LR3 with only 45K has major failure

[R_Lefebvre]

I just dont like the design of that part, had that been a BMW or MB it would be a forged steel piece or cast aluminum and much larger.

Not so fast. The new BMW 1 series has stamped arms. Now, is it because it's their smallest/cheapest model, or is it because it is there newest... we'll see.

Time for the aftermarket to spin up some axle/suspension upgrades. If it is welded as stated in other forums, just takes one scrape of the weld to introduce moisture into it. I fear you may be right that this is systemic. Are the RRS and RR's stamped as well?

How is moisture in a weld, moisture in sheet metal, or moisture in a forged part any different?

Imagine a flat sheet of steel being heated and stamped into shape. Basically the cheapest, weakest way to fabricate anything.

Not necessarily. Sheet metal can come in some pretty nice alloys, much better than you'd ever get on a casting. It doens't take nearly as much metal weight to get a given strength with this construction method as casting.

And casting or forging isn't infalible either. Ask Ford about the control arms on the GT44. And didn't Toyota have to recall some trucks because of bad forged tie-rods?

I blame the quality programs myself. All I see theer is a Six Sigma analysis engineere with his bell curve saying that based on the cpk we can say that 99% of parts will be good.

I agree with this. I've seen way too many parts engineered with Six Sigma with prototypes parts made in one batch, and the results from that batch being used to qualify a design based on statistics. Quick Six-Sigma programs do NOT do a good job of catching batch-to-batch differences (particularly in steel), tooling wear, etc.

All that a quality program ensures is that the part will be made to spec. While I'm no engineer, it appears that this isn't a quality issue, but a design issue. Have you ever heard of a Discovery having a catastrophic failure like this in the front suspension? Even 15 year old Discovery radius arms still are working flawlessly.

I think my Honda Pilot has beefier suspension components.

No, this is a quality issue. I'm sure the design is fine as long as the steel is good, the welding robot is good, etc... the problem is Six-Sigma design does not do a good job of predicting long-term potential for problems and just plain bad batches. This is also more likely a problem more due to supplier self-certification. "You certify the steel shipment meets our specs, and we'll trust you and not check it ourselves." :Wow1:

In fact, given the low miles on this failure, I'd predict that is EXACTLY what caused this. If this was a design issue, it never would have gotten through durability testing.

RR sport is forged or cast not stamped. I think we are looking at the results of Ford ownership. LR parts were much more heavy duty on the older trucks. even the interior leather seats etc don't age as well on the new stuff as the old Rover vehicles. Remember Ford wanted to sell 50,000 LRs in the USA per year. Can't keep costs down and pump out that many vehicles from one assembly plant without losing some quality. Ironically though the new products have far fewer problems than the older stuff, at least as far as service related issues, go figure.

You've pretty much answered your own question. This has nothing to do with Ford. Ford did great things for LR quality as you yourself admit. This has everything to do with people's demand for more and more comforts in their vehicle, which drives in weight, and the engineers are forced to take weight out where customers can't see it. So, they designed lighter weight suspension components, which are probably at least as strong (by design) as a cast part, and half the weight. And I'd wager they are actually NOT cheaper.

This is probably due to crap steel coming from the mills. It looks to me like the bushing cup (which started life as a tube) tore through at the HAZ of the weld where the arm stamping meets it on the bottom. It's probably an alloy steel, with too low of an alloying element in that sample.

If castings are more reliable, it's only because they expect them to be crap steel, and design accordingly. When designing with welded alloy steel, you expect a certain quality.

We had cases with tubing coming out of American tube mills with large solid carbon or lead inclusions.

Another thing to add to the question of "will it still be drivable in 40 years?"

No modern cars will. Not even vaunted BMW and Mercedes. They all become "not economically viable to repair" after 10 years.

For example, it's amazing that considering the lower control arm isn't doing anything to hold the wheel/tire on there, the rest of the suspension held the whole knuckle/hub/tire assembly on there without failing. That is a stress factor way beyond what the parts were designed for.

Well... it's probably more because the sheet metal held it all in. When I worked in Detroit, I saw a whole lotta late 80's/ early 90's GM sedans with front suspension failures on the side if I-96 where the tire was packed up into the fender well. They almost never fall right off, no matter the design.

that suspension is torn up. first of all, there is no way a lca arm end should be able to rip open and loose the bushing. Those are some tiny bushings btw. There is no physical way that should be able to happen. Look at a Toyota truck ifs (even a $20K Tacoma) and tell me the LR3's are "very beefy". My sedan has way more beefier suspension pieces than the LR3.

Yes, it should not be able to tear open like that. It's obviously a failure. The bushing size has NOTHING to do with it.

I am sure that simulated destructive testing was done during the design process. I am also sure that a bean counter then looked at the many designs and made the decision where to draw the line.

No, the design was theorized way before anything got tested. The decision to make the arms this way was set from day 1, and it had nothing to do with cost. It probably was a weight decision. Once the design direction was set, the arms were designed, and then the design would only be tweaked from that point to meet requirements. The bean counters have very limited control over a safety related parts like this. If the design has to be changed, it has to be changed. Period.

They are probably involved now though... looking at the failures and trying to figure out if they should recall it or not.

If you are not doing 100% inspection all the quality program does is show that statistically you can expect a certain percentage of parts to meet print based on process capabilities. Design for cost and design for quality are both factors that go into every part. Six Sigma is a growing area of engineering which works very well for mass production but is far less effective on low production runs.

Even 100% inspection is ineffective. You can't test every part to failure, obviously. You can't even do metalurgical testing on every part. You can only look at the batch certification, and the assembly process. The weld *probably* met specification, but even 100% visual inspection is only 50% effective. As I said, we saw steel with solid carbon and lead inclusions, coming from batches which met spec. The average content of the steel met spec... unfortunately sometimes the contaminants were concetrated in one place...

In a business operations definition, quality simply means how effective the production process at making repeatable parts that match the specification.

It's gone further than that. Quality to some, means how close can you hold your parts to the BOTTOM end of the specification, without going under? Or even in some cases... how far under specification can you go without anybody noticing. I've seen managers make conscious decisions to ship bad parts because they *felt* they would be fine, and it was too costly to scrap them.

 

[MattScott]

Thom,

I have to admit you called this a long time ago with the stamped steel, bravo.

 

[timmy!!!!!!!]

Aren't XJ control arms stamped steel also? I remember awhile back one of my close friends bent a stock xj control arm on a street curb. He then quickly upgraded.

 

[muskyman]

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[nickw]

I have to admit guys - it seems 'most' of you are jumping the gun a little.

It is ONE failure, every manuf. has them and besides, we dont know the previous history of this rig. I will be the first to admit that those pictures are a bit surprising, but I wont pass judgement until I see alot of rigs with the issue.

 

[muskyman]

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[Mike_rupp]

One failure that we've seen from within our group. Has anyone ever reported or read of a single radius arm failure on a Discovery?

R Levebre: if weight was the primary consideration when designing the suspension arm, would you like to explain why the LR3 has a unibody construction mounted to a conventional frame? With a curb weight of nearly 6,000lbs, do you really want to stick with that logic?

 

[greenmeanie]

Mike,
I think you misread Rob's statement a little. He makes the point that an overall weight target is set usually for performance reasons based on marketing. In order to meet the requirements for features, size and all the rest of the equation in the requirements materials and manufacturing processes will be chosen to minimize the weight of an individual component while still meeting its functionality. His point is that the components on the underside of modern vehicles are not usually observed by the projected owner and are thus prime areas to achieve weight savings to allocate to other parts that will add to the saleability of the vehicle. The choice of a unibody on a separate frame is most likely due to a marketing requirement to create a stiff platform to help handling.

As manufacturers are in the business of making money, or at least they used to be, engineering will use their experience to determine the cheapest way of meeting the functional requirements of a part to keep unit cost down. This is where things get a bit subjective as you have to throw their supplier base capabilities, design reuse, design tool capabilities, lead times and previous experiences such as material quality stated above into the mix. Very rarely are we given the remit to use a more costly material or process than necessary.

 

[AndrewP]

Nice argument here. That front end is PATHETIC. That metal is what, 18ga? And it's holding arguably the most important part of the car's suspension? Look at those pencil sized steering rods! What a bad joke. Stamped or not the seat of the pants engineering would say it's less than half the size it needs to be. Once people start to off road these things, I predict there will be lots of failures and handwringing, and talk of solid axle swaps.

The bottom line is that the people in this LR3 are lucky to be alive. Can anyone think of another vehicle ever with spontaneous front end failures?


Disclaimer:
My only reference is the 1986 Subaru I drove and worked on for 15 years which was easily twice this robust, and the c/v joints were larger! And I'm leaving on a trip monday with a friend who drives a Discovery-ie not a hater.

 

[R_Lefebvre]

Thats just total BS Rob and you know it, every single design is looked at for cost constraints and those contsraints sometimes change when other issues in production change.

If the target cost is higher better materials are considered during the design period.

If a total overall weight target is lower different materials and production techniques are adopted to get to those targets.

All this comes into a balencing act that the bean counters sort out and then word comes down the pipe to make the changes needed.


Now I do agree with you about the bean counters also playing a part in the calculations of when to recall. And I do mean caculations, you know like where they are deciding how mant people can die before they should admit that a problem may exist.

Yes, every design is looked at from a cost constraint. But the choice to use a stamped steel arm instead of a forged arm would be made very early on, before any prototypes were built. While the general price comparison of different systems would be known, the real pricing of a part would not. Suppliers usually quote on a system before the design is even known.

Never once in my career did I see massive changes in direction due to cost or design issues. Usually the engineers fumble around with a given design trying to make it work. Whenever we made significant changes in technology, it always happened at the next model refresh point.

I've had many cases where I wanted to make a change to improve quality, but the cost of the change was "more than zero" so it was denied. Even to the point, I had one change which has zero piece cost increase, and a $100 tooling charge, and it was denied. The program budget was frozen and that was it. However, I was able to work out a deal with the supplier where I purchased the first production part off the new tooling as a "prototype" part for $100, and we then submitted the production change as a zero cost, and it went through.

HOWEVER, I NEVER had a change denied that was related to safety. On the DFMEA, if the Detectibility is 10 (meaning low), and the Severity is 10 (meaning certain injury), the change ALWAYS went through. Now, I did occaisionally have managers argue with me over my rating to get it under 8, but those were on debatable parts. But the ratings on control arms are NOT debatable. They are 10 and 10. Maybe they could sqeak by with a 9 and 9, but that means the Probability MUST be low, under a 2 or 3, and that means you test the MMMM out of it. And if you have a failure in testing, Bill Ford probably heard about it.

Now... once the MMMM is out there, and they're deciding whether or not to recall... I know very well what goes on, I've been in the room when MY parts were on the bubble. It's NOT fun.

R Levebre: if weight was the primary consideration when designing the suspension arm, would you like to explain why the LR3 has a unibody construction mounted to a conventional frame? With a curb weight of nearly 6,000lbs, do you really want to stick with that logic?

You know, I wasn't in the room when they did the initial design... but my guess is somebody decided to build the chassis that way, and then that influenced everything else. The reasons for decisions may be surprising to you. It might have been that since they already had tooling to make frames, they wanted to keep using it, instead of investing millions on all-new real unibody tooling.

I DO know why they went from cast/forged parts on the U152 to stamped on the U251 (Explorer). And that was because of weight. They saved 100lbs on the front end... Which they had to do because, IIRC they were going to an iron block or heads on the V8.

Look guys, I don't like the suspension on the LR3 any more than you do, but I think you're over-reacting. First of all, this isn't just an LR thing. Everybody is using stamped steel parts, and on expensive trucks too. Secondly, as I alluded to, we've had some pretty significant steel problems.

Again: Have you SEEN the Jeep/Dana axle TUBE failures?!?! I mean, HELLO...

 

[R_Lefebvre]

Green Meanie, thanks, you're saying it better than I could.

Nice argument here. That front end is PATHETIC. That metal is what, 18ga? And it's holding arguably the most important part of the car's suspension? Look at those pencil sized steering rods! What a bad joke. Stamped or not the seat of the pants engineering would say it's less than half the size it needs to be. Once people start to off road these things, I predict there will be lots of failures and handwringing, and talk of solid axle swaps.

The bottom line is that the people in this LR3 are lucky to be alive. Can anyone think of another vehicle ever with spontaneous front end failures?


Disclaimer:
My only reference is the 1986 Subaru I drove and worked on for 15 years which was easily twice this robust, and the c/v joints were larger! And I'm leaving on a trip monday with a friend who drives a Discovery-ie not a hater.

I have to refrain from telling you what I really think of your analysis, due to the maturity expected on this board. I'm glad you have a CSI magical video card that can zoom in capture microscopic detail and reverse engineer something based on a crappy photography. I guess my video card is just a regular consumer model.

Seems most are assuming the suspension is weak due the size, and have never heard of alloy steel. You know, there have been some advances in the past few years... some alloy steels are 10 times stronger than cast iron.

Maybe it's just my age, but I look at anything made of cast iron and thing "wow, what a heavy, cheap piece of crap!"

Oh, and I decided to look through the NHTSA record or consumer complaints for the LR3. There's 10 complaints logged for alignment problems, NONE for suspension failure. No consumer has complained about this.

And other vehicles having suspension failure? Are you joking?

 

[muskyman]

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[Life_in_4Lo]

Green Meanie, thanks, you're saying it better than I could.



I have to refrain from telling you what I really think of your analysis, due to the maturity expected on this board. I'm glad you have a CSI magical video card that can zoom in capture microscopic detail and reverse engineer something based on a crappy photography. I guess my video card is just a regular consumer model.

Seems most are assuming the suspension is weak due the size, and have never heard of alloy steel. You know, there have been some advances in the past few years... some alloy steels are 10 times stronger than cast iron.

Maybe it's just my age, but I look at anything made of cast iron and thing "wow, what a heavy, cheap piece of crap!"

Oh, and I decided to look through the NHTSA record or consumer complaints for the LR3. There's 10 complaints logged for alignment problems, NONE for suspension failure. No consumer has complained about this.

And other vehicles having suspension failure? Are you joking?

are YOU joking?
it's got some special alloy steel that allows pathetically wimpy suspension components to be just as strong as properly designed ones? Where is your proof?
["Don't believe your eyes, believe me"]? That suspension is cheap crap period.

The only comparisons to the LR3's suspension parts are the BMW 7, 1 series and X5... because we all know what fantastic wheelers those are? C'mon.

It is what it is. Owners need to keep an eye on it and the LR guys who called it out at the LR3's introduction were right on.

 

[Mike_rupp]

I was joking about the Pilot as an off the cuff response, but I had to do an oil change on the mini-van, I mean Pilot, so I took some pics of the suspension.

Maybe its just my gut and I'm completely off base, but the Pilot sure does look beefier than the LR3.

 

[greenmeanie]

are YOU joking?
it's got some special alloy steel that allows pathetically wimpy suspension components to be just as strong as properly designed ones? Where is your proof?
["Don't believe your eyes, believe me"]? That suspension is cheap crap period.

The only comparisons to the LR3's suspension parts are the BMW 7, 1 series and X5... because we all know what fantastic wheelers those are? C'mon.

It is what it is. Owners need to keep an eye on it and the LR guys who called it out at the LR3's introduction were right on.

Oh brother, it's the seat of the pants shool of engineering. I love it when somebody eyeballs a part and tries to compete with several million dollars worth of design and analysis software followed up by thousands of hours of testing. It may not be pretty but it sure is designed to be effective under normal use.

And yes, there are alloys out there that have superior strength properties. If you ever look up the popular topic of half shafts you'll see endless discussions of alloys and their respective qualities for shafts. If you ever fancy a good read look up the Rockwell B1b aircraft. They ended up going to a boron fillament impregnated aluminium metal matrix for the spine of the aircraft in order to meet weight, strength and stiffness. A rather extreme example perhaps but a good indication of what materials science can do.

Listen to what Rob tells you as he has lived in the industry. On a part such as this which is seen as safety critical a lot of effort is put into making them safe. That is not to say a bad part cannot get through the quality process, but then LR are not known for their attention in that area.

The only comparison that can really be made for these parts is a vehicle of the same weight and suspension design. You're Subaru suspension component may have to be bigger and beefier because it sees higher loads - or it may just be design reuse or even inefficient design. Without knowing the exact life of that truck you cannot just say 'Oh it just fell apart going down the road' If it has ever been off roaded, even once, can you tell me that it was not bounced off something?

The LR3 was not designed to be a rock crawler and it reflects that. Despite what the salesman would have you believe by showing you pictures of the Camel Trophy and old series trucks in Africa he is only using a marketing tool to get you to buy a vehicle that is more and more orientated towards the footie mums and road use.

I think you'll find that a solid axle conversion on these is pretty much impossible unless you re-engineer the entire machine.

Personally I wouldn't buy one but I have found my level of technology in the series trucks. Leaf springs rule.