New tranny and a vibration?

[Jakethesnake73]

I blew the tranny in my blazer so i bought a completely rebuilt one and put it in.  My issue is is that when i let pff the gas their seems to be a slight vibration, you would have to be looking for it to notice and a big part of it is just feel on the pedals. It almost is like its staying in gear. Maybe im just not used to the new tranny or its part of some sort of break in period?


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[FlatBlack77]

im guessing its an automatic

witht hat being said i think it is possible that if the flexplate and converter arent matched back up hole for hole then there could be vibrations because the plate is flexed slightly different all around and bolting it back up in another position could cause vibration.

if you get what i mean. i read it in an old chilton/haynes manual

[74k20]

When I did my last install, my 14yo son installed the drivelines.  I felt a vibration, so I crawled under and saw he didn't quite seat the u-joint.  Got REALLY lucky to have caught it before a BAD day.  Something to do a double/triple check on.  Would be nice if it's that easy to fix.

[Jakethesnake73]

When I did my last install, my 14yo son installed the drivelines.  I felt a vibration, so I crawled under and saw he didn't quite seat the u-joint.  Got REALLY lucky to have caught it before a BAD day.  Something to do a double/triple check on.  Would be nice if it's that easy to fix.

i already checked those ill get down there with a wrench and try to tighten them up


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[Jakethesnake73]

So it quit for a while and came back today and much worse.  The vibration is so bad that i cant tell what the car is behind me using the rear view mirror.  The steering pulls to the left sometimes and that got better but still happened after rotating tires. Im going to replace the rear tranny mount tomorrow and see if that helps. Could it be a bearing that didn't squeak for some reason? What about a shim on the u bolts the raise the angle of the rear pinion?


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[Irish_Alley]

make sure the u joints are in phase

[Jakethesnake73]

make sure the u joints are in phase

i just looked and they seem fine, i dont know what its called but some drive shafts are "extendable" and this one is a solid piece so i dont think it can go out of phase.. When i had the tranny out i replaced the rear seal where the driveshaft goes into the transfer case and it still leaks, which is why i thought the u bolts may need shims and maybe the driveshaft being to short could cause a vibration?


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[Irish_Alley]

there are slip yoke drive shafts and bolt on drive shafts and two piece. with the slip yoke no you cant get it out of phase, some say you can install it 180° out and cause it to screw up idk. the drive shaft being too short can cause slop in the splines and this causes a vibration

[Jakethesnake73]

So i checked my u joints a total of 4 times. The first 2 it was fine, the 3rd time (yesterday) it was sloppy and totally shot, and i checked it one more tume before i put the new ones in (one was sloppy, the other ceased) and they were fine again.  We saved the worn drive shaft eyelets by hitting them with a chisel. Anyway the vibration is gone and i thank y'all for your help


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