[Causes for loss of wheel?]

4 minutes ago, Snagger said:

Ask yourself how many times you see "professional" tyre fitters just use an air gun to tighten the nuts, banging away to get them as tight as possible without a thought to torque specifications.

I've actually had a stand up row in a Skoda dealership after I damaged the lock nuts trying to remove them after a service. Demanded they replaced them all. It's been high on my priority list to replace the standard wheel bolts too. I didn't see them wizzy gun them on but I couldn't shift them with a length of pipe on my breaker bar!

Got a torque wrench in my boot at the moment as I've just fitted the spare wheel due to a punture. But I am certainly not infallible. Had a wheel work loose earlier this year but caught it just before it went AWOL. The was on a standard road going car whose biggest bump is a pot hole. Perhaps why this case struck such a resonance with myself.

[Causes for loss of wheel?]

Yes, that is the case that triggered me into thinking about it in far more detail. I'd suggest it wise not to delve to much into the specifics of that case as it is active, and there is a good chance it maybe someone from this forum. It's a gut wrenching case with a recently new owner of the truck and the girl passing following the accident. I feel there's a fine line between rubber necking style reactions and genuinely wanting to make sure I've minimised the risk of it happening on other cars.

[Causes for loss of wheel?]

1 minute ago, dailysleaze said:

Stub axle bolts too. I once bought some M10 bolts from eBay to replace with new. When tightening, they never got to the right torque. They were actually stretching before it got there. I looked closer and they weren't rated, unlike the advert said. So I put the old ones back on. If they failed the only thing holding the wheel on would be the disk to caliper interface, i.e nothing

This was probably what I had picked up on, thanks. I'll make sure I have a close look at these.

So these bolts hold the hub assembly to the half shaft? If the half shaft snapped would it not have the same effect?

[Causes for loss of wheel?]

Thanks for the comments. I was planning on using 8J ET0 modulars which off the top of my head shift them out a further 30mm. I needed this to have the inner edge of the tyre in a similar position to a standard set up with the larger ~33" diameter tyres. I am aware that this may give the bearings a harder time but I was expecting a lot of warning signs before something as catastrophic as this would occur.

The larger tyre would however increase the torque loadings on the half shafts. I was originally liking someone else's idea of using these as a weak point to protect other more expensive items in the drive train. But I will be pouring over the axle rebuild threads to get a better idea of them!

[Causes for loss of wheel?]

Hello,

There was a recent case in the media covering an accident where a wheel came free from a modified mk1 Discovery and collided with a pedestrian. I'm not in any way interested in fault in this accident. I do however want to understand the possible route causes and mitigate the risk in my build as far as possible.

I've read in other posts in this forum in the past that certain single point component failures can lead to the wheel detaching from the vehicle. Other than the wheel bolts (which arguably are not a single point of failure) what are these single points of failure that can lead to the loss of a wheel? Differential to hub shafts? Bearing failure? Are there advised preventative maintenance/inspection tasks relating to these items or is it predominantly random failures?

[A few electrical Q’s]

On 08/03/2018 at 12:52 PM, GW8IZR said:

 

Many years ago I built a regulated 13.8v power supply that could deliver 300A, this was quite a beast and had remote sensing to ensure the load always saw 13.8v.

When completed I tested it using lift motor brakes and had them glowing bright orange at 300A.

I tested it by starting a car, I almost _ _ _ _ myself as the engine twisted round the engine bay stretching the mounts to the limit.

Never again .. and yes, there does need to be a bit of volts drop to the starter.

Cranking drops battery voltage to around 9-10 volts. Car battery voltage is around 12.6 while the engine is not running and 13.5-14.5 while the engine is running and alternator is running.

I'm going to assume the starter is a resistive load just to make maths simple. 200A at 10V is 0.05Ohm. Winding voltage upto 13.8V would increase current to 276A. 200A @ 10V = 2000W. 276A @ 13.8 = 3808.8W.

So assuming resistive load your constant voltage test is forcing around 1.9 times the rated power through the starter motor than the design intent? Not surprising it turned over quickly! Yes the system may need voltage drop from 12.6V but doesn't most of this come from the chemistry of the battery and its response to load?

The mentioned 35mmsq has a rated load of 240A and resistance per meter of 0.00056ohm (or at least the extra flexible battery cable from 12V planet does). Guessing a 2m run thats 0.00102ohm. We'll ignore connection losses as they'd be similar for different cable csa. So 0.001Ohm in cabling, and 0.049ohm in starter. Assuming a simple voltage divider between cable and starter your only dropping 0.2V in cabling leaving 9.8V at the starter. Hooking the starter direct to the battery will see the current draw rise to 204A, and the total power output increase by 5%, rather than 90% in the constant voltage test.

Something else a factor here?

 

.

[discovery 2 abs retrofit]

Ignore my comment about the IVA. Couldn't find anything in the manual similar to what I was thinking.

Bosch motorsport do do an off the shelf tunable system but it was £5k ish on the forums that it's mentioned on and full of disclaimers removing as much liability from bosch as possible if the system was used on the road. It's mentioned that it is tunable for wheel diameter which raises the question about how bigger tyres on ABS equipped LRs effect the opperation of the ABS system. Unlikely to have hill decent, but I stopped looking at it after seeing the cost and disclaimer!

 

[discovery 2 abs retrofit]

I'd considered this but wondered/worried about break balance. I avoided it in the end because I thought the ECU was probably tuned to the weight distribution of the D2. Ideally both axles should be in ABS activation point at the same amout of 'foot'. That and for me I didn't have the bits so it would be a large investment for a gamble.

I also looked into kit car systems and for some reason there is no off the shelf ABS system for kit cars. You have abs if it came with the donor, but no generic systems. Think there was something in the IVA manual too but will doubke check on that. Not suggesting you're needing it, but there attitude towards retrofit of ABS may have been telling.

I'd wanted it for similar reasons and having heard how interesting live axle trucks with all terrains can be on wet roads!

[Major IVA change]

Yeah. My bighest problem with the regulations around current crop of electric cars is there is no incentive to get something with limited power, or better efficiency. Efficiency is just as much an issue with electric as IC, it's just the emissions are remote.

I'd love to do an electric project but need to get my head around the thermal management issues for the battery pack. Heat loss from the battery pack being another efficiency issue as well as safety.

[A few electrical Q’s]

Brain fart! Sub single digit ohms as for instance 120A at 12v would only be 0.1 ohm. Guess the figures I've seen may have been measured with equipment that couldn't  record or catch the initial starting current. Doesn't leave much room for cable resistance before you effectively have a significant voltage divider, even before battery voltage drop under load is considered.

[A few electrical Q’s]

Yeah, great idea for the head lights that isn't it?! Nice single point of failure on that high current switch too. ;-)

Back to your comment though that's interesting. I'd suspect a significant voltage drop due to the resistance and high load does act as a current limiter. Windings on the starter are low or single digit ohms if that.

Essentially they have used under capacity wire under the assumption that the significant heat loss through the wire is manageable due to the low duty the starter sees. Most likely by accident this is protecting the starter as other vehicles using the engines would have  used varying cable lengths. Far better would have been a coil or two more on the starter motor that would have resulted in more torque for cold morning starts.

If money was less of an object I'd seriously consider the geared starter motors. They promise more torque for less current draw. Major draw of mormal starters is for the torque required to intially get the motor spinning over. Higher speed electric motors have got far better in the last couple of decades.

 

[Major IVA change]

Classic car owners have it easy as they aren't effected unless they are doing significant mods.

As hinted to in my letter if enough points to keep old reg or age related then testing should be the same as a vehicle of the same reg.

I think Q plates and new reg kits are going to find it difficult to avoid tighter testing and old engine loop hole is likely to be closed.

[A few electrical Q’s]

There's good info on wire and I think fuse selection on the 12v planet site.
Some would argue I've gone over kill too. Got a lovely chunk of a bus bar ready for my loom. Big enough to happily take a feed to a winch. They pull daft currents. Serious enough for me to be thinking hydrualic is the way to go on my truck.

 

[A few electrical Q’s]

If you have sized cabling to handle at least 250A and you batteries can kick out more than 500cca or whatever the more conservative value is rather than CCA then the fuse will protect the wiring as intended.

Arc damage at whatever is shorting the lead is almost definate, but it should blow before your wiring ignites, or the batteries overheat.

Putting a 200A fuse in an OEM loom is probably no help as they tend to undersize the cables on the basis that the starter is rarely used for more than 20 seconds or so.

Undersizing with regards to voltage drop on LR looms is an issue as demonstrated by the benefit a headlight relay can give. This however is likely exacerbated by poor components.

[A few electrical Q’s]

You tend to fuse at around 80% of the rating of the wire. As already stated you're protecting the wiring, not the device. The wires are typically sized to cause less than a 10% voltage drop at full load and to within the manufacturer's specified limits. A fuse will fail more-or-less instantly at double it's rated current. Run at it's rated current and you're in the zone where it may blow at any time, or never!

I will be trying to fuse it on my loom but accept I may need to bridge the fuse if I get nusance trips. Seem to recall coming up with an expected current of 150-200A for my V8i starter.

You've got to also be aware that there is a maximum current the batteries can dish out. If for instance you picked a 250A fuse with appropriate wiring your batteries would need to push 500A through the fuse for a guaranteed fuse blow. Less than that and the fuse is somewhere between a sound safety addition and a useless voltage drop and potential failure point.

[Major IVA change]

Four routes mentioned. I was going to discuss the use the same registration route if you bypassed the IVA by keeping the same chassis, but scrubbed around it as since it doesn't need an IVA I thought it would confuse matters. Alas forgot to change four to three!

Cock up #2. Following sentence should have been significant rather than insignificant:
The comparatively small number of vehicles within this market would suggest that directly targeting this section is not going to result in an insignificant change in the total UK emissions.

Any how, not posting here for a grammatical review, merely sharing what I've sent in. Writing letters like this aren't easy when you've a ten month old intent on slapping your keyboard!

 

[Major IVA change]

Here's my letter. Alas with two cock ups which I'll post next!

Dear Robert Lloyd­Smith

Road Vehicles: Improving air quality and safety

I am writing to raise questions about the draft report that proposes changes to the emissions testing for IVA and submit a formal objection to the neglect these proposals appear to show to the kit car industry in comparison to mult­stage build based SMEs and vintage/classic rebuilds.

The report proposes an exemption for multi­stage build SMEs acknowledging the cost implications of these changes with receipts proving vehicle purchase before the implementation date. There is however no similar exemption for kit car builders whose projects are typically on far longer time scales and on tighter budgets.

The kit car industry has been a development ground for many well known originally British manufacturers who started off as kit car manufacturers such as TVR, Lotus, and Ginetta. Without significant safe guarding the industry is likely to suffer significantly, directly effecting a large number of supporting SMEs over the country and the death of the industry would have negligible difference to total UK emissions.

In direct relation to the text of the document it does not clearly address the four different routes to vehicle registration for the builders:

1. All parts new, heading for a new registration. This does allow for a number of major components to be re­used if they are fully refurbished.
2. If enough parts are re­used from the original vehicle then an age related registration is granted.
3. If too few of the parts come from a single donor then a Q plate is issued.

I believe the MOT testing to be related to the age of the registration plate number (when there is not a specific entry in the MOT guide book) whereas new MOT regulations relating to emissions do not tend to be retrospectively applied to a generation of vehicles to the point where they’d be forced off the road. So current MOT standards could be interpreted as the MOT tests that the donor vehicle would have been subjected to if still on the road.

The proposal seems to focus on the use of older engines (perhaps targeting carburettor and / or pre catalytic converter) but is ambiguous to what is actually meant by “date of registration” in relation to age related registrations.

In addition, “We are proposing that for kit cars, compliance with the MOT emissions standards current at the date of registration will be required” leaves amateur builders in an impossible situation where we are needing to double guess what the government is going to do over the period of time it would take to go from design to IVA test. This proposal itself demonstrated the short time scale between proposals being released to the general public and the proposals being implemented. Few kit car builds fit within a year!

It does appear that the kit car industry is being unfairly targeted here in comparison to the vintage rebuild or multi­stage build industries. The comparatively small number of vehicles within this market would suggest that directly targeting this section is not going to result in an insignificant change in the total UK emissions.

While I personally believe that the days for carburettors on new builds has past and kit car builders should consider moving over to more modern EFI engines, forcing ambiguous changes on us like this and in such as short time frame without offering similar concessions as offered to other sub­ sections is wholly inappropriate.

Perhaps vehicle excise duty is a far fairer way to tackle this issue?

 

[Major IVA change]

Multistage builds are commercial things like coach building or motor caravans. Doesn't apply to amateurs, although just incase it does I have sent a letter to the dvla ask for permission to transfer a vin or get a new one for my custom D1 chassis as a vague time stamp on top of receipt of the body.

Modern car emissions are not tested to the same level as needed for a class of engine to pass one of the euro standards. This is demonstrated by the imminent changes to the MOT that tighten the emissions testing for recent cars but doesn't exceed or match the performance required to achieve a euro level of performance.

I think the main loop hole they are trying to close is building an otherwise new kit car and being free to drop in a pre 94 lump to avoid the need for cat and potentially use carbs rathet than EFI.

The proposals are vague, and probably purposely so. If they had successfully  got a regulation change approved with vague wording it leaves them free to tighten it later!

What is not clear to me is date of registration. When modifying a car you keep the current registration if you reuse enough of the donor and don't mod the chassis. These projects are not effected by this change. You do however have the option to target an age related plate, new registration, or Q plate. I'd argue that the age related should be tested to the same standards as the donor. Q plate and new registration for kits or significantly modified vehicles are at real risk here even with my proposed  interpretation.

I have also raised the point in my objection letter that the changes will have an insignificant effect to the total uk emissions. I bet total annual number of amateur BIVA'ed vehicles compared to new registrations of type apprived vehicles is probably single digit or fractional percentage levels, and annual mileage in these is also likely to be less as these are often second vehicles.

 

[ibex 300 build]

There's strict requirements on the radii on the exposed edges. A lot of aftermarket steering wheels are not compliant.

[ibex 300 build]

Yeah, I've been making life awkward for myself by wanting toggles, but not wanting to use much electronics that weren't open sourced.

Little concerned my LED lights probably don't have much in the way of protective design, but that's another topic!

 

[ibex 300 build]

With regards to the fog lights I agree that the method you describe should get through the IVA.

There are other ways too judging by the IVA forum on locost builders. As I understand it you can do a simple switch if only on with the mains or dipped, and I think there is a way to use a buzzer that allows you to have a latching switch that adds 'if the front fog lights are on' to the list of permitted on states without needing latching relays or an electronic modules.

Not much point to locking out fogs if mains are on. Shouldn't have mains on if people are coming the other way anyway and you'd need to ensure they don't  cut out when you flash your lights rather than simply select mains.

[Bollinger Electric 4x4]

Anyone who has ridden a fixed gear bicycle with no brakes gets a real good appreciation for how much work the brakes do!

For emergencies I guess you could short the coil to stop quicker than standard regenerative braking but essentially you are just trying to convert a huge amount of kinetic energy into something else. If you short the coils you are going to change it to heat in the motor requiring the motor to be designed to take that heat and so less efficient in normal usage. Using discs to convert the kinetic to heat is just an easy way to do it. With regenerative braking you are trying to convert that energy from kinetic, to electrical, and into chemical energy with unwanted heat being generated at each point. In a similar way to not being able to get the energy into the battery quick enough when charging (granted some of those problems are on the supply side) you have a similar problem when trying to use regenerative braking for hard stops.

I like the idea of the brakes being a completely different system, but as super capacitors and battery technologies advance I have little doubt that eventually it may get to the point where the hydraulic braking systems we use now are shown to be statistically less reliable than just using the power train to brake. Like others have hinted at the finances have a hell of a weight in these kind of moves and the though of being able to get shot of a complete system would be beneficial for costs. Wouldn't want to pay the indemnity insurance for the people who make that call though. Essentially they will have a figure of an acceptable number of accidents due to system failure rather than saying it will only be used if it is impossible to fail!

With regards to the four motor system I was looking at something very similar before my truck arrived for a radio controlled car. Have the bits still in the loft somewhere. Basically just a robot project but had four wheel steering and I was looking to replace the diffs with a double belt drive to achieve independent wheel control. No real reason why, just because!

[Bollinger Electric 4x4]

Using compressed air is inefficient.

Hub motors may be fine if you are crawling but increases unsprung weight and where gearing is needed exacerbates this further. They are also subjected to the highest levels of shock/impulse on the vehicle apart from the tyres.

[Bollinger Electric 4x4]

The combo of gearbox and clutch or gearbox and torque converter are to compensate a little for the 0 torque output of an IC engine from 0 rpm upto stall speed, and of course the peak torque being some where around 2k rpm. Straight onto the transfer box would probably be an option, but thanks to the brick like aerodynamics I'd forget about trying to get any decent range at motorway speeds. I think aiming to replace the transfer box with something a little more purpose built that allowed the complete disconnect of a small petrol engine so that it could run electric only would be ideal. That way you could do a long distance trip if needed but get the bonus of monster torque when needed while only running something diddy like a sub 1l toyota three pot. Do the same adaptive charging trick seen on modern alternators to get a little regenerative braking.

The two speed on the tesla is probably to enable the electric motor to run a little more effectively at both the higher speeds and lower speeds. From my limited experience with RC electric models there is still an element of it can be wired for low torque or high speed. Perhaps the more recent electric vehicle motors are wired for both with multiple windings.

[Bollinger Electric 4x4]

I'm looking forward to tearing apart a few of these current electric cars and seeing what I can do in a home build in a decade or so once the get cheap second hand. Torque curve of the electric motors would appear to have IC engines beat for off roading. Trouble is our usual builds are just too heavy for decent range. Other slight issue is many companies are leasing the batteries rather than selling them with the car.

With a hilly 70-90 mile round trip to work, family 180 miles south, and an annual mileage of 20-25k miles electric just isn't cost effective for me yet.