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109" springs on a 88"


cra42
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Physically they'll fit, but the ride will be pretty firm as they're intended to carry around double the weight.

If you're buying new then proper SWB springs are a better idea. If you're wanting to make use of some LWB springs you already have in stock, then removing a few leaves before fitting will make them a bit more supple.

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Fitting a set of parabolics from Rocky Mountain would seem the obvious thing to do, especially since your on the west side of the pond. They'll be an easier swap with no modification and will give a comfier ride and better handling than 109 springs will. Some people go for the two leaf rear springs for softer ride and more articulation, but for road use with a load, three leaf rear springs are probably going to be more appropriate and last much longer - the only occasion I have heard of RM springs deforming has been on one guy's trailer (much modified), and he kept bending the same corner spring and it was two-leaf.

I'm pretty sure front 109 springs will fit without alteration, but the rear springs are considerably longer and would need new mounts on the chassis.

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I am sure that this used to be, and may be still a popular conversion to change the rear springs. I seem to remember that the ride actually improved as the 109 springs were dual rate with the lower rate being lower than that of the 88 springs. I am not sure what it does to the ride height, but I know there are two lengths of rear spring shackle as I experimented with both when I had vibration issues on my 88 series 1 so you can reduce the ride height by an inch or so. I think it has gone out of favour now due to the introduction of parabolic springs.

Toby

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I am sure that this used to be, and may be still a popular conversion to change the rear springs. I seem to remember that the ride actually improved as the 109 springs were dual rate with the lower rate being lower than that of the 88 springs. I am not sure what it does to the ride height, but I know there are two lengths of rear spring shackle as I experimented with both when I had vibration issues on my 88 series 1 so you can reduce the ride height by an inch or so. I think it has gone out of favour now due to the introduction of parabolic springs.

Toby

Changing shackle lengths without altering front mount heights screws up the diff pinion angle, which screws up prop shaft geometry and causes vibration problems. On the front, it can cause the front UJ to bind, and will also cause the steering castor angle to be changed, altering steering loads and stability. It's basically a very bad practice, so bad that an LRO technical editor recommended it in the magazine. ;)

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There are actually three lengths of Spring shackles.

I run 1 tonne shackles (the longest) you just need to grind the pads on the front axle tube to correct the castor angle. Not difficult to do.

On the rear I've found no ill effects from leaving the pads standard. I've run this set up now for many years.

Jon

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88", Jon? For some bizarre reason, 88" drivers seem to get away with it while 109 drivers don't - my UJs only last 500 miles several times before I went back to the standard shackles, which cured the vibration problem and transmission damage. I still recommend against it on 88s; while the vibration with that prop length and angle may not be obvious to the driver, the unequal UJ deflections will still be hammering the system and accelerating wear or damage.

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