I have a few noises coming from under my 71 coupe. I have looked at the u-joints and wheel bearings they appear to be ok.

I was wondering if I can run the car in gear while up on jack stands?
I believe the noise is loud enough that I should be able to hear where it is coming from if the wheels are turning.

 

Yes, put the jack stands under the trailing arms so the drive shafts are level and don't bind.

 

Could be dangerous. Be extremely careful.

 

Hi m,
It would make me nervous running the car in gear on jack stands.
Also, with none of the car's weight on the suspension the trailng-arms, hang down at such an angle that the u-joints on the half shafts at the differential bind and the wheels can't turn.
What sort of noises are you hearing?
Does the noise frequency increase as the car's speed increases?
Can you change the noise by slightly applying the brakes?
Regards,
Alan

 

No!!!

 

Hi Alan,
I have what sounds like a rotating squeeking sound. It increases with speed but does not get louder. I have tried to apply the breaks nothing changed. If a push in the clutch and let the RPM drop the sound does not change with the lower RPM.

I was also thinking of removing the spedo cable and driving the car to see this may be the problem.

 

With the weight on the trailing arms it is the same as the weight on the wheels so the drive shaft are at the same level ( not the same as putting the jack stands under the frame) but I should have mentioned safety not thinking about what works for me might be dangerous for someone else. Thanks for mentioning it.

 

My mysterious noise of that description turned out to be the emergency brake spring in the rear wheel on my '78.

 

you just have to get the rear tires off the ground, so you can leave the front tires on ground, chock those. The rear have to be blocked level, so the rear half shafts dont bind. I would go buy a 4x6 at lowes/ home depot, cut it into 1 foot lengths so you can stack them (probably only 2 high) and put them under the trailing arms, but just use enough to get the tires clear of the ground. jack stands can tip easily or slide when the car is at an extreme angle if you just used them on the rear. A block eliminates that danger, and you can have the front tires on the ground and chocked so it doent go anywhere if something does happen.

Auto shops lift cars into the air, put stands under drive axles, then lower the lift just enough to get the tires rotating, so professionals do it, but take safety into mind.

Your description says its something after the clutch, so it could be the speedo cable, 1 or more of the 6 u joints, any one of the rear bearings, the rear end gears.

You're right in eliminating the easiest things first listening for it to go away after each part removal. I would start with the cable, then remove one half shaft at the rear diff, then the other, then the drive shaft at the tranny. hopefully when you find the noise gone you will find a stiff u joint or a bad cable. after those it can be pricey.

If the noise goes away with the car off the ground you could have a tire that is separating at the plys internally. They make a weird squeak too.

 

 

Yes it can be done safely, all good ideas from other posts, if you feel confidant in doing it, you will be fine,,, if you have any doubt, don't do it, especially alone!!! ----

 

What I would do first is get a can of lithium grease. Spray one u-joint. Drive the car. Does the noise go away? If not do another u-joint and so on. The parking brake spring is that someone mentioned is a good idea to look at.
With the car in the air and not under a normal running load you may not hear your noise

 

I had the car on jack stands this morning to change the spark plugs, could not get the right side easily from the top. While I had it up I tried to get to the speedo cable on the trans. Not an easy task. I decided to wait until I can get someone with me before I raise the car high enough and go under the center far enough to get to the cable.

Life would be so much easier if I had a lift in my garage.

 

The only way you can run the rear half-shaft system with the car on jack stands is if you put the stands under the bearing pods on the trailing arms...WHICH IS A VERY HAZARDOUS THING TO DO!!! If you let the wheels drop by putting the jack stands on the frame, the angle of the half-shaft U-joints would put them in a bind and THINGS WOULD BREAK if you fired the engine and put it in gear.

Just don't do it. You can't tell if a U-joint is operating freely by looking at it. I've opened up joints that looked just fine--and found rust, zero grease, waffled bearing races and little-bitty rusty rollers which could never have rolled on anything. You just have to disassemble one end of each joint and test it by hand. If someone else knows a GOOD WAY of detecting problem U-joints without any disassembly, I'd be thankful for that info.

 

I guess it is not a great idea to try to run the car on stands.
With the fact the car is 46 years old I am thinking it may not be a bad idea to just install new u-joints and be done with it. I have only owned the car for a year and have no idea if they have ever been replaced.

 

Do those U-joints have grease fittings? The factory units did not. If those [still] do not, they may yet be the original units...and definitely NEED to be replaced. If they have grease fittings, shoot some grease into each one and pay particular attention to TWO things as you are putting grease to them:

1) Make note of how much grease it takes to get any excess to come out of the cap seals. If grease comes out immediately, then the bearing pack was already full and the joint is likely A-OK. If it takes quite a bit of grease to get any excess, then the joint was likely DRY and probably should be replaced.

2) Look carefully at the excess grease as it first oozes from each cap seal. If it is ONLY clean grease, GREAT! But, if you see tiny specks of rust or particulate in it, the joint has likely already failed.

 

If you are going to use jack stands I agree , never try to put them under the bearings on the rounded part . That would be suicide . The stand would never sit there . I always put the jack stands just ahead of that area so the full weight of the rear is on the same area as the tires , keeping the drive shafts in a straight line. But this is why I would just say don't do it if you don't have any concept of what and why you are doing it . It could be dangerous to your health or life !

 

would it not be easier, and safer/smarter to just replace the ujoints on a nearly 50 year old car ?

 

Pretty much made up my mind. I am going to replace the u-joints.

After reading a few post's on U-Joints I think I can do this myself.

Does anyone know the Spicer part numbers I will need? And a good vendor to buy them from?