Jag IRS noise

[rdorman]

I have a noise that appears to be coming from the rear suspension that I can not track down and am wondering if someone else has run into this.

The best way I can discribe the noise is it sounds like when we used to put playing cards on our bicycles so that they would hit the spokes when the bikes was moving. A clicking if you will. I generally only here it at free way speeds. It is not always present and the intensity vary. It does tie to the speed being traveled. It happens most just in steady state cruising and you can often get rid of it by lifting or accelorating. It does not sound all that loud but when you pass by another car you can really hear it echo of the other car.

I have looked for stuff that was loose, lubed everything, changed the rear end lube and added the proper friction modifiers and looked carefully for some thing that might come in contact with half shafts and drive shaft with zero results.

If any one has run into this one please let me know!

Rick

[rob frink]

..........

[rdorman]

I usually can make it go away with even gentle acceloration or deceloration. Also on the way home from Mid-Ohio I noticed that it often went away when I changed lanes.

Pretty sure it is linked to car speed. I will pay more attention next time. I already know about a exhaust gasket leak at the head, it sounds like lifter noise, which I what I first thought it was. But in listening to the valve train with my stethoscope I found it to be nice and quiet.

The echo is off of surrounding objects such as other cars, concrete barriers etc. With the echo I can hear it almost as much as the exhaust!

Rick

[Goober]

I had the same noise on my last Cobra with a 3.31 jag powerlock rearend. Had bearings changed, re-set all specs and it was still there. Guess what it turned out to be?

Brake Disc/Caliper noise.
Only did it when car was sitting with load.
Jack it up and it went away.

Hope this helps

Mark

[rdorman]

So how did you cure it? I jack it up and rotate every thing and can not here it. You may have nailed it!
Rick

[mickmate]

I wouldn't drive it till I knew. Sounds like a universal clicking, especially changing being loaded and unloaded. Get a jack under it and check for play especially on the universals cause if they come apart they hold your butt off the ground and a big steel whip in check. Let us know how it pans out.

[rdorman]

So universals click like that? Come to think of it, after I lubed them I didn't notice the noise for a while then after a couple hundred miles it came back. Progressively gets worse as time goes by. Never seems to happen right out of the gate either. Takes a few miles.

Rick

[Goober]

Rick, I never did get completely rid of the noise. Because the diff is right behind you and there is no insulation for noise, the sound carries and it makes you think it's actually the gears, u-joints, bearings ect.
I changed out all u-joints with genuine Jag parts (was living in the UK at the time) and had it set up with an ex-jag mechanic who was involved with Jaguars factory racing team at one time.
He said all the Jags IRS would make noise. Problem is, they were installed in big passenger cars originally and you never heard the disc noise.
Once I knew it was the discs/pads, it never bothered me again because I knew it wasn't anything serious.
Do you use your handbrake often. This can also bind and it takes time to relax.

Hope this helps
Mark

[rdorman]

Well I finally got under the car and tracked down the noise. It was caused by the sway bar links. The bolts that attach the spherical ends to the lower control where contacting the outer halfshaft. All I needed to do is limit the movement of the sway bar from side to side and problem solved.

Piece of cake.

Thanks for the help.

Rick

[Excaliber]

Hey Rick, thanks for following up on this. I think a good followup to a problem is something we need more of.

[SCOBRAC]

I have 20k in my salisbury. I changed the oil to Mobile 1 gear oil and had the same problem. The sound you hear are the powr-loc plates moving against each other (a normal thing). If you recently switched lubricants to a synthetic I'd go back to a standard 80/90 weight made for locking differentials.

It may not be the problem but it is the cheapest solution.

[rdorman]

Thanks Ernie. I hate it when you follow a problem and once the solution is found it is not posted. Then no one except the person experiencing the problem knows the solution. Speaking of solution, I haven't really decided on a perminant fix as of yet. I just put a couple of hose clamps on the sway bar to limit its free movement. Not real sophisticated but it is working for the moment.

Thanks for the feedback SCOBRAC, but if you where addressing the problem I was having, it is definiatly the spherical rod end hardware hitting the halfshafts. The knuckle was 'polished' smooth and part of the bolt head worn away. Speaking of lube, I went through the selection process and ended up using Moroso Climbing gear oil along with two tubes of the GM limited slip additive. One thing I found of interest during my research is an article about 'tuning' the limited slip with the additive. The article suggested that you add the additive in small increments until the unit worked smoothly and then add no more. This as opposed to just adding 8oz. blindly. I didn't take the time to do it but it was of interest.

Rick

[Goober]

Rick, glad you found your problem. Thanks for posting the information about the fix. This is the kind of info needs to be passed on to fellow members.

Mark

[casaleenie]

Rick,

I had the same problem and me being the ace mechanic that I am... I installed a radio... Now the rear-end noise is gone and I can listen to great music...

[rdorman]

I just used the loud pedal to drown out the noise. Never thought about a radio!

Al, are you going to the picnic next weekend?

Rick

[decooney]

On a side note for some of the cars running older unserviced Jag/IRS rears... , any time you suspect something might be wrong with the U-joints, don't wait and see what happens.

Over the last few years especially I've come across a few close calls with friends cars where we talked them into going ahead and pulling out the rear or the 1/2 shafts at least to check things out more closely. For example, finding one U-Joint cracked but still together somehow, and and the other U-joint just starting to crack, with a mildly twisted stub-axles, etc... When these things let go, its not a great experience since the 1/2 shaft IS the upper control arm. When the U-joint goes, so does your upper control arm, and maybe the entire back corner of your car if you are one of the unlucky ones. Seriously, check it out or have it checked out by someone professionally if you have the slightest concerns about your old Jag/IRS.

One clue is to raise the car and check for play fore/aft on the axles. Should be snug with minium play, if any. If you start hearing clunking when you are just taking off or transitioning from reverse to first, check it out. .... Good Luck.

[casaleenie]

Duane is correct on this.. Those Jag rear suspensions require constant checking. Over the past 18 months I've had a broken right rear fulcrum bolt that required replacement.
Left end side seal was leaking onto the rotor and pad. Needed repair and the safety wires replaced.
replaced right rear inner and outer bearing. All safety wires replaced.
Unique Motorcars has a bracket that connects the lower control arm brackets together.. Won't stop it from breaking but it might possibly hold it together until you get it stopped.