coil conversion geometry

[ipace]

Hi all,

First of all, please excuse me if this is a stupid question but i have tried searching and all threads referring to a coil conversion all end up with the same conclusion which is either a designa chassis or buy a 90.

I currently have a swb series III.

Lets say i want to go ahead and do it since it does not effect my road tax or anything of the sort.... i already have defender axles and coils in hand so that should not be an issue.

Am i correct in saying that, if you measure an already converted chassis from another swb series and use those exact same measurements to weld the new brackets on the new chassis, everything should line up perfectly on the new conversion..... or am i totally wrong and talking bull...?

I would apriciate your input on this as it has me quite confused.

Thanks,

Ian

[ToyRoverlander]

If it's another coil converted SWB you're taking your measurements from I don't see any reason why it shouldn't work for you.

[FridgeFreezer]

If it's another coil converted SWB of the same model, and it's straight, and yours is straight/square... given LR's tolerances I would measure three times or more before cutting.

...Actually, I wouldn't, I would buy a 90 or just fit decent parabolics & good shocks.

[ToyRoverlander]

Or properly 4link/3link it and have an allround better suspension

[Gremlin]

How do you know the coiled chassis you are taking the measurements from is correct?? I have seen too many horrible coiled series chassis around, and they all seem to have something wrong somewhere.

You also cannot cross over measurements from a coiler chassis to a series chassis quickly, the belly and kick up for the axles are of different shape. I am not saying its impossible, and it can be done correctly, but its a hell of a lot of work!

I do suggest that you sell your series and get a 90/110, or put some good springs on, or as a last resort try to get a coiled chassis from the UK if they still make them.

IMO if you are going to offroad the hell out of the landy,and you are determined of going trough the hassle of changing axles then get a set of nissan or toyota ones and link it, transferring rover items is a sort of pointless exercise and probably a waste of time.

G

[samc88]

If you want a coiler and like the look of a series why dont you get a 90 and stick a series front end on it to make it look like one? Would probably be a much simpler task and it means a series still has its original design chassis under it

[tacr2man]

Its a hell of a lot of work for not a lot of improvement over a set of parabolics , as suggested previous its a better result to just sell and buy a 90 JMHO

[Team Idris]

I'd go direct to coil-overs

And I'd use D2 radious arm as well, rather than defender ones. (or 4 link for a proper job).

Would you need to measure another truck? The aim is the get the coiler axel tube in the same position as the series. That's the datum to keep. Then the props are happy.

[missingsid]

Designa chassis has taller chassis rails (1.5"?) than a Series chassis (according to therm) in order to add nedded strenght and vertical seperation for the suspension points.

Marc.

[henk]

Take a RRC chassis and shorten it to 88" and put in a 200tdi, that's my current rebuild project

[MattMatt]

Designa Chassis. There are very good - I have one on my series running early RR axles. I've had different gearboxes/ engine combinations from stock series to 200tdi and now V8, from standard series box to LT77. Every time the bolts holes have been there to suit, never had to drill or modify apart from letting in a piece in the cross member to allow the front prop shaft through with the LT77. It saves you loads of time and effort and will pay for itself - I've never regretted it!

[Jamie_grieve]

I have an 88" with a coil chassis if you need any measurements or pictures. It has a 200tdi and an LT77/LT230 with a standard length rear prop. I really have to be honest, I wouldn't bother, what are you going to achieve with the coils you're not getting with the leafs?

Getting a 90 makes the most sense to be honest.

A 90's a bit more stable at speed but I think the extra length helps. The 90 has a slightly better heater, almost as effective as a mouse farting on the window, maybe the 5 gears helps it along too. I'd say keep the series and move the damper mounts if you just want a bit more travel.

Check out my stage one thread if you need some convincing what you can do with leaves. The most flex you can get out of standard radius arms is 11" at the chassis, you can do more than that with either leafs or links. Look at Bill's series for some ideas too, I think you might want to link it, the standard Landy stuff isn't worth going to the effort of copying and it's a shame to cut up a good series.

[bill van snorkle]

And I'd use D2 radious arm as well, rather than defender ones. (or 4 link for a proper job).

Is it possible to design a 4 link with a reasonable degree of anti dive geometry, that also gives good articulation, in addition to giving the 'leading arm' effect of countering front end 'jacking' on steep climbs ?

[ToyRoverlander]

Is it possible to design a 4 link with a reasonable degree of anti dive geometry, that also gives good articulation, in addition to giving the 'leading arm' effect of countering front end 'jacking' on steep climbs ?

I assume you're talking about front suspension, as you mention anti-dive. I wouldn't even bother with a 4link up front. The nicest 4link would be a double triangulated one. That would be practically impossible with an engine in the way. So that would leave a 3link. I'm sure it can be designed to give what you ask for. The jacking on steep climbs can be reduced by keeping the bottom links as flat as possible. The steeped the angle of the bottom link the more it wants to lift to chassis up when the wheel is forced into an obstacle. Same as the rear links do on rovers with ridiculous amounts of droop travel. It it has traction it just pushes the back end up.

I don't think you can eliminate it completely, but keeping the links flat helps a ltot. A suckdown winch is another option.

[bill van snorkle]

I assume you're talking about front suspension, as you mention anti-dive. I wouldn't even bother with a 4link up front. The nicest 4link would be a double triangulated one. That would be practically impossible with an engine in the way. So that would leave a 3link. I'm sure it can be designed to give what you ask for. The jacking on steep climbs can be reduced by keeping the bottom links as flat as possible. The steeped the angle of the bottom link the more it wants to lift to chassis up when the wheel is forced into an obstacle. Same as the rear links do on rovers with ridiculous amounts of droop travel. It it has traction it just pushes the back end up.

I don't think you can eliminate it completely, but keeping the links flat helps a ltot. A suckdown winch is another option.

IMO it is the front suspension of leaf sprung LandRovers that lets the side down,at least for mountain goat type 4wding.3 link front end modifications are quite easy to do. No bush binding or rapid wear. Dial in the amount of antidive you want and it doesn't affect articulation.But One Links are even easier, easy to package, give similar Antidive and leading arm effect, positively control axle wrap,and only require one bushing (at chassis). Unlike 3 links, a centred One Link can't be designed to counter propshaft torque roll, but Unimog front axle One Links (torque tubes) are off set to the left, so I wonder if, aside from diff/engine clearance reasons, it was also done to counter torque roll?

[ToyRoverlander]

I remember you mentioning that before, about shackle location on Rovers compared to other 4x4's regarding climbing ability. I have to say mine climbs very good the way it is with rear shackles. If it's better with front shackles? Perhaps, dont know. The theory behind it makes sense but I can't be bothered to change it to try and find out. If I change anything I would go straight to a 3link.

I've never given 1links much thought. I think with a 3link one can try and let it behave the way you want. I would also be more comfortable with more mounting points on the chassis.

I'll have to read up on what can be done to reduce or counteract driveshaft torque. I've never noticed it on mine, but perhaps I don't do terrain thats extreme enough.. dunno.. How much of an issue is it really?

Not familiar with mog suspension. I haven't got a clue how the torque tube connects to the transferbox, would love to see though..

[Jamie_grieve]

Given the OP had one post and hasn't been back we should be right enough to drift off topic?

More fuel for discussion:

I can see how the torque reaction with the rear shackle will tend to elevate the front on a steep climb but at the other extreme, climbing a rock step will be performed better with the shackle at the back than the front. Leading links don't do anything to improve getting up in the first place other than generally being longer and by virtue of that being part of a longer travel and generally speaking softer suspension.
As an example, you can drive a front wheel of a leaf sprung land rover up a face higher than the middle of the tyre. You will probably be unable to reverse up the same obstacle even with the more supple rear suspension and less weight and better traction on the front wheels trying to push it up.
The point the axle is rotating about is higher than the middle of the wheel so the resultant is trying to lift the vehicle up.
This is also why the back wheels will follow the fronts easier over obstacles than the fronts do.
A bit like how it's easier to pull a wheel barrow over rough ground or sand than to push it.

If you are winching through deep mud or peat bog where the front wheels have broken through the ground the leading link will cause the front wheels to dig deeper, the same situation with a trailing arm on the front like a leaf sprung Land Rover will tend to pull the front up.

Longer links will tend to reduce the jacking effect compared to really short links.

I think that any supple suspension is going to perform better than a more rigid one on a hill climb and the steeper you go the further the front springs will extend regardless of wheel reaction torque but simply due to weight transfer. By trying to drive in front wheel drive only you realise how little the front wheels are doing on a climb and the feeble amount of torque the front wheels will take I don't see reacting too much to unloading the tyres compared to the difference weight transfer is going to make.

I also have an old Austin Gipsy (I will admit is a dreadful thing) which is significant to the current conversation on shackle position as it only has four trailing arms to hold the wheels on. I cant think of another vehicle with this arrangement which is partly why I got it as I was genuinely interested how it could possibly work. It climbs way better than my coil sprung Jeep Wrangler with radius arms at the front and got up a rough steep hill my BJ 40 couldn't. To be fair to the Toyota the Gipsy has a P76 engine in it and the BJ had a 3B diesel so that wasn't fair but climbing is certainly one of it's very few attributes it seems to have.
Being able to have front or rear wheel drive is an interesting feature and by separating the selector forks you can have front low as well as an added quirk. The massive castor changes are amazing and the camber is always the same regardless of wheel position so it's got some interesting handling.

[bill van snorkle]

Have to disagree on a couple of points Jaime.

First off, try crawling over a wet log on levelish ground. Front wheels go over easily, but generally you have to 'bump' it to get the back wheels over.

Secondly, try climbing any steepish off road gradient in rear wheel drive only, then engage 4wd once vehicle comes to a halt. A significant difference in traction wouldn't you say? Traction equals torque reaction, and torque reaction produces the leading arm effect to counter lift with either front radius arms or leaf spring front ends with shackles up front, and jacking when shackles are behind.

As an aside, whilst delivering recovery gear to a badly stuck and overheated WildFing the other day in my Stage One twin cab, I was astonished at its ineptitude in climbing out of a muddy but shallow, by my standards gulley, so I tried it in reverse gear. The relative difference was like driving on a sealed road! The tyres (highway type) felt really hooked up to the track surface. I have noticed this phenomena on other leaf sprung LandRovers, both long and swb before.

Thirdly, every time I've attempted to climb a rock step with a single front wheel with unlocked diffs, I get massive axle tramp, yet LandCruisers just walk over that stuff, and once again, Landies do it easily in reverse gear. Be careful of those CV joints though.

The only conditions where IMO, shackles behind the front axle offer any advantages is hitting obstacles at speed, but even then I have observed leaf sprung landrovers in mixed make short course stadium type offroad racing, where it appears that the 'plunging' front propshaft slip joint tends to bind/lockup and negate a lot of this theoretical advantage and causes the front end to contort much more than the Toys, Jeeps etc, where the slip joints on these vehicles 'telescope' not plunge.

I have recently become friendly with an enthusiastic group of 40 series LandCruiser owners. Some of them have done shackle reversal modifications to their trucks, others keep them up front. The difference in offroad ability is very noticeable when they try to drive my more extreme gulley tracks.

The reverse shackle trucks produce much the same axle hop/wrap theatrics as leaf sprung Landies, whilst the 'standard' 40's do the job much more smoothly and competently. A bit like a coil sprung Rangie in fact.Except they don't destroy their steering trackrod everytime the front axle drags over a rock or stump.

Anyway, as you state, it is fuel for discussion.

Oh, I once owned an all leaf sprung Austin Gipsey. Great truck with hypoid diffs and a proper commercial gearbox! With the possible exception of the engine, they were mechanically superior to and stronger than contemporary leaf sprung Landies. No front axle wrap either due to factory fitted tramp rods. Chassis seemed to be designed by a real engineer and was less susceptible to rust out. The least said about the body the better though. Unfortunately it decided all by itself one day to commit suicide against the biggest ugliest tree on my property.

Bill.

[bill van snorkle]

I think with the independent suspended Austin Gipsey, due to the differential being bolted to the chassis, that the forward projecting arms of the front suspension would behave on climbs in an almost neutral manner as they are not subject to differential torque in the same way that leaf springs or radius arms attached to live axles are.

[Jamie_grieve]

Have to disagree on a couple of points Jaime.First off, try crawling over a wet log on levelish ground. Front wheels go over easily, but generally you have to 'bump' it to get the back wheels over.

Totally agree with that, on level ground on a wet log, the rear tyres pushing will generate more tractive effort than the front tyres pulling and a wet log will get you every time.

Taking the same scenario with say a square stone block slightly higher than the centre of the wheel and I'd contend that a trailing arm front would climb before a leading arm would. Like pushing vs pulling a wheel barrow over a brick.

Secondly, try climbing any steepish off road gradient in rear wheel drive only, then engage 4wd once vehicle comes to a halt. A significant difference in traction wouldn't you say?

I'd say it depends what you were driving, a tractor wheelieing backwards down a steep hill (having overcome his centre of gravity) without having to engage the front axle at all compared to say a tram on steel rails if he could switch on his front bogie on a slight incline. I'd say for most off roaders where a change in suspension geometry is required to enhance off road performance it would lie somewhere more towards the tractor end of the spectrum than the tram.

If we were to take the series Landy in the first post as the victim in low 1st with the front hubs unlocked on a high traction surface like the rocks you see in America you'd get to the point of little difference easily, in a wet grassy field you might not get up a modest incline in 2wd.

Being able to reverse really makes the difference in a 4wd.

I'd say a 2wd with a locker in the back would out climb a 4wd without a locker both having effectively 2wd.

My point is that by the time you've got steep enough to make a difference the front wheels aren't making much difference to the success of the climb.

my Stage One twin cab, I was astonished at its ineptitude in climbing out of a muddy but shallow, by my standards gulley,

I can relate to that, I didn't realise how bad the Landy leaf front suspension really was until I got the stage one and it's centre difflock. On even very moderate climbs on a gravel haul road with the centre diff lock open you would get a sudden and violent axle hop going on like nothing I'd ever seen before. The only thing you could do was start again in difflock although to play with it you couldn't get it to do it in low 1st, there had to be some element of flexibility going on. Another problem for me being young and stupid was losing drive on roundabouts where the front wheel would lift really easily but the back was planted.

I ditched the heavy leafs and changed the dampers and mounts and the problem disappeared. The standard leaf spring setup is just too short to be effective.

I can't really defend Land Rover front leafs from any kind of credible technical stand point other than to say just moving the dampers will make it loads better, kinda polishing a turd really.

so I tried it in reverse gear. The relative difference was like driving on a sealed road! The tyres (highway type) felt really hooked up to the track surface. I have noticed this phenomena on other leaf sprung LandRovers, both long and swb before.

I would have to agree with this and would say it would hold true for most any front engined vehicles, the greater weight transfer to the front wheels when reversing is keeping them on the ground that due to their stiff nature they cannot do when climbing forwards. The more supple rear springs following the ground better will also assist slightly in the climb.

A front wheel drive car will reverse up a snow covered hill before it will drive up forwards for the same reasons of weight transfer.

Thirdly, every time I've attempted to climb a rock step with a single front wheel with unlocked diffs, I get massive axle tramp, yet LandCruisers just walk over that stuff, and once again, Landies do it easily in reverse gear.

Oh no, walking into dangerous waters here, Rover vs Cruiser in a debate on a Rover forum!!

it's not really fair to compare them, I've had two BJ40's one for a few years in NZ then I rebullt one in Nundle, NSW and toured the Simpson, east coast trails went four wheeling anywhere I could find a play buddy and spent the best month of my life on Fraser island with it. I got all nostalgic and then got an FJ 40 in Kenya and I love them to bits and got a little bit familiar with them. The front chassis on them is flexible, well, the whole chassis is as you know but especially the front, that combined with longer springs and the better weight distribution of a heavier more powerful engine I think is where the better climbing comes from. I was with an old Jeep I tagged along with after meeting on Fraser island and it had the shackles at the front and it used to bounce on the front like a Landy but they were short springs with lots of free camber too. The Cruiser climbed better than it too.

where it appears that the 'plunging' front propshaft slip joint tends to bind/lockup and negate a lot of this theoretical advantage and causes the front end to contort much more than the Toys, Jeeps etc, where the slip joints on this vehicles 'telescope' not plunge.

That's an interesting one. I have a friend restoring a Lotus Elan just now and there is a trend to replace the old unreliable rubber doughnut driving members with UJ's and sliding shafts. The purists with handling in mind maintain that if the shaft is transmitting significant torque it will bind and prevent the suspension from working. I've noticed that all quality modern drive shafts have some kind of blue teflon coating on them to minimise this.

The Land rover transmitting torque during bump would bind and the Cruiser during rebound would tend to bind but be unlikely due to wheel slip.

In that regard I'd have to concede the Landy setup to be inferior.

.Except they don't destroy their steering trackrod everytime the front axle drags over a rock or stump.

Anyway, as you state, it is fuel for discussion.Bill.

On that point, we most certainly agree!!!

The old Gipsy would seem to have the best of both worlds then with the independent setup as the reaction torque is not in the suspension links, there is no torque to counter from the propshafts and the prop doesn't bind. Shame it feels like I'm going to die every time I drive it. I really need to finish it, it's marooned in a hole in a hill in NZ just now.

[Jamie_grieve]

I think with the independent suspended Austin Gipsey, due to the differential being bolted to the chassis, that the forward projecting arms of the front suspension would behave on climbs in an almost neutral manner as they are not subject to differential torque in the same way that leaf springs or radius arms attached to live axles are.

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Yup, I was a bit slow in writing my reply and cross posted, exactly that. Terrible things, worse even than Champs.

Still no reason not to have one to see if I couldn't do something with it.

pics here:

http://s208.photobucket.com/user/jamie_grieve/library/austin%20gipsy?sort=3&start=all&page=1

[bill van snorkle]

Totally agree with that, on level ground on a wet log, the rear tyres pushing will generate more tractive effort than the front tyres pulling and a wet log will get you every time.

Taking the same scenario with say a square stone block slightly higher than the centre of the wheel and I'd contend that a trailing arm front would climb before a leading arm would. Like pushing vs pulling a wheel barrow over a brick.

In the US rock crawling scene, a well known truck builder by name of Walker Evans built a rig with trailing arm 4 link front end, and it proved to be quite uncompetitive due to jacking effect. Whether Jacking, squatting or remaining neutral, I'd assume that the amount of weight that a wheel must lift when surmounting a vertical obstacle such as the stone block from levelish ground would be constant.

I'd say it depends what you were driving, a tractor wheelieing backwards down a steep hill (having overcome his centre of gravity) without having to engage the front axle at all compared to say a tram on steel rails if he could switch on his front bogie on a slight incline. I'd say for most off roaders where a change in suspension geometry is required to enhance off road performance it would lie somewhere more towards the tractor end of the spectrum than the tram.

If we were to take the series Landy in the first post as the victim in low 1st with the front hubs unlocked on a high traction surface like the rocks you see in America you'd get to the point of little difference easily, in a wet grassy field you might not get up a modest incline in 2wd.

Being able to reverse really makes the difference in a 4wd.

I'd say a 2wd with a locker in the back would out climb a 4wd without a locker both having effectively 2wd.

My point is that by the time you've got steep enough to make a difference the front wheels aren't making much difference to the success of the climb.

My Stage One, being a modified wagon, with rear petrol tank, LPG tank, plus tools, recovery gear and accumulated junk has very close to even weight distribution fr/rear, so weight transfer on a given gradient should be more or less equal in forward or reverse gear. The difference in traction in reverse gear must be due to other factors. if not shackle location, then maybe the longer rear springs don't unload as much as the shorter front ones.

I can relate to that, I didn't realise how bad the Landy leaf front suspension really was until I got the stage one and it's centre difflock. On even very moderate climbs on a gravel haul road with the centre diff lock open you would get a sudden and violent axle hop going on like nothing I'd ever seen before. The only thing you could do was start again in difflock although to play with it you couldn't get it to do it in low 1st, there had to be some element of flexibility going on. Another problem for me being young and stupid was losing drive on roundabouts where the front wheel would lift really easily but the back was planted.

I ditched the heavy leafs and changed the dampers and mounts and the problem disappeared. The standard leaf spring setup is just too short to be effective.

I can't really defend Land Rover front leafs from any kind of credible technical stand point other than to say just moving the dampers will make it loads better, kinda polishing a turd really.

I even experience violent front axle hop in my Rangie when cornering fast on roundabouts etc or when giving it some welly from rest with a bit of left hand steering lock such as when accelerating into a traffic stream at a T intersection. I suspect that moving the dampers either for or aft of the axle may improve that situation.

Oh no, walking into dangerous waters here, Rover vs Cruiser in a debate on a Rover forum!!

I think most owners of series vehicles here are mature enough to acknowledge the various weaknesses of the breed.

That's an interesting one. I have a friend restoring a Lotus Elan just now and there is a trend to replace the old unreliable rubber doughnut driving members with UJ's and sliding shafts. The purists with handling in mind maintain that if the shaft is transmitting significant torque it will bind and prevent the suspension from working. I've noticed that all quality modern drive shafts have some kind of blue teflon coating on them to minimise this.

The Land rover transmitting torque during bump would bind and the Cruiser during rebound would tend to bind but be unlikely due to wheel slip.

In that regard I'd have to concede the Landy setup to be inferior.

When Rover originally brought out the Rover 2000 Saloon way back in the day,The reason given for choosing De Dion rear suspension was because of slip joint bind they experienced with other arrangements they experimented with.

On that point, we most certainly agree!!

I must try to design some forward facing high steer arms for a coiler front end someday. Possibly something that picks up the bolts on to both upper and lower swivel pins. Like you, I hate the way LandRover designed the trackrod to be below the bottom of the axle tubes, and will not consider ever using such a system on any of my serious offroaders.

The old Gipsy would seem to have the best of both worlds then with the independent setup as the reaction torque is not in the suspension links, there is no torque to counter from the propshafts and the prop doesn't bind. Shame it feels like I'm going to die every time I drive it. I really need to finish it, it's marooned in a hole in a hill in NZ just now.

Flog it off and get one of the later all leaf Gipseys if you can find one. I used to curse British Motor Corp back in the day when both marques came under common ownership, for not taking the best of both breeds and designing a Gipsey/ LandRover hybrid.

Wonder where the OP of this thread got to?

[Jamie_grieve]

Flog it off and get one of the later all leaf Gipseys if you can find one. I used to curse British Motor Corp back in the day when both marques came under common ownership, for not taking the best of both breeds and designing a Gipsey/ LandRover hybrid.

Lol, I had one of them too, a long wheelbase series IV I put together in NZ. It's getting embarrassing the number of oddball vehicles I had that I thought were cool. This one got a Mazda diesel in it grafted onto the Gipsy gearbox and was surprisingly good. I wish I kept it, I sold it near Tauranga 11 years ago. They had two torque rods above the front of the front leaf springs in a trailing arm fashion.

A gipsy chassis and driveline with a Land rover body and maybe engine would have been a better vehicle for sure. hind sight is an amazing thing to have.

Not a great photo but you get the idea:

[deep]

Gold panning?

[Jamie_grieve]

Gold panning?

Yup, well spotted, most folks wouldn't have recognised that nowadays. Had a collapsible sluice in the back pack and a coil of pipe to get a wee sort of mini dredge going on to clean shallow bedrock and under stones that were too big to move. Most of the gold just came from lots of digging and pushing gravel through the sluice. The ground was pretty well worked out. I sold the bigger bits, not really nuggets though while busking in Nelson and kept the fine stuff to make something with one day.