Cressida Wagon vibration blues

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  1. #1
    CelicaSupra.com Member
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    Cressida Wagon vibration blues

    After installing the MK1 axle in my Cressida MX72 it vibrates starting at around 30 and becomes strong at 50 mph. The vibration wave is of medium frequency and feels like it comes from the rear but is also felt in the steering wheel. The vibration does not change when coasting in neutral up or down hills.

    The single piece driveshaft was new two years ago, was checked and fine tuned by the shop with new u-joints. I also tried a known good driveshaft from my friend's MX72 and it vibrated the same.

    The axle is mounted on T3 adjustable 4 links and panhard. The pinion angle is set 2.5 degrees up while the drive shaft is at near zero and the transmission output shaft is at 2 degrees down. From what I understand this seems to be correct. The panhard was adjusted to make the tires even on both sides.

    The differential is newly rebuilt with Weir LSD kit and OEM Toyota bearings. The temporary open diff that was in previously also vibrated nearly the same exact way.

    The front wheels have 1" spacers to allow room for the 87-88 MX73 disc brakes. There are no spacers on the rear wheels so there is an offset or whatever it may be called between the wider front and more narrow rear. Could this odd wheel set up cause such a vibration? The tires are 2 year old Michelins and were re-checked and balanced by Discount Tire.

    The last thing I can think of is a possible bent axle. The large MK1 wheel bearings are new.

    I do not know what else to offer in terms of configuration and condition. The closest shop I trust is 30 miles down the freeway so that is currently not an option.

    Thanks for listening.

    David
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  3. #2
    CelicaSupra.com Member ddd228's Avatar
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    THAT is a tough nut to crack!
    Tires,wheel,drive shaft,U joints. There is no other places to look!
    Tail shaft bushing?Warped rotors?
    If you get it up the ass end and run it while underneath. Get a buddy,(or cruise control) You may see the issue,right away!
    Balanced wheels/tires will not cause an issue but bent wheels and a separated tire will,even if they are balanced,dynamically.
    Cruise control will allow a 40 MPH speed. JACK STANDS!!!!!
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

  4. #3
    CelicaSupra.com Member
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    Thanks Dave,

    Last night I did what you suggested and it looks like the culprit is a bent pinion shaft. The rear u-joint was oscillating so that is where I focused. The pinion flange seemed bent so I swapped it out (love the solid Weir Spacer) however it still wobbled. The run out is about .038 on the flange face so I'll have to buy a new R&P and try again.

    This will be my 4th attempt to rebuild this same diff. On the previous attempts I tried using non-OEM Toyota bearings and was not able to get the correct pinion depth and angle for the gear mesh. Once I installed the Toyota bearings it hit the sweet spot. 'Oh what a feeling!".

    David
    School of hard knocks honorary student
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  6. #4
    CelicaSupra.com Member ddd228's Avatar
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    A bent pinion shaft or a bent pinion flange?
    I wonder if shimming is possible if it's just a bent flange............Sorry,you tried that!
    How do you un-bend a bent pinion shaft? How could it get bent?That's just too weird.

    You are getting to be a master of differential set ups!They can be a PITA to get just right.
    The Weir spacer makes life much easier.
    Oh,I forgot! Yours is the pumpkin style!Sheesh,I'm blind.

    Such beautiful photos!
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

  7. #5
    CelicaSupra.com Member
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    I am also still in disbelief that the pinion is bent even though I replaced the flange with another known good one and it had the same wobble when installed. If the pinion is indeed bent I guess that it happened at the boneyard where I got out of a Previa. Maybe the forklift hit it or bounced the Previa onto something.

    I wanted a 4.3 so either back to the boneyard or settle on a new 4.1. Anyone have a 4.3 or 4.1 with true trac they want to sell?

  8. #6
    CelicaSupra.com Member Funkycheeze's Avatar
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    Nitro gear sells 4.10 ring and pinions for Toyota standard rotation 7.5", brand new. That is probably your best bet for quiet trouble free operation.
    '84 P-type, 5spd, torrid red, black/grey leather
    Built 7MGTE (JE's, ARP studs, MHG), BOSS STG4 60mm, AEM standalone, R154, 2 1/2" IC and 3" turbo back - the works
    Coilovers, ROH wheels, 4 corner BBK, Konis, ADDCO bars, PST bushings etc. etc.

  9. #7
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    Hi Funky, I am seriously considering of going with the brand new 4.1 as you suggest to build a whole new differential around a Truetrac.

    In the meantime I discovered that the problem with my existing diff build was that the spring inside the pinion seal came off and was seated between the oil slinger and pinion yoke. I used a Timken seal and the rubber around the OD made for a high resistance install so maybe it came off then.

    Pretty much a fluke but it is not the first time I have seen such a thing. When I was a young man working on diesel trucks we always had difficulty replacing rear main seals on the motors because the spring would pop off during install. After install I had to re-seat the spring by inserting my finger inside the seal which was always a tricky and delicate operation.

    Well, after removing the offending spring and replacing the yoke which was slightly bent the deflection on the new assembly is a very nice .002 instead of .038.

    Remember to give a hug to your loved ones and check your seal springs after install.

    David
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  10. #8
    CelicaSupra.com Member Funkycheeze's Avatar
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    Aha! I have had this issue before with rear mains - a good idea is to put some grease inside the lip of the seal on top of this spring in a few locations to help secure it into place as the seal is driven into place or in your case as the output flange is installed. I have heard of people putting a small dab of gasket maker / FIPG in the same area as an even more secure method, but you need to be careful to keep it away from the lip of the seal. Glad it is a simple fix.
    '84 P-type, 5spd, torrid red, black/grey leather
    Built 7MGTE (JE's, ARP studs, MHG), BOSS STG4 60mm, AEM standalone, R154, 2 1/2" IC and 3" turbo back - the works
    Coilovers, ROH wheels, 4 corner BBK, Konis, ADDCO bars, PST bushings etc. etc.

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