Dislocating Spring / Bump Stop Idea

An idea I had the other day and made a sketch of it… a way of letting the standard Jimny front springs dislocate with the long Grand Vitara shocks I’ve got in stock for this build… (same front and rear as I’m using two narrowed Jimny front axles).

Before I reveal my sketch I must admit I was obviously inspired by this sticking in my mind…

This is from my good friend and greenlaning cohort Riccy’s ”Ulysses” awesome pickup build, this is a Terrafirma air bump stop mounted where the standard Jimny bump stop is usually located… See how the bump stop is on a piston full of air to give some cushioning rather than a fairly hard rubber bump… Ok, mix that into my sick mind, and you get…

Obviously very similar, but the idea is to have one tube inside another -note the grease nipple – so that as it drops it allows the spring to dislocate from the seat until the top ”stop” lands on the top of the outer tube, that allows the spring to travel down only as much as I want until the shock absorber almost reaches it’s full extended length (the ones I’m using are rear Grand Vitara ”Black Raptor” own-brand shocks from JimnyBits which are 29” extended and 15” closed, so that’s 14” of travel available, probably too much, but this proposed setup should limit up and down travel.

Ok, that’s the droop, on upward travel the spring – with the spring clamp on the end of the ”piston” and held in place by the threaded rubber bump stop – will close the piston fully (the inner tube will protrude up through the outer tube) and return to the rubber seat, and will then be compressed until it reaches the bump stop rubber cone… Some experimenting will limit the up travel such that the axle comes to the bump stop before the shock gets fully closed and the piston inside the shock would ”top out” and damage the shock… in reality this would probably never happen with 14” of shock travel available.

Again, remember this is all being built on a tight budget using home engineering and cheap readily available and easily replaced (Suzuki / Jimny) parts I’m used to working with… I did look longingly at Fox Air shocks, but i bought all four springs and shocks for less than one air shock…

I posted this idea on the BigJimny discussion board and a fellow use Lambert suggested added a smaller diameter helper spring inside the main spring to push the main spring down under downward droop! Great idea mate, I’ll have a go at that too 🙂

15/04/22 photo of stock front suspension added for compaiison –

Updated 19/04/22 – I spotted these cheap on eBay –

and got them for £22 including postage…!

2-25” internal diameter coilover springs, three at 5.5cm and one at he 6.5cm which I can soon trim down to the same size as the others… Ideal helper springs as they’ll fit nicely over 2” rollcage seamless tube! 😉

Updated 20/04/22 – After some discussion about “spring rates and the anticipated final weight of the buggy”, I’ve changed the initial sketch to –

… hoping the 5.5” springs will compress to around 3” when the buggy is at rest. When I originally zoomed in on the eBay listung photograph they look to be wound from around 8mm diameter wire and the coils look to be about 20mm apart. I need them to ”push” the top seat of the main suspension springs down at the point of dislocation, so they need to be fairly sturdy.

So I pointed out on the forum that these just popped up at the right price, they’ll be fine for experimenting, and that this sort of mulling over ideas is keeping me sane having been in hospital(s) for nearly four months, and subsequently when I do finally escape from hospital and recuperate, and then finally return to the man-cave for some well needed spannering…

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