Parabolics or Leaf Springs

Technical questions and answers
Post Reply
DPuckey
Posts: 39
Joined: Mon Apr 24, 2006 10:36 am
Location: Bicester, Oxon

Parabolics or Leaf Springs

Post by DPuckey »

I run my Stage 1 on leafs at the moment, they were changed several years back but are now on their way out, the ride has got rougher and I have a couple of cracked leaves.

The wagon is now mainly used for towing a horse trailer and the leaf springs give a good firm ride and tow.

Would changing to parabolics cause the back end to move more with the softer suspension and cause towing problems?

If I go for parabolics whose springs work best on the Stage 1?

How do parabolics compare to a new set of good leaf springs?

Would I need to change shocks as well? as they have recently been renewed?
disco2hse
Posts: 1637
Joined: Sun Apr 27, 2008 3:51 am
Location: Auckland NZ

Post by disco2hse »

Howdy,

In answer to your questions, in no particular order, I would say that:

The fact that you are towing a horse float is not a major issue as to whether you stay with standard leaves or go for parabolics. The weight on the tow ball could be a factor though.

Parabolics are used extensively on very large trucks that carry and pull extremely heavy loads both on the tray and in trailers. So, conceptually, there is no reason for them to not be a good choice for you.

Parabolics are leaf springs but they use a different geometry to absorb the weight put onto them. That means that they typically use fewer leaves to perform the job, but the manner in which shock and weight are absorbed results in a smoother ride.

They do not sway about but they will make your vehicle sit higher and so you will need longer shocks. They can cause the vehicle to roll because of the increased ride height, increased spring travel, and softer/easier compression of the spring. I would specify very clearly with the supplier what the springs are going to be used for and get them to recommend the right springs for the job. You may need to have them made for you.

I do not think that standard off-roader parabolics will be up to the job. They are intended to increase tyre contact on the ground, clearance, and articulation. They are not intended to replace heavy duty truck springs, so I would not recommend going to the usual Landie parts suppliers. Instead I'd contact a commercial truck parts supplier.

They are a lot more expensive than standard springs. If you are pulling and carrying very heavy weights you could be better off by replacing with heavy duty springs instead.

I have heard reports that parabolics are more prone to breaking leaves but I have not seen much evidence of that. Admittedly there are fewer leaves but as the weight goes onto the spring the number of leaves in use increases progressively. Therefore the amount of steel supporting the vehicle increases as the spring travels and you should be less likely to break a spring, not more.
Alan

1983 ex-army FFR 109 Stage 1
2005 Disco 2 HSE TD5
map1275
Posts: 1076
Joined: Mon Jul 21, 2008 2:48 am
Location: Brisbane, Australia

Post by map1275 »

I am in a similar situation. However I have more or less decided upon standard springs with longer shackles and spacers for the bump stops to give some extra height.

The main problems I have found locally is lack of choice and lack of information.
There are two brands of spring made in Australia but I can't assess how different they are from the originals. No suppliers seem interested. I haven't found anyone yet selling genuine new springs.

Parabolics appear to have the same lack of stock and service.

One of my other concerns was that If I break a spring in the middle of nowhere, it will be harder to find a parabolic than a standard unit.
Kiwistage1V8
Posts: 130
Joined: Tue Oct 25, 2005 4:07 am
Location: New Zealand

Post by Kiwistage1V8 »

If your original units are sound, but with no "spring" in them, you can have them re-tensioned.

Don't bother if they are very rusty though, but I had mine re-tensioned, and 2 years later they are still perfect.

i think from memory it only cost around NZ$180 for all 4 to be done.

Oh, and I got them tensioned with an extra 2" height in them.
Stop Global Whining.
disco2hse
Posts: 1637
Joined: Sun Apr 27, 2008 3:51 am
Location: Auckland NZ

Post by disco2hse »

Alan

1983 ex-army FFR 109 Stage 1
2005 Disco 2 HSE TD5
map1275
Posts: 1076
Joined: Mon Jul 21, 2008 2:48 am
Location: Brisbane, Australia

Post by map1275 »

My Rover still has its original springs which were reset a few years ago. However they have since started to list and sag.

I'd prefer to fit all new and be able to forget about them.

I tried both the links but it hasn't really left me any the wiser. Obviously there is a lot of variation depending on precisely what model you own and what your intended use is.

Within five minutes drive I have one manufacturer and the outlet for Rocky Mountain. The manufacturer is evasive on precise comparison between their product and standard. The Rocky Mountain outlet, I usually try and avoid as they have about one in ten of every part I ask for. I have never found them to have much specific Land-Rover knowledge either.

I tried the major outlet in Melbourne once and that was enough. They seemed to be focused on near enough is perfect.
Bumpkin
Posts: 440
Joined: Sun Feb 06, 2005 8:51 pm
Location: Mid Cornwall

Post by Bumpkin »

I have a set of Paras to go on my Hi-Cap (And i need them now)The rears are standard but i have been able to add a 4th helper which only comes into use when the weight is on. The general concencus is a higher better ride.
Tel
1 Stage 1 V8 HiCap
1 Series 3 HiCap
1 LWB Steies 2
1 SWB Series 2
1 300 TDi Disco
1 4.6 HSE P38
1 V8 90 County
Tattiebogle
Posts: 58
Joined: Wed Jan 09, 2008 4:00 pm
Location: Logie Nr. Glamis Castle

Post by Tattiebogle »

I contacted the UK agent for Rocky Mountain springs earlier last year..He had in stock the parts i needed but had promised them to someone else ..He then said he would ring me when more stockl arrived but nearly a year later i,m still waiting...


http://www.rockymountainspares.co.uk/?page_id=41
disco2hse
Posts: 1637
Joined: Sun Apr 27, 2008 3:51 am
Location: Auckland NZ

Post by disco2hse »

Hi Map,

That is just one of the problems with trying to specify what springs to use and where. I don't think the manufacturer is necessarily trying to be evasive, they may just not know what the difference is between what they might normally make and Rocky Mountain since there are a large number of variables that have effect. But if you were to say this spring of theirs and that one from RM, they could identify differences there.

However, that is why you need to state such important measurements as the camber, length, rate of descent, max. laden weight and tare, usage, that kind of thing. With that specific information you can have springs custom made to suit your requirements and possibly at a lower cost than the branded RM springs. Any spring maker ought to be able to make parabolics.

One point though, if you are having the springs reset, say if they are stock items that are being reset for your vehicle make certain they are set in a furnace and not cold set. Cold set springs flatten out sooner than hot set.
Alan

1983 ex-army FFR 109 Stage 1
2005 Disco 2 HSE TD5
DPuckey
Posts: 39
Joined: Mon Apr 24, 2006 10:36 am
Location: Bicester, Oxon

Post by DPuckey »

Thanks everyone for the replies, gives me plenty to think about.
John Roach
Posts: 59
Joined: Tue Dec 09, 2008 8:20 pm
Location: East Sussex

Post by John Roach »

There has been some talk of a "Stage 1 meet" in the next few weeks, somewhere in the South (of UK). A little vague I know, but I'm up for it. I've got CPC (formerly Chris Perfect) 4 leaf rears and could bring a trailer, big enough to put another Stage 1 on, to experiment with.

Regards,

John
1982 Stage 1
1982 88"...dormant in back garden!
DPuckey
Posts: 39
Joined: Mon Apr 24, 2006 10:36 am
Location: Bicester, Oxon

Post by DPuckey »

Thanks for the info John. How does your Stage 1 handle with parabolics compared to leaves? (assuming thta you got it wth leaves on) It obviously gives a softer ride but do you get much extra body roll on cornering?

How does it perform when towing your trailer with a heavy load at reasonable speeds? ie have you noticed any increased tendency with the back end moving more and snaking?

I guess that you are happy with the CPC parabolic springs and ahve had no problems with them?
John Roach
Posts: 59
Joined: Tue Dec 09, 2008 8:20 pm
Location: East Sussex

Post by John Roach »

Unfortunately I'm not able to offer much in the way of objective advice at present as I've only had the Stage 1 a few weeks, it came with the parabolics fitted and I've done no towing or meaningful load carrying with it. It does ride much better than the three other 109's I've owned, all on standard springs, with much less roll when cornering, but bear in mind the Stage 1 is Polybushed and is a truck cab, weighing about 200kgs or so less than my previous Station Wagons. For what its worth, I would say the set up I've got would be more than up to heavy towing and would be at least as stable as any Series I've driven. No problems yet so am obviously very happy with it.

Check out http://www.heystee-automotive.com/ Formerly TIC, I believe these are the best off the shelf parabolic springs available: Chris Perfect was the UK distributor and I've only ever heard good things about all their products (and not sure CPC still exists). Unfortunately, the exchange rate is not too clever at the moment!

You should replace standard dampers if you do go the parabolic route, as advised by the spring supplier. I believe polyurethane bushes would be beneficial too, regardless of spring type being used.

Regards

John
1982 Stage 1
1982 88"...dormant in back garden!
landdani
Posts: 274
Joined: Sat Sep 27, 2008 12:40 pm
Location: damascus

Post by landdani »

John Roach, Can you manage to pout some photos of the (stage1 meet) if you could know any thing about it ?
wonderful sport!
1984 SeriesIII ex-melitary, 109 inch, V8 stage one
DPuckey
Posts: 39
Joined: Mon Apr 24, 2006 10:36 am
Location: Bicester, Oxon

Post by DPuckey »

Finally got my Rocky Mountain Parabolics and they have been on the wagon a week.

A good quick service from the UK distributor at Rocky Mountain Spares once he had got them from Canada..which did take a while.

Very impressed with the ride, I had been a little concerned that the softer ride would result in a wallowing ride that leans alarmingly in corners, the reality was pleasantly far from it. Handling is good even on corners and I don't bounce up and down on every minor bump in the road all the time any more. Someday I'll get round to tightening all the things that got shaken loose by the old springs..which could be just above most things.

In short guys a well recommended upgrade.. I went for the shocks as well. Just as well do the job right once!

If you are contemplating it I would recommend them but get a shift on as I suspect when these run out there will be a long wait for the next lot from Canada.
Post Reply