RetroRanger

OK so saturdays for the past several months since acquiring the Cutlass (72 Supreme) have been devoted to repair, replace, and upgrades on the OLDS

Well this saturday we started talking driveline vibrations and checked out the u joints as the vibes dont seem to be a tire balance issue.

U joints OK

trans mount tight

driveshaft ...hey wait a minute the driveshaft isnt centered in the body cavity (of the car ) ok so rear end and then I saw it the drivers LCA isnt straight, I know the car was hit in the drivers rear quarter at some point (from evidence of past bodywork that appeared unrelated to rust repair)

So the question is what else should I consider / check for damage. the pass side LCA and upper CAs appear OK

Note the period correct use of a 60s era wooden ruler to check the LCAs in the photos

Lady72nRob71

Are BOTH rails of that bent arm, bent? I would assume so, but from the pic, the other 'looks' straight...

BTW, I have some 60's era rulers, too. New ones do not work on old cars...

oldcutlass

I don't think thats bent enough to really effect any thing. Measure between the front and rear wheels hub to hub and see if there is a dramatic difference!

J-(Chicago)

I have a nice set here if yours turn out to be junk. Not sure if they will be exactly the same though. Mine came off of a type o rear.
Just drop me a message if you need any measurements, and I can dig them out.

MDchanic

That doesn't look like collision damage to me - it'd have to be a HELL of a collision to bend those, and there wouldn't be much left of the rest of the car.

It DOES look bent, though, and I'd replace it.
Those arms are a dime a dozen - they fit every Cutlass, Skylark, LeMans, and Chevelle from '68 to '72 (excluding those with boxed arms, though they'd stil fit), if I'm not mistaken.

You can scrounge one, or you can buy a new one from a number of suppliers.

I vote for scrounge (Surprise!).

As for the vibration - I doubt that caused it. Consider your driveshaft being out of balance if nothing else turns up.

- Eric

RetroRanger

yup the other side is dished i double checked it last night its not bent as much tho I get maybe 1/8" deflection over the length of the ruler

I used a tape measure and think it lacks the precision I would like but 3 out of three measurements showed 1/4 - 3/8" shorter on the drivers side (bent side) additionally i get "3 fingers" front and rear of the pass side wheel to wheel well clearance and a tight 3 fingers and 3.5 fingers on the drivers side

thanks J here in the northeast we only have a limited "cutlass season" so i dont like to waste any of it, I already hunted down a decent deal on a boxed set and rear sway bar

Heres the the facts as I have them so far.

the driveshaft sits to the passenger side of the body hump not in the center, I checked the body mounts all intact and none visibly offset, the body does appear to be offset ~1/4" in relation to the frame

Oh yeah while inspecting the u joints and driveshaft I observed three marks around the circumfrence of the driveshaft the DS had contact w the seatbelt bolt the body and I think another bolt at some point (possibly before I owned the car) there are new springs in the back the previous owner may have changed those to alleviate bottoming out. The contact between the DS and body/bolts is so minor that it doesnt appear to be any deeper than the rust on the DS (no shiney metal) the cotact is on one side of the car (pass) because the offset of the DS in the body hump. I Dont Think it would hit if it was centered

I bought the car 3 months ago and immediately needed to replace the rear pinion seal (it doesnt appear to leak now, unless i do a bunch of full throttle runs then it starts dripping) I did not note any scoring on that part where the seal rides

The car has been hit on the bent LCA side (drvrs side) as evidenced by body work done from back of the drvrs door all the way back to the rear side marker light

The vibes cant really be felt until +- 50mph and not all the time im not sure if its driveline load dependant or there are some other factors involved I hadnt really thought much about it until i saw this (still documenting conditions)

I spun that tire last night while watching the brake drum to backing plate clearance there doesnt appear to be any offset as the wheel spins like from a bent axle flange or similar

my concern is what else could be damaged i can see the LCA is I double checked everything else but cant spot anything more, it doesnt seem like the bent LCA is enough to cause all of the above but IDK

MDchanic

Bent LCAs can easily re-locate the rear to an off-center position, but that shouldn't, in and of itself, cause a vibration.

The body and frame being imperfectly aligned by such a small amount is probably just a manufacturing variation.

I'd put the rear end up on jack stands and run the motor at 60mph and see if you've got any obvious vibration - if so, then you know it's in the driveline (as opposed to front wheels or something else) and can troubleshoot from there. You MAY be able to get a sense of where the vibration is, but maybe not. (Have a responsible person in the driver's seat, and some open space ahead of the car in case it falls off )

A driveshaft place should be able to balance your driveshaft for not too much money (less than $50 probably), so long as it doesn't have any other fatal flaws.

And I'd definitely change those control arms - it'll feel much better on the highway.

- Eric

RetroRanger

OK hopefully that stuff gets in for this weekend...Ill report back on any changes it makes

oldsguybry

what would cause a back end wobble ( like a bent rim ) ? it seems to be noticeable on my car until you hit 2nd gear

RetroRanger

Bry if it was a bent rim that should be easy to see by spinning the tire while its in the air, a tire flat spot or broken belt might do it too, move the suspected tire to the front to see if it follows the tire.

In other news:


I got my boxed arms in and put them on no issues, I added a rear sway bar too. I dont think the LCA being bent was as bad as I was worried about, its true 1 side of the arm was worse than the other but the least bent side I would likely have never noticed without measuring.....

I also replaced the u joints as they were an unknown, I couldnt get any play in them by grabbing the driveshaft but well anyways, they were the original u joints front and rear, just over 40 years old according to the sept build date of my car. I know they were the originals as they are the saginaw style that used injected nylon as a retainer and not the traditional clips. ( i read about that before hand in the CSM lucky for me cus I woulda been like WTF is going on here no clips ???) blah blah is there a point mr ranger sir ? indeed lad there is !!! one of the spiders was dry but not rusty and needle bearing impressions were in the spider, (trans side) upon removal of the DS I could readily see that one was stiff and didnt move freely like all the others...now there all replaced and move freely

pics show the original u joint w nylon retainers and the needle bearing impressions in the spider

side questions how did those NB impressions get in the spider ??? arent they both hardened ???