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Suspension Mods for Faster Off Road?


WesBrooks

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Although not an out-and-out video about his vehicle I'm always amazed by how well Shannon Campbell's vehicle is dampened and you can see after some of the jumps / whoops how quickly his vehicle can get on the power compared to others.

There's a reasonable overview of the components used on Driving Line. Shows the value of the suspension because I think when he built that vehicle it wasn't the most powerful (don't get me wrong - it's still north of 800hp) but overall just looks a very well thought out machine and was able to utilise all of it's ability more of the time.

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On 5/16/2020 at 7:48 PM, WesBrooks said:

Having diverted the Grenadier topic by mistake I thought I'd spin off the suspension talk to a seperate thread!

Most talk on these forums around suspension centre around increasing articulation and low speed off roading performance. So out of curiosity what mods are made to make the typical coil landrover suspension behave well at speed?

I've seen a couple of clips of hill rallys on TV and they look great and there is a large green oval contingent which implies there must be a reasonable body of knowledge on the subject.

So stock ride height is probably preferable along with good condition/new shocks and springs and Poly bushing. What about tyre size, how large can you go before tyre size and weight becomes a hindrance? Wider track / offset rims a little?

 

I'd say it is all about the shocks really. Other factors will effect handling and the like. But it is the shock that does the dampening.

I had some friends who did Hill Rallying, they stopped going once they got to the point they were spending about £4k/corner on shocks alone. This was 20-25 years too.

Shocks as fitted to the likes of the Ford Raptors or Chevy ZR2 look pretty capable for road vehicles. And all reviews say how well both vehicles run at speed on the rough. I believe one of the design targets for the Ranger Raptor was to be able to run a 100mph off road in terms of suspension design.

 

In other competition I think most use some sort of by-pass shock setup and hydraulic bump stops.

 

httpwww.polyperformance.comimages104572_

 

 

Take a look at some of the rock bouncers

 

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1 hour ago, Ed Poore said:

Although not an out-and-out video about his vehicle I'm always amazed by how well Shannon Campbell's vehicle is dampened and you can see after some of the jumps / whoops how quickly his vehicle can get on the power compared to others.

I dunno, if he's the one consistently bouncing end-over-end after jumps I'd say he's got it wound up too high, truck looks too bouncy to me - you want it to look smooth, although that can be a challenge for Americans.

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19 minutes ago, FridgeFreezer said:

I dunno, if he's the one consistently bouncing end-over-end after jumps I'd say he's got it wound up too high, truck looks too bouncy to me - you want it to look smooth, although that can be a challenge for Americans.

im assuming you mean this video?
 


personally wouldnt say its a suspension issue, i think if you were to be half as succesfull as him would be no mean feat

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In the 80s and mid-90s when I used to be a rally comms-person/marshal we often used to have, at the end of the main rally, a few teams from BAMA (British Army Motoring Association) come through in Land-Rovers; one year we also had teams participating in "Cop Drive' (which was a motorsport event for Police forces).

This was back in the 90/110 days - though one team did appear in a nearly-new LHD white Discovery V8 complete with UN markings, and there were still a few 'leafers entered by the Army teams.

Lowered ride-height was normal - remember you're driving on rally stages which have to be passable by a Peugeot 205 or a Ford Escort. 15-inch wheels and 'soft' rubber were ubiquitous [alas Fred Henderson and his Colway Competition Department are no longer with us]. Go-to shock-absorbers back then were the orange-bodied gas-filled Konis, which could be adjusted "to account for in-service wear" according to the blurb-of-the-day. I guess gasfilled Bilsteins would be the modern equivalent [I've got them on my 90TD5 and they really do work well when hustling it down twisty lanes].

Brakes were always a problem: when your two driving-positions are full-throttle/max-revs-in-low-gear, and stand-on-the-brakes-to-get-controlled-wheel-lock-to-put-you-into a slide you soon find that drums are *not* your friends. Various 'kludges' to provide dashboard-controllable front:rear brake bias were tried, but the mechanics of Land-Rover brakes don't adapt to this as easily as the classic 'bias-adjustable pefal box' of the Mk.2 Escort days.

110s tended to do better than 90s; the extra wheelbase means that power-on slides are more controllable. Even so it's kinda fun to see a 110 hardtop powering through a gravelly bend under just a touch of opposite-lock!

Even the Marines thought a 110 Ambulance could fly!

https://youtu.be/33LFWliJ1Zo

Edited by Tanuki
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2 hours ago, RedLineMike said:

im assuming you mean this video?

No, the one Ed posted, seemed like a few times he flew over jumps etc. only to bounce end-over while others were landing a bit more controlled. Just felt that a lot of the clips his truck looked a bit bouncier than you'd want, especially the rear end - although obviously with the stuff they're doing it's hard to say if it's suspension or the fact he's launching it off obstacles at 100mph :lol:

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54 minutes ago, FridgeFreezer said:

the fact he's launching it off obstacles at 100mph

This I think, he does tend to approach things either flat out or not at all. You can see in some of the clips where he's going considerably faster than the competitors. On the clips where he's not rolling it over (those I think the back kicks up because of the speed at which he's going) when the back end comes down it's actually pretty well dampened. Certainly to my eye appears to be much more critically damped than Loren Healy's vehicle in the Milk Run video.

I think his mentality is summed up in another clip somewhere at King of the Hammers where someone's too slow in front of him and simply drives over them to get past them :hysterical:

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16 hours ago, Ed Poore said:

This I think, he does tend to approach things either flat out or not at all. You can see in some of the clips where he's going considerably faster than the competitors. On the clips where he's not rolling it over (those I think the back kicks up because of the speed at which he's going) when the back end comes down it's actually pretty well dampened. Certainly to my eye appears to be much more critically damped than Loren Healy's vehicle in the Milk Run video.

I think his mentality is summed up in another clip somewhere at King of the Hammers where someone's too slow in front of him and simply drives over them to get past them :hysterical:

 

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All interesting but the intended topic is mods to twin live axle suspension that would make landrovers better mannered at pace.

Also looking for advice refering to road legal vehicles.

Many of the recent links are at least independent front suspension.
Think it has been summed up a few posts back as best shocks you can afford, potentially hydrualic or gas bump stops, stock or slight lift. Possibly uprated anti roll bars with disconnects to use if needed.

 

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16 minutes ago, WesBrooks said:

Many of the recent links are at least independent front suspension.

True but there are a lot of KOH / Ultra4 vehicles still running solid axles up front so might be worth looking at the builds that go into those categories. The biggest issue they have (and of particular importance for road manners) is that any thing one wheel does impacts the other opposite (part of the reason why they are still good for technical off-road).

It really hit home on the way back home from two independent trips down to the south coast where I used to take Lyra beating. There was a particular corner where there was a pot hole right on the apex. I hit it at a reasonable pace in the Defender the first time and the whole front jumped sideways as the inside wheel clipped the pothole. The following weekend I took the Range Rover down (3.6 TDV8 L322) and did exactly the same thing and it was a complete non-event because only the inside wheel was affected.

I suspect there's also quite a lot you can affect handling wise by adjusting the angle of the radius arms both sideways and vertically.

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Fair enough, I'll take another look at those competitions when I get the chance.

Well aware of the reported peculiarities of the live beam front suspension, thats what made me mention it in the Grenadier topic to begin with, raising the idea that they may even register it in a commercial category in the UK along with the lower speed limit in order to discourage people who are buying it as a status symbol and driving it like a saloon unaware of some of the nastys that can bite.

I'd love to have a crack at a ground up build of an electric ATV. That would definately be independent suspension and light. This project is a far more sensible starting point though! 😄

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Some comp safari/ultra4 cars have more money in their shocks than most of us have in their entire car, so I'd say we shouldn't waste too much time looking at these. Anyway, from how I understand suspension for going fast in the most simplistic way is this:

You need to aim for the softest spring you can possibly fit without the wheel hitting the bump stops too often. And to do that the shocks are the main thing. So too high a damping rate will make it a bone shaker. So dampers have a variable damping rate. To achieve this, there are 2 options:

A bypass damper, which makes the damper rate higher the further it moves up the stroke. These are being used for baja and ultra 4, and in recent years also getting used in comp safari.

The other option is  different damper rates for different speeds. So dampers that have adjusters for high speed and low speed.  These are used in WRC and Dakar.

I am not sure why the different approaches are used in different disciplines. I think a big problem with the setup on ultra 4 etc, is 3 dampers per wheel: so there is a coilover, a bypass and the hydraulic bumpstop. So you have 12 dampers on the car. Where as WRC have everything, including the bump stop built in a single damper, so you only have 4 dampers on the car. Dakar cars have usually 2 dampers per corner. 

The tricky bit is setting them up. the dampers can be rebuild and revalved to make the car handle the way you like. To do this you need to go testing and try several different valvings and springs untill it behaves the way you want. Ideally, you need to get a couple of sets of dampers, so you can test while your shock technician revalves another set, than swap over. When I mention a shock technician, we probably start to think it gets a bit involved. So once you have spend a load of money on the actual shocks, you are going to spend even more money on getting them dialled in properly. Here is were we just cannot keep up with big spenders basically.

Interestingly, In a tuning guide for fox shocks, they stated that they make many more shocks than they make valving sets, so the majority just fits them out of the box and call it done, never really get the full benefit.

Anyway, back to the level were most of us operate, I have never got too far into dampers myself, but Fox does the truck & SUV range, which allows their dampers to be used as a direct fit to your car. There is this one, called the IFP which has no external reservoir:

https://www.prolinx.biz/Catalogue/Shock-Absorbers/Truck-SUV/Land-Rover-Shocks/Fox-20-Land-Rover-Defender-Rear-PSeries-IFP-2-Lift-FOXLANDROVERDEFENDERREARPS2

Or this one with external reservoir and adjuster:

https://www.prolinx.biz/Catalogue/Shock-Absorbers/Truck-SUV/Land-Rover-Shocks/Fox-20-Land-Rover-DefenderRange-Rover-Front-PSeries-RRes-Std-Hgt-wCD-Adjuster-FOXLANDROVERDEFENDERFRNTPSSTDA

I had an adjustable set at the front, and the IFPs at the back for croatia. (Prolinx only had 2 external reservoir versions in stock at the time) And they were a different league from the old man emus I had previously. So that is my recommendation. even just fitting the IFPs will be a big improvement over any mass production damper. And at that price, i'd say it is the best bang for buck you are ever going to get for your suspension.

I don't think a bypass damper has much to offer on a defender, as it is not a good fit at the front, but the high speed/low speed adjustment approach is certainly a good thing to have.

There are problems though,as the the pin fixings have very stiff rubbers. I didn't dare to do them up fully, which resulted in 1 damper loosing its rubbers somewhere on the M40. So Then I did do them up as tight as possible. This resulted in the shafts bending under full articulation. So although I recommend them, I would replace the bottom pin fixings for rodends at the bottom.

When we have are soft springs, cornering gets interesting, so an anti roll bar can be used, but this makes setting up harder again as the roll bar also influences wheel movement at speed. Also for cornering, castor is good for steering feel and it means your wheel will roll on camber in corners, which is good to get it to turn in.

Anyway, from my little knowledge of suspension.

 

Daan

 

 

:

 

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I'm by no means a suspension expert but I'd hazard a guess that the reason Ultra4 has a wildly different setup is they push the vehicle harder.

I'd put Dakar, WRC, Trophy trucks (and to a certain extent comp safari) into roughly the same category, high speed off road driving. Now look at KOH which is the foundation and pinnacle of Ultra4, you take all of the stuff that the above do but throw in rock crawling / winch challenge into the mix. There aren't many trophy truck vehicles I've see that are 4wd or have a winch fitted.

I'll see if I can dig out the video but I watched something recently where it was said that most trophy trucks were 2wd because no one at the time built strong enough front (steering) axles that would handle the pace and power required to be competitive in the Baja 1000. Then along comes Ultra4 where 4wd is essential and pushed the development forward. Vehicles changed from being modified rock crawlers to more like desert racers because that's where the biggest times could be made, yet they still needed the rock crawling ability. This then pushed manufacturers like Currie and Spidertrax to build stronger axles suitable for KOH. People like Shannon then started experimenting with things like IFS (if I remember correctly he was the first to win KOH in an IFS vehicle, although not the first to experiment) which pushed the damper developers to up their game for rock crawling setups.

Now in a twist you see some trophy truck builders taking knowledge from Ultra4 to make 4WD trophy trucks which are extremely competitive.

I've seen various interviews with the big names in off-road racing such as Currie, ARB, Fox, WARN, Toyo etc., who have all said that the one event they must be present in is KOH because they get more testing and development done in those few weeks than most of the rest of the year.

Having said that from the original race where they were just weekend vehicles to the current crop which are hundreds of thousands of dollars in parts alone they are more expensive! Mind you the same can be said of some amateur racers. A friend of ours who used to do historic rallying a lot (and was good) had more money in his headlights than his friend had in his entire vehicle. Now considering his friend had a cosworth built race engine, a Mk2 escort shell, custom power steering rack (we made) then the lights were damn expensive. This was just a hobby, they had proper jobs.

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At the risk of being called a luddite, what's wrong with good old fashioned air suspension, coupled with ground radar and lidar scanning coordinated by a machine learning AI to anticipate the territory and speed requirements, so the wheel is actively assisted to be in the best position at the right time?

Or am I oversimplifying things?

 

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