Astro_Al Posted January 28, 2008 Share Posted January 28, 2008 Ok, no in-box thinking permitted. Lets get it over with: Yes yes, its for my vapour build. Get over it. Its slow, but it won't be vapour forever. Right. I'm trying to have a bit of fun with it and try something a bit different. I wanted to keep a relatively short wheelbase - around 90". This will be a far cry from your regular land rover stuff. I am seriously considering independent suspension. Bear with me. There are many advantages of independent suspension, along with a few for live beam axles: cost for production cars is less, axle 'lifts itself' out of the way when one side goes over a bump, and 'possibly' more sideslope stability. Apart from those (and cost in my case is not a factor, cos its all got to be made anyway), indy is usually superior. Now, before we get too far in - are there any advantages to live beam that I've missed? Indy seems to solve a lot of issues: * reduces the unsprung weight as the diff can be fixed in the chassis. * means I can either run no rear prop or a very short one as needed between the transfer box and diff - so I can shift the engine/boxes backwards for better weight distribution, and put the front diff in front of the engine (propshaft to be cleared by custom sump). * since there is no need to allow propshaft bump clearance, I can run the engine/boxes lower in the chassis to make it more stable. I'm looking to run Mog portals on the indy - for a bit of a different flavour. I haven't worked out the angles yet, but it could be pretty good clearance even with full bump. The only real issue I'm having is the possible need to have forced articulation (selectable?) in case the 'self lifting' properties of a live beam are needed. Running against that is the added weight which I'd like to avoid. If it could rival the live beam plus add the advantages of indy, that'd be the ideal goal. So come on, this is a bunfight thread - lets hear anything and everything! Cheers, Al. Experimenting. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 28, 2008 Share Posted January 28, 2008 2-leaf fronts, 3-leaf rears... OK, I'll behave, despite the tempting references to your vapour build. I have some porn here with a weird indy j**p thing in it that looks like it ticks a few boxes, if you're about on the weekend I'll dig it out. Unfortunately I think you're falling between the world of racing (where Indy is king) and the more sedate world of off-roading where live axles are still a far more practical answer to many of the questions. My concern for your design is building indy strong enough to support a portal end without having a brace further down the portal end that compromises the clearance gain and ends up being almost as heavy and much more complex than just running a live axle. A Mog axle tube is a very rigid thing to try to replace with a few links. Perhaps you need to find a ratty Pinzgauer to cannibalise, easier to start with something and alter it than try to herd vapour around the workshop. Quote Link to comment Share on other sites More sharing options...
T1G UP Posted January 28, 2008 Share Posted January 28, 2008 Are you nthinking using production parts? ala sierra 4x4 gear etc? these are subframe assemblies that could quite easily be mounted to a ladder type chassis? cheapo and the 2.9 v6 a worthy engine aswell! Rear subframe assembly Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 28, 2008 Author Share Posted January 28, 2008 Chassis is custom, so anything can be mounted anywhere. Especially if it only ever exists on paper! - Hey, I'm allowed to, you're not. Components are: NV4500, Atlas transfer box (see 2008 Vape-Off thread at the top of the International section), LSx engine (the new LS3 is starting to appeal), Mog 406 portals. Not really thinking of using parts from something else - its getting more and more the case that starting from scratch is just easier and less restrictive, but ideas are good. Fridge - I saw those pics. If I hadn't, I'd be less inclined to try it! The idea of a completely flat belly is grooovy. B) I take your point about weight. Though Mog axles are WAY too heavy for smallish buggies. That's what I'm after - what ARE the advantages of live axles? Al. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 28, 2008 Share Posted January 28, 2008 That's what I'm after - what ARE the advantages of live axles? Off the top of my enfeebled brains: - You only have two CV joints not eight, and they don't have to be protected from the elements as much as they're usually inside an axle casing - The axle is self-supporting, it doesn't need anything to keep it straight - The half shafts are inside a nice oily axle casing, can float, and don't need to slide in and out of a joint as the suspension cycles. - The mounting is less complicated, and you have more area to attach mounts to. - Just think of all the articulated joints on an indy setup, if you use heims and run in mud you're going to be forever replacing the things no matter how good they are. - The track rod is a straight bar along the line of the axle Quote Link to comment Share on other sites More sharing options...
jules Posted January 28, 2008 Share Posted January 28, 2008 I have a book on suspension set ups. Building from scratch type thing and all about COG geometry etc. etc.. More for Rallying but your welcome to borrow it. Quote Link to comment Share on other sites More sharing options...
Night Train Posted January 28, 2008 Share Posted January 28, 2008 Buy a copy of Classic and Vintage Commercial vehicle magazine and look in the ads for a Scammell Explorer and then then nick the axles and suspension from it. Drill a few lightening holes in strategic places and you should be able to get your unsprung weight down to about 3 1/3 tons. You will have the added advantage of being able to fit some really big rubber! Quote Link to comment Share on other sites More sharing options...
clbarclay Posted January 28, 2008 Share Posted January 28, 2008 Have you seen the underside of a pinz? They have a simple back bone type chassis containing the diffs and propshafts with simple swing arms fixed to it. One advantage of the suspension on 6x6s like the one above is the rear axles are linked so as one wheel rises, the one next to it can drop whilst still applying the same load to both wheels For articulation with indipendant suspension one possibility is to do like some RC monster trucks have which is like a reverse anti roll bar. A link coming up from each side to rocker arms and a spring between the rocker arms. More pictures of the same suspension in this link http://www.rcuniverse.com/magazine/article...?article_id=457 Quote Link to comment Share on other sites More sharing options...
Daan Posted January 28, 2008 Share Posted January 28, 2008 I reckon a de dion axle with portal boxes is the way forward; low unsprung weight, much clearance and with the axle acting as a beam (one wheel moves in while the other moves out) you can still have a lot of travel. You also dont have clearance issues with things like engines, because the diff doesn't move up. Daan Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted January 28, 2008 Share Posted January 28, 2008 Hmmmm, What about REALLY long air suspension units but with 'additional' shocks (either air or hydraluic) that can be raised lowered manually or via a gyroscope to assist suspension up or down, on a beam axle this could be one side to move across a side slope jacked hard up to help avaiod rolling, or raised both sides to push axle down etc, but could equally be popped on Indy too I'll leave now before the laughing starts Nige Quote Link to comment Share on other sites More sharing options...
portal pete Posted January 28, 2008 Share Posted January 28, 2008 I'm looking to run Mog portals on the indy - for a bit of a different flavour. I haven't worked out the angles yet, but it could be pretty good clearance even with full bump. A bit like this Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 28, 2008 Author Share Posted January 28, 2008 Oh for the love of God... Where did THAT come from...? Yes Pete, exactly like that! Honestly, you try to come up with something different and THAT happens. Right, thanks for the inputs guys. I'm amazed at the lack of P extraction! Very refreshing. Lets wait until Tuesday... Side-slopes have been nagging away in my head, I'm liking the horizontal spring idea a lot on that front. I'd MUCH rather run something passive than active. Pinz chassis is interesting, there was something similar on Pirate a few weeks ago. Backbone chassis with some seriously nice fab work in it. The more I think about this, the better it gets. Jules - thanks for the kind offer. Being stuck in a strange land for most of the time means I have too many books already... I thought I'd throw this out there to the Mob to get some off-road specific inputs. One day someone will write a book on off-road suspension to rival Milliken (Race Car Vehicle Dynamics) or Gillespie (Fundamentals of Vehicle Dynamics), but sadly not yet... Good places to start though, if you can't do anything else in the evenings! John - some good points there: - Its just for fun, sure there are more joints, but I don't mind - it won't cover any many miles... - Same goes for wear on shafts, there are plenty of offroaders eating sand all day long with indy, so its cool. - True, it is more complex. And therefore probably weaker, but thats why I studied Brain Surgery. - Track bars are do-able, there's plenty out there to steal tech from... Hi Daan - yeah the diff will be fixed in place somehow. I'm wondering how much movement I need to allow for between transfer box and rear diff. Bolt them together hard? Short slip joint? UJs? Cush drive (not). Hmmm, I suppose it partly depends upon chassis flex and mounting flex. I will think on deDion's system, unless he was French. I really want it to be a good all-rounder. I wondered about some kind of gyroscopic / accelerometer based input to the outside shock as it cornered, for example, or just a simple hydro or air input to each shock, possibly with 'horizontal' sensors to provide inputs, so Mr From Hell - we think alike! Its not impossible to envisage some type of body-roll input into the outer side top shock mount giving stiffness proportional to roll force... This could fit nicely with the coupled shock mount idea from clbarclay. I must muse further. I suppose it could, if done right, also help on sideslopes, and not be overly heavy. Pete - since you've stolen my thunder , would you care to expand at all? Isn't it nice to see references quoted in a post? Al. Raising the standard, by vapour pressure alone. Keep it coming! Quote Link to comment Share on other sites More sharing options...
sheeppimp Posted January 28, 2008 Share Posted January 28, 2008 I really want it to be a good all-rounder. I wondered about some kind of gyroscopic / accelerometer based input to the outside shock as it cornered, for example, or just a simple hydro or air input to each shock, possibly with 'horizontal' sensors to provide inputs, so Mr From Hell - we think alike! Its not impossible to envisage some type of body-roll input into the outer side top shock mount giving stiffness proportional to roll force... This could fit nicely with the coupled shock mount idea from clbarclay. I must muse further. I suppose it could, if done right, also help on sideslopes, and not be overly heavy is this not similar to citroen's hydropneumatic system? could just find an old bx and rob it's suspension Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 28, 2008 Author Share Posted January 28, 2008 Too French. I'm about to leave - does it show...? Quote Link to comment Share on other sites More sharing options...
sheeppimp Posted January 28, 2008 Share Posted January 28, 2008 Too French.I'm about to leave - does it show...? maybe not quite soon enough. seems like you may have taken on a little Gallic influence... Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 28, 2008 Share Posted January 28, 2008 Or rob the EAS off a P38 / Disco II which does a very similar thing. Quote Link to comment Share on other sites More sharing options...
Milemarker Type S Posted January 29, 2008 Share Posted January 29, 2008 Surely on a vapour build you can incorporate thought controlled independant suspension... You merely look at the ground you wish to drive over and the vehicles suspension automatically allows you to drive to your envisaged destination... Its ok I have already applied my outer weather resistant garment and alighted from the premises... Shrek Quote Link to comment Share on other sites More sharing options...
Night Train Posted January 29, 2008 Share Posted January 29, 2008 Forget diffs, springs and dampers. What you need is this! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 29, 2008 Share Posted January 29, 2008 This is only a couple of years old although I've yet to see another, apart from the green one of course Curiously they didn't bother portalling the frogs, I guess with no left-to-right underhangs it's just not required? I suppose with indy the diff is already higher than the bottom of a "normal" axle, with a bit of design it could be higher up than even a portal as there's no beam to worry about. Quote Link to comment Share on other sites More sharing options...
Night Train Posted January 29, 2008 Share Posted January 29, 2008 Is that thing driven by chains or gears, Fridge? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 29, 2008 Share Posted January 29, 2008 Is that thing driven by chains or gears, Fridge? Yes. They're quite secretive chaps so don't volunteer information, they get quite grumpy if you wave a camera near it when they've got the bonnet up. Not that we'd do such a thing Quote Link to comment Share on other sites More sharing options...
Daan Posted January 29, 2008 Share Posted January 29, 2008 Hmmmm,a gyroscope That is just to much vapour, nigel. Quote Link to comment Share on other sites More sharing options...
muddy Posted January 29, 2008 Share Posted January 29, 2008 Hydrostatic drive? I like the suspension system of the frogs and some other buggies (CORR pro trucks? droool ) where the coilover setup is mounted high up the 'sway arm'?? giving masses of travel for a comparitivly short spring/damper, i remember reading somewhere about one with 36" of travel wich in my book is a reasonable amount personaly i'd stick with beams and try to fab some seriously groovy mounts in order to get 'superflex' . Will. Quote Link to comment Share on other sites More sharing options...
portal pete Posted January 29, 2008 Share Posted January 29, 2008 Oh for the love of God... Where did THAT come from...? Yes Pete, exactly like that! Honestly, you try to come up with something different and THAT happens. sorry for stealing your thunder The trucks my old mans and has bin in the build process for about 4 years now. The front end is a cut down l/r axle with a 3.54 diff and arb. Custom shafts with outer cv spline wired into mog imput gear. As soon as my trucks completed in a couple of weeks i will be finishing this one for hopefully the end of the year. Quote Link to comment Share on other sites More sharing options...
SteveRK Posted January 29, 2008 Share Posted January 29, 2008 I think most would agree that in principle independant suspension is a more superior design in terms of allowing each wheel to cope independantly with its own requirements for suspension travel - its just it doesnt work reliably in off road in extreme conditions. I would have thought that fundamentally the problem with any independant set up is how well it withstands rocks and snags. With a live axle tube there is virtually no snagging risk and in the event of grounding out on rocks providing the casing is strong enough to take the weight/impact there shouldnt be a problem. Once you start getting into link arms or wishbones below the drive shafts then i would be wary of rock climbing. Quote Link to comment Share on other sites More sharing options...
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