C4 auto with a vibration
08-02-2015, 07:35 AM
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C4 auto with a vibration
I recently had my 1989 auto transmission recond , and from then on had a vibration . Rebalanced all the wheels , new universal joints on the half shafts , and brand new , steel main drive shaft . Still got a vibration , but the automatic repairer says it's got nothing to do with him . It's gone from being a pleasure to drive , to just being a worry now . I would appreciate any ideas . Thank you .
08-02-2015, 09:45 PM
#2
Can you get a second opinion from another trans shop? Seems obvious that something changed since having the trans rebuilt. Good luck maybe a transmission person here will have some more specific advice.
Rick
Rick
08-03-2015, 09:25 AM
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Vibration could stem from the torque converter or pressure plate (not very likely), or the too the main drive shaft balance.
Balance issue w/in the transmission? Not so much. But, if you put it in park and rev to the rpm where vibration was experienced and you have the vibration, then I'd suspect something amiss with the converter/pressure plate. However, if the vibration is only present when in drive, I'd be looking at the main drive shaft next.
I experienced a severe "buzz" vibration (especially on the gear shift ****) right after I'd changed U-joints. I'd read but forgotten a note in the FSM (I think it was?) that said to reference (mark) the driveshaft and the yokes before removing the shaft from the car so as to install the shaft in the same position, relative to the yoke(s) to assure balancing is not disturbed.
Sure enough! All I had to do was remove the shaft and turn it 180º relative to the differential yoke, and the vibration was gone for good. (I guess I got lucky(?) on the slip-yoke end of the shaft.)
If you determine (while in PARK) the vibration is in the possibly in the driveshaft(s), and since they're new, I'd consider taking it to a drive-line shop and have them check the balance and also see that the yoke centerlines are true with the new shaft while they're at it.
I kinda doubt the half-shafts would be out of balance enough to cause any vibration, due to the relative low rpm, unless something is really out of whack. But, if you have a vibration that starts at low mph and continues from there up the scale, then maybe.
Chances are you'll find the problem to be other than the transmission. But, "never say never"! If everything checks out, leaving only the trans, I agree w/ what Rick said. Or, at the very least, it's time to pull it and spin it and see what's what, I recon!
Balance issue w/in the transmission? Not so much. But, if you put it in park and rev to the rpm where vibration was experienced and you have the vibration, then I'd suspect something amiss with the converter/pressure plate. However, if the vibration is only present when in drive, I'd be looking at the main drive shaft next.
I experienced a severe "buzz" vibration (especially on the gear shift ****) right after I'd changed U-joints. I'd read but forgotten a note in the FSM (I think it was?) that said to reference (mark) the driveshaft and the yokes before removing the shaft from the car so as to install the shaft in the same position, relative to the yoke(s) to assure balancing is not disturbed.
Sure enough! All I had to do was remove the shaft and turn it 180º relative to the differential yoke, and the vibration was gone for good. (I guess I got lucky(?) on the slip-yoke end of the shaft.)
If you determine (while in PARK) the vibration is in the possibly in the driveshaft(s), and since they're new, I'd consider taking it to a drive-line shop and have them check the balance and also see that the yoke centerlines are true with the new shaft while they're at it.
I kinda doubt the half-shafts would be out of balance enough to cause any vibration, due to the relative low rpm, unless something is really out of whack. But, if you have a vibration that starts at low mph and continues from there up the scale, then maybe.
Chances are you'll find the problem to be other than the transmission. But, "never say never"! If everything checks out, leaving only the trans, I agree w/ what Rick said. Or, at the very least, it's time to pull it and spin it and see what's what, I recon!
08-03-2015, 05:03 PM
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Vibration could stem from the torque converter or pressure plate (not very likely), or the too the main drive shaft balance.
Balance issue w/in the transmission? Not so much. But, if you put it in park and rev to the rpm where vibration was experienced and you have the vibration, then I'd suspect something amiss with the converter/pressure plate. However, if the vibration is only present when in drive, I'd be looking at the main drive shaft next.
I experienced a severe "buzz" vibration (especially on the gear shift ****) right after I'd changed U-joints. I'd read but forgotten a note in the FSM (I think it was?) that said to reference (mark) the driveshaft and the yokes before removing the shaft from the car so as to install the shaft in the same position, relative to the yoke(s) to assure balancing is not disturbed.
Sure enough! All I had to do was remove the shaft and turn it 180º relative to the differential yoke, and the vibration was gone for good. (I guess I got lucky(?) on the slip-yoke end of the shaft.)
If you determine (while in PARK) the vibration is in the possibly in the driveshaft(s), and since they're new, I'd consider taking it to a drive-line shop and have them check the balance and also see that the yoke centerlines are true with the new shaft while they're at it.
I kinda doubt the half-shafts would be out of balance enough to cause any vibration, due to the relative low rpm, unless something is really out of whack. But, if you have a vibration that starts at low mph and continues from there up the scale, then maybe.
Chances are you'll find the problem to be other than the transmission. But, "never say never"! If everything checks out, leaving only the trans, I agree w/ what Rick said. Or, at the very least, it's time to pull it and spin it and see what's what, I recon!
Balance issue w/in the transmission? Not so much. But, if you put it in park and rev to the rpm where vibration was experienced and you have the vibration, then I'd suspect something amiss with the converter/pressure plate. However, if the vibration is only present when in drive, I'd be looking at the main drive shaft next.
I experienced a severe "buzz" vibration (especially on the gear shift ****) right after I'd changed U-joints. I'd read but forgotten a note in the FSM (I think it was?) that said to reference (mark) the driveshaft and the yokes before removing the shaft from the car so as to install the shaft in the same position, relative to the yoke(s) to assure balancing is not disturbed.
Sure enough! All I had to do was remove the shaft and turn it 180º relative to the differential yoke, and the vibration was gone for good. (I guess I got lucky(?) on the slip-yoke end of the shaft.)
If you determine (while in PARK) the vibration is in the possibly in the driveshaft(s), and since they're new, I'd consider taking it to a drive-line shop and have them check the balance and also see that the yoke centerlines are true with the new shaft while they're at it.
I kinda doubt the half-shafts would be out of balance enough to cause any vibration, due to the relative low rpm, unless something is really out of whack. But, if you have a vibration that starts at low mph and continues from there up the scale, then maybe.
Chances are you'll find the problem to be other than the transmission. But, "never say never"! If everything checks out, leaving only the trans, I agree w/ what Rick said. Or, at the very least, it's time to pull it and spin it and see what's what, I recon!
08-03-2015, 05:12 PM
#8
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What is the frequency of the vibration? Drive shaft speed? Engine speed? Or wheel speed?
08-04-2015, 02:32 AM
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well the vibration seems to be between 60 and 80 kilometers an hour . At 70 is at its worse and does not seem to make a difference if in drive or neutral . It is still under warranty . I rang around and made some enquiries from other transmission places . They say it's rare , but could be the flex plate , or torque converter out of balance . Trust me to draw the short straw . Any how thanks for asking , cheers
08-04-2015, 05:03 AM
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Vibration could stem from the torque converter or pressure plate (not very likely), or the too the main drive shaft balance.
Balance issue w/in the transmission? Not so much. But, if you put it in park and rev to the rpm where vibration was experienced and you have the vibration, then I'd suspect something amiss with the converter/pressure plate. However, if the vibration is only present when in drive, I'd be looking at the main drive shaft next.
I experienced a severe "buzz" vibration (especially on the gear shift ****) right after I'd changed U-joints. I'd read but forgotten a note in the FSM (I think it was?) that said to reference (mark) the driveshaft and the yokes before removing the shaft from the car so as to install the shaft in the same position, relative to the yoke(s) to assure balancing is not disturbed.
Sure enough! All I had to do was remove the shaft and turn it 180º relative to the differential yoke, and the vibration was gone for good. (I guess I got lucky(?) on the slip-yoke end of the shaft.)
If you determine (while in PARK) the vibration is in the possibly in the driveshaft(s), and since they're new, I'd consider taking it to a drive-line shop and have them check the balance and also see that the yoke centerlines are true with the new shaft while they're at it.
I kinda doubt the half-shafts would be out of balance enough to cause any vibration, due to the relative low rpm, unless something is really out of whack. But, if you have a vibration that starts at low mph and continues from there up the scale, then maybe.
Chances are you'll find the problem to be other than the transmission. But, "never say never"! If everything checks out, leaving only the trans, I agree w/ what Rick said. Or, at the very least, it's time to pull it and spin it and see what's what, I recon!
Balance issue w/in the transmission? Not so much. But, if you put it in park and rev to the rpm where vibration was experienced and you have the vibration, then I'd suspect something amiss with the converter/pressure plate. However, if the vibration is only present when in drive, I'd be looking at the main drive shaft next.
I experienced a severe "buzz" vibration (especially on the gear shift ****) right after I'd changed U-joints. I'd read but forgotten a note in the FSM (I think it was?) that said to reference (mark) the driveshaft and the yokes before removing the shaft from the car so as to install the shaft in the same position, relative to the yoke(s) to assure balancing is not disturbed.
Sure enough! All I had to do was remove the shaft and turn it 180º relative to the differential yoke, and the vibration was gone for good. (I guess I got lucky(?) on the slip-yoke end of the shaft.)
If you determine (while in PARK) the vibration is in the possibly in the driveshaft(s), and since they're new, I'd consider taking it to a drive-line shop and have them check the balance and also see that the yoke centerlines are true with the new shaft while they're at it.
I kinda doubt the half-shafts would be out of balance enough to cause any vibration, due to the relative low rpm, unless something is really out of whack. But, if you have a vibration that starts at low mph and continues from there up the scale, then maybe.
Chances are you'll find the problem to be other than the transmission. But, "never say never"! If everything checks out, leaving only the trans, I agree w/ what Rick said. Or, at the very least, it's time to pull it and spin it and see what's what, I recon!
08-04-2015, 10:06 AM
#11
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well the vibration seems to be between 60 and 80 kilometers an hour . At 70 is at its worse and does not seem to make a difference if in drive or neutral . It is still under warranty . I rang around and made some enquiries from other transmission places . They say it's rare , but could be the flex plate , or torque converter out of balance . Trust me to draw the short straw . Any how thanks for asking , cheers
Anyway, if it "does not seem to make a difference if in drive or neutral", and that is true, then we can pretty well eliminate the engine, flex plate, and torque converter. That leaves the driveshaft and wheels, as most likely suspects.
08-04-2015, 10:21 AM
#12
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You didn't really answer my question. I didn't ask what speed the vehicle goes to make the vibration, I asked when the vibration occurs, what is the frequency? I ask this, b/c you can quickly determine if it is wheel, driveshaft, or engine, by the frequency.
Anyway, if it "does not seem to make a difference if in drive or neutral", and that is true, then we can pretty well eliminate the engine, flex plate, and torque converter. That leaves the driveshaft and wheels, as most likely suspects.
Anyway, if it "does not seem to make a difference if in drive or neutral", and that is true, then we can pretty well eliminate the engine, flex plate, and torque converter. That leaves the driveshaft and wheels, as most likely suspects.
Question tho... How would I go about determining the specific frequency of the vibration, Tom? Are you asking for specific frequencies, or rpm where it occurs?
08-04-2015, 10:25 AM
#13
Tech Contributor
I recently had my 1989 auto transmission recond , and from then on had a vibration . Rebalanced all the wheels , new universal joints on the half shafts , and brand new , steel main drive shaft . Still got a vibration , but the automatic repairer says it's got nothing to do with him . It's gone from being a pleasure to drive , to just being a worry now . I would appreciate any ideas . Thank you .
08-04-2015, 10:39 AM
#14
Team Owner
Pro Mechanic
Good questions^
Seriously, I mean, basically some common sense. Wheel/tires out of round or balance make a frequency so low you can almost count it (at say, 60mph), and a driveshaft is way to fast for that; 2.5-3.5 times higher frequency....so it sounds more like a low hum or Bass through the center console/shifter.
Engine is easy b/c the frequency would change (as would intensity) with engine speed -moving or parked in neutral.
One thing that is odd, is the OP said it is worst at ~70 KPH...which is something like 43 mph. That is awfully slow to be getting serious driveline vibes....tire too.
I guess if I couldn't isolate it by frequency, I'd throw it on 4 jack stands, have someone "drive" it 70 kph and lay under it to see where the source is.
08-04-2015, 11:07 AM
#15
Melting Slicks
Why not get it up above the 'worst' speed, after checking all bolt tightness and security of the shafts, then select neutral, to isolate the engine from the driveline? I think Chevy recommends NOT 'driving' the car while elevated for a few reasons, besides safety.
I recall reading the import of marking the shafts prior to removal and ahd some half-shaft vibe issues before I'd read that.
Having had a driveshaft exit a Chevelle while driving, I'd want to ensure someone didn't screw up and leave some rotating part loose!
In any event, if there was no such vibration before this ONE shop did the work, and there is now, guess who bears the responsibility to redo it properly? Hopefully, their denial is not an indication of their workmanship, but.....
I recall reading the import of marking the shafts prior to removal and ahd some half-shaft vibe issues before I'd read that.
Having had a driveshaft exit a Chevelle while driving, I'd want to ensure someone didn't screw up and leave some rotating part loose!
In any event, if there was no such vibration before this ONE shop did the work, and there is now, guess who bears the responsibility to redo it properly? Hopefully, their denial is not an indication of their workmanship, but.....
08-04-2015, 11:13 AM
#16
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Let's not scare our selves out of doing something that is perfectly reasonable (when done with a brain). That is why you use 4 jack stands...safely
A little commons sense and awareness goes a long way.
08-04-2015, 11:38 AM
#17
Melting Slicks
Well, yeah. Anything done under a car should involve 'a brain'.
I don't have time to research it, now, but it dealt with the high U-joint angles with the rotation.
I see you have 'driven' yours while elevated, too.
I don't have time to research it, now, but it dealt with the high U-joint angles with the rotation.
I see you have 'driven' yours while elevated, too.
08-04-2015, 11:43 AM
#18
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Good questions^Easy....just use a Snap-On Vibrationometer.
Seriously, I mean, basically some common sense. Wheel/tires out of round or balance make a frequency so low you can almost count it (at say, 60mph), and a driveshaft is way to fast for that; 2.5-3.5 times higher frequency....so it sounds more like a low hum or Bass through the center console/shifter.
.
) It's been a while, so I don't remember specifically what my speed MPH was when the first harmonic appeared. But, I seem to think it was less than 70 mph (IIRC).
It was more than just a minor vibration too, becoming quite audible as well as felt throughout the cabin. Some loose change in one of the cup holders rattled and buzzed quite noticeably. No question: Something was seriously wrong. I was glad it turned out to be a simple fix.
08-04-2015, 07:35 PM
#19
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If you jack stand the rear of the car (safely) under the knuckles, axle shaft angles are the same as when driving on the road.
However, when I did mine, it was w/the axle shafts removed, b/c I already knew (from the frequency) that it was a drive shaft issue.
08-05-2015, 05:48 AM
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You didn't really answer my question. I didn't ask what speed the vehicle goes to make the vibration, I asked when the vibration occurs, what is the frequency? I ask this, b/c you can quickly determine if it is wheel, driveshaft, or engine, by the frequency.
Anyway, if it "does not seem to make a difference if in drive or neutral", and that is true, then we can pretty well eliminate the engine, flex plate, and torque converter. That leaves the driveshaft and wheels, as most likely suspects.
Anyway, if it "does not seem to make a difference if in drive or neutral", and that is true, then we can pretty well eliminate the engine, flex plate, and torque converter. That leaves the driveshaft and wheels, as most likely suspects.
