Parabolics???

[Kime]

Whats everyones thoughts on the parabolic leaf springs for series 3's????

[123rover50]

Whats parabolic look like?
How does it differ from a standard landy spring?
My understanding of a parabola is a curve that gets more pronounced the further it goes.
Didiman

[101RRS]

Whats parabolic look like?
How does it differ from a standard landy spring?
My understanding of a parabola is a curve that gets more pronounced the further it goes.
Didiman

Conventional multi-leaf springs often require somewhere from eight to 11 leaves within the pack to carry the desired weight demanded by many 4WD owners. Parabolic Springs will do the same job with only two leaves.

Parabolic springs have leaves with a tapered profile. This tapering is based on the parabola that for every mm that the leaf thickness decreases this amount relates to the square function of the leaf. This is the technical way to say that each parabolic leaf has the same shape & function of a complete multi-leaf spring - thick at the center and thinner at the outer ends. This means that a single parabolic leaf is able to cope with the same forces inside the leaf as a complete conventional 8 multi-leaf or more spring.
The ideal parabolic spring only requires one single leaf but for safety reasons 4WD parabolic springs have a minimum of two leaves. The second leaf is a wrap style leaf acting as a safeguard in the unlikely event of a breakage.

[ajps72]

Whats everyones thoughts on the parabolic leaf springs for series 3's????
A couple of friends have change from normal leaf to parabolic, and its a huge difference, specially if your leafs are all rusted and has no "springness" left.

It will be my number 1 upgrade if a had a series

[Kime]

thanks guys

I did get a quote, all round with shocks to suit was just over $ 1000...

Mine don't have much "spring" left anymore.. the ride is like concrete.. :(

Will be saving up for them i think.

Cheers

[slug_burner]

thanks guys

I did get a quote, all round with shocks to suit was just over $ 1000...

Mine don't have much "spring" left anymore.. the ride is like concrete.. :(

Will be saving up for them i think.

Cheers

While your saving up, take your leaf springs apart, give them a clean with a rotary wire brush or sanding disc, removed the edge of the tip of the leaves so that the leaves don't bite into each other. If the springs are not sagging you can reassemble the leaf packs and you should get a bit more flex due to the reduced friction between leaves.

If the springs are sagging you can reset the springs or have them reset by the local spring works.

Do a search for threads where isuzurover has posted on the topic of leaf suspension elliptic or parabolic, I think he has a series 2 with a lot of suspension travel.

I did a basic search for you and found the following. I did not hit the jackpot as I recall a more extensive discussion on the refurbishment of your leaf springs.

http://www.aulro.com/afvb/series-iii/146658-parabolics.html

http://www.aulro.com/afvb/general-chat/105680-springs-stage-one-worn-out.html

http://www.aulro.com/afvb/technical-chatter/61740-parabolics-stage-1-a.html

http://www.aulro.com/afvb/series-iii/58058-axle-check-straps-question.html

PS: I think this might be the thread I was think of but don't hold me to it I just looked at the pics of the series 2 flexing and figured that would have to be it.

http://www.aulro.com/afvb/members-rides/33787-my-iia.html

the mother load

http://www.aulro.com/afvb/series-iii/111680-109-suspension-upgrade.html

[driftn69]

G'day Kime,

Just to muddy the waters a little I'll relate my experience of parabolic rear springs. In a previous life I spent a few years working as a light vehicle mechanic in an underground Nickel mine in the WA goldfields. Most of the LV's were Landcruiser 79 series utes working in extreme conditions (ground water was hyper saline around 7-10x sea water). To try and reduce the number of spring packs being replaced due to broken leaves and other damage that had to be seen to be believed I trialed parabolic springs. A set was also fitted to a Nissan Patrol tray back. Several problems became apparent.
- diff housings broke just outboard of the U-bolts
- noisy, they had a load leaf and the guide straps would rattle
- the ride was rough
- chassis rails broke
Remember these were in extreme conditions used by ham fisted operators most of whom didn't give a toss about what they broke. In the end the best option was a heavy duty spring pack, with a couple of leaves removed to the same number as a genuine pack. These seemed to give good service and a reasonable ride.

I wouldn't recommend them at all but no doubt other people will have had different experiences and outcomes.

Cheers and good luck,
Colin

[101RRS]

A set was also fitted to a Nissan Patrol tray back. Several problems became apparent.
- diff housings broke just outboard of the U-bolts
- noisy, they had a load leaf and the guide straps would rattle
- the ride was rough
- chassis rails broke

Colin

That experience is probably more relevant to the particular circumstance and mismatching springs to the vehicle.

For series 3 vehicles - because the internal resistance in the spring is less than normal springs the vehicle rides very well and gives a softer feel. However you need to get a brand name spring like Rocky Mountain. There are a few dodgy springs out there that are hard as rocks and do not fit well. I suspect Colin got some of this lot and not "brand names".

The 101 has parabolic springs and has a 1.5 ton payload - as well you sit right over the front wheels. The unladen ride on a 101 is generally good and certainly better than a series landie. Load the vehicle up and it rides really well. Its parabolic springs are two leaf and very flat.

Garry

[Kime]

Wow,

Awesome advice from all :)

Thanks guys.

I did get the quote originally from Rocky Mountain.

They say they do two packs, a standard 2 leaf set for normal weight conditions or pay load and a upgrade pack that allows a bigger pay load. Can't remember how much though....

Cheers all. some really good info.

[mnhowe]

Does anyone know if the rocky mountain parabolic springs will provide any lift/ride height

[mick88]

I have parabolics on my 88" S3 and i am very happy with them, fitted them 5-6 years back. They are not rocky mountain brand, i got them from the UK.
Mercedes Sprinter vans have single leaf parabolics on the rear and they ride well.
Just one thing on the standard springs to get them moving freely is to jack your vehicle up by the chassis and let the axles hang. Then spray liberally with innox and let them sit for a day or so. I used to do this to my original springs every 2-3 months and it realy frees them up and gets them moving. The only downfall was it made the springs clack a bit as the leaves moved over the worn sections on the adjoining leaf. Nothing a brush with an angle drinder wouldn't fix though if you stripped them down.

Cheers, Mick.