NP 3.2 Cruise Control Issue

[Bazooka]

Hi All,

For a few years now on occasions when I engage cruise control (I don't use it that often) I get a sporadic jerking through the vehicle at the point-of-balance between acceleration and deceleration, like when just after cresting a slight rise in the road when the vehicle might be coasting so to speak. This happens primarily at highway speeds ~100kph.

I'm thinking it is caused by play in the driveline somewhere, BUT the jerking stopped when I tested for its occurance in 4wd high range.

The jerking in 2wd is what I would describe as like a sudden intermittent electrical clitch or bad contact. It's quite a sharp jerk.

Is anybody familiar with this situation and can explain what is causing the problem? It's nothing I can't live with, but it's just annoying and I like to fix annoying things.

Thanks for any input.

Bazooka.

[erad]

The 'snitchiness' in 2WD is probably caused in part by a bit of wear in the driveline system - the universal joints in the tailshaft and the CV joints. At 370000 km, you would expect some wear. The snitch in 4WD could be explained by having the front wheels taking some of the load. I suspect that one r more of your CV joints in the rear axles may be worn.

[El_Freddo]

It’s a normal phenomenon, more pronounced in manual vehicles when on a down hill slope. The cruise will run up to the set speed, over it, let off the throttle to slow the car down, if the car slows down enough its back on the throttle and that’s where you feel the jerk bit. No sooner is the cruise on the throttle, it’s back off again as the slope of the hill helps accelerate the vehicle beyond the set speed.

My manual Subaru does it (aftermarket system), our auto Pajero does it, and our old commodore used to do it (both autos, both factory systems). Some vehicles do it more than others. My work around is to manually operate the throttle on hill descents and around certain corners on regular runs or corners I’m not familiar with.

Cheers

Bennie

[Bazooka]

Yes thanks guys, I thought as much but I was hoping it might have been something else and easily fixed. Not to worry!

The jerky sensation might also be exacerbated by the probability of the failing rear carbon-fibre drive shaft.

By way of explanation: if I grab the tailshaft and rotate it back and forth gently, I can hear a metallic clacking sound prettymuch in the centre of it. That probably means it's worn, or worse, imminent breakage maybe

I figure most of the driveline has worn elements from one end to the other so I guess I have to expect these things at 380k k's.

Cheers..

[Bazooka]

This issue is FIXED - for my Paj anyway.

Following up on this problem I had the suspension and driveline thoroughly inspected by a couple of mechanical establishments and I was told that the rear tailshaft CV's were buggered and that the metallic clacking sound 'seemimgly' coming from the centre of the tailshaft when it was lightly rotated back and forth, was because the carbon fibre had separated from the metal barrel inside the shaft. (The metal barrel was supposedly support for the application of the carbon fibre during the manufacturing process).

Right then, I thought, and promptly ordered a new tailshaft via part number MR581616 from Partsouq. After a wad of cash and a few weeks, I opened the slightly damaged carton to reveal a shaft with part number MR498390 displayed on it

Fortunately it fitted just fine so I'm guessing MR498390 must be the European or US equivalent because that part number didn't register on my local Mitzi dealerships computer system.

I'm happy to say that the 'snitchiness' (thanks erad for the apt description) in cruise control as well as the normal backlash problem has 99% gone

I suppose the degree of success attained in eliminating the backlash by replacing the tailshaft means the other 9 CV's in the Paj are in pretty good shape given the mileage on the clock now. This Paj belonged to a 'boatie' before me and I have since towed a caravan (~ 2 tonne) around Australia a couple of times over the 10+ years I have owned it.

Anyway, believing the tailshaft was unrepairable I decided to chop it in half to check out this separation situation. I discovered that rather than being wrapped over a metal barrel, the carbon fibre is wrapped over a couple of layers of cardboard (see pics). Hardly a product that would cause a metallic sound, which, as it turns out, must have been sound-transfer from the buggered CV's.

It was an expensive fix, but a fix nonetheless and it makes me wonder if the vibration/backlash in a lot of Paj's is caused by their worn tailshaft CV's also.

Thanks erad and Bennie for your input on this issue.

[Gerard2]

Thought I'd tag onto to this with some extra info. MR498390 is interchangeable with MR581616 and these carried over to teh 4th Gen NS. I've just had something similar on my NS.

Initial inspection does leave the impression that the carbon fibre exterior is loose but the play is in the joints as discovered by Bazooka.

The shafts are repairable if you can source the joints but not from Mitsubishi.

The joints are made by NTN which is no real surprise as they are a major OEM driveline supplier in Japan and Globally.

You would expect wear to be in the roating joint but for me and I suspect in other cases it was not. The wear was in fact in the splines but not on the shaft but the rotating joint.

When you see the splines it's hard to imagine they would be strong enough in comparison to what I see on driveshafts, I thought they were quite shallow but clearly they do the job.

When I realised where the wear was I had that sinking feeling I'd need a whole tailshaft, fortunately not.

My fix was to obtain a late model low K shaft off a GEN 4, decouple teh joints and transfer to my original shaft. It would appear the main bady of the shafts are all the same dimensionally but how they are finished at the mating splines is where they alter the length of the tailshaft which is what stops using later Aisin Warner Auto shafts or manual tranmission props.

The Donor shaft I used was from a 2017 4m41 Auto, The removed joints are my old ones. I found them easy to remove and refit. The clamp on the boot is like a lever type, once to open the tab and release it , fairly easy to expand to get off and back to re-use. I packed some extra moly grease in but you could argue a thorough solvent bath and repack would extend the life.

What I did see on those splines where there was wear and on the donor was rust or red oxide and I guess that contamination would act to help cause wear.

To remove, it's the boot clamp, on the other end it's a metal cover with fine o-ring. A very fine tip screwdriver wedged at the cap joint and keeping working it around slowly until that gap is big enough to take the next size blade. eventually it will work off with no damage or deformation able to be reused.Remove circlip and then gently work that assembly off tapping the flange.

Slow and steady wins this race.

I'd avoid anything FEBEST for joints. Not Cheap though I did find these but freight and exhange rates tennds to pump things out. Cheaper than a whole shaft.

Hardy Spicer carry the joints but the prices were ludricous like over $500 an end

https://www.driveshaftparts.com/CVJ022

https://www.dormanproducts.com/p-89193-932-002.aspx

[El_Freddo]

Awesome info there Gerard2

This could be the answer to our running vibration at 110km/h. It’s very mild but enough to notice it. I’ll have to look into this now!

Cheers

Bennie

[Gerard2]

Awesome info there Gerard2

This could be the answer to our running vibration at 110km/h. It’s very mild but enough to notice it. I’ll have to look into this now!

Cheers

Bennie

Not so sure? Is it raised? I'm working on 2 NS, both raised and both have drivetrain vibration(still). Both have new engine mounts , one unknown, the other kelpro. The kelpro NS seems a lot smoother but we're talking 350 - 420K vehicles. Lots replaced, The sloppy one had clunks on gear selection and shock on and off throttle on the Hwy. So don't be disappointed if it persists. Short of ballancing the prop or replacing half shafts it's not horrendous. Not noticeable except over 100

[El_Freddo]

Yes the NP is raised. Our other one is raised the same but doesn’t have the same vibration.
NP1 with the vibration we purchased from the original owners unlifted. It’s done two laps off the island and is now at 420,000km.
NP2 was purchased as a parts car due to a dead engine but was too good to part out. I scored an ex-rally Pajero’s engine which was a bit of a gamble, but it’s turned out to be great. Also purchased basically unlifted. History unknown but believe it may have done some towing as it had raised springs in the rear and stickies up front, it sat with the rake of a hot rod… It’s lagging behind with 390,000km - it was the one with the most kms by a long shot when we got it compared to NP1. I guess that’s what happens when you’re not the family bus…

Always something look into with one of them anyway…

Cheers

Bennie

[SnapBowen]

Yes thanks guys, I thought as much but I was hoping it might have been something else and easily fixed. Not to worry!

The jerky sensation might also be exacerbated by the probability of the failing rear carbon-fibre drive shaft.

By way of explanation: if I grab the tailshaft and rotate it back and forth gently, I can hear a metallic clacking sound prettymuch in the centre of it. That probably means it's worn, or worse, imminent breakage maybe

I figure most of the driveline has worn elements from one end to the other so I guess I have to expect these things at 380k k's.thanks

Cheers..

Had same issue, the play of joints resonates in the middle of tube. Freaky shit. I have play on my splines, failing fwd joint, balls picking up from fouled grease from torn boot. Good info thanks