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Defender Springs


Aragorn
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I'm wondering if anyones tried running standard defender springs on their Disco?

They look to be around the same length and approx 25lb/in higher rate, so i would imagine they should give a small lift and stiffen up the ride a bit without going too extreme?

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The defenders have 175lb fronts and 225lb rears

The disco appears to have 133lb fronts (its a V8) and 115/210 rears

Done some quick maths and i expect 1-1.5" lift from fitting the defender springs, which seems pretty decent.

Sounds like a plan!

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on a 200tdi they have 150lb front springs and it will probably lift it slightly less that i expect them to lift the V8.

If you measure the spring lengths with the vechile sitting level, and what springs they are (ie standard or otherwise) i'll be able to calculate how much lift the 90 springs will provide you.

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they are standard, however they will have sagged quite a lot and ive added a hefty steering guard to it.

i already done calcualtions for it, overall weight of vehicle inc rear bumper + steerin guard etc = 2180kg

49% front 51% rear weight distribution

1068.2kg front

1111.8kg rear

ill get you spring lenghts tomorrow, as im out finishing my straight through exhaust :D

mikey

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to get an accurate picture i'd need to know how much of that weight comes from the unsprung mass, ie the axle itself, wheels/tyres, and partially the springs themselves, the props and suspension linkages, which is why its better trying to use the spring compression to calculate the loading, but this will only work if the springs havent fatigued with age.

If we very roughly assume that 100kgs of each axles weight is unsprung, then the numbers look like this:

Front:

Standard Disco 150lb spring will compress by ((968/2)*2.2) / 150 = 7.09", the stock springs are 16.1" long, giving a compressed spring length of 9"

Defender front springs will compress by: ((968/2)*2.2) / 175 = 6", the drivers side spring is 15.2" long, giving a compressed length of 9.1"

Doesnt look particularly great tbh, perhaps it would be worth looking at defender 110 fronts (which are actually the same as the disco rears):

D110 fronts are progressive, meaning the rate changes, the first ~510lbs on the spring will compress it around 3.3", and afterwards it will act roughly like a 215lb spring.

So on your truck, 3.3" + ((968/2)*2.2) - 510) / 215) = 3.3 + 2.6 = 5.9", again they have a shorter free length of 15.1" so a compressed length of 9.2"

Again not much point. What kinda ride height are you considering? There are other OE springs that might do the job, but i'd need an idea of how much higher you want over the stock springs.

NRC4234 are from RRC LHD's and might lift it around an inch looking at the figures quickly

NTC8477 are designed for a disco with winch and will lift it a bit more, perhaps 2" or so.

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Just to clarify the main differences between your figures and my original ones, is that the V8 springs are both a lower poundage than the TDi ones (133 instead of 150) and shorter, (15.4 vs 16.1"), meaning the defender springs make a bigger difference on a V8 disco.

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right,

my rear springs come in at 310mm

front are 240mm

so far ive gathered that if i put 110 springs on the front ill gain 0.2" whoch is 5.08mm ooohhh a lot there lol

what abput the back, its that which has sagged the most due to the rear bumper on it probably want around an inch and a half-2 inches of lift there, ill probably not bother with the front springs then. but just to get it more or less level, if slightly rear high would be nice.

mikey

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Looking at the length of your fronts they seem pretty close to what i calculated on a guess for the unsprung weight, so as you say not much point changing them (and the seem to be doing quite well for their age).

if we look at the rears now:

You measure 12.2" compressed length.

The spring is the same as the D110 front above, so the compression will need worked out in two stages.

The first 510lb on the spring will compress it 3.3" then each additional inch will require 215lb more weight.

The problem is that the free length of the rear springs is 15.1", which means from your figures its only compressed by 2.9"

This means the total weight on the rear axle is <1020lbs, which doesnt make any sense whatsoever... especially as you've said there is ~1100kgs on the rear, almost double what the spring compression would suggest....

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This means the total weight on the rear axle is <1020lbs, which doesnt make any sense whatsoever... especially as you've said there is ~1100kgs on the rear, almost double what the spring compression would suggest....

[confuzed] right, try working it out from your disco, cant be that much difference, just add 30kg for the rear bumper [/confuzed] would that work, ive probably done something wrong :rolleyes:

mikey

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on our old 200tdi disco we put the disco rear springs on the front and defender rear springs on the back - gave about 1" of lift all round and was quite nice. Firmed it up on the road nicely.

no idea how it would have performed off road, as it was mainly a tarmac muncher with a bit of laning so never max'd it out.

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well ye, the disco rear springs are the same as D110 fronts, so i'd expect a bit of lift, but really not that much.

Using the corrected numbers, ie 210mm:

a defender rear spring is 225lb and ~15.3" long

with 1100kgs on the rear axle that equates to around 1210lbs on each spring, meaning it will compress around 5.3", giving a compressed length of around 10". Your current springs have a compressed length of 8.2" from your measurements, so a pair of defender rears should do the trick.

You can always try the disco rears on the front as well.

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thanks guys :) slightly more pressing problem atm though, either ive done in the third diff in 9 months, or a halfshaft :ph34r: so im going to rebuild my front axle on tuesday after my exam.

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  • 2 weeks later...

stop the maths i've got def 90 HD on the front and back of my discovery 300 TDI auto it gave it 1 inch on the back and 1/2 inch on the front it can get a bit choppy on bumpy roads when empty but with 7up or 5 and stuff in the back its good on the road with alot less body roll 6 mouths best mod so far i did all def shoks to ;)

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