Parabolic results with standard springs? (Series Leafer Cont

[Tikirocker]

G'day all,

Been reading about Para's for nearly two years now and a few people have had some interesting things to say about standard leaf springs in their defence which led me to ask this question.

Since most of the trouble with standard leaf springs is that they are in such large packs, this seems to cause the problem of axis torsion flexability.... a problem the Paras seem to have licked. I have read of people who have greased up their old springs and broken them back in with large weights in the tub and had greatly improved rides.

Some of these people have removed the check straps and fitted longer shock absorbers...there seems to be the front end springs issue that causes most of the articulation limitations on Series Landy's.

So what would happen if you simply removed or thinned down a standard leaf pack, had them reset and re-tempered, given these might be your old ones in good shape; then removed the check straps and bought longer/better shocks? Alternatively you could have a thinner pack made for you.

Wouldn't you be able to achieve an improved ride with improved articulation approaching that of a Parabolic sprung Series Rover for wayyyyy less money?

Discuss...

[Tikirocker]

Hey Das...

What are your thoughts on this? For some reason I though 68Landy (Ben) did something similar to this and never looked back.

[ISUZUROVER]

Hi, it's me 68landie, aka Isuzurover aka Ben.

Yes, I modified my existing springs to improve off road travel (removed and cut down leaves to reduce the spring rate). Removed the check straps fitted longer rear shocks and modified front bump stops.

The problem with the comfort of semi-slliptic leaf springs is the interleaf friction which means that it slows down the movement of the spring. Coils have no such frictional problems (you will find this out if you take the rear shocks off a range rover and drive it over a speed bump) so they move much more rapidly to react to loads. Parabolics approach coil-like low friction because there are fewer leaves and they only tough at the ends and the middle so this greatly improves things (even though friction is independant of surface area). Smaller numbers of leaves, softer spring packs and grease will help semi elliptics but they will never be as good (in terms of comfort) as parabolics (although properly designed semi elliptics will be better offroad IMHO than currently available rover parabolics).

[red90]

http://www.outerlimits4x4.com/PHP_Modules/phpBB2/viewtopic.php?t=18823

[Tikirocker]

Hey Ben!

Nice to see your still about mate. I have a question for you regarding standard springs. I know that Lovells in Sydney made the springs that my IIA is sitting on right now and I can get some made for me again. Could you tell me what to ask for a SWB Civvy if I were to get them to make me some that would offer the best benefits for wheel travel? By the way, that image of your
Landy tackling that cross axle-worthy ditch should be an advertisement for the potential of standard springs in Land Rover mags.

Cheers...Simon

[ISUZUROVER]

Cheers John for posting the link.

Cheers Simon,

Can you measure your existing springs (no of leaves in each pack and thickness of each leaf - and also if the rears are single or dual rate). It may be possible just to modify them and get them reset.

The std 88" has 220lb/in springs on the front and 160lb/in in the rear, and this is usually a good compromise between travel and load carrying ability (you just need to do some work with the shocks and bump stops) - you can go softer if you are primarily interested in wheel travel though.

In theory, the spring packs that Land Rover used of a large number of leaves should be better than the modern practice of a smaller number of thicker leaves - since the stress differential (between the side of the leaf under tension and compression) is less when the leaf is thinner, and should thereby allow a longer life of the spring before failure. However, 5mm thick leaves is about the thinnest that most spring makers seem to be able to get these days.

[Tikirocker]

Hey Ben,

I just went out with the torch and got this...

Front springs (very rusty and need replacing)

10 leaves

From top to bottom

5mm - 4mm - 4mm - 5mm - 4mm - 4mm - 4mm - 4mm - 4mm - 4mm

Back Springs (Good nick)

8 Leaves

All 8mm thick...

Whats the score mate? Oh, sorry..I didn't know what you mean't by double or single rated. If you let me know I'll do what I can to answer that question also.

Thanks!

[ISUZUROVER]

OMG - if the rears are 8x 8mm thick the spring pack will have a rate of about 500lb/in!!! that is heavier than the heaviest springs fitted to a std 109" !!! I have 6x7.1mm leaves in my 109, but cut down a lot which gives me about 260lb/in. If they are really 8mm (not 7.1 - which LR used) then you could go down to 3 or 4 of those and still have good load carrying ability.

Single rate rear springs have the leaves all the same curve. Double rate have a few leaves at the bottom that are flatter than the rest, for when you carry heavy loads.

On the front if your springs need replacing it would be best to get some made with 5 or 6 5mm leaves in each pack. depends on the weight of your motor and if you have a winch or not.

[Tikirocker]

OMG - if the rears are 8x 8mm thick the spring pack will have a rate of about 500lb/in!!! that is heavier than the heaviest springs fitted to a std 109" !!! I have 6x7.1mm leaves in my 109, but cut down a lot which gives me about 260lb/in. If they are really 8mm (not 7.1 - which LR used) then you could go down to 3 or 4 of those and still have good load carrying ability.

Yeah, no kidding! I think the rear ones which seem to be in quite good nick are the ones the previous owner had made up at Lovells. I don't know what use he had with that kind of heavy duty rear spring but he may have been towing heavy trailers or boats etc. It's a Station wagon 88 by the way with a Holden red 186 donk.

Single rate rear springs have the leaves all the same curve. Double rate have a few leaves at the bottom that are flatter than the rest, for when you carry heavy loads.

Gotcha... they are all single rated from what I can see, both front and back. Do you mean flat like the helper springs that TIC seem to use?

On the front if your springs need replacing it would be best to get some made with 5 or 6 5mm leaves in each pack. depends on the weight of your motor and if you have a winch or not.

So 5 or 6 per side at the front at 5mm per leaf, yeah? Could you explain how this will then help in the wheel travel department and what I might need to do next in regard to the shocks and bump stops? What kind of shocks would you recommend?

[ISUZUROVER]

OK - if the rears truly are 8mm thick, then they are about 530lb/in which is ridiculously stiff. I would reccommend removing all but the first (main leaf), second (leaf with loose eyes) and the 4th leaf. That will leave you with 3 leaves and a rate of about 220lb/in (if my hazy memory serves me correctly and the rear springs are 48" long (when flat)). You will have to get the springs reset and retempered. If they are 7.1mm you will probably need 4 leaves not 3. WIth 8mm leaves you could go to 2 leaves (approx 160lb/in - std swb) but with the station wagon body you may need some extra stiffness - and you can always make them softer later.

Yes I mean flat like the TIC helper spring - also have a look at at any trayback utility, they will have 2 stage springs.

How heavy is the holden engine compared to a 2.25 petrol. If you had a 2.25P in a swb I would think that 5x5mm would give excellent wheel travel, or maybe 6x5mm (what I have on my 109 with 2.25 diesel) if you want it to be a bit stiffer.

The softer springs (lower spring rates) will mean that the springs will flex more easily (at lower loads) offroad and it will also be a bit more comfortable (anything will be more comfortable than what you have now). To make the most of the wheel travel you then need to fully compress one side each of the front and the rear (without shocks) and measure the distance between shock mounting points. You then need to buy shocks with that minimum length. You can get more travel by moving the shock mounts but that should be plenty for you.

[Tikirocker]

OK - if the rears truly are 8mm thick, then they are about 530lb/in which is ridiculously stiff. I would reccommend removing all but the first (main leaf), second (leaf with loose eyes) and the 4th leaf.

When you say loose eye's what does this indicate? Can I just undo the leaf pack from the centre screw and remove those suggested springs and then just take them to Lovells to get reset and re-tempered without having to do anything else?

If they are 7.1mm you will probably need 4 leaves not 3. WIth 8mm leaves you could go to 2 leaves (approx 160lb/in - std swb) but with the station wagon body you may need some extra stiffness - and you can always make them softer later.

Sounds good...

How heavy is the holden engine compared to a 2.25 petrol. If you had a 2.25P in a swb I would think that 5x5mm would give excellent wheel travel, or maybe 6x5mm (what I have on my 109 with 2.25 diesel) if you want it to be a bit stiffer.

I checked my Holden service manual and strangely enough there is no record of the engines weight. I have resorted to asking elsewhere to get this figure... I'll get back to you on that.

To make the most of the wheel travel you then need to fully compress one side each of the front and the rear (without shocks) and measure the distance between shock mounting points. You then need to buy shocks with that minimum length. You can get more travel by moving the shock mounts but that should be plenty for you.

Whats the best way to achieve this compression? Will I need to get some kind of long plank to make a ramp? I like this plan allot actually since buying Para's would totally blow out my rebuild budget. I suppose doing these tests with the springs is going to require the Landy to be fully restored and weighted with the Station wagon hard top ON also?

I understand measuring the minimum shock compression but how do you determine the maximum length you need in the schock; is this relevent or do you only need to know the min distance for the shock mounts? And finally whats the deal with the bump stops after this? Whats the word on spring shackles, should I get different shackles from standard also?

Thanks...

[Nick (in the Falklands!)]

...Two small additional thoughts (btw, interesting stuff on spring rates & capacities Ben)....

I know some people in UK used to grease their springs then wrap them in 'Sylglass' tape (the stuff thats like a self-amalgamating greasy duct tape)....but MOT examiners used to insist on its removal for annual test.

You can create a softer spring rate too by adding a thin tin shim between
the leaves just between the U-bolt pressure area....this has the effect of reducing the surface area contact betwen leaves that creates additional drag & stiffness.

I like the spray-on motorcycle chain-lubes that are really sticky...& apply it when the spring has a coating of clay/dirt on edge of leaves;
this then wicks into the spring leaving a dry semi-permeable coating on the leaf gaps that stops dust getting drawn in....& the silicon or whatever seems to improve things no end.
EP 90 oil is good too in non-dusty conditions; its extreme pressure attributes mean it stays where put for some time (engine oils dry out).

On subject of spring travel....there is only so much flex a spring can take
or acheive on the front of a Landie....they are too short to do more.

That is why the 101" (i.M.H.O.) is one of the best landies off road...its springs on front are same length as rears.

..And this is where the Land Cruiser leafers scored over L-rovers..they have full-length front springs......if I had the time, I would love to experiment fitting in chassis extensions to a LWB & fitting 88" rears to
it to see how it behaved.

[Tikirocker]

. On subject of spring travel....there is only so much flex a spring can take or acheive on the front of a Landie....they are too short to do more.

Hey Nick,

Thanks for your contributions to this discussion. With regards to the spring travel I think Ben has shown that good wheel travel is possible on a standard leafer and with a certain approach you can get great results.

See Bens rig below with standard springs (customized ofcourse)... don't know about you but I'm impressed.

[ISUZUROVER]

Hi Nick - thanks for the input. Yes, I have heard of the tape wrapping - but never seen it - I think for a spring with a lot of flex it would probably not last very long.

Adding a shim between the leaves doesn't really reduce the rate as such, it reduces the interleaf friction, so it seems like it is reducing the rate, but what it really does is reduce the damping effect of the interleaf friction, making the spring react faster.

I have tried oiling my springs with both motorcycle chain oil and spray on grease (even better). They both make a bit of difference but again just affect interleaf friction, they don't make the overall travel any better.

At the moment my truck shown above (thanks for posting the pic simon) has 15" of wheel travel front and rear. The front is limited by the shock and the back is limited mostly by spring rate (but I still want to carry loads). I know people who are running longer front shocks and have even more front travel. While a longer spring would be better it would limit approach angle. I think the length of spring is not a problem in terms of reliability. I have been running these springs for many years now and have not had any problems.

There are guys in the US who have fitted chevy springs to the front of there land rovers (do a few searches on pirate4x4.com) and they seem to be happy with that setup. I am more than happy with my setup though and the travel is nicely balanced front and rear - and when I eventually fit longer front shocks I will have even more travel.

[Tikirocker]

Hey Ben,

So could you address my recent questions two posts above? Just regarding the compression etc?

Thanks mate.

[ISUZUROVER]

When you say loose eye's what does this indicate? Can I just undo the leaf pack from the centre screw and remove those suggested springs and then just take them to Lovells to get reset and re-tempered without having to do anything else?

The Landrover springs are unlike most other springs in that the second spring in each pack has loose wrap around eyes at each end (not just the front like most other 4x4's) which mean that if the main leaf breaks the axle and spring pack will still be attached to the chassis (do your custom springs have this 2nd wrap around eye at each end?). Yes with the rears you should just be able to take the pin out (clamp the pack in a vice before you take the pin out), remove leaves and then take them and get them reset and re tempered. However you need to work out what height you want them set to, as you probably can't trust the spring place to get it right - as they are very much custom springs.

Whats the best way to achieve this compression? Will I need to get some kind of long plank to make a ramp? I like this plan allot actually since buying Para's would totally blow out my rebuild budget. I suppose doing these tests with the springs is going to require the Landy to be fully restored and weighted with the Station wagon hard top ON also?

I have always used ramps (or big mounds of dirt), but there are other ways to do it - some sort of ratchet strap around the axle and chassis to compress one side should work (while you jack the axle up on one side). Otherwise if you can keep the axle in the right place you can disconnect the springs from the axle on one side and jack it up (though you have to attach something the thickness of the spring pack to the bottom of the axle and then the lower plate that contains the shock pin). If your existing shocks are leak free and at least partially working you can wait until you have it finished and driving to worry about changing them.

If you are good at trigonometry you can calculate where the axle will be at full compression and work out the minimum shock length.

I understand measuring the minimum shock compression but how do you determine the maximum length you need in the schock; is this relevent or do you only need to know the min distance for the shock mounts? And finally whats the deal with the bump stops after this? Whats the word on spring shackles, should I get different shackles from standard also?

You measure the minimum shock length you need (centre of eye to centre of eye) on full compression, then go and buy a shock with that minimum length. The maximum length is just proportional to the minimum length and you don't have to worry about it (but there is some slight variation between shocks. unless you move the upper shock mounts and fit really long shocks you don't have to worry about them being too long.

Bump stops... the front of series LR's generally have shocks that are too short, meaning that even after the axle has fully compressed the bump stop there is a lot of shock travel left. Some people shave the bump stop to allow the full shock travel (rather than buying longer shocks), but it is probably not the best thing to do. On military Land Rovers there is a 1.5" spacer between the chassis and the bump stop (because the suspension is 1.5" higher). On the front only of my LR I have removed the bump stop spacers as the std (reconditioned military) shocks I have allow full bump stop compression without the spacer, meaning that I have gained an extra 1.5" of uptravel by doing this.

Remember that the new packs will be a lot thinner than your old spring packs and you may have to buy new u-bolts. It would probably be worth fitting military shackles to the rear, but not the front as it will affect the diff pinion angle.

[ISUZUROVER]

Some more pics (since they are worth 1000 words). These are the original springs I made for the rear of the 109 (in 1997). They have 6x7.1mm leaves, with some leaves cut down so that the interleaf spacing is even, and are dual rate. These springs were not tempered by the spring works after resetting (so they sagged). I also did not get them reset to quite high enough free camber. And the inner clamps I made are far too long (I shortened them later). After the springs sagged I reset them in 1998 when I modified the front springs (and had them tempered this time) - since then I have had no problems with the front or the back.

[ISUZUROVER]

This is how I used to test the wheel travel, using car ramps. Even with the ramps on the drainage ditch (second pic) it was hard to get full travel though. The first pic was 1997, the second 1998 (after fronts had been done too).

[ISUZUROVER]

This was a bit later again at a club even using a travel (RTI) ramp built by Sam (Strangerover) and Chuck his business partner. Ramp was 20deg if memory serves correctly and RTI score was mid 800's (again memory hazy. So who can pick what the vehicle is in the LHS of the top photo??? (there was a prototype 4-gear portal box on a bench next to the vehicle too). And there are a lot of obvious and not so obvious changes to my IIA over the years - compare with the pick Simon posted at the top. Since these pics I have made a few tweaks and fitted wheels with a wider offset, so I bet a few inches more than these pics, but haven't been on an RTI ramp again.

[ISUZUROVER]

Hey Ben,

So could you address my recent questions two posts above? Just regarding the compression etc?

Thanks mate.

I was getting there...

feel free to ask any more questions.

[ISUZUROVER]

To do all the leaf spring design calcs I used tha "Leaf Spring Design Manual" by the Society of Automotive Engineers, which is a very good book and covers parabolic (more correctly called "single leaf") springs as each spring acts individually.

However I have found a spreadsheet on the web where you can calculate spring rates and free cambers (height to reset spring to) yourself easily. It seems to be correct.

http://www.auburn.edu/~kruegdr/leaf_spring.xls

The SIII manual contains the factory spring rates, spring lengths (needed as input) and the vehicle weights (so you can work out the approximate load on each wheel).

As a rough guide, for my SIIA 109 with 220lb/in front springs and 260lb/in rear springs, the free camber that worked were:

8" Front LHS
9" Front RHS
10" Rear LHS
12" Rear RHS

With these the truck sat flat and has since it was built. The springs have not sagged because they were tempered properly when reset (the rears weren't the first time).

[red90]

So who can pick what the vehicle is in the LHS of the top photo???

That belongs to a Mr. Story.

[Nick (in the Falklands!)]

...& I beleive its been featured in some mags..? ( Looks like a welsh - built Land Master, but steers both ends like the 130 he built a while back..?) Home built hybrid with polished alloy panels...?

Thats not bad travel on your truck Ben....our 109" twisted quite well when required....& had the interesting habit of shearing all 7 rear leaves just in front of the rear axle....we used to carry shackle plates & bolts to get home with when we knew a few leaves were gone....We had 35" tall 900x16s on it which used to effect some evil stresses too...must finish putting it back together one day.....

Somewhere, I have an american mag where a guy put twin rear axles on a CJ-7, & he met coils & leaves halfway....cut the leaves right off about 6"
behind the axles leaving the rest as a flexible radius/locating arm & then set a coil spring mount on the rear bit of leaf pack & was able to put a
long coil between that & chassis....think he did have Panhard rods on it too.....

[Tikirocker]

Hey Ben,

Excellent info mate, I'll go and digest all that and get back to you for any further clarification. By the way, that spread sheet link...I couldn't open it on my system. Is there some other way to get to it, or view it?

I am crap at maths and trigonometry...the only kind I know involves 6 bullets in a ported chamber. I may have to get someone to help me work out the technical details of determining the spring heights and free camber etc if I can't get it sorted alone.

[daddylonglegs]

As Ben has abely demonstratedYou can do a lot with Landy rear springs to acheive good articulation, and you can improve the front as well but the biggest problem I have found with the front end is axle tramp. The engineers at Toyota,Nissan , Jeep etc are not silly and contrary to popular opinion Landies have the spring shackles on the wrong end of the front springs. It is ok for driving into ditches at speed, but shackles at the back of the front springs magnify axle tramp and reduces the front axles contribution to traction in severe off road conditions. Take a look at the front shochers on most landrovers that are used regularly off road and you may notice they are severely dented. This is caused by the shocker bashing itself against the swivel housing flanges during axle tramp. I modified a friends Stage 1 V8 landy to have excellant articulation and much reduced axle tramp by fitting a shortened Rangey Radius rod to a bracket bolted to the middle top of the front axle housing running forward to to another bracket under the front winch bar.
This is one of the most capable vehicles around, but before fitting the torque rod it wasn't much chop and would regularly break front springs.
Bill.

[DaveS3]

Bill,

I've seen this setup, what bushes did you use at the connenction to the arm at the cross member / bullbar end?

Dave

[ISUZUROVER]

So who can pick what the vehicle is in the LHS of the top photo???

That belongs to a Mr. Story.

Exactly right of course John.

Nick - you are pretty spot on too. The vehicle is called a "Sidewinder" and is a one off built by Mal story a while ago. While it looks like a cross between a Range Rover and a Land Rover, the body and chassis are almost 100% home made, of brushed aluminium and stainless steel. It has had a few different drivetrains over the years, starting with ENV axles, a small holden (GM), auto box (C4???) and a Series T-case converted to 3-speed. When I last saw it it had RR axles front and rear, fitted with Maxi Drive lockers (of course) and Maxi-Drive rear steering (which uses 101 swivels inside new swivel balls), a RRV8 and an R380/LT230 (with Mal's 30% lower low range). It is very impressive to see it in action.

[ISUZUROVER]

Hey Ben,

Excellent info mate, I'll go and digest all that and get back to you for any further clarification. By the way, that spread sheet link...I couldn't open it on my system. Is there some other way to get to it, or view it?

I am crap at maths and trigonometry...the only kind I know involves 6 bullets in a ported chamber. I may have to get someone to help me work out the technical details of determining the spring heights and free camber etc if I can't get it sorted alone.

You need to have Microsoft Excel on your computer to open the link. If you can get the link working it should save you any difficult calculations.

[ISUZUROVER]

the biggest problem I have found with the front end is axle tramp. The engineers at Toyota,Nissan , Jeep etc are not silly and contrary to popular opinion Landies have the spring shackles on the wrong end of the front springs.

I agree Bill, there is a problem with axle tramp on series LR's, especially with softer springs, that is why they tend to climb obstacles better when you drive slowly and smoothly, rather than going faster and on and off the power. However I think that compared to the forward shackle vehicles I have been in, having the shackles on the back makes for a more comfortable ride, as the axle is not trying to move forward against bumps as the spring compresses. And the shackles often get hung up on rocks on very steep jump-ups (especially with the long springs of cruisers and hiluxes).

I like your method of controlling the axle tramp. However you can also achieve some lessening of axle tramp by using very stiff shock absorbers.

[daddylonglegs]

Hi Dave and Ben, Yes I made up a torque rod from a rangey rear lower rod, but I cut off the front pin end and welded the pin end from an old rangey front control arm, mainly because it was easier for me to make a bracket for the two piece rubber bushes that the front control arm uses.
Now that I have got the correct size hole saw I would simply use a shortened rear rod and make a bracket for the chassis mount using the 3 bolt rear rangey bush.
Some years ago I bought a 1964 all leaf spring Austin Gypsey, and the more I drove that vehicle and studied the engineering in detail, the more I became convinced that the Austin engineers had got hold of a LandRover, thrashed it ,abused it and disected it . They identified where the design, construction and performance deficiencies were and within the constraints of using many existing Austin components, they built an engineers interpretation of what a contempory Landrover should have been. This vehicle had the front shackles at the back like a landy but had
twin torque rods and much superior abilities when climbing steps, rock shelves etc. I am getting misty eyed when i remember that old truck but alas it rolled away on its own one night and demolished itself against a bloody big tree.
The main problem with the forward shackles on a Toyota etc, aside from the spring being too long for good approach angle,is that they should have angled up the front of the spring slightly to avoid snapping when driving too quickly over drains and ditches etc.
Bill.