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Thread: D1 300Tdi spring options

  1. #1
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    Question D1 300Tdi spring options

    Looking for some info regarding springs.

    A couple of months ago I fitted new suspension. I went with King KRFR-03HD and KRRR-04 springs with EFS shocks. The front springs feel a bit too stiff, and the front sits noticeably higher than the rear now. At the moment the vehicle is fairly standard apart from the ARB steel bullbar, however I plan to fit a different ARB steel winch bar with winch and an aux battery under the bonnet. The hope was the new springs would be a good match for the extra weight, however I'm not too sure about this now. I can sit 100+ kg to the bullbar and it only drops 10mm or so.

    The rear springs ride pretty well, but do sag a fair bit with even just a light load in the back or the empty camper trailer on. I noticed they're progressive rate, so this may explain it to some degree.

    It's also lost a bit of front axle articulation, but seems to have gained some at the rear. I did delete the rear swaybar at the same time as the geometry didn't look great with the lift and I didn't have any spacers at the time, however being such a small diameter I didn't think it would make such a big difference. The front roll stiffness far exceeds the rear now, and the vehicle definitely understeers on dirt where it was fairly neutral before. I'm tempted to disconnect the front swaybar to see how it behaves.

    To summarise, the front seems to stiff, the rear seems too soft, but overall I'd like a vehicle that sits fairly level and similar ride quality and roll stiffness front to rear.

    For the front:
    KRFR-03HD are listed as Defender 110 Tdi/TD5 Raised with 50-100kg constant load.
    KRFR-03 are the standard rate raised spring for Disco 1 and 110Tdi/TD5. Not sure if they'll be too soft?
    KRRR-02 is standard rate raised spring for 110 County diesel, I assume even stiffer again? (Same as 110 County/Range Rover standard rate raised rear coils)
    KRFR-06 is standard rate raised spring for Disco 2 TD5, would these be somewhere in between? Are they even compatible?

    For the rear:
    KRRR-04 are the standard rate raised spring for Disco 1&2.
    KRRR-04HD are the same application but 100-300kg constant load, I'm fairly confident these will be too stiff.
    KRRR-02 are listed for 110 Country/Range Rover standard rate raised rear, and KLRR-05 Defender 110 same application. Would one of these be somewhere in between?

    I'm happy to use spring spacers for fine ride height adjustment.

    A couple of photos of how it currently performs:




    Thanks!
    1970 Series IIA 88"
    1997 Discovery 300Tdi

  2. #2
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    The front springs are designed to carry that steel bar, winch etc, I would re-evaluate once they're installed. They're actually a Defender spring, so it doesn't surprise me that it is stiff. Being a raised spring it will give you probably 40mm over standard, then more because of the expected weight. I suspect the KRFR-03 will not be stiff enough, probably at approx 190lb/in

    The rear is a relatively light spring, probably about 240-270lb/in progressive. These only give about 30mm lift.

    At this stage, I'd just put some 20mm shims over the rear springs and then reevaluate once you've installed the new bar, winch and batteries.

    The springs are also not normally standard rates, just about all lift springs are have a higher spring rate.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

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    Can also try refitting rear sway bar….and remove the front one….already a lot of roll stiffness due to the radius rod design anyway.

    The rear bar will invert the links with raised springs, I have 25mm spacers at the chassis mount on mine, so far so good.

    What’s the tie out in the front? Makes a huge difference in the way they turn in.
    '93 D1 V8 auto
    '93 D1 200Tdi 2-door, ARB's, MD transfer, sill tanks, winch, 2"lift.......
    '95 D1 V8 auto......gone
    '86 V8 RRC.....gone

  4. #4
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    I agree, I would also leave the rear sway bar connected. One of the challenges with Disco's is controlling the rear and the rear sway bar is a big part of that solution, especially with some lift.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  5. #5
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    Quote Originally Posted by Rick1970 View Post
    .......................

    What’s the tie out in the front? Makes a huge difference in the way they turn in.
    Don't you mean 'toe in'?

    DL

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    Quote Originally Posted by 350RRC View Post
    Don't you mean 'toe in'?

    DL
    Should be toe out……1-2mm roughly.
    '93 D1 V8 auto
    '93 D1 200Tdi 2-door, ARB's, MD transfer, sill tanks, winch, 2"lift.......
    '95 D1 V8 auto......gone
    '86 V8 RRC.....gone

  7. #7
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    Quote Originally Posted by Slunnie View Post
    The front springs are designed to carry that steel bar, winch etc, I would re-evaluate once they're installed. They're actually a Defender spring, so it doesn't surprise me that it is stiff. Being a raised spring it will give you probably 40mm over standard, then more because of the expected weight. I suspect the KRFR-03 will not be stiff enough, probably at approx 190lb/in

    The rear is a relatively light spring, probably about 240-270lb/in progressive. These only give about 30mm lift.

    At this stage, I'd just put some 20mm shims over the rear springs and then reevaluate once you've installed the new bar, winch and batteries.

    The springs are also not normally standard rates, just about all lift springs are have a higher spring rate.
    Thanks! Where have you found the spring rates? I'd really like to compare them all before I try something else. Do you know if there are any other King springs of a correct diameter/length I should check that I haven't listed?

    I did take some measurements before and 1500km after:


    Quote Originally Posted by Rick1970 View Post
    Can also try refitting rear sway bar….and remove the front one….already a lot of roll stiffness due to the radius rod design anyway.

    The rear bar will invert the links with raised springs, I have 25mm spacers at the chassis mount on mine, so far so good.

    What’s the tie out in the front? Makes a huge difference in the way they turn in.
    Is it true that early Discos weren't fitted with sway bars from the factory? I'm keen to try it without the front sway bar as well, for both handling and articulation. It'd certainly make oil changes less messy as well.

    Not sure what the toe is set to, it's due for tyres soon so I'll get an alignment then. Turn in feels fine, it just feels like the roll stiffness imbalance is making it push mid-corner. Given what I've done to it so far, that makes sense to me. The rear doesn't feel bad at the moment however I won't know while the front end is doing all of the roll control.
    1970 Series IIA 88"
    1997 Discovery 300Tdi

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    Quote Originally Posted by Dauntless View Post
    Thanks! Where have you found the spring rates? I'd really like to compare them all before I try something else. Do you know if there are any other King springs of a correct diameter/length I should check that I haven't listed?

    I did take some measurements before and 1500km after:


    Is it true that early Discos weren't fitted with sway bars from the factory? I'm keen to try it without the front sway bar as well, for both handling and articulation. It'd certainly make oil changes less messy as well.

    Not sure what the toe is set to, it's due for tyres soon so I'll get an alignment then. Turn in feels fine, it just feels like the roll stiffness imbalance is making it push mid-corner. Given what I've done to it so far, that makes sense to me. The rear doesn't feel bad at the moment however I won't know while the front end is doing all of the roll control.
    Early ones didn’t have bars fitted, dropping both Dosnt really do that much, leaving rear on goes some way to forcing a bit more articulation into the front. Had all on, all off, and only front or rear on mine….. rear only seems to be best compromise…… and certainly better on road that none at all.
    '93 D1 V8 auto
    '93 D1 200Tdi 2-door, ARB's, MD transfer, sill tanks, winch, 2"lift.......
    '95 D1 V8 auto......gone
    '86 V8 RRC.....gone

  9. #9
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    Quote Originally Posted by Dauntless View Post
    Thanks! Where have you found the spring rates? I'd really like to compare them all before I try something else. Do you know if there are any other King springs of a correct diameter/length I should check that I haven't listed?

    I did take some measurements before and 1500km after:


    Is it true that early Discos weren't fitted with sway bars from the factory? I'm keen to try it without the front sway bar as well, for both handling and articulation. It'd certainly make oil changes less messy as well.

    Not sure what the toe is set to, it's due for tyres soon so I'll get an alignment then. Turn in feels fine, it just feels like the roll stiffness imbalance is making it push mid-corner. Given what I've done to it so far, that makes sense to me. The rear doesn't feel bad at the moment however I won't know while the front end is doing all of the roll control.
    Years ago I installed the D2 version of them and we tested the rates at Lovells Springs. This was while developing a very new and different setup with Lovells and Bilstein. There is a bit of parts sharing. Your Disco is more level than just about any other Disco on the planet with those H2G measurements, I'd be very happy with that aspect of them. If you're not happy with the stiffness of the fronts, then the KRFR-03, but if it is the ride you're feeling, then more than likely it will be due to shock valving. Even stiff springs (within range) don't affect the ride comfort significantly, but shocks can. I'd also look at the Old Man Emu range, I think they're closer to the spec you're after but you'd have to check the rates - I haven't run them. You're probably looking at about 220lb/in front and 270+ on the rear depending on load. But, as I was saying previously, I'd wait and pass judgement after your bar, winch and batteries are fitted as those springs are designed to carry those loads.

    Early Discos didn't run sway bars, but they also drove and handled like a boat - which is why they were fitted ever since. My Disco2 has electronic swaybars (ACE) which I can switch off, and it handles and steers really badly with the sway bars in floppy (disconnected) mode. I'd never drive it on the road like that. If you try it out then you will have experienced it. Maybe consider sway bar disconnects instead. The Disco update in 1994 is a far better handling version.

    In relation to mid corner push, is it actually push or does it feel like push? If it is actual push from hitting corners stupidly hard and putting it into a slide, then LandRover build that in and I think it is a part of the reason why they spec such low tyre pressures which also induces a safer push and removes some twitchiness. If it is twitching and just feels like midcorner push, that can also happen because it hasn't got enough roll control at the rear which is why it twitches after turn in. ie Turn in, body rolls creating the feeling of push, then it takes that set for the rest of the corner and exit. Thats a Disco problem with a high steel roof, rear links on an angle and little rear sway control. That was a problem I spent a lot of time on developing a solution to in the Disco2 with big lifts and the solution is sway control on the rear. It also removes the flightiness and twitch out of it at higher road speeds.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  10. #10
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    where did you take the measurements from (and too), for example to get 895mm for FL .. and so on?

    I've never measured actual height of car/spring/hub/body/etc.

    I've been taught to measure the bump stop clearance, from many moons ago when I ran my RRC back in the early 90s.
    Make sure the bump stops are the same thickness first, that haven't hardened and shrunk, or been wornn/chipped, cut or whatever by some unknown process/person.

    Have a look at LRA(Les Richmond Auto) website HERE

    They have a range of springs with various rates and lenghts. If you go to their site(ie. click the link) you will see they have a graph of what spring (length) is appropriate for a give weight over the axle.

    The way the graph works (and it's small, so hard to see) but they have colour variables for each spring type(length and stiffness) .. eg. purple/yellow .. and each spring has a dash of paint to show this.
    On the graph, see the diagonal line for purple/yellow(ends at the bottom rh corner).
    if you also click on the buy springs link in the link, it takes you to a grid of 'colour images' instead of pics of springs .. again this is just the dash of paint on the springs.
    Their springs are dobinsons, and will be the usual dobinson blue coated springs, with the dashes of whatever paint.

    The purple and yellow colour relates to a spring that is 390mm in free length, and a rate of 235lbs/inch.
    Every 235lbs(106-ish kgs) will compress the spring by 1 inch(25mm).

    If you weigh each axle on the D1, you then know how much each axle will then sag by with that weight(following the line of the colour chart). So the purple/yellow spring on a std 1200 kg axle on a D1, will start of with 260(ish) millimeters of length and drop to 225mm length with an extra 300kgs over it. Remember that each axle has 2 springs(so half the rates in effect) .. so the 35mm of drop with 300 kgs(ie. 150 kg per spring) ... 100kg per 25mm rate ... ie. roughly 35mm of drop/sag/droop/compression/whatever you prefer to call it.

    Workshop manual is a bit sparse on data, and spring lengths are not listed for the D1(they are for the D2, as well as bump stop clearances). RHS springs are almost always longer lengths than the LHS springs, this then balances out weight of driver only, transfer box weight and whatever, so car sits level.

    Another thing to note with springs shims and spacers: on the rear of the late D1s should be an isolator. rubber ring. these can wear, or get lost by a previous owner or prior mechanic or something. Make sure these are in good condition .. and then add any spacers.
    From memory on their own they make up 20ish mm of spacing. Old chopped out isolators can make more road and bump noises .. new ones can eliminate some of this. They are cheap too($10 or something) if your disco fuly flexes and doesn't dislocate it's springs, you could add another isolator at the bottom of the spring too. double isolation(rather than hard clangy metal). The isolators, when new, should have a very defined 'castle top' pattern on them, not batted to a smooth finish.
    Arthur.

    All these discos are giving me a heart attack!

    '99 D1 300Tdi Auto ( now sold :( )
    '03 D2 Td5 Auto
    '03 D2a Td5 Auto

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