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Rear spring noise?

1K views 15 replies 5 participants last post by  ianrandom 
#1 · (Edited)
Non-SLS suspension.
Left rear today, and right rear in the past. Very infrequent.
I was leaving a stop sign today and heard/felt a "sprong" sound like a coil spring broke, but not that violent. I was the only one in the car. No luggage/freight. I was driving normally (not stomping the gas). It has happened a few times in the 3 summers I've owned it. I can't make it happen. It seems totally random and rare.
The right rear has done it more if I have passengers in the back seat.
I just had a safety inspection and while I was there asked him to put it on a lift and look for the cause. Also asked him to explain the "knock" I get from the front end when I go through a dip slowly when turning. He couldn't find anything, front or rear. (small local indy. shop)
Any ideas?

I believe this is totally unrelated but I'll throw it in there just in case it's not.
I was vacuuming the floors tonight (after sproing incident) and when I opened the left rear door the hinges felt like they were binding. Very rough operation. Never did that before. I don't think there's any springs in there?
 
#2 ·
Hey Brian,

Do you think that possibly the 'sproing' from left rear and the binding left rear door are possibly related? I have a feeling they could very well be so.

I don't know if your car is driven/has been driven regularly in the wintertime up there.. We have plenty of snow & salt on our roads here in Massachusetts, but nothing compared to where you are in New England… Don't know if thats a factor.. but it might be food for thought..

On the knock in the front turning & low speed.. I believe you will find a brake support / guide support/ caster joint worn with play… That was the symptom my 560 had years ago and that replacement solved it…

Good Luck man,

MBL
 

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#3 · (Edited)
Thanks for your picture/advice on the front end. Very nice! I got new rotors and pads to do over the winter also.
I guess I'll take the left rear door skin off to see what's in there and why it just started operating roughly.

I don't drive it in the winter. I think today was it's last day on the road for this year.
I got it 3 years ago with not a speck of rust anywhere and I intend to keep it that way if I can. They use salt and the brine liquid on the roads up here. My truck is toast from that.

Any more thoughts on the rear springs "sproinging" appreciated.
 
#5 · (Edited)
Each time has been leaving from a full stop. It seems to happen after just a few inches to a few feet of movement, but not immediately when leaving the line.
185k miles on it.
I think it only happened twice this summer and I put @ 6K miles on it.

Love the car. I gave it new Michelin Premiers and rear rotors + ceramic pads this year.
Adjusted valves. Front rotors and ceramic pads waiting in the garage for my next free weekend.
I'm back to driving a 2000 Pathfinder until the spring rains wash the salt off the roads. :(
 
#6 · (Edited)
Okay, in short: I think your slide splines on the propeller shaft need grease.

When you accelerate, the rear suspension loads dynamically and the propeller shaft shortens a bit to follow the movement of the differential. That "shortening" while transmitting the torque is possible because of the slide splines. If there is not enough grease on the splines (or they are dry) the splines can't slide, the shaft opposes the shortening up to a point when it will suddenly slide with a "sprong/pop/clunk" noise. GM had this problem on many trucks.

Before splitting the two halves, please note the marks on the two halves and make sure you put them back in the same relative position one half with the other. My shaft was out for more work, you need to remove only the rear half. Also a good opportunity to inspect your flex disks.
 

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#7 · (Edited)
Okay, in short: I think your slide splines on the propeller shaft need grease.
Brilliant! I think you nailed it! That makes perfect sense. The jarring of the rear end transmits through to "ring" the springs.
Thank you!

I think I'll use this stuff on the splines. I've used it for years on the swingarm pivot bolt of my dirtbike and have been amazed at what a great job it does through the absolutely nasty conditions that it sees.
https://www.amazon.com/Jet-Lube-Marine-Moly-Molybdenum-Disulfide-Paste/dp/B001QF9PEA

Are these splines on the end of the prop. shaft that goes into the rear diff. or are they at the joint in your 1st pic.?
I guess I'll plan to change diff. fluid too while I'm under there.

I checked the flex discs while it was on the lift. The mechanic agreed that they looked great and fairly new so I think I'm safe to assume that the carrier bearing was probably replaced at the same time. The whole underside of the car looked great. Especially to someone from the Rust Belt.
 
#10 ·
To be honest, I don't remember on which half the male and female splines are. In my case I took the entire shaft down and then I split it. As indicated above, putting it back in the relative position is crucial. Take picture and mark it before you even start taking bolts off. You'll thank me later when you wonder where and how that bolt was initially mounted.

Because you will have time (I understand that you plan on working on it during the entire winter), I think is a very good idea to change the differential fluid. I may suggest to look at other things while you are under the car: the boot that protects the greased splines, the intermediate bearing rubber holder, etc. Parts will not be expensive, the inconvenience is greater, but since you'll be in that area and already have some parts off, why not do it now and get it over with for many years to come.
 
#11 · (Edited)
I may suggest to look at other things while you are under the car:
Yup. Thanks.
My neighbor's garage has a pit so I'd like to get as much done as possible while I'm down there.
Will do tranny filter and fluid too and the speed sensor is leaking a bit.
I can't decide whether to drain the converter or not, but that's a subject for a different thread. :argue:
 
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