Suspension clunk when articulating.

Hi I have a gen 3 2014 Jimny. I have a lot of mods done and won’t list them all as this is about the suspension. 

I have the black raptor 4” lift from Jimny bits. I have the castor corrected radius arms for the 4” lift and adjustable panhard rods with poly bushes. I changed all the other bushes with the Jimny bits ones that are like factory ones when I did the lift a few months ago. I have a 25mm prop shaft spacer on the front and a 10mm on the rear.  I have extended brake lines all around and I’ve extended the abs wires and diff breathers and also the vacuum lines for the hubs. I have the black raptor winch and the Jimny bits winch plate with a dessol4x4 front bumper for extra clearance(mentioning for the extra weight). I have Enki -35mm offset wheels with 235 75 15 mud tyres, they only just touch the body a little bit at max articulation. 

The issue I have is when rear suspension goes to max flex one way it clunks loudly. Then if you reverse back over the same thing it wont clunk. If you turn around and flex the suspension the opposite way it’ll clunk again. It’s like there’s a bush snapping into place or something. It seems to be coming from the rear but there isn’t anything obviously wrong. All the bolts are tight and nothing seemed to hit or bind. 

Does anyone know what this could be? There are other heavy things on the car like a bash plates and a roof rack and canopy, light bar and other heavy things. 

This may be a problem with your bump stops. I would suggest you simulate max. flex by use of a jack and then load the same side to get the axle to touch the bump stop. If it won't touch, then your shock is at maximum depression and the clunk could be the shock bottoming out. If this is the case you need suitable spacers to extend the bump stops. If the deflection does touch the bump stop, then measure the shock from eye to eye - or eye to spindle - remove the shock and measure full compression and compare measurements with previous. When the bump stop comes into play, you need a little freeway to allow the stop to absorb the full suspension movement.

Roger

Thank you for your reply. I just had a look at that and the shocks have about 2cm more to go before bottoming out when the axel hits the bump stop. I was hoping your suggestion was the issue as it’s an easy fix. I did find one torn bush on on the side the sound seems to be coming from. I’ll have to replace it. I wonder if poly bushes would be better instead. 

Is it the rear springs moving on the bottom (axle) spring cup?
I had this annoying bang on ours (ok it's standard) and it turned out to be the above. Rust / crud was making the spring tight on the cup, pot holes or flex would make it all "bong" as it moved around. A shot of oil on the top/ bottom cups confirmed it, subsequently cured by knocking the rust / crud off and a coat of oil. Real pain to find as it was never consistent, what made it bang one day wouldn't the next.
Simple one to check.

Sounds normal to me. Bigjimnys suspension will click & clunk when offroading. At least I tell myself it all sounds normal I hope

wrote:

I wonder if poly bushes would be better instead. 

It depends on where the bush is fitted.

As a general rule, poly bushes are quite a bit harder than rubber and they will limit flex - I would not want them on a radius arm suspension like the Jimny has.

I had this clicking sound recently. Allways had the spring slipping in the seat sound on full flex but this was different as it was clicking when the load shifted from side to side before full flex. I too have recently had the radius arm bushings changed. Seems that I did not tighten the bolts enough so the holes in the rear axle bracket was worn. Made some washer with the correct inner diameter of 11.8 or 12mm and welded them to the outside of the brackets before tightening the bolts very hard.
Noise gone now!

I will never use any poly bushings again if I can avoid it. They wear out too fast from sand and are way too stiff.