72 IRS problem

[george romano]

Well, I asked everyone I know what would cause this, and I still haven't got it straightened out.
I can hear this noise while taking off from a dead stop, or decelerating. As I let the clutch out I can hear a distinct "click" or two from each rear wheel as the driveline is loaded. Every time I load the driveline with the throttle it would click, and then again if I let off the throttle and let the engine slow the car down. I parked in the garage and rocked the car, noise is still there. I just had the T arms rebuilt last winter, and they also rebuilt my half shafts and strut rods. There is only about 3000 miles on the rebuild. I removed the brake pads from the rear calipers thinking it may be the pads rocking, but that didn't help. I also removed the trim rings, no difference. The noise is coming from just inside each rear wheel. I'm begining to think there is a clearance problem between the spindle/flange splines, and thats causing the noise. Its loud enough that I can hear it inside the car with the radio on. If it is the spindle/flange splines, can I simply retorque the spindle nut to spec and replace the cotter pin? The car did NOT make this noise until after the T arm rebuild.
If anyone has any ideas, I'd greatly appreciate it.

George

[Joe L.]

Re: 72 IRS problem

George----

This sort of problem could be originating from a variety of sources. However, I really don't think that it has anything to do with proper toque of the spindle nuts. You've already tried several things that I would have suggested, but here are a few more:

1) check that the inner dust shield (pressed onto spindle support)is properly positioned and not contacting the spindle flange dust shield. In order to do this you will need to remove the spindle flange;

2) at the same time as you do the above, check that the cotter pin(s) is not improperly installed and contacting the spindle flange OR the u-joint flange;

3) check the bearings by rotating the rear spindles by hand. They should be quite smooth with no "clicking", whatsoever, on rotation;

4) check for excessive rear rotor runout. Excessive runout will cause the brake pad backing plates to "click" or "squeak". You can check this by rotating the rotors by hand with the brake pads installed. It's best to have the half shafts disconnected at the flange, though. You'll need to do that for items (1) and (2), above, anyway;

5) check the u-joint flange for smooth operation. The flanges should be reasonably tight on the u-joints and there should be no "clicking" or "roughness" as you work the joints through their range of motion with your hand. If there is, then the flanges could have been distorted (and ruined) during u-joint installation.

6) check the u-joint trunnion bearing surfaces by carefully removing the caps. Unfortunately, if you want to check all 4 per u-joint, you'll have to remove the joints from the flange. However, check the 2 "easy ones" first. If there is ANY brinneling, WHATSOEVER, on even ONE trunnion, the joint is scrap. Then, you have to remove and replace regardless. You may think that the joints are new so how can they be bad? The answer is that they can be bad for a variety of reasons. If any joints other than Spicer or NEAPCO were used, expect problems, even at low mileage. The half shaft u-joints are "worked hard".

[george romano]

Re: 72 IRS problem

Thanks Joe.
I had Bairs rebuild the T arms, and they reused my spindle, my rotor, and my spindle support. They used their own repro T arms, and a repro backing plate. They installed new bearings, races and seals and SS parking brake parts. They also reriveted the rotors and turned them prior to returning them to me.

I had them rebuild the half shafts as well and they used U joints with grease fittings. I don't know what brand they are but they have blue rubber seals under the caps. When I got them back, I inspected the half shaft U joints for smooth operation. I noticed that one axis ON THE FLANGE END had a smooth operation, while the opposite axis on the same joint had a somewhat rough operation ON BOTH HALF SHAFTS. I called Bairs about it prior to installation, and a guy named Ed told me that is normal, and that it would smooth out once it was installed in the car and the 4 retaining bolts were torqued.

Judging by the sound of the "clicking", it almost sounds like a brake pad click, but not as pronounced.

I asked Dan at VanSteel about it and he thinks its a U joint problem as well. Isn't it strange that it clicks from BOTH rear wheels?

I appreciate your advice as always.

George

[Joe L.]

Re: 72 IRS problem

George------

Bairs does excellent work and uses excellent parts, too. The blue-seal u-joints are likley Spicer.

And, YES, I do find it curious that it's happening from both sides. I meant to mention that in my original post, but forgot. It's very hard to believe that Bairs made a mistake on BOTH sides even if they could make it on one side. I think that figuring out what sort of malady could have afflicted BOTH sides is the key to figuring out this problem.

[george romano]

Re: 72 IRS problem

Joe
Do you think its a possibility that (now keep an open mind here) the bearing races weren't fully seated upon reassembly, and now that the car has been driven, they have seated themselves, creating a loose clearance problem between the spindle/flange splines? Is that a possibility?

George

[Joe L.]

Re: 72 IRS problem

George-----

I'd say it's a remote possibility, at best. It's easy to check, though, with the spindle flanges disconnected. If this is the case, you'll note a lot of end play in the spindle. Also, if this were the case you would note excessive runout on the rotors, even if the rotor/spindle flange are otherwise in spec.

[Klaus Friedrich #33362]

Re: 72 IRS problem

Gentlemen,

please don't laugh.
Try to remove the trim rings from your rear wheels.
I've got the same noise and changed everything - the clicking noise stayed.
One day a friend gave me the advice to remove the trim rings. My 69 was quiet now. I'm still driving with the trim rings but I know where the noise comes from.

Greetings from Germany
Klaus

[Joe L.]

Re: 72 IRS problem

Klaus-----

I won't laugh; you're absolutely correct. The trim rings are a very common source for this problem. They fooled me once, too. However, removing the trim rings is one of the things that George tried to no avail.

[Wayne P.]

Re: 72 IRS problem

I know you said this started after the rebuild, but worn spider gears in the rea end will do this. Has anything been done to the rear end(internally)? How many miles on it?

[george romano]

Re: 72 IRS problem

Wayne
Nothing was done to the diffy since the car was new. It has 82000 easy miles on it. The stub axles don't move in and out more than a hair. 22000 of those miles are mine.

George

[Dave F.]

Re: 72 IRS problem

Wayne - I was thinking the same type of question. Could it possibly be the positraction ?

[george romano]

Re: 72 IRS problem

Dave
The noise is coming from both sides, and I can tell its coming from just behind the rear wheels, not the center of the car.

George

[Dave F.]

Re: 72 IRS problem

George,

What about parking brake/cable assembly ?

[george romano]

Re: 72 IRS problem

Cables are original, but move freely. The shoes and related hardware are new. I dropped the E brake adjustment all the way down thinking it may be the E brake, and the noise was still there. In fact, I applied the E brake loosly, and drove the car like that looking for a change in the clicking sound. The noise didn't change at all.
Its in the driveline at the rear wheels. It has to be the U joints, or something within the spindle support somewhere. I never heard a U joint make a clicking sound.

George

[Terry F.]

Re: 72 IRS problem

You need to disconnect the half shafts and rotate the wheels. That is the first thing. It will tell you a lot. Terry