat up the splines though.
hammer and cold chisel is another way. those were the old ways and were fast and efficient if you knew what you were doing. 4 1/2" angle grinder or a smaller cut-off wheel on a die grinder and cut it off except for the last little bit of the inner race so you don't cut the splines; just split the cut with a cold chisel
note about hammer and chisel, make sure that you wear face protection as that outer race can shoot nasty little projectiles when it breaks. when you crack the outer race all the ball bearings fall away and then all you have left is the inner race.
the safest way is to just take it to a driveline place or machine shop and they will change it for you