First, let me say that I am a relatively new member and have poked through the forum and have been so easily sidetracked following along other peoples' projects that I often forget what I was looking for

I also found that everyone on the site seems friendly and helpful, so I feel comfortable posting my dumb questions and hopefully someone can point me in the right direction to figure out my problem.

I have recently purchased a '68 plymout satellite and I seem to be experiencing what I have seen described in various forums as a classic U Joint problem - chassis vibration (sometimes quite severe) at highway speeds, some amount of chassis vibration at lower speeds during acceleration. It seems that the U Joint(s) need replaced, but just having picked the car up recently I have not crawled under it to inspect the potential problem areas (partly because of time and partly because I'm not sure I would know what a problem U Joint would look like). So my questions are these:

How does one identify a bad U Joint or maybe imbalanced drive shaft / or is maybe something else to blame for vibration at high speed?

When replacing the U Joint(s) - what else should I be looking at doing at the same time? I think I need a new Auto Transmission output shaft seal, anything else I should keep in mind while I've got these things apart?

Replacement U Joints seem to come in a variety of sizes - how can I determine what size I need, do I just measure the diameter / width?

Slightly off-topic - the satellite has a 440 in it, I know not from what year or model it came from - how might I go about figuring this out? I have been looking up replacement parts for a '68 plymouth fury III, 7.2L engine and seem to come up with the right parts, but I'd feel more comfortable knowing what model and year this engine is.

Thanks again, and I'm really liking the looks of everyone's projects - it is clear that a lot of care and love is going into these awesome machines.

 

on the motor, it doesnt matter what car it came from
mopar is mopar
any 440 part would work on it
only the internals and manifolds really changed on them throughout the years
if you look at the block, to the right of the clamp that holds the distributor in, there will be a ridge on the block
stamped into that is the block's size and what year car it went into

 

Just replaced the u-joints on my dart....

Get under the car, and hold the drive shaft with one hand on either side of the u joint. Twist your hands, there should be no play. They're pretty easy to replace, lots of hammering involved. You only need a new transmission seal if it leaks.

here's a link for all the how to videos you could ask for:
http://www.youtube.com/results?searc...rch_type=&aq=f

good luck, keep us posted!

 

awesome, thanks for the replies. I found some great holley carb tuning videos on youtube, I just forget to check there for other things like this - I appreciate the link.

The transmission is leaking, so I bought a replacement seal, but as for the u joint(s) I'm not sure what size to get. I guess I can just take the old ones out, measure and then get a ride to the store

 

the parts store you use should be able to look up your size of u-joint without measuring. or you can try a bearing specialty store. my local parts store sell u-joints for my ride for the price of around $20 or the bearing specialty store for $7 bucks. just a thought.. also a loose flex plate/ out of balanced tires/ and too tight of axle end play can cause shaking

 

Keep in mind that the vibration could be caused by something else. You might want to double check that you don't have an out of round or bent wheel or a tire with warped tread or a bump or bubble on it. Most likely a u-joint, but check these other things as well just to be sure.

 

Thank you all for the suggestion - just the other day before I posted this I had the pitman arm replaced and at the same time had an alignment done and tires balanced. Before that I also had the carburetor tuned and timing adjusted (apparently it was way over advanced). After each job it runs and drives better, but it's still too scary to drive around.

I know this is the Do-It-Yourself section of the forum and so far I've had others doing my dirty work, I just haven't had much personal time to get into it. I've got a long stretch of days off coming up and I'm planning to get under it and replace the U Joints, trans output shaft seal, inspect the transmission speedometer gear (speedo doesn't work), and a host of other odd jobs that I'm sure I'll be posting questions about here. After that I'll feel a little more like a respectable do-it-yourselfer.

Again, thanks for the feedback.

 

Good luck with your diagnostic session. Let us know if we can e of help.

 

OK, I replaced the rear U joint and the front is on order. I replaced the transmission shaft seal as it had been leaking. I let the engine warm up and shifted through all the gears, put it back in park and checked the trans fluid level - the dip stick came out bone dry (blah) so I added synthetic ATF+4 fluid and took it for a test drive and while it seems to have smoothed out somewhat, at highway speeds it still feels like something is getting ready to tear loose and take me out with it...

Anyone want to check me on my latest theory: transmission (maybe just 3rd gear?) is shot? In the past I had a chevy truck with a 700r4 that leaked but at some point the level would be too low for the torque converter to fully engage but the low fluid level just took more gas to push the thing around, loss of power, etc... Maybe if my car was driven around long enough with low fluid level the tranny overheated and now needs serious servicing / replacing?

How would I go about testing a broken transmission theory? At speed I can keep giving it gas - there's plenty of acceleration left and so it seems the transmission is putting power to the tires, but in this game of chicken I always bow out first and let off the gas, returning back down to around 50mph and the vibration reduces to tolerable (but not quite nonexistent) levels. There's no carpet and no sound deadener and no headliner and several panel bolts missing and so I know there will be some shake and noise, but there's something more definitely wrong here than that... loose motor mount? loose transmission mount (although the shifter never vibrates, just the car...)? any other ideas??

Thanks in advance for your thoughts.

 

you are sure all the tires are in good shape? even new tires can go bad. like gtxclone said a bubble or tread warp or even a missing wheel weight can cause bad vibes. try taking it to a tire store most will do a free check on things like tires they make take it out for a drive. they will try to sell you the labor for the repair. but after they tell you whats wrong. fix it your self.

 

wait till you replace the front u-joint, then see where you're at. that's a lot easier than some other things.

 

U joints often cause nasty vibrations, but so do things like bent wheels, out-of-round tires, or unbalanced wheels. You might also inspect the driveshaft for damage, it might be bent. You can usually get a new driveshaft made in a couple of hours for a couple hundred dollars, or you can try to find a straight one at a junk yard.

There are a few different 440 engine variations around, but basically 2 types, those with steel cranks, and those with cast iron cranks. The cast iron crank 440s are easy to spot as they are externally balanced, and have very large harmonic balancer. Steel crank engines have a much smaller balancer. There are 2 high performance 440 engines, one is an HP1, and the other is the HP2. You can tell if your 440 is an HP or not by looking at the pad on the front top of the engine block above the water pump, it will be stamped with a series of numbers. If you want to know what kind of car your engine came from, there should be a VIN number stamped on the bottom side of the engine block near the oil pan.

Check your throttle kickdown linkage which runs from teh carburetor to the transmission. When you step on the gas, the rod from the carburetor to the transmission will cause the transmission to shift down. If this linkage is not adjusted properly, you will have shifting/transmission problems. If 3rd gear is worn out, reverse will probably fail soon (does the car back up quickly? Or does it take some time to engage?).

 

**SOLVED**

So the drive shaft was bent... apparently not enough for me to notice while I was replacing the rear u joint, but then again I didn't roll it across the pool table to check it either...

Wow, this car rolls nice now. Thanks so much to everyone for the suggestions and ideas and information. I'll put up some pictures of my work in progress - not as nice as so many others, but maybe some day.

 

wow, how the heck does a drive shaft get bent? Must be a monster of a 440! Glad you figured it out, feels good gettin it right, huh?

 

Oh man, you ain't kiddin!

No clue how it got bent. It's behaved this way since I bought it, no telling how it happened or what else may have been damaged - my theory is some kid had it and was playing dukes of hazard or something. I don't see any obvious signs (no scratches, dents, gouges, etc) of undercarriage damage though so I dunno.