Thread: Plugger and The Camel

I've just bought a full set of parabolics, but the vehcile is a way off being back on the road to test them. My 101 has factory parabolics and they've been on there for 40 years without sagging, issue or breaking so I wouldn't worry about that.

There seems to be the odd person that has trouble getting the heights right, and I've seen posts on LR forums from people that have had 1 spring colapse over a fairly short period of time - both the Britpart units and the Rocky Mountain ones, but I think it's propab.y fair to say they are few and far between.

I bought the Britpart ones as they were heaps cheaper and all the reviews I've read on global forums say they work as well as the RM units, but if you go that route you wouldn't go far wrong either.

If you go for a soft enough spring rate to be comforatable you will lose carrying capacity, but if your not going to fully load it all the time it won't be a problem.

Those that actually run them will chime in im sure, but everything I've heard about the ride has been positive.

Well worth the extra dollars if it's going to be a daily driver.

Oh, and last time I looked 4wd industries were out of stock of the rears for a 109 I think, but they should have some back in stock soon I would think.

Dont' quote me, but I think that 4wd industries order them when you order them.... no stock kept. Seems to be the way they operate, I got a gearbox/trans rebuilt and they ahd stuff listed on the site, but then told me they had to order it in (not taht it takes long, only a couple weeks)

I'm keen to throw paras under my SWB! but have to save up for them

Let's think about how these springs work. Leaf springs, as fitted to Series Landrovers, have three major functions.

1. To provide a sprung support for the vehicle

2. To locate the axles

3. To handle braking and acceleration torque loads on the axle housings

4. To provide some damping by interleaf friction.

Parabolic springs do all of these except 4. (note that coil springs or airbags on other Landrovers only do (1))

The load on these springs decreases from the U-bolts to the spring eye, and to spread the strain or bending evenly along the spring according to the load, the original springs are fitted with a large number of leaves, of varying length, to effectively taper the spring according to this load imposed at each point along the spring. So-called parabolic springs achieve this by having only a very few leaves, usually two or three, but instead of varying the length, the thickness is varied along the length, this being a parabolic function.

The advantage of the parabolic springs is primarily that they reduce to a very low and constant figure the interleaf friction (usually contact between leaves is only at the ends, and is via a nylon block). This also means that there is no possibility of the springs developing a wear step at the end of each shorter leaf on the bottom of the next leaf, which causes a harsh ride on small bumps.

A further advantage of parabolic springs is that they can be made to closely duplicate the spring rates of the originals (not to claim that they actually do so). This is difficult to do with new leaf springs, as the original leaf thickness is no longer made, so that new springs (from about 1980 I think) have somewhat different performance.

The drawbacks of parabolics are several. Since there is essentially no frictional damping, they must be used with non-standard shock absorbers, as with the original type they will be underdamped.

Another problem is that as far as I know, they are not available 'handed'. All Series Landrovers have different left and right springs, as otherwise, having long travel suspension and no sway bars, they will inevitably lean, usually to the driver's side.

Further, if a leaf breaks on a parabolic spring, it is likely to disable the vehicle, since each leaf carries such a large proportion of the load. With the conventional spring, even breaking the main leaf is not a serious issue, as the second leaf wraps round it at each end, and it is only perhaps 10% of the spring strength.

Claims are usually made for a far better ride and handling of parabolics compared to conventional springs, but it must be realised that most of these comparisons come from owners who have replaced completely knackered springs! Another point to consider is that many Landrovers were fitted with heavy duty springs from new (including all military ones), and these inevitably give a harsh ride when empty. Of course it rides better when these are replaced with standard strength springs, be they parabolic or conventional.

In Australia, where salt is not used on roads, most old springs can be easily revived, as discussed earlier in this thread, for far less than new parabolics will cost. And there have been reports of early failures of some of the cheaper parabolics, so perhaps that is something to watch.

I hope this discussion helps.

John

As always John, very well written.

I just thought as a side note about howthe original leaves can give a harsh ride, I now have a decision to make with my Hilux - rough as guts when empty as most utes are, but I picked up 6 truck trailer drums the other day and the ride is now like silk (well, not quite, but much smoother).... . I'm thinking of just leaving them in there.

Moral of the story is that if the vehcile is not going to get heavily loaded, then look at a spring rate that will work better at lighter loads. I've gone to parabolics in the back of the series 3 - which is a tray, but it won't get heavily loaded and if I stuck the original springs back in, it wouldn't be much fun to drive.

Actually, with my 2a (ex-army, lwb) I have transformed the ride - not by fitting parabolics, which would not be practical, as it is regularly heavily loaded.

I managed to find a pair of "station wagon" springs. These are dual rate, and have resulted in a major improvement in ride when empty. But they are not readily available. Fortunately, I spotted them advertised as "heavy duty" springs, which they are not.

John

I run parabolics on my series 3 shorty and they are great, but 100kg in the back makes all the difference. Fitting them was a matter of necessity as the originals worked well when frequently lubricated with Innox, however they were badly grooved and worn.
Something worth noting is the Mercedes Benz Sprinters vans run a true parabolic spring (single rear leaf), and they seem to do the job and hold up well. The vehicles are sold internationally and used from goods carriers, to ambulances, where there is a demand for a compromise between high speed stability, and a ride that provides comfort for the occupants.


Cheers, Mick.

Mick, John Homestar and Debruiser - thanks for all responding!!

From the information I have received here, from what I have researched online and from what Paul (Redcliffe Spring and Suspension) has stated I think its unanimous - Parabolic springs are the way to go!

To this end, I have contacted 4x4 Industries, Rocky Mountain, Paddock Spares, British Off-Road and Britparts for price on availability of a full set. It seems that prices vary wildly!!

>While 4x4 Industries list a full set, the front set only for $345 plus freight while a full set for $890 plus freight they are nil stock and dont know when they will be restocked. A full set of four Pro Comp shocks were $440
>British Off-Road have a front set for $484. Pro-Comp shocks an additional $102. I didn't inquire about a full set. I expect at least $900...
>Rocky Mountain UK have a full set listed at 520 pounds - AUD$902 plus freight to Oz (Holy cow!!)
>Rocky Mountain USA (actually Canada) has the fronts listed for USD$246 (AUD$328) or all four for USD$506 (AUD$675) plus freight to OZ!! A full set of shocks & straps from RM are USD$240 (AUD$320) plus freight
>Britparts are a bit slow in getting back to me with a price and availability but I do believe they are supplied by RM
>Paddock Spares seem to be the best value. They stock two different brands - OEM and GME. OEM for fronts only is 110 pounds (AUD$190) while all four are 280 pounds (AUD$486). For the GME brand they are slightly cheaper at 97 pounds (AUD$168) and 232 pounds (AUD$402) respectively. All four Pro Comp shocks from Paddocks is 110 pounds (AUD$190). All these prices are plus freight to Oz of course.

It seems in terms of pricing that Paddocks is the clear winner. I have researched if there is any bad press regarding the Paddock products and I am yet to find any. So, if we have a look at four springs and four shocks the price comes to 390 pounds (AUD$677) plus freight. This is for the OEM Brand which is slightly more expensive but it also comes with a 24-month warranty as opposed to the GME brand which is only 12-months (not that this would mean a great deal in Oz...). The cost, I think is acceptable. So we applied to the Chancellor of the Exchequer for and increase to the budget and this was granted!! I have contacted Paddock Spares for a freight cost and they are yet to get back to me - hopefully in the order of 100 pounds or less!!

Ok, some questions for the educated. Paddock spares carry two different brands of parabolic springs are previously mentioned. The fronts are identical but the rears are different...
OEM Brand:


GME Brand:


As you can see the OEM brand seems to employ a 'helper spring' as opposed to 3 leafs in constant 'play' (for want of a better word). My thought process would think that the OEM spring would be better for wheel articulation and ride etc as the 'helper spring' would only come into play under heavy loads or maximum compression - what are peoples thoughts and which would you choose??

I think we will pull the trigger on these springs this week and get them here ASAP.

Also, through the week some other bits n pieces started arriving. 4 x Hub bearing and seals kits from R&C


and 2 x pinion seals from Crossland Restorations.


Cheers and thanks,
Tricky

Hi Everyone,

Just a real quick update as I have already posted today and you guys might be getting sick of the long-winded posts with a thousand questions....

More disassembly of the front suspension yesterday, with Plugger doing some more detailed cleaning of the disassembled parts.


Seals, bearings and cups were punched out as new items arrived through the week - see previous post. The half-shaft bearings were in a sorry state as were the wheel (hub) bearings


and tapered swivel-pin bearings...


Finally after a few hours we had them all cleaned and washed and drying in the sun:


Put away and almost ready for painting next week:


Cheers,
Tricky