Drive train clunk

[BKW]

Originally Posted by SKEET

Mine is fine from a dead stop only when coasting and then getting back on the gas.I guess its axle wrap what ever that is, Ive heard alot about it on this site and seems to be common and seems to be the problem with the thump when touching the gas after coasting.

Axle wrap has been common on GMC/Chevvies for years....

Play in your driveline is the cause, I'm guessin'...when you get on it, driveshaft slaps a bit before engaging.

[XRING600]

Originally Posted by BKW

Axle wrap has been common on GMC/Chevvies for years....

Play in your driveline is the cause, I'm guessin'...when you get on it, driveshaft slaps a bit before engaging.

I believe this is what is causing much of the "clunk" in our trucks. Crawl under your vehicle, wrap your hands around the shaft(that is the ONLY time I will say that!), and move it back and forth. I can do this and produce a "clunk" in my 06'. Now, put some torque behind that play and I am sure that is the cause of some of our noise.

[SKEET]

Originally Posted by JetTech

ok all, let me see if I can explain this without confusing myself and everyone else. I'll attach a few photos and give a brief description of each one and then try to summarize it the best I can so here it goes.

The pic below is a depiction of an axle mounted below the leaf springs (like on the Titan) in a static condition.



This is a picture of what happens to the leaf spring during acceleration more commonly known as axle wind-up, or axle wrap. The nose of the vehicle would be to the right of the picture to help you visualize what's happening.



Many manufacturers have this same problem, common cures are traction bars or ladder bars for off roaders and racers. Usually it's not as noticeable as it is in the Titan, Nissan should have used either thicker main springs or a multi-link suspension to help cure this but I'm sure cost was the biggest factor.

Here's a few pics of what I installed to eliminate this problem





Here you can see how they are just barely visible from the side



What your looking at are $22 helper springs I bought from Advance Auto Parts. I installed them in front of the axle instead of the rear like most would do. During acceleration this big beefy spring will transmit the twisting motion of the axle to the front of the spring where the attach bushing is. I've had these installed for several months now and will never take them off, that's how much I like them. They eliminated all the clunking noises I would hear from the axle twisting up and down during acceleration and when I came to a stop.

Another benefit I've noticed is they really work like traction bars because I can barely spin my tires now at take-off, but it feels like the front end is going to come off the ground. It transmits all but a few percent of the torque directly into the chassis rather than leaving it on the ground in the form of burnt tires.

The Nissan Tech took some photos of what I did and sent them to their engineering department in California. He loves the fix but agrees that Nissan will never approve such an item for axle wind-up and that it will probably take eons before the issue is seriously looked at. So that's it in a nutshell. It fixes all the clunking for $22 and doesn't negatively effect the ride at all. As a matter of fact I can really feel a positive difference in corners, the truck stays much flatter and feels much more solid when the corners get bumpy.

I would love to stick around and see what you all think but it's night night time for me......4:30am comes early and I've still got a heck of a honey-do list. I'll check back in tomorrow night and try to answer any questions you all might have.

Dale

For what ever reason my computer won't let me see the pictures but I remember looking at them a while back so I do have a idea how the install looked.I've had the springs for a while and started to put them on a few minutes ago but I have a question.I see that the end with the big U bolt presses the springs together but I don't see the purpose of the other end with the bolt just coming end from the side.I know I'm missing something but why not just put a u bolt on the spring and call it good.Thanks.

[sudden urge]

Originally Posted by SKEET

For what ever reason my computer won't let me see the pictures but I remember looking at them a while back so I do have a idea how the install looked.I've had the springs for a while and started to put them on a few minutes ago but I have a question.I see that the end with the big U bolt presses the springs together but I don't see the purpose of the other end with the bolt just coming end from the side.I know I'm missing something but why not just put a u bolt on the spring and call it good.Thanks.

Good observation, you can just put on a U bolt and get the same preload effect. I discussed that same question with a spring shop a long time ago, and they said you will get the same result. I went with the Hellwigs because they don't compress the spring and lower the rear.

[SKEET]

Originally Posted by sudden urge

Good observation, you can just put on a U bolt and get the same preload effect. I discussed that same question with a spring shop a long time ago, and they said you will get the same result. I went with the Hellwigs because they don't compress the spring and lower the rear.

I'll check out the Hellwigs.I remember a while back you said you had put them on your truck and hadn't had any problem with them coming loose are anything like that.

[sudden urge]

Originally Posted by SKEET

I'll check out the Hellwigs.I remember a while back you said you had put them on your truck and hadn't had any problem with them coming loose are anything like that.

That's correct.

[SKEET]

Originally Posted by JetTech

No I didn't. I think it's got plenty of spring tension without them....here's a couple of pics that better show the mounting of them..

Is it just me that can't see these pics any more or have they been removed?

[StuntDriver06]

just an update on my situation... the clunk in my drivetrain was a failing diff, its at the dealer being replaced right now, along with the driveshaft

[StuntDriver06]

rear end replaced, clunk completely gone, this feels like a different truck now, amazing difference. no more slop.. when i touch the go pedal, it goes instantly...

[Saintwho]

man what exactly did it sound like? I have a ting going on back there not exactly sure what it is, but I just bought these bars and installed them like the box says too...I know what they are saying as far as installing them in the front of the axle, but it looks like it would be less ground clearance, Imma go drive around and see if I notice a difference

[BLUEDEMON]

Can someone re-post the pictures on these spring helpers as well as a location to buy them in nor-cal any help would be awesome thanks!!!

[ArtechnikA]

No pictures.
the image server at us.pixago.com seems to be unreachable...

[ArtechnikA]

> a location to buy them...

I bought mine through Amazon. Cost another couple of bucks (I am remembering $32) but since it was sold directly by Amazon, it qualifies for 'Prime' (i.e. 2-day free) shipping. And no tax.

The FLAPS websites were useless for trying to check stock at any local retail chain and I could see burning up the price difference in gas (and a day) just driving around from store to store trying to save a buck. One click and done. On the second day, I had parts.

It was not packaged well and the box was a bit shredded but amazingly, all the hardware bits were in the box.

However, I was unimpressed with the fasteners and ordered replacements in stainless from McMaster-Carr. I'll post more pictures and installation notes when I've got the stuff installed. Had been scheduled for this weekend (first nice weather in many weeks) but ran out of daylight long before running out of stuff to do. Next weekend I hope.

[ArtechnikA]

Originally Posted by ArtechnikA

I'll post pictures and installation notes when I've got the stuff installed. ... Next weekend I hope.

Yesterday morning I was up early and the weather was still good so, encouraged by the "30-minute" installation reports, I gave it a go. My hardest issue was getting the long bolt through the front bracket, but finally got that to happen. A combination of re-bending the legs 'taller' (I think they got squished a bit in shipping) and finding just the right position to hold the spring.

I hate rust, so as I mentioned in the earlier post, I got replacement hardware in stainless. The long bolt retaining the fore-end clamp was 90mm long in the kit so that's what I got, but it is -very- close to the frame rail and I'll probably replace that with an 85- or 80mm. The kit stuff in 8mm so that's what I used - I prefer to keep my metric vehicles metric where I can.

As others have noted, the purpose of the fore-end clamp is to keep the front of the aux spring from sliding sideways (for which purpose some have used a big stainless hose clamp with reported success...). So the long bolt isn't really under any stress. If there -is- stress, it's in the little rivet holding the clamp to the spring, and that's in shear. If that were ever to fail, I am kinda liking the hose clamp concept for lightness, non-corrosive properties, and simplicity. But a small carriage bolt - if you could find one in quality material - with a nut on the bottom would be fine, I think.

The back shackles in my kit were threaded 1/2"-13 so there goes that metric concept. However, the stainless nuts I got were 3/4" (19mm) across the flat so unless you have a reason to care about the thread pitch, you still only need one set of tools for this job.

I saw a couple of questions in this thread about "how tight" and I think the real reason for that question is that no one has come right out and said explicitly that the object of the game is to preload the BIG leaf so that it is completely compressed. So you're slowly and evenly tightening up against that spring compression and you keep at it until the stack goes solid. You can feel it. -Then- you can ask your 'how tight' question where a torque figure is meaningful. I have a suitable torque wrench but I was using a good long 19mm ratcheting box end and put a good hard pull on it. The object of the torque is make sure it stays tight, and I'm not worried about that since I used a pair of half-height jam nuts to lock the main nuts in place. (I don't like and I don't trust spiral lock washers, and I didn't use them. And I got good, real, substantial washers for between the nut and the shackle crossbar.)

I'll let this all jiggle around in use to settle in and crush any grit or sand that may have got between the spring leaves making my initial 'tight' seem tighter than it was. This weekend I'll back off the jam nuts, recheck the torque, and lock down the jam nuts and decree the job done.

Most of this is probably obvious to you guys with lots of truck experience, but this is my first truck and my first leaf-spring vehicle. My use of jam nuts and stainless hardware is probably seen as overkill but I hate working on rusty vehicles and stuff simply does not loosen and fall off my vehicles. (I am also a big believer in safety wire but that's another story.)

I'll get my photographs uploaded to my web server this week and back-edit some picture links in these posts.

Oh - the test-drive results. It was fantastic. Much more solid under accelleration and braking. I measured the bed height at the wheel arch before and after. Before, the left was 38-3/4" and the right was 39". (I'm thinking for most of this truck's prior 60,000 mi the driver was a big guy...) After, the left came down to 38-1/4" and so did the right - so by taking out the 'sag', the preloading evened out the sides - the left came down 1/2" but the right came down 3/4".

For completeness, I'll mention that if the back is down ~3/4" you should have a look at your headlight aim. If it was marginally almost-annoying for oncoming traffic before, you may be into fully annoying range now. I was looking at bringing my aim up a bit (I overcompensated when I put in the HID's) but now I think it is perfect.

[fpd7]

bump bump