Hi everyone,
I’ve put together a couple of plots which users may find helpful, as it is a bit difficult to compare the resultant lift from different lengths of coil springs without a plot. These plots are made by using the “suspension database” and “suspension measurements 2” threads, where users have reported their vehicle lifts.
Some points to note:
1. Lifts reported are bottom of rim to guard measurements, all on 17” Prado rims.
2. None of these measurements include coil or strut spacers.
3. All front lifts are bottom circlip position unless stated otherwise.
4. Lifts are typically reported immediately after suspension install, so do not include sag.
I haven’t included TFR-118EHD as part of the trend-line fit for the IFS, as it is a very short coil with extremely high spring rate. Notably, large 0.5-1” lifts are achievable by moving up circlip positions on front struts, by virtue of pre-load increasing.
When using inflatable airbags in the rear for GXL and VX models, reported lifts for the rear can reach 3.5”. It is clearly better to report your lift with airbags deflated/minimal pressure, so the lift from the coils alone can be discerned.
Most of the reported lift measurements are for vehicles that have bullbar/winch/dual batteries in the front, and a constant loaded cargo area (drawers, fridge etc.) in the rear, which gives everyone an idea of the lift that is achievable in a typical off-road configuration.
Some users are reporting more satisfactory results on the 120 IFS with stiffer 150 series coil springs such as C59-352 and C59-350 (725lb/in compared to 586lb/in), less nose diving under brakes with bullbars etc.
It appears that to achieve a 2” lift (the most discussed in the forum) with close to factory spring rates, you will need >390mm coils in the front, and >400mm coils in the rear. The lift from these length coils are constrained by the spring rate, as provided in the suspension database, and the pre-load in a strut assembly. Lift in the rear can be strongly influenced by a heavily loaded vehicle (e.g. fully loaded cargo area + roof rack), so I would personally be using at least 410mm for heavy off roaders, and have airbags to combat load sag.
I’m also quite interested to hear reports of coil sag after ‘n’ months. Having read through many different suspension threads, it seems Ridepro, Kings, Lovells and OME coils can sag quickly over time, while in contrast, some users report Dobinsons coils not sagging at all over many years. Some users report the complete opposite of this, so it’s very hard to get a consistent picture without a bunch of sag measurements. Dobinsons have been reported as being quite stiff, but note that Dobinsons make Ridepro coils, which can sag significantly.
Are there many users who have pulled their coils out and checked the change in free length after heavy/long use?
One other measurement to be aware of for the selection of coil free length can be seen from the following plot;
For my current setup with BE5-A712/ZC7296, the maximum shock travel of 570mm on the front IFS in this case shows a coil working height of close to 350mm. So if you choose very short coils (such as TFR-118EHD 345mm free length) with long travel struts, you may reach the coil free height on full extension and your coil spring will be loose. On this basis, it seems sensible to stay above the OEM free length of 370mm, so the coil always remains pre-loaded.
Best from the Bris
Mark
I’ve put together a couple of plots which users may find helpful, as it is a bit difficult to compare the resultant lift from different lengths of coil springs without a plot. These plots are made by using the “suspension database” and “suspension measurements 2” threads, where users have reported their vehicle lifts.
Some points to note:
1. Lifts reported are bottom of rim to guard measurements, all on 17” Prado rims.
2. None of these measurements include coil or strut spacers.
3. All front lifts are bottom circlip position unless stated otherwise.
4. Lifts are typically reported immediately after suspension install, so do not include sag.
I haven’t included TFR-118EHD as part of the trend-line fit for the IFS, as it is a very short coil with extremely high spring rate. Notably, large 0.5-1” lifts are achievable by moving up circlip positions on front struts, by virtue of pre-load increasing.
When using inflatable airbags in the rear for GXL and VX models, reported lifts for the rear can reach 3.5”. It is clearly better to report your lift with airbags deflated/minimal pressure, so the lift from the coils alone can be discerned.
Most of the reported lift measurements are for vehicles that have bullbar/winch/dual batteries in the front, and a constant loaded cargo area (drawers, fridge etc.) in the rear, which gives everyone an idea of the lift that is achievable in a typical off-road configuration.
Some users are reporting more satisfactory results on the 120 IFS with stiffer 150 series coil springs such as C59-352 and C59-350 (725lb/in compared to 586lb/in), less nose diving under brakes with bullbars etc.
It appears that to achieve a 2” lift (the most discussed in the forum) with close to factory spring rates, you will need >390mm coils in the front, and >400mm coils in the rear. The lift from these length coils are constrained by the spring rate, as provided in the suspension database, and the pre-load in a strut assembly. Lift in the rear can be strongly influenced by a heavily loaded vehicle (e.g. fully loaded cargo area + roof rack), so I would personally be using at least 410mm for heavy off roaders, and have airbags to combat load sag.
I’m also quite interested to hear reports of coil sag after ‘n’ months. Having read through many different suspension threads, it seems Ridepro, Kings, Lovells and OME coils can sag quickly over time, while in contrast, some users report Dobinsons coils not sagging at all over many years. Some users report the complete opposite of this, so it’s very hard to get a consistent picture without a bunch of sag measurements. Dobinsons have been reported as being quite stiff, but note that Dobinsons make Ridepro coils, which can sag significantly.
Are there many users who have pulled their coils out and checked the change in free length after heavy/long use?
One other measurement to be aware of for the selection of coil free length can be seen from the following plot;
For my current setup with BE5-A712/ZC7296, the maximum shock travel of 570mm on the front IFS in this case shows a coil working height of close to 350mm. So if you choose very short coils (such as TFR-118EHD 345mm free length) with long travel struts, you may reach the coil free height on full extension and your coil spring will be loose. On this basis, it seems sensible to stay above the OEM free length of 370mm, so the coil always remains pre-loaded.
Best from the Bris
Mark
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