serious shaking at speed: front end? transmission?

hi folks,

well, i've been away for a bit (from town, and from these forums), but i'm back with more symptoms from my poor beat-up old 84 automatic (that got in a crash six months ago).

one day, since it seemed like we had most things figured out, we packed up the van for a little trip. heavy with people and stuff, the van started wobbling alarmingly as it built up speed (around 30mph), but then got a bit better (up to around 50), but then as we got on the freeway it seemed suddenly like the tire had popped, or was about to. we pulled over, and the tires seemed fine, and there was no obvious malfunction. but we turned around and came home, of course.

on closer inspection, at home, i definitely notice some wear on the outside of both front tires. it's pretty significant, and i suppose it could be the cause of the problem, but it might also be a symptom. i've jacked up the car, and tried wiggling the wheels at 9&3 and 6&12 o'clock. wiggling side-to-side jiggles the whole steering mechanism, up to the steering wheel, but there's no obvious play that i can feel in any of the linkages or bushings. wiggling up and down produces a tiny amount of give and a sound, that seems localized to the wheel itself and doesn't seem to to be communicated anywhere. bearing in the wheel, maybe? on that front, both front wheels have a bit of friction as i turn them -- when i spin them they stop within a few rotations. is that normal? some of the bushings are worn -- see pic below. but maybe that's ok?
Attachment 709

at any rate, i think i can rule out the major problem being the front end (which is a relief, since failure there can be life-threatening). right?

secondly, i've heard from a friend that the automatic transmission can wobble, causing a resonance. indeed, there is a wobble where the tranny connects to the driveshaft -- see pic below. the wobble is pretty big -- about an eighth of an inch. and transmission fluid seems to be leaking directly out of the connection. any ideas what might be causing this? how to fix it? (there's also some give where this connects to the chassis up above -- but there's some kind of rubbery boot there, so maybe it's normal?)
Attachment 710
this wobble in the transmission seems a major issue. would love to get input on it.

thanks so much, in advance, for all the help (once again)!.
brush

These kind of issues are hard enough to nail down when in the vehicle, let alone on a forum, but I'm going to take a stab.

The low speed wobble could be related to the transmission tail shaft. If there is 0.125" of movement, that seems like about 0.123" too much. That wobble would be more apparent under load, such as the acceleration from 0 - 30. Once you've reached that speed, you probably mellow out on the throttle, lessening the load, and thus, the wobble. You say there is tranny fluid leaking out, so a seal replacement is in order, which would be done with a bearing replacement. I'm unclear if the movement is the output shaft, or the u-joints. If that movement is in the u-joints, it's not as dire, but still indicates replacement. Even if it's a u-joint issue, the seal should be replaced.

The wear on the outside of the tires, sounds like an alignment issue. This is something that you would have to have done in a shop that deals with alignment. Abnormal wear, like that, indicates alignment, or possibly worn suspension components.

The high speed wobble could be tire balance, or even improper inflation. Another possibility is an out of round tire, or a busted ply (or if retreads, trouble on the horizon of it letting loose).

It doesn't seem that your issue can be nailed down to just one problem. You may have to eliminate things one at a time, but you're probably going to have a combination of repairs to be done.

Good luck,
Scott

Quote:

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Originally Posted by skibum

The low speed wobble could be related to the transmission tail shaft. If there is 0.125" of movement, that seems like about 0.123" too much. That wobble would be more apparent under load, such as the acceleration from 0 - 30. Once you've reached that speed, you probably mellow out on the throttle, lessening the load, and thus, the wobble. You say there is tranny fluid leaking out, so a seal replacement is in order, which would be done with a bearing replacement. I'm unclear if the movement is the output shaft, or the u-joints. If that movement is in the u-joints, it's not as dire, but still indicates replacement. Even if it's a u-joint issue, the seal should be replaced.

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thanks so much for the reply! yes, the movement in the tail shaft is too much. the movement is not in the u-joints themselves, but between the output from the transmission and the rest of the driveshaft. there's kind of a housing, and the pushing on the driveshaft moves the "male" part inside that housing, which remains solid.

would it be possible to replace the bearings/seal myself? pointers to instructions? if i had a shop do it, what's the likely cost?

thanks so very much!.
brush

so here's a bit of an update. i spoke to the mechanic at oregon drive axle in tigard, who have a pretty good reputation and have done a bunch of older toyotas. he said that if he could do the bushings (he didn't think it was bearings) in the housing without removing the tranny, it would be about $125. but he's concerned that this isn't just the bushing -- that it means the yoke is bad too, or something inside the tranny case that holds the shaft from that side would need replacing. any of the latter mean refurbishing the whole tranny, i guess, which he put at around $1500-1800. yikes! (and the driveshaft may be damaged, which is a whole additional problem.)

i've looked around, and i've found used trannies for $250-350, but i know that's a crapshoot. still, i'm wondering how hard it would be to swap trannies myself? that may well be too much for me, of course. would labor in a shop be around $400?

i can't see investing very much more in this vehicle at that point. unless i can get it running fairly well in the low hundreds, the best i would do from there would be part it out, i guess. :no:

of course, maybe the transmission (with it's bang-shudder hard-shifting from 1st to 2nd) is actually ok, and fixing the bushing & seal alone would do it. the drivetrain shop figured it would be about $60 to open up the rear housing and look -- seemed like a decent guy, likely to tell the truth, esp. since i've been frank that i can't pay for a big job on it. does it seem worth it to look and see?

if that doesn't work out -- any sense of the value of trying to part out the thing?

thanks, folks
.brush

Third try to reply, I wasn't ignoring you. I'll copy and paste this one, just in case.

Replacing a transmission isn't exactly an "easy" job, but it's not particularly technichal, either.

I had to replace a tranny in an old Chevy pickup, in the woods, at a logging site, trying to save $10 per cord on my firewood. The tranny decided that it wanted to die, right after I had loaded up and was ready to leave. I got a salvage tranny from a friend of mine (who wouldn't have tried to swindle me) and did the swap. I got it in and backed up to leave, which went OK, but when I put it in drive, there was nothing. I ended up backing all the way home, which was about 4 miles away. My buddy replaced the first tranny and I got the second one in, no problem. Granted it was easier at home, in my driveway and having just done the first one, the steps were fresh in my mind :).

I think if I was you, though (and I'm making an assumption from reading your posts), I'd have the garage you're dealing with do the $60 diagnostic and repair. It is certainly something that a shop with a hoist is going to have an easier time with. It is just a remove and replace operation, so again, it's not rocket science, but my reservations come from your statement, "What are U-joints?"

You have to factor in the cost and frustration of looking for, finding, purchasing, registering and troubleshooting a new (to you) vehicle.

Parting out your vehicle can return some money, but unless you have a place to store it, tools to take it apart, time to deal with a bunch of buyers, etc.

I google-earthed Portland to Battle Ground WA and you're only about 24 miles from Tim. I'd see if he might have the time and inclination to help you out on a "commercial" level. He's seemed pretty sharp with forum responses, so if I lived that close, I wouldn't hesitate to use him as a resource.

thanks, skibum. i would indeed be interested in what tim has to say. tim? i have a feeling he may not be around at the moment, but sure might be wrong. anyway, i'm headed out of town for the coming week, but will have to move on this one way or the other when i get back.

a lot of this decision depends on my mechanical abilities, or lack thereof. :wnk: it's true that i'm inexperienced working on cars, so don't know a lot of the lingo or simple tricks (as tim found helping me figure out how to set the timing). it's also true that i'm pretty mechanically inclined, a reasonably quick study, and persistant. :lol: i have a decent garage and a lot of the basic tools, and some pretty mechanically-skilled friends. on the other hand, i don't have tons of time (which is often required for DIY-learn-as-you-go).

i've been looking a bit more at the factory service manual (for the 87, but i think for this issue it's the same) at http://yotavans.org/community/tips/m...ELLERSHAFT.PDF . the removal of the driveshaft (propeller?!) seems pretty easy on these -- i'm tempted to pull it out and have a look myself, except that i don't have a plug to keep the ATF from pouring out. could i just use a rag? anyway, this would hopefully give me a chance to ascertain whether the driveshaft itself is damaged (the spline yoke, right?), and potentially to explore the transmission side to see if it's damaged as well. that's my big issue -- lacking experience, i'm not sure i'd be well suited to diagnose correctly. on the other hand, taking it to the shop i'd effectively be paying $60 for someone with experience to look and say, "yep, tranny's been rattled to pieces" or "yoke looks fine" or whatever. but maybe that's worth it. anyone know of folks in portland they particularly trust?

i looked at the tranny replacement in the service manual, and i agree that it seems both non-technical and a bit finicky. i'm particularly concerned about ensuring the correct tolerances before installing the new one -- seems getting things not quite snug can ruin the whole thing? would be great to have someone with experience who could at least help with that part -- the rest looks simply time-consuming, not so delicate.
then, if the tranny's in fact shot, the issue would be where to find a tranny that i'd trust for reasonable cost. here again, tim could perhaps be useful. :thmbup:

well, i'm feeling slightly more positive that we should at least see if the bushing would do it. i'm almost tempted to try and replace the bushing myself, doesn't look that hard. hahaha.

so, in short: if you or tim or anyone else thinks that (potentially with y'all's help) i could try to diagnose whether the tranny or yoke or shot once i have the driveshaft off, i'd be down to try -- even on a semi-commercial basis, if it's cheaper than the shop. otherwise, i think i take it to the shop and watch them do it.

my major concern in all this is investing lots of time/energy in fixing something, and something else even bigger immediately pops up! ah well. at least there's no signs of coolant in the oil! :wnk:

thanks skibum, really appreciate it.

Hey jbrush,

I admire your confidence and willingness to explore new worlds :). We all had to R + R our first tranny sometime, right :thmbup:.

The manual is pretty comprehensive regarding the steps to take in fixing just about any problem with our vans. If you have a grasp, after reading through the process, some time to do the work and the tools and room, I'd say go for it. Keep that 12-pack in the fridge, so you can entice your buddy(s) to hang out and help, as well.

Bearing/bushing replacement generally requires a press, so that may be something that you don't have laying around the garage. You might ask the guy that you've been talking with if they would be willing to help with some of the specialty process(es), if need be.

The drive-shaft (propeller shaft) process seems pretty well laid out, and could be a cause for your trouble. Just to spell out what's going on: the yoke is able to run in and out, to allow the length of the drive-shaft to change as the suspension goes up and down. So those splines need to fit reasonably tight, so there isn't a "banana" effect. The splines being tight keep the drive-shaft straight. The U-joints (spider bearings) allow the transmission to stay in it's fixed position, while the suspension is moving up and down. They also need to be tight, as shown by the tolerance of "0 mm". The U-joints have a "cross" with 4 "shafts". The shafts run on needle bearings inside the caps (which are the visible part inside the "circles" on the drive-shaft. follow the directions for checking that there is no movement, at all, when attempting to turn the yoke, or flange, as directed (PR5 - PRO117). The picture above it (PR5-PRO118) shows a solid drive-shaft, but if you have a drive-shaft with a yoke, you would want to do the measuring with the supports on both sides of the "yoke joint". Remember, the yoke must fit tight to ensure that there is no flex (< 0.8 mm, or <1/32") in the drive-shaft. Make sure you do the "match-marking".

I can't tell you how much fluid might leak out of the tranny, or rear end, but a rag may not completely get it. If I remember, there is about 6 quarts of tranny fluid, so if you have a 2 gallon pail you should be able to stay ahead of an oil spill. The rear end is probably a half gallon or less. Maybe consider changing fluids, if the repair goes well.

Good luck!