Castor problem?

[R_Lefebvre]

Well since I did predict the type of failure that happened to this LR3 years before it did, I guess I do have some ability to judge build quality by looking at it.

You're missing the point.

You looked at the LR3, and said it was a crap design. We had maybe 3 failures, maybe, we don't even know the real cause. Anyway, the point being argued was 3 failures out of however many thousand samples does not indicate crap design. It indicates a quality defect.

Then you talk about the redrilled swivels and claim they are a good design because there haven't been any failures in a relatively small sample. I'm just pointing out that you've got this stuff backwards. That's a bad design, any engineer would be tarred and feathered by his peers by releasing a design like that. It's only OK because there aren't THAT many instances of it, relatively speaking.

And I guess you missed it when I said drilled swivels "are probably fine". There's probably a few hundred to a few thousand driving around like that, which is far shy of 10,000's.

I'm just trying to bring a little perspective to the situation.

Machining after welding does happen, but if the axle is drill in two different set-ups, one end at a time. Tolerance on hole alignment from "end to end" may very as much as +/- 1 degree. I doubt they drill both ends at the same time.

All trucks have un-equal caster. Just look at any report from the Alignment Shops. I have never had one of mine end up prefect side to side.

Almost missed this with everything else going on. I would strongly think they actually do machine the whole axle with one setup. Seems implausible to have 3 or 4 machining centers on one line, but when you're manufacturing a lot of axles per year, it makes sense, to reduce tollerance.

Unequal caster is probably because of the stackup of all the other tollerances on the assembled pieces.

 

[R_Lefebvre]

well 3 failures in any number is still higher % then none in a few hundred right?

By simple math, yes. But it's not that simple.

And, you're making the assumption that since you haven't heard of any failures, there are none. On the other hand, you've made the assumption that there are probably more than just 3 FCA failures.

And about the MOT cert, do you really think they'd notice? Not likely. I've watched an expose where they didn't notice a car that had been written off on a front end crash, had a new front end grafted on, badly, and bondoed up.

MOT is a good process, but it's not perfect, and shouldn't be used as evidence that something is good.

 

[ntsqd]

I got off on the wrong foot here by not making myself clear. Let me state this again: I have no problem with a re-drilled swivel ball so long as they are not left as slots or are not positively fixed from rotation should the bolts work loose. The method is nearly as structurally sound as LR delivered the axle. Like a lot of things, it is the execution of the mod that is critical to the success and the safety of the modification.

The bushing in Steve's first picture is a clear example of a rotational fix. Even if the bolts were only hand tight the swivel ball could not rotate more than the clearance of the bolt to that hole. The anal part of me would like to see those bushes in every hole, but only one is far and away better than all slots.

I've been employed to fix vehicles. I've been employed as a fabricator of vehicles. I don't know that I'd call myself a Professional Mechanic or a Professional Fabricator, but I do consider my 35-odd years of experience in building, fixing, and modifying vehicles and machines to have considerable weight and value. That doesn't mean that I'm always right or that mine is the only way, just the only right way for me.

 

[Antichrist]

And about the MOT cert, do you really think they'd notice? Not likely. I've watched an expose where they didn't notice a car that had been written off on a front end crash, had a new front end grafted on, badly, and bondoed up.

I'm not saying it's perfect, but I expect, unless the inspector is a complete wanker, that if someone brought in a Tomcat for it's MOT that they might suspect some mods had been done and check more closely. That's a bit different than bringing in a more or less stock car that has a bunch of bondo.

I have no problem with a re-drilled swivel ball so long as they are not left as slots or are not positively fixed from rotation should the bolts work loose.

The swivel pictured isn't exactly the same as being slotted. First, the sides close in towards the center of where the two holes meet, so, while not a lot, there is some meat there making it unlike a "slot" to prevent rotation. Secondly, for the swivel to rotate the two adjacent holes, even if they were connected by a slot with parallel sides, would have to be connected by a slot forming an arc, not a straight one. Once the swivel ball tries to rotate in relation to the flange, the hole is no longer the right distance from the radial center line of the flange.
Granted it would be ideal to have the holes plugged, so you have 100% solid material under the bolt head, but a hardened heavy washer handles that.

 

[Snagger]

It is useless arguing here. Knocking my head against the wall would make more sense. I'm headed out to the garage to modify my Disco. I'm sure all of you Engineers would be critical of what I'm doing.

Quite right - it is pointless arguing against you. You have little understanding of the forces involved, and as pointed out, regard the failure of one vehicle as a design flaw and the success of three vehicles as 100% validation.

Those bolts are all in tension, not shear, but you keep banging on about the lip on the swivel preventing shear forces. I haven't seen how you did your mod, but the comment about hardened washers will certainly help reduce the uneven loads on the bolt heads. If they're thick enough, then it should prevent the bolt heads being ripped off. As for the QT radius arms, I named them as one example of many suppliers. Reading up on it would suggest that display stock was somehow mixed with trade stock, so weakened examples have failed. The thing is, more than three sets have survived, and by your standards, that makes them perfectly safe.

I just don't understand the mentality where people from your side of the pond continually bemoan LRs for being weakly constructed, and then set about removing more material from critical parts.

 

[Antichrist]

As for the QT radius arms, I named them as one example of many suppliers. Reading up on it would suggest that display stock was somehow mixed with trade stock, so weakened examples have failed. The thing is, more than three sets have survived, and by your standards, that makes them perfectly safe.

That makes no sense to me. For the record I'd never put a set of those on my truck. I've never heard of a stock radius arm failing there. In just one thread there were two failures of the QT. So either they are a poor design, or QT is so disorganized you can never be sure you're getting a production version as opposed to a display version. Either way, it's a dangerous situation. (And don't blame it on vendors. If you have a display that looks exactly like a production version, then it's the mfg's responsibility to clearly mark the display unit "For Display Only".)

Then you compare them to the castor corrected swivel ball results where there have been no failures of the swivel balls (that I've ever heard of). How do extrapolate from that that the QT arms are perfectly safe??
You seem to be saying (3*y)+5 = 10 and (3*x)+5=15 so y=x

 

[Mike_rupp]

I'll leave the across the pond comments alone as I don't want to get into a yelling match. Normally, I'd take the bait, but I'll pass.

As far as the LR3 is concerned, I'll concede that the design of the control arm is most likely fine, and there was more than likely a quality problem with that arm. That being said, my issue with the control arm is that the specifications were lowered. LR has the ability to make a bullet proof control arm, yet they chose to make a stamped steel control arm. While a stamped steel arm will serve the needs of the vast majority of owners, it doesn't serve my needs. If that arm gets dented, it will lose its strength. I think all of us agree on that.

On to caster correction: do you understand that the swivel ball caster correction has a benefit? The whole reason for the modification in the first place is to make the vehicle easier to drive and more stable at highway speeds. Of course nobody would just remove metal from a part for no benefit. There is a slight risk that one takes on when doing the modification, but the upside is substantial.

 

[Steve Rupp]

Reading up on it would suggest that display stock was somehow mixed with trade stock, so weakened examples have failed. The thing is, more than three sets have survived, and by your standards, that makes them perfectly safe.
.

For an Engineer your logic amazes me. First of all I think the "display model" is a lame excuse for a prototype or bad design cover up. Second how do you rationalize one failure out of how ever many (it's still an aftermarket part so you can't compare to stock parts) is better than zero failures on probably a bigger sample. You keep going back to the 3 truck sample which is just plain wrong. Trust me this is not a new mod.

 

[Antichrist]

Second how do you rationalize one failure

Two reported failures. Someone else in the same thread on Pirate said their's failed in the same place, they just caught it before it became a catastrophic failure.

 

[Michael Slade]

Holy crap.

 

[R_Lefebvre]

As far as the LR3 is concerned, I'll concede that the design of the control arm is most likely fine, and there was more than likely a quality problem with that arm. That being said, my issue with the control arm is that the specifications were lowered. LR has the ability to make a bullet proof control arm, yet they chose to make a stamped steel control arm. While a stamped steel arm will serve the needs of the vast majority of owners, it doesn't serve my needs. If that arm gets dented, it will lose its strength. I think all of us agree on that.

That's a much more reasonable stance. I would say the issue is not that it's a bad design, I'm sure it's an adequate design. The real difference is that it is not an overbuilt design as we have come to expect, which makes it more vulnerable to manufacturing defects or trail damage. That is what makes it unsuitable as an expeditionary or heavy off-road type vehicle.

The swivel ball here is a perfect example of that. The fact that so many people can perform such a bad modification without problems, is an indication that that part was way overbuilt to start with.

I've said for a while that modern advances in engineering, design, testing and manufacturing have not been employed to make vehicles better than they were in the past, but rather to whittle them down to the bare minimum weight and cost.

 

[R_Lefebvre]

No, I'm a very skilled driver, that's how I know it's fine.

Please explain using your mechanical omniscience how it's any different that driving with a trailer with a 440lb tongue weight, which the the truck is rated for? Particularly when I have 200lbs extra on the nose.

Good work on continuing the Ethug pattern of being unable to continue a logical discussion and therefore resorting to trying to discredit me.

 

[Mike_rupp]

Thom, its apparent that even when you try to be reasonable with R-Levebre, he can't drop the holier than thou engineer attitude.

He is completely biased when it comes to his statements on this discussion. He will do anything possible to defend the engineer who designed the control arm on the LR3. In the same manner, regarding the redrilled swivels, he is quick to point out that the entire reason for the fact that there are no failures with that modification is that the LR engineer who designed the balls must have done a great job.

It doesn't matter what type of evidence you provide him regarding the design of the swivel modification or empirical evidence, nothing will convince him. It is pointless to discuss the modification with him.

Now he's trying to take the high road again by calling you an Ethug. LOL

 

[I Leak Oil]

Wow! 9 pages of this. I think you guys need to get a room. Really...who cares? Like I said in the LR3 thread,
If you don't like the mod, don't do it.
If you do, knock yourself out.

Both sides are making themselves look foolish with all this carrying on. Let it go....
Jason T.

 

[Steve Rupp]

The swivel ball myth was tested and busted. :victory: