Sort of, Take it out of gear, and it is still there, but is more noticeable under load.
Kind of Off Topic
- Thread starter Moseman
- Start date
The rear diff is now a suspect, before we go to the trans. But, as I said, the 1200 mile from Portland, the vibration wasn't there, sloppiness in the steering, yes, leaking valve cover, yes, but no vibration at 70+ mph. It has me and several others stumped. I guess we go to the other 70 year old mechanic here. He is good, but slow, and the cars sit in the 95 degree New Mexico sun until he gets to the car.
67Monaco
Old Man with a Hat
Just throwing it out there... Have you checked diff fluid level?
no, good suggestion, a task for tomorrow.
Lots of time and money with little benefit, it seems.
Why the rear spring change? Were they sagged or otherwise?
Even with the Iso-Clamp rear axle mounts, the pinion angle is related to how the spring pads are welded to the end of the axle housing. Same as with the more solid mountings used previously. You'll need a twin-post lift so the rear axle is lifted individually so the suspension remains at "ride height". Driveline angle measurement is a straight-forward bubble-level measurement. There's a special tool just for drivelines, but the same readings might be done without that particular special tool.
Torque converter "lockup"? IF it has a lockup converter, happened at 27mph on the first several years of cars. By '80, it was more like 53mph.
Steering "slop" might be something that could be addressed as a separate item, but NOT for a vibration issue. Gearbox adjustments (on BOTH places!) should take care of that, I believe.
What type of "Frequency" is the vibration? Is it the same at all speeds or is it road-speed-related?
Where did the trans leak come from? Just curious.
IF perhaps, you got a lockup converter trans rather than a non-lockup converter trans, when the converter locks-up and slips, it's a higher-frequency vibration that will disappear when you throttle OUT of the motor. Trying to accelerate through it makes it more intense. But those things don't usually start to fail until about the 80K+ mile range. The Chrysler lockup is purely mechanically controlled with no vacuum switches or such as GM used.
On u-joints, you need to look to see that the caps were installed to the same "depth" on all sides and that there is NO lateral movement in the joint. Everything should be "tight", in that respect.
Balance weights on the driveshaft CAN come loose and be slung off, but not usually. If they do "leave", where they were can usually be determined by an easy cleaning and thorough inspection of the shaft for "patterns" where they used to be. What CAN happen is a foreign object which might put a slight bend in the shaft body. OR a worn tailshaft housing bushing in the trans, which also knocks out the adjacent trans seal.
Seems like some of those cars had a rubber-mounted "weight" on the tailshaft housing, mounted with bolts? More of a vibration damper of sorts, but probably NOT for the type of vibration you seem to have.
Does this car still have the factory wheels? Have the tires been "road force balanced"?
Other than the time and money, the "no joy" issue might be that you're "barking" in the wrong "forest"? Or might there be something in the car's prior history that might be of interest?
Just some thoughts,
CBODY67
Why the rear spring change? Were they sagged or otherwise?
Even with the Iso-Clamp rear axle mounts, the pinion angle is related to how the spring pads are welded to the end of the axle housing. Same as with the more solid mountings used previously. You'll need a twin-post lift so the rear axle is lifted individually so the suspension remains at "ride height". Driveline angle measurement is a straight-forward bubble-level measurement. There's a special tool just for drivelines, but the same readings might be done without that particular special tool.
Torque converter "lockup"? IF it has a lockup converter, happened at 27mph on the first several years of cars. By '80, it was more like 53mph.
Steering "slop" might be something that could be addressed as a separate item, but NOT for a vibration issue. Gearbox adjustments (on BOTH places!) should take care of that, I believe.
What type of "Frequency" is the vibration? Is it the same at all speeds or is it road-speed-related?
Where did the trans leak come from? Just curious.
IF perhaps, you got a lockup converter trans rather than a non-lockup converter trans, when the converter locks-up and slips, it's a higher-frequency vibration that will disappear when you throttle OUT of the motor. Trying to accelerate through it makes it more intense. But those things don't usually start to fail until about the 80K+ mile range. The Chrysler lockup is purely mechanically controlled with no vacuum switches or such as GM used.
On u-joints, you need to look to see that the caps were installed to the same "depth" on all sides and that there is NO lateral movement in the joint. Everything should be "tight", in that respect.
Balance weights on the driveshaft CAN come loose and be slung off, but not usually. If they do "leave", where they were can usually be determined by an easy cleaning and thorough inspection of the shaft for "patterns" where they used to be. What CAN happen is a foreign object which might put a slight bend in the shaft body. OR a worn tailshaft housing bushing in the trans, which also knocks out the adjacent trans seal.
Seems like some of those cars had a rubber-mounted "weight" on the tailshaft housing, mounted with bolts? More of a vibration damper of sorts, but probably NOT for the type of vibration you seem to have.
Does this car still have the factory wheels? Have the tires been "road force balanced"?
Other than the time and money, the "no joy" issue might be that you're "barking" in the wrong "forest"? Or might there be something in the car's prior history that might be of interest?
Just some thoughts,
CBODY67
A lot of questions here, I hope I will be able to answer them all and to an extent that is satisfactory.
- The car was sagging at the rear, the new springs leveled the stance.
- The transmission leak occurred due to old brittle pan gasket.
- Still has the factory wheels, not sure about "road force balance" but they have been balanced both for inside and outside weights rather than static balance.
- I am the third owner of the car. "A little old lady" owned the car, and then a guy purchased it from her as he thought the car was "cool". I am sure that he didn't abuse the car, and was sad to see it go. It was kept indoors all of its life and I have much documentaion of the repairs performed on the car.
- Photos are from the previous owner.
Thanks for the pictures and info. A nice looking car!
If the car is sitting at level ride height, the pinion angle, being a "welded-in" at the factory situation, should be fine or "within specs". Once assembled and it got as far as it apparently has, it doesn't change. Most "shake on acceleration" issues arise when the vehicle has some load in the trunk or rear seat, not just driving around, from what I've seen. But even then, certainly NOT normal within the arc which the rear u-joint makes during top-to-bottom vertical rear wheel travel.
But "something" had to have made the rear springs sag as they apparently did. Like towing a light trailer or heavy items that were in the trunk for extended periods of time. Both my '70 Monaco Brougham and '80 Newport have sagged rear springs. The '70 had been used to haul a travel trailer around for a good while. When I got it, it had rear load levelers on it, and it STILL sagged until I replaced them with Gabriel Hi-Jackers, which have worked well for me. The '80 had been owned by an oil field tools rep and had a angle-iron trailer hitch on it, with Midas-brand air shocks. With no pressure in them, the rear end was too low. So a new set of Monroe air shocks fixed that nicely. The air shocks were and still ARE a band-aid fix, but all of that was done before I knew of ESPO and such. But as it's all working well for me, I'll keep things as they are. The '70 is a 383 "N" car with no trailer package, but the '80 has the "load carrying" HD suspension (no rear sway bar) from the factory.
Barring any significant body re-alignment with respect to the spring mounts and front structure mounts, which should be obvious on a lift, that leaves the only OTHER spinning item under there. The driveshaft. As a noise control strategy, some manufacturers have used various dampening methods for their tubes. One is the varied-diameter tube. In some, when cut open, there's a thin piece of soft cardboard inside of the inner circumference. Others have used rubber donuts inserted into them. If some of that stuff has deteriorated, they can move around internally, which can cause some unbalanced situations. As they can now move around, the vibrations might change between driving cycles, possibly. All of this has nothing to do with how "straight" the tube might be.
The issue of the cracked trans pan gaskets is interesting. Unless some very substandard rubberized cork gaskets were used (not OEM-spec, or similar), the only thing that might make them brittle and hard is heat. They can't dry out as when the engine stops, the torque converter partially drains into the pan, and the fluid level can get higher than the neutral safety switch on the side of the case. No way the gasket would ever "dry out" from sitting, that I can see, with the trans oil level being that high when the engine stops and sits overnight, stopped.
"Road force balance" is a tire/wheel balancing technique which more new balancers incorporate, especially at the dealership level of things. Once the wheel is mounted to the balancer, a fixed tube is rolled against the tread as the balancer slowly spins the wheel/tire assembly. Then the balancer will spin it faster, sometimes, then give the readout of "road force variation" as it also indicates where the balance weights should be. No "splitting weights" with these electronic balancers. The road force variation amount is also displayed. Sometimes, you can reposition the tire on the wheel to minimize it, which I believe happens BEFORE the wheel assy is spun for the weight applications. Goodyear calls it "ride variation", or something similar, not embracing the "road force variation" terminology that the OEMs typically use. I think that in the "old days", such road force variations were termed "hard spots" where the tire carcass is put together and the plies overlap?
With the rear axle safely supported on jack stands, slowly turn the rear wheels and look for wheel lateral run-out, which could be an axle shaft flange situation in addition to a separate wheel issue. Is the vibration there with the wheel covers off the car? Just curious, considering how heavy those are in comparison to the standard Cordoba wheel covers of those years.
Does the rear trans crossmember show any evidence of being deformed? What about the rear trans mount? The only other place where driveshaft angularity can be altered.
Just some thought,
CBODY67
If the car is sitting at level ride height, the pinion angle, being a "welded-in" at the factory situation, should be fine or "within specs". Once assembled and it got as far as it apparently has, it doesn't change. Most "shake on acceleration" issues arise when the vehicle has some load in the trunk or rear seat, not just driving around, from what I've seen. But even then, certainly NOT normal within the arc which the rear u-joint makes during top-to-bottom vertical rear wheel travel.
But "something" had to have made the rear springs sag as they apparently did. Like towing a light trailer or heavy items that were in the trunk for extended periods of time. Both my '70 Monaco Brougham and '80 Newport have sagged rear springs. The '70 had been used to haul a travel trailer around for a good while. When I got it, it had rear load levelers on it, and it STILL sagged until I replaced them with Gabriel Hi-Jackers, which have worked well for me. The '80 had been owned by an oil field tools rep and had a angle-iron trailer hitch on it, with Midas-brand air shocks. With no pressure in them, the rear end was too low. So a new set of Monroe air shocks fixed that nicely. The air shocks were and still ARE a band-aid fix, but all of that was done before I knew of ESPO and such. But as it's all working well for me, I'll keep things as they are. The '70 is a 383 "N" car with no trailer package, but the '80 has the "load carrying" HD suspension (no rear sway bar) from the factory.
Barring any significant body re-alignment with respect to the spring mounts and front structure mounts, which should be obvious on a lift, that leaves the only OTHER spinning item under there. The driveshaft. As a noise control strategy, some manufacturers have used various dampening methods for their tubes. One is the varied-diameter tube. In some, when cut open, there's a thin piece of soft cardboard inside of the inner circumference. Others have used rubber donuts inserted into them. If some of that stuff has deteriorated, they can move around internally, which can cause some unbalanced situations. As they can now move around, the vibrations might change between driving cycles, possibly. All of this has nothing to do with how "straight" the tube might be.
The issue of the cracked trans pan gaskets is interesting. Unless some very substandard rubberized cork gaskets were used (not OEM-spec, or similar), the only thing that might make them brittle and hard is heat. They can't dry out as when the engine stops, the torque converter partially drains into the pan, and the fluid level can get higher than the neutral safety switch on the side of the case. No way the gasket would ever "dry out" from sitting, that I can see, with the trans oil level being that high when the engine stops and sits overnight, stopped.
"Road force balance" is a tire/wheel balancing technique which more new balancers incorporate, especially at the dealership level of things. Once the wheel is mounted to the balancer, a fixed tube is rolled against the tread as the balancer slowly spins the wheel/tire assembly. Then the balancer will spin it faster, sometimes, then give the readout of "road force variation" as it also indicates where the balance weights should be. No "splitting weights" with these electronic balancers. The road force variation amount is also displayed. Sometimes, you can reposition the tire on the wheel to minimize it, which I believe happens BEFORE the wheel assy is spun for the weight applications. Goodyear calls it "ride variation", or something similar, not embracing the "road force variation" terminology that the OEMs typically use. I think that in the "old days", such road force variations were termed "hard spots" where the tire carcass is put together and the plies overlap?
With the rear axle safely supported on jack stands, slowly turn the rear wheels and look for wheel lateral run-out, which could be an axle shaft flange situation in addition to a separate wheel issue. Is the vibration there with the wheel covers off the car? Just curious, considering how heavy those are in comparison to the standard Cordoba wheel covers of those years.
Does the rear trans crossmember show any evidence of being deformed? What about the rear trans mount? The only other place where driveshaft angularity can be altered.
Just some thought,
CBODY67
bluefury361
Old Man with a Hat
Not sure if your car has an overdrive, but a worn bearing there will cause that issue.
Also a worn tail shaft bushing at the slip yoke.
Nice car.
Also a worn tail shaft bushing at the slip yoke.
Nice car.
no overdrive
https://www.hurst-drivelines.com/files/Driveline-Vibration-FAQ.pdf
A pretty fair overview of diagnosing driveline vibrations in the link above. They left out torque related issues, which would be checked by hard acceleration and/or power braking.
The only thing I've gathered from this thread thus far is that there MAY be a pinion issue, which I'd expect to have an accompanying noise if a depth issue or get far worse on heavy acceleration if angle related.
A pretty fair overview of diagnosing driveline vibrations in the link above. They left out torque related issues, which would be checked by hard acceleration and/or power braking.
The only thing I've gathered from this thread thus far is that there MAY be a pinion issue, which I'd expect to have an accompanying noise if a depth issue or get far worse on heavy acceleration if angle related.
Thank you, I want to thank everyone who has given this issue their thoughts. We chased the vibration to the pinion angle issue because the vibration seemed to become prominent after the springs were replaced. Will continue to troubleshoot later this week. Again, I really appreciate everyone's help on this.
Was there an issue with vibration before the shop worked on it?
If it were me, I'd take the driveshaft to a good driveshaft shop and have the balance and phase checked before I started digging into anything else.
Chrysler liked to use those driveshafts with a rubber piece isolating piece in the middle and I'm wondering if your car has one. If they slip, the two u-joints go out of alignment with each other. That "twist" will cause a vibration just like you are describing and drive you nuts trying to find the cause. Most shops won't even think of looking for that.
Good suggestion. This week when I Have the car up on stands, I will pull the drive shaft and see. Thank you.
70bigblockdodge
Old Man with a Hat
I'm with Big John on this, it is most likely in the driveshaft. Who put the u-joints in, and was a large hammer involved? The yoke ears bend quite easy.
Also to check, for free I might add is the rubber iso pucks on K member. I had a Cordoba that they were failing and it shook, although not at that low of speed and cowl shake. Free and easy check anyway.
Also to check, for free I might add is the rubber iso pucks on K member. I had a Cordoba that they were failing and it shook, although not at that low of speed and cowl shake. Free and easy check anyway.
An Update, Yesterday I opened up the rear diff and changed the gear oil to a synthetic oil. Pretty pathetic looking oil came out of the diff, and a little frothy looking. Buttoned things up, and took it for a test drive. I think the new oil and full diff may have fixed my problem. Gotta chase down the leaky trans. Still am seeing some trans fluid on the floor. The PO stripped a bolt hole on the trans, so I am thinking that may be the major culprit.
I am still kicking myself for not making all of the mechanical repairs and maintenance issues on this car (which is my standard practice on all of my used purchases). As it seemed a good driver I skipped the step of draining and replacing all of the fluids, brakes, steering, etc..... My bad. (A good engineer doesn't do things half assed. Oh well!)
I am still kicking myself for not making all of the mechanical repairs and maintenance issues on this car (which is my standard practice on all of my used purchases). As it seemed a good driver I skipped the step of draining and replacing all of the fluids, brakes, steering, etc..... My bad. (A good engineer doesn't do things half assed. Oh well!)
Most of the time one stripped or missing bold will not cause a leak from the pan gasket. Check the torque on your pan bolts, cork/composite gaskets will compress some after installation and need to be re-torqued. Next check the area around the dip stick tube, the 727 is famous for leaks there. Next, check the front of the transmission for a leak from the front seal, it was cause a drip out the lower cover drain hole. These are the three major sources of leaks from a 727.
Dave
rags
Senior Member
along with selector shaft seal, pump seal (big rubber band that goes around the pump), neutral safety switch...
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