'89 5th Ave, new u joints & tranny mount question

Transmissions and Rear Ends

  1. gomopar89

    gomopar89 Active Member

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    I just had new u-joints and a new tranny mount installed and now I can feel engine vibration in the floor pan! It's also noisier now inside the cabin....WTF???

    Any ideas why?
     
  2. gomopar89

    gomopar89 Active Member

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    No more clunking at all though!
     
  3. Aspen500

    Aspen500 Well-Known Member

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    What type of trans mount did you use? A urethane one will transmit noise and vibration to the floor. Ask me how I know this, lol. If it's a rubber one, the rubber could be too stiff.
    You also may want to check that the trans mount is neutralized, meaning not in a bind. Loosen the through bolt and the 2 bolts that attach it to the trans and wiggle the tailshaft up and down a couple times, then retorque the bolts.

    Unless the driveshaft is now out of balance for some reason (weight fell off while changing the joint, etc), or one of the new u-joints is tight, replacing the joints shouldn't make any noise or vibration that would transmit into the floor pan.

    Just a few ideas of things to check.
     
  4. volare 77

    volare 77 Well-Known Member

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    Vibration/noise while driving or just sitting idling? If idling I would see if something was goofed up under there and maybe hitting the floor or something like that. Also I agree with using a quality rubber mount. China/india made mounts are iffy at best. Make sure they put the thick spacers/washers back on the mounting bolts. Check for tightness too. If the noise /vibration is when driving make sure the u joints were installed correctly. C clips installed. I have seen many times where people don`t put the c clips on the rear u joint and not center it in the rear yoke.
     
  5. gomopar89

    gomopar89 Active Member

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    OK lets see...I had them install a Mevotech tranny mount. Yes the vibration is engine related only and I can feel it in the body from the moment I start her up. So yes at idle and also when accelerating. It's like a low frequency humming sound...
     
  6. volare 77

    volare 77 Well-Known Member

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    Hmmm. Sounds like the issue is with the mount or mounting of the mount. I wonder if they canned the harmonic weight when they put on the new mount. I would ask them to check it out.
     
  7. Aspen500

    Aspen500 Well-Known Member

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    Is the new trans mount urethane or rubber? Never heard of Mevotec until now but I don't see a trans mount listed on their site. As I mentioned, if it's urethane you'll have to get used to the moan/vibration or change to a rubber one.

    When I originally built my car, I put a urethane mount in. Then once I got the car back on the road (finally......) I chased a drone/vibration and above 50 mph it was a cyclic vibration and resonance that would come and go in 3 second intervals. Drove me nuts and I didn't even want to drive the car over 35-40 mph. Tried everything I could think of with no luck. As a last resort, I bought a stock mount at Carquest, bolted it in and,,,,,,,,,,,,,problem solved. That's why I suspect the new mount they put in so much, in case you were wondering.
     
  8. BudW

    BudW Moderator Staff Member

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    For what was described, it sounds like an engine mount sagging or a part rubbing something - like exhaust touching crossmember or any number of other moving item(s) touching stationary item(s).

    I do know it is not un-common for a shop to install the wrong transmission mount on car – for some mounts have a bracket welded-on for exhaust to attach to, and some do not. If the exhaust is not supported in center of car, that alone can cause a noise or vibration.
    Here is a photo of two different versions. There are other versions of transmission mount out there as well (the welded-on bracket is what is different).
    Mount A.jpg
    Mount B.jpg


    There should be some sort of weight bolted to or close to the rear of transmission (on most vehicles). If that weight is missing – that can also cause noise or vibration.
    This is a couple of tailhousing weight designs (out of several designs):
    Tailhousing Weight 727.jpg
    Tailhousing weight PU.jpg

    I hope this helps
    BudW
     
  9. Mr Volare Imperial

    Mr Volare Imperial Well-Known Member

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    As I understand them, the lock-up torque converters can weld themselves together if the specific ground strap from the frame to the transmission becomes damaged or is removed. This can cause the TC to fix itself in an out of balance position causing a substantial vibration that coincides with engine speed and not road speed. The TC spins at engine rotation, of course. A new TC would be the fix if this were the case.
     
    Last edited: Sep 5, 2018
  10. BudW

    BudW Moderator Staff Member

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    I was under my ’77 wagon this weekend and it has the transmission harmonic weight still attached (which may be a different design than yours).
    20180902_161449r.jpg
    This design has a bracket welded onto transmission mount which mount attaches to (via rubber bushing).

    If a shop installed the wrong transmission mount, they might have left the weight off (maybe).

    Some versions of transmission use a similar transmission mount that the welded-on bracket that attaches to exhaust (mid-exhaust support) (see pictures in post # 8).



    I had not seen that happen to a Chrysler vehicle (yet) but that doesn’t mean it won’t or can’t. I have seen that occur to other car lines, though.
    Usually, on Chrysler lock-up converters, when in lock-up mode, if the clutch plate material inside of torque converter is wore out, it can cause a vibration when engaged.

    On most lock-up transmissions, if you are going up an incline with low throttle pressure, you can usually feel each time the transmission shifts and lock-up engage. If feels somewhat like a 5-speed transmission, shifting 4 times (if that makes sense).
    On our vehicles, the lock-up disengages during shifts, to allow for more torque multiplication, then engages about mid-way before next up-shift.

    Now I have seen bearing failure inside of the torque converter – but generally it causes more of a gear or whine noise when lock-up is not engaged and not so much of a vibration.

    Usually if the lockup clutch plate is (out of lack of better description) spot welded itself, it generally acts like a manual clutch vehicle when coming to a stop – without pushing in on the clutch first, for in effect, it is doing the exact same thing.
    Note: the lockup-clutch is always disengaged below a certain speed, no matter what gear vehicle is in at the time.

    In his case, especially, after a transmission mount was replaced, I don’t think his torque converter is his problem.
    BudW
     
  11. volare 77

    volare 77 Well-Known Member

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    That was the weight that was on my 77. That`s why I why asking because it was attached to the trans mount.
     
  12. Mr Volare Imperial

    Mr Volare Imperial Well-Known Member

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    Ya, I hope not, too. My '88 5A provided lock-up just after I bought the old car, but with it was a massive vibration. Shortly after, it lost lock-up and settled into a more regular engine speed vibration.
    Not looking forward to the replacement.

    Upon inspection, the ground strap was broken off one end.


     
    Last edited: Sep 7, 2018
  13. BudW

    BudW Moderator Staff Member

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    I miss the lockup on my ’77 wagon (which came out mid-year ’78).
    The front pump seal is leaking at a pretty good clip on my wagon – so I need to get it fixed before it leaves me stranded somewhere. My current plans (once my current project is done), is to rebuild my ’84 Gran Fury police A999 I have in my garage and just replace the existing A904 in my wagon. That would give me lockup, give me the better first/low gear ratio (than the A904) and give me better shifting points – so a win/win/win.

    So, to fix either a torque converter problem (for Mr Volare Imperial) or a front pump seal problem (myself) – removing the transmission is not a fun job.


    There are a dozen methods Chrysler used to remove the harmonic powertrain vibrations/noises – and the examples shown (above) is a couple of those methods.

    In the case of my wagon, there is a bracket welded onto the transmission mount that the round weight attaches too as well as a bracket to exhaust (exhaust mid-position support). This picture shows the mount a bit better.
    20180902_161541r.jpg

    More pictures of what the mount, weight and exhaust bracket looks like, for the ’77 car version.
    78 PM pg 9-16e.JPG
    NOTE: the above is a MIRROR IMAGE of what it should look like, on car! The bracket is on other side of mount and both bolt holes are on one side (not both sides)!
    78 PM pg 11-6b.JPG

    The ’84 car version:
    84 PM pg 11-435c.JPG
    84 PM pg 21a-700b.JPG

    One thing that is rather ODD is my ’77 parts manual shows two different versions of the transmission mount (for F/M body):
    77 PM pg 9-17c.JPG
    Note the F57 sales code (S/C – F57) means police mount or special order (aka: HD)(not sure if for Kit Cars or other versions, as well) – which is painted white or yellow (instead of black or no paint at all). The only real difference is the rubber is tad harder (but way way softer than urethane).
    I hadn’t seen a yellow or white mount for sale in a long time. I “think” (but not sure), there is a white paint stripe on the police mount with bracket welded on.
    H, N is F-body, F, G is M-body, P, D, C is C-body, R, W is 4-door B-body, X, S is 2-door B-body). Generally, the vehicles with a catalytic converter has the welded-on bracket (for mid-exhaust support).

    If you look at the ’78 parts book, it only shows two different (V-8) transmission mounts (for all bodies):
    78 PM pg 9-17c.JPG
    There is only one F-body (or M-body) V-8 transmission mount part number (for non-police vehicles), which is part # 3726821.

    RockAuto.com shows basically 4 different versions of transmission mounts (for MY 1977 Volare). Normal and HD (which are interchangeable providing no-bracket to no-bracket or bracketed mount to bracketed mount). Note: a bracketed mount will fit fine into a no-bracket location – if you don’t mind the extra bracket being in your way when under the car. That said, cars with cat converters, do need a little something to help hold up the heavy exhaust parts – so the other way (placing a non-bracket in place of a bracketed mount) is not a good idea – and is known to cause a few problems.
    Also have Bracketed and no-bracket.
    They also have urethane (polyurethane) – which I do not recommend for engine or transmission mounts.

    This is one of their mounts: https://www.rockauto.com/en/moreinfo.php?pk=226920 and it lists the part number for normal and police (aka: HD) as same replacement part number.

    ALSO: the bracketed transmission mount IS NOT THE CORRECT ONE for my ’77 Volare! Now you can get the bracketed mount to work (the one shown above) – if you also fabricate an exhaust bracket, as well – to make it fit into my ’77 – but otherwise THE EXHAUST BRACKET WILL NOT BOLT UP TO IT!
    Look at the top two pictures on this post vs.:
    Mount B.jpg

    When I need a transmission mount for my ’77 – the only option is to remove my mount, and use a press to press out the mount insert. Then press in a new insert (which is also sold on RockAuto’s site). A pain to do – but is doable if you have access to a press. I will do this when replacing the transmission (in a couple of months).
    Trans Mount EM-2525.jpg
    Some FMJ versions – do use the non-bracketed trans mount. The exhaust attaches to a bracket that bolts to the transmission tailhousing (via rubber bushings) - look at the 1984 version picture (above).

    BudW