Turbocharger

Managed some fiddling today (cold and windy) - once the rear shocks and springs were stripped out I stuck two springs under the rear, for the visual reward of appearing to make progress. It might look to the uninitiated like the rears are just wedged in with some bits of wood and a piece of 2x4 for a bump stop extension. This is clearly a highly technical trials environment and shouldn't be misunderstood. Manual inflation allows each end to be lifted or lowered - I've got P38 rears at the front and fronts at the back, because they fit the spring chairs better that way round, but the extra travel of the rear springs at my front end is clearly visible. MOVIE.mp4 Here both axles just have the springs piped with a T-piece. It's very wobbly in roll even if I just hang off the cage. On the road it would be truly exciting. Separately I piped all four springs in parallel with 3 T-pieces, and the rear lifted to max height before the fronts moved much at all, the weight of the engine being much heavier. If I linked the wheels front/rear it could only be one side at a time and I think the handling would be very strange; that's one to try at an offroad site only I think. Next stop, mounting height sensors.

Today's progress- one end of one rear shock absorber removed. Short lunch and it was being stubborn. I'd seen the old thread, thanks. Some useful info in there! The trailer system is a good challenge - if any parts are fitted, are they adding value? I'd say if it's just air springs then it's the same as coils (arguably more fragile). Air springs with mechanical levelling valves would be bombproof but would only adjust for height, so doesn't give different ride heights and/or crossaxle performance. I did think about using mechanical valves with a worm gear and servo to change the link length, to 'fool' the mechanical valves into eg lowering the car as required. This has the benefit of benign failure modes, but I'd need to get small IP67 linear motors or similar and even then it would likely try to fight any cross-axle linking I put in. Solid farmer-proof idea though. I hadn't considered front to rear - I've no idea how it would handle on the road. It could be made to work if the springs were selected to recognise the extra weight of the engine over the front axle. By extension I could just pipe all four corners together and let nature do the work in equalising, bit I suspect that would handle like a bag of wet tits rolling down stairs. There's only one way to find out, and it's a small pipework tweak (or some temporary coding) once it's all working. I try... I have to balance out Nige's 2000A welding of 16mm shims 😉 I'll snatch off your hand for the air ride bits, if only to fiddle with and work out what's what - thank you! DM'd.

I think Ogden disappeared many years ago, though their legend lives on! I want my own controller rather than an aftermarket or P38 controller for several reasons - first is the learning (remember this is a hobby, not transport), and second is the control. Third is that they're all quite spendy, probably good value compared to buying new bits but I've got most of the ingredients for about £200 using second hand/scrap/begging etc. It's certainly more complicated than cart springs or bits of metal, but we understand the failure modes after twenty years of P38 (and 25 years since RRC got airbags) - we should be able to tackle the common issues: Airbag failure - they're fairly easy to change the bladders, off the car at least. Air feed failure - override control of the individual solenoids, and/or manual inflation points. Ride height sensor failure - some clever logic (see below), or back to manual solenoids for inflation/deflation Compressor failure - could have an inflation point for an external airline, or carry a Halfords tyre compressor. If the P38 loses a ride height sensor, it freezes or drops you on the floor. If the L322 loses a height sensor (bong bong SUSPENSION FAILURE), it'll only do normal height. Surely, if it's blind to the height at one corner (and assuming flat ground and no other leaks or faults) then it could work out one height from the other three, or cycle the car down to the bump stops and fill both bags on that axle equally until the one sensor shows a good ride height. It might need some manual trimming, and maybe adjustment every half hour, but that'll get you home. It's more complex but springs break, become unseated, bushes wear out, shocks break etc etc etc.

The springs themselves are fairly simple units, the rubber bag rolls over the lower piston. That piston is shaped, to adjust the spring rate at different heights, which means there's some scope for tuning this by swapping parts about. The Disco 2 springs are a different diameter and the bags are crimped on but the P38 and RR Classic springs are built like the bus springs I know, and they're easily disassembled: There's a small lip inside to retain the rubber bellows, but the spring is mostly held in place by air pressure - and by the constraint of the axle geometry so that it's never overstressed. Putting that piston back in is rather harder at first glance. Vaseline/silicone lube is your friend, twisting as you go, and just a little airflow into the bag helps to keep it in shape. I've done a 'how to' video to save anyone else the hour I spent chasing it around the floor before figuring this out. Lying across it and using your hands and knees also helps - recruit a helper to squirt a little air in, but not enough to put you into orbit if it pops!

Side discussion: crossaxling. Here's a picture of the same car many years ago, in a typical crossaxle. (Ignore the bottle on the front, I was trying to spray water on the intercooler for more power but the effect used too much water to be useful). Like everybody else I'd worked on improving the axle travel, longer shocks and wider travel on the joints etc to let the wheels move further, but the springs were the same. In this position all four wheels are touching the floor but the traction is quite marginal (on open diffs anyway) - all the weight, and therefore the grip, is on the front left and rear right. A heavy boot will spin the other two wheels with ease. Now imagine air springs, but instead of controlling the ride height there's a pipe between the front left and front right. The car would settle down slightly as the weight transferred equally across the axle, and there would be more grip as quickly as the air was able to transfer. LandRover have done this since L322/Disco 3 with a cross-axle valve, but the pipe they use is small so a lot of that work is done in the software too, which means it all looks very stiff and unnatural as these trucks make adjustments, and offroad progress is jerky. I'm hoping to make something much more responsive, even if I have to use a larger bore pipe. Professor Rafferty (SimonR) inspired a lot of this work, and he found an important point by actually going and trying this - by cross piping the axle the effect is to support the vehicle at the centreline - there would be almost no static roll stiffness if both axles were cross-connected. That would be exciting at any speed, but if climbing or descending a slope it could destabilise the vehicle. My hope will be to only open the crossaxle valve on the uphill axle, should be easy enough with an accelerometer, so that the vehicle climbs a slope like a Robin Reliant (supported on the two rear wheels and the middle of the front axle) and descends like a Morgan three-wheeler (two front wheels and the middle of the rear axle). The traction benefit will be more marginal on the uphill axle, but I'd prefer to stay the right way up).

Firstly I've played with the P38 front spring, because it's probably closest to fitting easily. For the sake of getting some numbers (and an easy, visual win which keeps my interest) I've bodged them in with bits of wood, it's not going anywhere on the road yet. Surprisingly simple, some 6mm pipe and a couple of fittings and "car goes up, car goes down". The natural frequency changes at different heights, I measured c.1.9Hz at normal ride height and 1.6Hz at +75%. If 1.6Hz is 'standard' then 1.9Hz for normal driving represents about +40% spring rate (since the natural frequency = sqrt [k / m] ). However it would be relatively easy to reduce that rate by piping another volume (say, a 1 litre pressure bottle) somewhere near the spring and allow air to push back and forth. With a tap or (posh) a solenoid, it could even be selectable, but let's not run away with ourselves yet.

Then I set about looking at springs and things. Three different springs (P38 front, P38 rear, Disco 2 rear) give different lengths, diameters and lower pedestals. Aside: an air spring is a clever bit of kit - if it was a parallel spring then the pressure inside would be the same at any ride height - it's a mistake to assume that they're stiffer at full height. In fact, though the *pressure* would be the same at full height (since pressure = force/area) the *effective spring rate* would be lower because the spring rate depends on the area of the lower piston and also on the enclosed volume - there's more air inside doing the work. This means it's more complex than just levering a spring into the wheelarch and piping it up. It's not so simple to measure the 'spring rate' with an air spring - the coils were about 170lb/in when they were new (they were RR Classic 'red & white', originally giving a nominal 2" lift). I used a phone app to get accelerometer data and work out the natural frequency. Much easier without the shocks connected but the bounce still drops away to nothing within five or six cycles, just from the friction in the bushes etc. The coil spring (with a 300Tdi, winch on the front, 6 point cage etc) is 1.6Hz. That fits the expected 1 to 2Hz range, anyway.

The coding was the biggest unknown so for the first step I stole bits of code off the internet and changed the words developed a programme which mocked up some control logic. Much more to do on interrupts, outputting via MOSFETs to drive the valve block and some PWM to stop the solenoids getting hot, but this was enough to make me believe it was possible. Video here:

<delurk> I'm creating a thread for my Ninety air suspension build - if only as somewhere to put my notes, in front of the LR4x4 "peer review panel". The car eats front prop UJs because it's lifted (and the engine is high, tilting the powertrain), and it doesn't fit in the garage. I also want to improve the crossaxle traction (more on that later), but first and foremost this is a condensing thought experiment and a chance to learn some coding, rather than a serious proposition for transport. I've been amassing bits for a while, as these projects tend to do, and coronavirus has developed some time for me to play in lunchbreaks while working from home. I've got: New mounts for the front shocks, to move them to the forward position A P38 RR compressor, and a couple of valve blocks A set of P38 front and rear springs A pair of Disco rear springs A set of RR height sensors An Arduino, some peripherals and a very vague memory of programming in BASIC from twenty years ago The Ninety went onto a new galv chassis three years ago so I will not be chopping bits off the spring cups. If I can't make it fit then it'll go back onto coils. If I can develop an open-source bolt-on air suspension system for other people to use, so much the better. I anticipate updates will be sporadic and probably inconclusive. I'll try to cover my approach as well as the actual build.

I'm very keen on getting Skytag, contacted them and they say they'll discount the up-front cost from £249 to £75 for a group buy. Monthly packages stay the same as here: http://www.skytag-gps.co.uk/ Drop me a message if interested, I'm keen to sort this out by the beginning of next month, after a neighbour's LR went walkies from his front drive last month.

I've a Trutrac in the back axle. Not a locker, so if you lift a wheel you're still stuck (or you'll be left-foot braking), but if it's slimey or on gravel you'll see a little more grip. The only negative I can assess is that, when cornering hard enough that the inner rear wheel might slip a little, it'll push from the outside rear wheel instead which gives you a shove around the corner but tends to tighten the line, feeling like oversteer. It's only just noticeable, enough that I'm not sure it's not just 'tuck' on the rear trailing links geometry or similar, but the ATB would explain it. It's no locker, but it's a great budget option.

Thanks guys. I think we've settled on the Crown at Llanfihangel Glyn Myfyr, camping next to the pub and there's even a ford to access www.thecrowninn.wales Three Pigeons came up as one of the other favourites too, the ford swung it though! I'll let you know how we get on.

Hi all, A group of us are heading to mid-Wales for a camping weekend, a day of laning and some time out with the kids. I'm looking for pub food and camping nearby where we can have a fire and a beer while the kids are (hopefully) asleep. I can trawl the websites but a recommendation would be invaluable. I'm looking around Bala but happy to be swung north or south. The lanes will hopefully be tame, scenic and aren't the focus of the weekend.

There's a few of us old hands dipping in from time to time. I've avoided the divorce but have moved house and added a moneypit to the fleet (and rechassis'd the Ninety). Anyone know how to put two child seats into a soft-top Ninety?

Bit of a hang time on this but I've been busy... Here's some pics of my setup, homebrew manifold and the turbo from an L200. It's not pretty... Boost control is just by pressure through a Td5 diaphragm and a counter-pressure spring to reduce the pressure for first movement. The effect is excellent pullaway performance (through an auto box) and comfortably 25mpg or better on a run.

Blimey, your diagram looks complicated. I'm running a Mitsubishi VVT on a 300Tdi, I have a Td5 boost capsule with an external spring (chosen by mostly trial and error, with a little science stirred in) to counterbalance the closing force. That moves the vanes and manages the boost. The result is great, really boosty at low revs, I see 0.8 bar at 1000rpm and 1.3bar at 1400rpm. It naturally targets full boost though so the vanes are always as closed as possible, which I think contributes to 25mpg (mine is an auto Ninety too). The hardest part was making the manifold to hold the turbo, it's run for about five years now and it's great. I've been to Spain and Morocco with it, it's really tuneable but I've turned it down now to keep it driveable.

Back to the top - we filled the place and now another has dropped out. The trip leaves this Friday for two weeks, but now the ferries are paid for so this is a cheap opportunity to see the desert! Be in Portsmouth on Friday 7th Oct for 8pm, we'll drop you back on Sunday 23rd at 8pm. The Volvo is going back to the Lake District so pickup is possible most places. Come and join us, it'll be a giggle!

I'm planning a three vehicle, six person 4x4 trip to Morocco in October, but one of the participants has had to drop out. We could go with five, but it'll be a drain on the group. Two of us made a similar trip in 2014 so the transfers and border should be fine, the intention is to cross from Portsmouth to Bilbao, have one overnight in Spain and get into Northern Morocco quite quickly. We'll travel south slowly to see the Dade's Gorges, Cirque du Jafar and cross the High Atlas. I'm planning to head west from M'hamid to Foum Zguid, spending a dark skies night in the desert as the highlight of the trip. Departure will be Sat 8th October, returning Sun 23 October. I know it's short notice but we need to be mindful of the group dynamic. The other participants are pretty easy-going, outdoorsy but not "boozy lads". We have a lab equipment salesman, a rail manager, a transport manager, a mechanic and a logistics administrator. Someone with medical knowledge, Arabic or "better-than-schoolboy" French would be helpful, but we survived the last trip without problems. To keep it interesting we're taking two old LandRover Ninetys and a Volvo C303. Cruising will be hot, noisy and about 60mph. Costs will be split sensibly between us, probably around £1100 each including ferries, fuel and food. There's no profit for anyone and no promises of organisation or success. Backup plan is via the other two cars. Contact me, John, on 07779 081520 if you're interested.

Does anyone know what the difference between 300Tdi and Td5 hard brake pipes are - diameter, unions, config? I'm rebuilding my Ninety at the moment, it's a 2.5NA but I have a Td5 bulkhead and servo and late 300Tdi or Td5 axles. I need to re-pipe the whole chassis anyway, but I can't see an easy way to buy a Td5 pipe sets. I'm going to use Llama flexi too - anything else to think of?

I bumped into Nick (Tangoman) in Cheltenham a couple of years back, he'd found he has too much spare time and cash since getting rid of his LRs so was thinking about getting "something for a little laning"...

I did some more investigation today. It clicks happily into both positions, the detent is working fine and the position looks good, 12 and 2 o'clock as per Ashcroft site. I lifted the selector plate and all looks clean and oily as it should - but both props still turn together! It looks like the diff is bust - off to the classifieds!

It's an auto so possible but not likely. I've certainly not sat spinning a wheel abusively to damage anything - by my understanding it broke "while it was in the garage" (but that's what they all say).

Not the usual issue with a difflock so the search isn't helping. My Ninety (with LT230) is stuck in difflock, can't turn either prop independently with wheels raised and a nasty windup feeling when cornering followed by a loud bang as it unwinds. The tricky question is the cause - the lever and mechanism are free so the plunger on the side of the box moves in and out freely with a click, but it's still in difflock either way. It moves in and out of hi/lo range easily too, but that's separate. All the online guides point at freeing the linkage but nothing deeper. It's going to have to come apart, if it's a common or easy fix. Otherwise I'm in the market for a difflock assembly!

Thanks guys. Mine are copies as they're welded and don't have the kink in the back plate. I'll pick a suitable shock, +5" is more than I expected!

After getting sick of the annual "just one more patch" welding session before the MOT I've bitten the bullet and bought a new chassis. While the spanners are out I'll fit all the accumulated "round tuit" bits I've picked up over the years. I've got these upper rear shock mounts - can anyone ID whose they are, and more importantly what pin-pin shock would fit and be suitable? It's for a softtop Ninety, lightly laden and rarely tows anything, will be used on laning, rough roads and the odd pay and play. I've extended the brake lines already and I bought them for additional articulation.