My crazy diff ratio change idea

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FEI said:
@RRMaximus you have alot of perseverance.

You keep on bleating that you want to lower your RPM but if not fuel economy then why?
If its for engine longevity you do realise that a lower RPM but higher throttle request cause higher cylinder preasures. Higher cylinder preassures cause, more bearing wear, more cylinder bore wear, more piston ring wear, higher combustion temps, more valve seat wear, this list can probably go on for quite a while.
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I think you are imagining an extreme situation and not looking at this in reality.

For example, someone else said that the oil pressure would be lower and that would damage the engine.

But I can drive now at 40mph at the same approximate revs as I will have at 50mph with the changed diffs and my engine has plenty of oil pressure at those RPM.

It might be 5% less oil pressure than normal which will be way inside what is required.

I think that you people are imagining things at an extreme to make an irrelevant point.

How much higher cylinder pressure would there be?

Do you have a way to calculate that?

How much extra wear would there be?

Lugging might happen if I was driving at 20mph in 5th gear, with the throttle wide open, but that will not be happening.

Given the low down torque of my engine, and the VANOS system, driving at 1,500 versus 1,900 at 70mph will not cause lugging.

The 6 speed L322 will do about 1,900 RPM at 70mph and the 8 speed L322 will do about 1,400 RPM at 70mph.

Why would Range Rover lower that RPM if there are so many issues with doing that?

Your comment only makes sense if I was loading up my car with a heavy trailer, but I am running it very light, as mentioned already.

Therefore the engine will be operating at the least weight end of the scale that it has been designed to run at, and it will easily handle the load of that weight at a lower RPM.

All of this has been explained by me already.

If I was driving a high revving 4 cylinder engine with a huge load at a low RPM in a high gear with the throttle fully open then I could accept your comment.

That is not the case at all, as my engine has a lot of low down torque.

This is just like someone who changes up gears early in a manual car because they do not need to squeeze that last bit of acceleration out of the car.

In normal operations this puts less stress on the engine.

Likewise, holding a car in lower gears longer than needed puts more stress on an engine.

In an extreme example there could be issues, but they typically come when the throttle is wide open, which is nowhere near where I will be in my modified L322.

As someone said on another forum, they knew someone who did something similar and they had no issues, just a reduction in their acceleration, which I do not care about.
 
kernowsvenski said:
For the benefit of all future readers it might be good if you shared the detail of that. It might make you come out of this thread less negatively
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I have no concern for how I seem here.

I asked a simple question and I was insulted and attacked from the start.

Those people will never change their opinion of me, especially after I called them out on their ridiculous behavior.

I will not post another question here again, because it is 99% garbage for 1% value.

The juice is not worth the squeeze.

I only remain here because it is funny to see those people desperate to prove me wrong, long after I have already got my answer.

But now it feels like the comedy value is diminishing versus the time that I have to invest in keeping the conversation going.

Eventually the outrage at my simple idea will die down, and I will be forgotten, happily.

I look forward to the day when no one new or old feels the need to comment here again.

I only see the comments because I am checking in on another thread where I got some very good advice on another issue.
 
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RRMaximus said:
I have no concern for how I seem here.

I asked a simple question and I was insulted and attacked from the start.

Those people will never change their opinion of me, especially after I called them out on their ridiculous behavior.

I will not post another question here again, because it is 99% garbage for 1% value.

The juice is not worth the squeeze.

I only remain here because it is funny to see those people desperate to prove me wrong, long after I have already got my answer.

But now it feels like the comedy value is diminishing versus the time that I have to invest in keeping the conversation going.

Eventually the outrage at my simple idea will die down, and I will be forgotten, happily.

I look forward to the day when no one new or old feels the need to comment here again.

I only see the comments because I am checking in on another thread where I got some very good advice on another issue.
Click to expand...
f2c28d76d0bd0c1d606f663e517e4ca1.gif
 
Here is the funny thing, the biggest actual potential problem that I have so far been alerted to is the torque converter lockup.

Here is what the ZF5HP guru RRPhil said on another forum: "Some aspects of the driveline control are vehicle speed related e.g. the torque converter lock-up clutch currently locks at 56mph... so I don’t know if those speed signals come from upstream or downstream of the final drive and therefore how they would be affected."

Do you see what he did there?

He pointed out a potential problem and then immediately said that he did not know if it would affect the operation or not.

Phil did not say: "You are going to cause the torque converter to not lock up and you will destroy it, are you crazy?!"

No hysteria, no exaggeration of information into a catastrophe, just the facts that he knew and the facts that he did not know.

The simple solution to this is that if I do the differential swap then I would use my OBD reader to make sure that the torque converter has locked up on the highway.

So the obvious next step is for me to plug in my OBD reader, select the gearbox control module and see if the torque converter lockup is one of the parameters that my OBD reader can see on my car.

If my OBD reader does not see this parameter then it would be costly for me to proceed, as I would have to buy a more advanced OBD reader which would probably be the gap iid tool at around £500.

The torque converter not locking up would be a major problem, compared to insignificant problems that people here have tried to turn into major problems.

This is a simple non hysterical factual approach to assessing the validity of doing this particular alteration to my car.

Here is what someone could have said to me, "The torque converter might not lock up, so you should have an OBD reader that can see if that happens or not, and test the situation as soon as you make the modification."

That would be a non-patronizing, non-arrogant, non-attacking, factual based piece of advice directly relevant to my question.

I have tried to find out the answer online as to what inputs determine when ZF5 HP torque converter lockup happens, but so far I have not been able to find this information.

Perhaps someone out there knows the answer to that question.
 
RRMaximus said:
Here is the funny thing, the biggest actual potential problem that I have so far been alerted to is the torque converter lockup.

Here is what the ZF5HP guru RRPhil said on another forum: "Some aspects of the driveline control are vehicle speed related e.g. the torque converter lock-up clutch currently locks at 56mph... so I don’t know if those speed signals come from upstream or downstream of the final drive and therefore how they would be affected."

Do you see what he did there?

He pointed out a potential problem and then immediately said that he did not know if it would affect the operation or not.

Phil did not say: "You are going to cause the torque converter to not lock up and you will destroy it, are you crazy?!"

No hysteria, no exaggeration of information into a catastrophe, just the facts that he knew and the facts that he did not know.

The simple solution to this is that if I do the differential swap then I would use my OBD reader to make sure that the torque converter has locked up on the highway.

So the obvious next step is for me to plug in my OBD reader, select the gearbox control module and see if the torque converter lockup is one of the parameters that my OBD reader can see on my car.

If my OBD reader does not see this parameter then it would be costly for me to proceed, as I would have to buy a more advanced OBD reader which would probably be the gap iid tool at around £500.

The torque converter not locking up would be a major problem, compared to insignificant problems that people here have tried to turn into major problems.

This is a simple non hysterical factual approach to assessing the validity of doing this particular alteration to my car.

Here is what someone could have said to me, "The torque converter might not lock up, so you should have an OBD reader that can see if that happens or not, and test the situation as soon as you make the modification."

That would be a non-patronizing, non-arrogant, non-attacking, factual based piece of advice directly relevant to my question.

I have tried to find out the answer online as to what inputs determine when ZF5 HP torque converter lockup happens, but so far I have not been able to find this information.

Perhaps someone out there knows the answer to that question.
Click to expand...
On the P38, torque convertor lock up is not wheel speed related as far as I can determine but engine revs related. Lock up in third happens at about the same revs as lock up in top but at lower road speed of course and depends on throttle opening. The L322 being much more complicated with a variable slip lock up clutch so may use more parameters for lock up. Another potential problem for you to advise us about along with the likelihood that it will not pull top gear unless you have the wind behind you. I also wonder if a fault may be logged as the wheel speed will not match the output shaft speed that the electronics expect. Lots of interesting things for you to tell us about.
 
RRMaximus said:
Here is the funny thing, the biggest actual potential problem that I have so far been alerted to is the torque converter lockup.

Here is what the ZF5HP guru RRPhil said on another forum: "Some aspects of the driveline control are vehicle speed related e.g. the torque converter lock-up clutch currently locks at 56mph... so I don’t know if those speed signals come from upstream or downstream of the final drive and therefore how they would be affected."

Do you see what he did there?

He pointed out a potential problem and then immediately said that he did not know if it would affect the operation or not.

Phil did not say: "You are going to cause the torque converter to not lock up and you will destroy it, are you crazy?!"

No hysteria, no exaggeration of information into a catastrophe, just the facts that he knew and the facts that he did not know.

The simple solution to this is that if I do the differential swap then I would use my OBD reader to make sure that the torque converter has locked up on the highway.

So the obvious next step is for me to plug in my OBD reader, select the gearbox control module and see if the torque converter lockup is one of the parameters that my OBD reader can see on my car.

If my OBD reader does not see this parameter then it would be costly for me to proceed, as I would have to buy a more advanced OBD reader which would probably be the gap iid tool at around £500.

The torque converter not locking up would be a major problem, compared to insignificant problems that people here have tried to turn into major problems.

This is a simple non hysterical factual approach to assessing the validity of doing this particular alteration to my car.

Here is what someone could have said to me, "The torque converter might not lock up, so you should have an OBD reader that can see if that happens or not, and test the situation as soon as you make the modification."

That would be a non-patronizing, non-arrogant, non-attacking, factual based piece of advice directly relevant to my question.

I have tried to find out the answer online as to what inputs determine when ZF5 HP torque converter lockup happens, but so far I have not been able to find this information.

Perhaps someone out there knows the answer to that question.
Click to expand...
f2c28d76d0bd0c1d606f663e517e4ca1.gif
 
Datatek said:
On the P38, torque convertor lock up is not wheel speed related as far as I can determine but engine revs related. Lock up in third happens at about the same revs as lock up in top but at lower road speed of course and depends on throttle opening. The L322 being much more complicated with a variable slip lock up clutch so may use more parameters for lock up. Another potential problem for you to advise us about along with the likelihood that it will not pull top gear unless you have the wind behind you. I also wonder if a fault may be logged as the wheel speed will not match the output shaft speed that the electronics expect. Lots of interesting things for you to tell us about.
Click to expand...
Now we are getting somewhere. Real issues without the "I know everything" attitude.

The lockup occurs at around 50 mph and will obviously be affected by RPM and throttle.

But a car with a trailer will have the same RPM but a higher throttle position than a car without a trailer, and this does not stop the torque converter lockup clutch working.

Therefore I cannot imagine that my set up would instantly disable the lock up clutch.

Given that I will probably be driving at 70 mph or 80 mph this is a significantly higher speed than 50 mph so likely there will be enough inputs for the lockup to occur.

But as I said, my OBD reader should be able to answer that question instantly.

As for not pushing fifth gear, it will currently drive in fifth gear at low RPM without any problem, so I don't see that happening.

But the L322 has a manual selection on the gearbox so I can put it into fifth gear as I start on the next section of Spanish motorway.

I have no problem with a fault being logged if it does not affect the engine or gearbox.

The issue would be if the (ABS measured) wheel speed, RPM and gear selection threw up an error that caused the car to go into a failsafe mode and not drive properly.

Some people put on oversize wheels for off-road driving on these cars and I have not seen any mention online of this action shutting down the car.

Also when off-road driving one wheel could be off the ground and spin rapidly under power and I have not seen any comments about this situation shutting down the car.

So while your comments are valid, if I look through each one, think about them, and look at the available information I can find online, none of them seem to be actual problems.
 
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