4.2 supercharged

craig jones tyres · Saturday at 16:08

Hi i have a 4.2 supercharged l322 when driving get a thumping noise and can feel it through through truck
I disconnected the plugs going to the transfer box and it doesn't make the noise
Could it be the motor on the transfer box or the box itself
Cheers

Graculus · Saturday at 17:01

What truck?
Could also be the rear prop centre bearing - internet 'diagnostics' on noises, thumps and bumps will be mainly guesswork, better to take it somewhere for a proper 'in person' diagnosis unless you want to play 'parts darts' with big chunks of metal.

craig jones tyres · Saturday at 18:23

I've had it on my ramps (2 post lift ) and cant see any perishing or play in propshaft and as said if I unplug the transfer box 3 plugs the noise / thumping stops

Graculus · Saturday at 18:28

IIRC you can't see the centre bearing without removing the heatshield.
Whilst you may have a lift, you username doesn't suggest you have a lot of experience or training in diagnosing drivetrain or NVH concerns - again, I suggest you take it to someone who does.

craig jones tyres · Saturday at 20:39

I'm 40 years old been a mechanic for 25 I came here for some advice thought someone would be more helpful than you are being
The reply I'm getting off yourself are the reason these forums get a bad name
And for you're information the heat shield is already removed that's how I inspected the center fu####g bearing

Graculus · Saturday at 22:53

Well I'll leave you to await someone more helpful then.
If you can't diagnose a basic drivetrain issue, then as your username suggests, stick to tyres because you clearly haven't the training or experience to go any further without professional help.

marjon · Sunday at 09:15

What year is you car?
So with no electrical plugs in the transfer box it doesn't do it, sort of tells me you have an electrical/control issue.
What circumstances does it happen or is it just all the time.
Would be handy if you could put diagnostics on and get some live data to see if its trying to engage the clutch pack (the LSD lock) or trying to engage low.
I take it you don't have any "special program" selected and its just in the normal position?

From what I can find the Hi/Lo shift motor also does the clutch pack if a solenoid is switched. (magna steyr box which I am sure is what you have)
If you have the NV type then it doesn't have the clutch pack only the range change.

There's a great write up here https://www.rangerovers.net/threads/magna-steyr-dd295-transfer-box-teardown.41233/

The guy is a member here by a different name.

J

Oh and internet diagnosis often includes what you would think are silly questions of things that arent said to clarify things

craig jones tyres · Sunday at 10:42

marjon said:
What year is you car?
So with no electrical plugs in the transfer box it doesn't do it, sort of tells me you have an electrical/control issue.
What circumstances does it happen or is it just all the time.
Would be handy if you could put diagnostics on and get some live data to see if its trying to engage the clutch pack (the LSD lock) or trying to engage low.
I take it you don't have any "special program" selected and its just in the normal position?

From what I can find the Hi/Lo shift motor also does the clutch pack if a solenoid is switched. (magna steyr box which I am sure is what you have)
If you have the NV type then it doesn't have the clutch pack only the range change.

There's a great write up here https://www.rangerovers.net/threads/magna-steyr-dd295-transfer-box-teardown.41233/

The guy is a member here by a different name.

J

Oh and internet diagnosis often includes what you would think are silly questions of things that arent said to clarify things

Hi its a 2005 55 plate 4.2 supercharged 6 speed automatic zf gearbox
When you first pull away and all the way up to 50 mph you get a thumping noise from the middle to rear of the vehicle is then unplugged the 3 plugs from the transfer box and get no noise at all
Inspected propshaft and all looks good no play or perishing

marjon · Sunday at 11:22

I would say it sounds electrical/control issue. So really needs to be plugged in and see if any faults and some live data.

I guess if you could get it wheels free on a ramp and get somebody to start it and drive. you could get under and see if you can narrow it down to something.

Have you tried to drive in Low to see if it makes the same noises?

J

Graculus · Sunday at 14:16

He'll have lots of DTC's stored because it's been unplugged, it still sounds like rear prop to me, mainly because there will be minimal power going to the rear wheels with the clutch motor unplugged - therefore less torque on the centre bearing and cardan joints. - reinforced by it disappearing over 50mph.
It could also be the drive chain shedding links but that'd tend to be there all the time.

marjon · Sunday at 14:38

Graculus said:
He'll have lots of DTC's stored because it's been unplugged, it still sounds like rear prop to me, mainly because there will be minimal power going to the rear wheels with the clutch motor unplugged - therefore less torque on the centre bearing and cardan joints. - reinforced by it disappearing over 50mph.
It could also be the drive chain shedding links but that'd tend to be there all the time.

Agreed there may be many DTCs stored but plug everything in and clear see what comes back.

Isn't the center diff 50/50 split under normal driving conditions? the clutch is only for limited slip locking, under certain conditions

It could be many places as noise/vibes travel. But unplugging the electrical connection to the TB must give a clue.

J

Graculus · Sunday at 15:26

The SC's usually have a rear biased torque split - the later 5.0l versions have a variable locking rear differential as standard also.
The activity maps I've seen for the Steyr TB show constant activity with a 'pre load' even in 'general' terrain response for the SC, even small amounts of wheel slip provoke (small) amounts of change of locking bias, a lot of it is good old physics, left to itself, there will be more torque sent to the front wheels by virtue of a shorter drive shaft, and an increase in potential torque steer, therefore the map for the centre differential is created to compensate for this, so yes, 'in most cases' it is a (managed) 50:50 split, as a purely mechanical, unmanaged differential it will perform more like a 65:35 split. Mechanical centre differentials are engineered to give close to a true 50:50 of course but a managed, variable locking differential is engineered to be just that and will perform differently when the control and feedback is not present.
Chassis ears would be the second logical step if a cursory examination didn't show anything - followed by removal for detailed examination / testing of suspect parts.

marjon · Sunday at 21:15

So we maybe getting away from the OPs posts but until he comes back with something, I have to ask….. to learn.

Graculus said:
The SC's usually have a rear biased torque split - the later 5.0l versions have a variable locking rear differential as standard also.

N/A in this case unless the original owner ordered it as optional extra, but still think N/A

Graculus said:
The activity maps I've seen for the Steyr TB show constant activity with a 'pre load' even in 'general' terrain response for the SC, even small amounts of wheel slip provoke (small) amounts of change of locking bias,

You have more info about maps, but yes small amounts of slip would be compensated by TC or center diff. But I would expect TC to take care of it in “general” terrain position before the diff was involved.

Graculus said:
a lot of it is good old physics, left to itself, there will be more torque sent to the front wheels by virtue of a shorter drive shaft, and an increase in potential torque steer, therefore the map for the centre differential is created to compensate for this, so yes, 'in most cases' it is a (managed) 50:50 split, as a purely mechanical,

Through a mechanical 50:50 split it’s a 50:50 split. Once the longer rear components have taken up the torque all is equal, that wouldn’t take much to do.

Graculus said:
unmanaged differential it will perform more like a 65:35 split. Mechanical centre differentials are engineered to give close to a true 50:50 of course but a managed, variable locking differential is engineered to be just that and will perform differently when the control and feedback is not present.

Mechanically it’s 50:50 split, torque will go the easiest route. If you spin a wheel you have just lost all of it or certainly the moving forward bit, which is when all the fancy controls come in on modern cars.

I am not naive enough to think that a 4x4 means you have 4 driving wheels all the time.

Graculus said:
Chassis ears would be the second logical step if a cursory examination didn't show anything - followed by removal for detailed examination / testing of suspect parts

Chassis ears?

I am genuinely asking as always learning, also value a lot of your contributions.

J

Graculus · Sunday at 21:58

A lot of my previous is 'received knowledge' from many years of manufacturer training, including several years from LR at Gaydon, there is a hell of a lot of information that is 'commercially sensitive' and not in the D&O documents in the workshop manual - things like the transfer box maps as a case in point. A lot of that stuff is developed by people well above my pay grade so you just have to accept it 'as-is' but, I do see examples of it in almost daily workshop life, for example, the most likely CV joint or wheel bearing to fail is the NSF - it's on the shortest propshaft and the shortest driveshaft so will have the highest torque applied (all things being equal), it's not the torque equality once established, it's the application of torque and the mechanical resistance to it, sometimes (as in variable locking differentials) an artificial resistance forcing the torque to places it doesn't want to go. Remember that differentials are in essence, lazy, and will allow all the mechanical effort to escape via the route of least resistance (hence the one wheel drive 4x4 you allude to) which is why the integration of ABS systems and variable slip differentials into a managed four wheel drive system is critical to on & off road seamless performance - although no-one has yet been able to counter the scenario of all wheels rotating on wet grass with no forward progress, as far as TR systems are concerned, everything is fine so no intervention required...

Chassis ears are essentially clamp-on / strap-on microphones either wired or Bluetooth connected that you can place at various locations to isolate NVH causal assemblies or parts. They range from ~£50 eBay / Amazon kits to many thousands for manufacturer-mandated equipment

Basic ones - Amazon product

Picoscope and Rotkee have various sensors available and Sykes Pickavant do a reasonably well regarded wireless kit, after that, you're into specialist transducer and software territory. Mercedes have a 'library' of chassis noises and claim to be able to isolate the customer complaint from a 10 second audio clip sent to them by a dealer (using a very expensive and precisely fitted microphone cluster) - currently only available for >2020 AMG models but the tech is interesting - to me, at least.

ETA - forgot to say, TC is there to regain traction by locking / limiting wheel slip, differential locking is used to keep forward momentum - if a small amount of wheel slip is detected, then it's better to tolerate but adjust the differential slip limits than invoke braking on one or more wheels, it's better for acceleration and better for customer perception. Imagine if you're hoofing along loose gravel and there's two choices - stop wheel slip by braking and reduce throttle response or accept controlled wheel slip but limit it's effect by controlling power distribution, which is better for progress?
Both my L319's were specced with a locking rear differential, in all cases, I (or other drivers) could prolong progress on challenging terrain and maintain driver control before TC kicked in, in most cases, it meant less distance to winch to driveable ground!

craig jones tyres · Sunday at 23:04

marjon said:
Agreed there may be many DTCs stored but plug everything in and clear see what comes back.

Isn't the center diff 50/50 split under normal driving conditions? the clutch is only for limited slip locking, under certain conditions

It could be many places as noise/vibes travel. But unplugging the electrical connection to the TB must give a clue.

J

Will clear / read fault codes tomorrow also will be popping in to see a specialist who is just round the corner to me to pick his brains too

Datatek · Monday at 07:42

Graculus said:
A lot of my previous is 'received knowledge' from many years of manufacturer training, including several years from LR at Gaydon, there is a hell of a lot of information that is 'commercially sensitive' and not in the D&O documents in the workshop manual - things like the transfer box maps as a case in point. A lot of that stuff is developed by people well above my pay grade so you just have to accept it 'as-is' but, I do see examples of it in almost daily workshop life, for example, the most likely CV joint or wheel bearing to fail is the NSF - it's on the shortest propshaft and the shortest driveshaft so will have the highest torque applied (all things being equal), it's not the torque equality once established, it's the application of torque and the mechanical resistance to it, sometimes (as in variable locking differentials) an artificial resistance forcing the torque to places it doesn't want to go. Remember that differentials are in essence, lazy, and will allow all the mechanical effort to escape via the route of least resistance (hence the one wheel drive 4x4 you allude to) which is why the integration of ABS systems and variable slip differentials into a managed four wheel drive system is critical to on & off road seamless performance - although no-one has yet been able to counter the scenario of all wheels rotating on wet grass with no forward progress, as far as TR systems are concerned, everything is fine so no intervention required...

Chassis ears are essentially clamp-on / strap-on microphones either wired or Bluetooth connected that you can place at various locations to isolate NVH causal assemblies or parts. They range from ~£50 eBay / Amazon kits to many thousands for manufacturer-mandated equipment

Basic ones - Amazon product

Picoscope and Rotkee have various sensors available and Sykes Pickavant do a reasonably well regarded wireless kit, after that, you're into specialist transducer and software territory. Mercedes have a 'library' of chassis noises and claim to be able to isolate the customer complaint from a 10 second audio clip sent to them by a dealer (using a very expensive and precisely fitted microphone cluster) - currently only available for >2020 AMG models but the tech is interesting - to me, at least.

ETA - forgot to say, TC is there to regain traction by locking / limiting wheel slip, differential locking is used to keep forward momentum - if a small amount of wheel slip is detected, then it's better to tolerate but adjust the differential slip limits than invoke braking on one or more wheels, it's better for acceleration and better for customer perception. Imagine if you're hoofing along loose gravel and there's two choices - stop wheel slip by braking and reduce throttle response or accept controlled wheel slip but limit it's effect by controlling power distribution, which is better for progress?
Both my L319's were specced with a locking rear differential, in all cases, I (or other drivers) could prolong progress on challenging terrain and maintain driver control before TC kicked in, in most cases, it meant less distance to winch to driveable ground!

The bit about the shortest drive shaft being the one to fail is interesting, it was always the shortest half shaft on my race car that would break

At the time, the consensus was that it was due to most corners being right handers.

craig jones tyres · Monday at 11:29

Update cleared all codes and took for a drive no codes return put into low box and the thudding is still present plugged diagnostic machine back in and no codes present

marjon · Monday at 12:04

I am just thinking out loud now as I don't really know but.

Could it be the ABS/TC kicking in? I don't know why it would go away when TB is unplugged as from what I can see no sensors (except for hi/lo position) but it could give feedback from clutch pack position. when it is all unplugged no feedback is given so no action on other systems (find that hard to believe)

I guess the next move would be to try and get it on a wheel free ramp. You could record the noise and post here. You say you can feel it, is it just a general feel or is it through the steering wheel or the pedals?

What code reader did you use and did you note the codes before you cleared them, should have said this before but to me its sort of standard practice.

J

craig jones tyres · Monday at 12:24

craig jones tyres · Monday at 12:25

Have also just dropped the oil out of the rear diff and its like chocolate really thick and stinks lol magnet had quite a bit of crud on it too

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