Suspension Issues

[Nath 1,975]

So I've been trying to sort out the fact that going over a bumpy road in my XD is a spinal injury waiting to happen...

 

Current suspension specs are:

 

Front:

Kings Low Springs, crappy old rubber spring pads, Monroe GT Shocks, Nolathane upper and lower control arm, old rubber spring saddle bushes

 

Rear

Stock Leaf Springs, 1.5Inch lowering blocks and shitty old rubber bushes, Monroe GT shocks

 

Biggest sway bars I could get my hands with all Nolathane bushes too.

 

Even though I'm still yet to do a few of the bushes, it corners really, really well.

 

I just did what really needed doing for roadworthy as I was on a deadline, but now it's about time I worked out some of the gremlins. I cut the bump stops at the front as there wasn't much clearance (about 2.5cm) and that helped, but there's still quite a bit of jarring and you feel absolutely everything. Goes over speed humps and even some potholes very smoothly but as soon I hit even a slightly bumpy road I'm expecting the screws to fall out of my dash and the glass to crack.

 

I know Nolathane makes the ride harsh but it's just ridiculous at this stage, no way that's the only issue. In hindsight I think I'll do steering and sway bars in Nolathane, and anything that involves up and down in rubber... But for now I'm stuck with what I have so I need to look at other stuff.

 

I heard Kings were like 15% harder than stock springs or something so maybe that's a big part of it... Would it be worth swapping them out with pedders?

Should I be looking at the shitty old spring pads and saddle bushes at all?

 

 

Also, on a slightly less urgent note, I also get pretty brutal axle hop under very hard braking or stupidly tight/fast corners. Not really an issue in everyday driving but I'd like to fix it nonetheless. I know the lowering blocks probably make it worse. Someone mentioned tramp rods but I'm not sure where I'd get a set (next to the rocking horse shit and unicorn meat at woolies?).

 

My spine, and the screws in my interior would be grateful for any advice.

[NZXD 2,328]

Most vehicles including very expensive machines that handle really really well have a harsh ride, some really harsh.

 

So some of what you are experiencing is out of your control, and part of a lowered and better handling car. You just have to sacrifice some comfort.

 

I once got to ride in a Ferrari 430, and on a smoothish road it was really hard riding.

[Nath 1,975]

I get that it'll be a bit harsher but is it seriously meant to rattle the glass and send shit flying everywhere on anything except the smoothest of roads?

 

What gets me is that it goes over potholes and speed humps ok but as soon as the bumps and small stuff starts it's like driving a washing machine.

[Mr Polson 10,214]

Are your front shocks to suit lowered suspension or normal?

If normal, that's going to be a big part of your issues. My ute used to be the same, ultra harsh, and once I put in lowered shocks it helped a lot. Also cut the front bump stops in half if not a little more.

[Nath 1,975]

I'd assume they were meant to be paired with the springs as they were sold together with them...

 

Doesn't feel like the shocks are bottoming out, although maybe they're too stiff so they don't do much on the little bumps?

 

I cut the bump stops about in half and it helped a lot. Went from "holy shit I just put the control arm into the engine bay" to "well that sucked" when you hit a pothole.

[Outback Jack 6,352]

Just the price ya pay for lowering shit as NZXD said. I have had some lowered cars but all have had standard tyre sidewall height , low profile tyres make it even worse.

Hope ya can fix it.

 

Jack.

[SLO247 1,713]

Must be the shocks, and the bushes contributing.

 

In my ute I ran SL coils in the front with standard pedders comfort shocks. Rode really well and never bottomed out. I didn't trim the bump stops either.

 

Softer shocks should sort it but you may lose some handling? I haven't heard much good about Monroe shocks for years.

[wagoon 2,429]

Nzxd hit the nail on the head, if your car handles the corners really well you have stiffened up the suspension/chassis to a point where it no longer rolls and is rigid. This the transfers in the harsh ride and small bump response. If you have every watched top gear where the guys drive super cars on the road and you can see the pain in there face when they drive over bumps and hear the bang in the camera microphone.

Now the fix is a combination of a lot of things.

First I know your tyres aren't the best and it sounds like they are a harder compound so what pressures are you running day to day? Dropping a couple of pound will make a difference and if you have hard wearing tyres they shouldnt wear to fast if only drooping a few pound.

Second is your leaf springs. How old are they? Why you put blocks in you are changing the spring rate of you springs. Leaf springs are a progressive rate spring but are opposite to coil springs, leaf springs are firmer at the start and softer as they move. So by putting in lowering blocks you have changed the shape of the spring which means that you are increasing the firmer part of the ride and have create a heavy duty setup to a certain point. This is the small bump harshness you speak of but big bumps and speed bumps are fine cause they compress the spring past the firm section into the softer section of movement. My 60 series landcruiser with leafs springs from and rear was exactly the same some one had put in lovell heavy duty leaf springs and the ride was stupid harsh over small bumps but over bigger bumps it was actually a smoother ride, take it off road and it almost felt like your were driving on a cushion.

Next is the bushes, nolathane are the hardest polyurethane bushes superpro are softer. So when you go to replace the nolathane when they crack and break from being so hard you can put in the superpro bushes then. It is also a good idea to have a mixture of rubber and polyurethane bushes like you said if you put polyurethane in the wrong spot it makes the car very bad. I would look at the spring saddles and spring pads as if they are crappy rubber they are no longer supple and will give a harsh ride because the rubber can't take up the bump and just passes it through to your spine.

Lastly the shocks, don't ever assume that if someone is selling low springs they are including short stroke shocks. Basically when they make short stroke shocks they change the time it takes for the valves inside the shock to work making them respond faster so they can control the body response over a shorter travel distance. Standard height shocks take to long to control the bumps and allow the body to come in contact with bump stops more often, and the standard shocks won't always bottom out. The shocks wont be able to react fast enough over the smaller bumps but over a bigger bump they are travelling through there stroke further and have more of a chance to control the bump. Short stroke shocks in themselves won't make the car ride more harsh, it comes down to the valving inside and how it is setup. You could get bilstein shock rebuild to suit a really low car but get the shocks valved to feel standard but don't forget the lower the springs the harder the spring rate because they also have body control and have to work over a shorter travel.

But it all comes back to then very first sentence, if it handles it will be more harsh.

[Nath 1,975]

Good posts guys.

 

I was under the impression that it could be a combination of 3-4 different things causing the problem, which means I can improve it a bit. Cutting the bump stops helped, for example. I will try dropping the tyre pressure a bit.

 

The car still has body roll but it's quite minimal. Feels really good through corners.

 

The back I don't really give a shit about. It's going to suck regardless because it's leaf sprung. Besides that I'm not one who has to sit back there so I really don't care

Since you asked, the leaf springs are old but only have about 90,000km on them. I was hoping to be able to do more about the axle hop than the ride quality at the back.

 

I think it might be both the gas shocks not compressing enough over small stuff, and the springs being too stiff. Might see if I can find a decent second hand set of each and see if it makes a difference...

 

Cheers guys.

[wagoon 2,429]

I was under the impression that it could be a combination of 3-4 different things causing the problem, which means I can improve it a bit. Cutting the bump stops helped, for example.

Cutting the bumps stops helped so much because it gave the shocks a little more travel to work but being standard height shocks they will still not be able to cope with the short travel distance. The only way to fix it is to buy short stroke shocks. Jump under the car and see if you are still hitting the stops. This will tell you if the shocks are not good, if your not hitting the stops then your springs are hard and the bushes arent helping

 

 

The back I don't really give a shit about. It's going to suck regardless because it's leaf sprung. Besides that I'm not one who has to sit back there so I really don't care

Since you asked, the leaf springs are old but only have about 90,000km on them. I was hoping to be able to do more about the axle hop than the ride quality at the back.

The back is probably the most important end to focus on. Those leaves are original and regardless that they have done 90,000kms they are old, in fact because the car has only done 90,000kms may well be the reason for the back end issues because that meant that it sat around for a long period of time. Spring steel has a memory it will always spring back to the position it was set in, if the car has sat for long periods that places a constant load on the springs but since it is not moving that constant load never changes so over time it can actually reset the springs. Then when you put in lowering blocks you are changing the working range of the springs as described in my above post. This would be contributing to the harsh ride just as much as the front.

 

Dropping your tyre pressure is really only useful if you have no choices left or a short term fix. But even then it will only work if you are running high pressures already. For example if you are running 36psi then try around 30-32psi. If you running 32psi already then dropping past 28psi for an everyday driver is not a good idea.

The other thing that hasn't been mentioned is you seat, if the foam is not the best your going to be feeling a lot through the seat and fixing this may make it bare able till you fix the shocks

[broken-wheel 659]

get some Koni's, the price will be forgotten in the first 5km

[Nath 1,975]

Found some tramp rods/hens teeth.

 

Will these mount right up or are there parts missing? Was a bit hard to hear over the phone but he said something about using U bolts.

 

http://www.gumtree.com.au/s-view-details.html?adId=1076442733

 

Not gonna lie... No idea how the hell that is supposed to mount. Isn't it meant to have a bush either end?

[NZXD 2,328]

 

This is a picture I got off the Google man.

[Nath 1,975]

There is no way that's even halfway legal on the road...

 

I thought that they connected to a bracket thing on top of the U bolts holding the axle, and that the other end went through a hole in the chassis.

[NZXD 2,328]

Yeah nah, the just fix to the spring. Surprisingly they work to a degree.

[NZXD 2,328]

You can buy them new and cheaper through summit in the USA.

[Nath 1,975]

Ahk. My understanding of it was that the axle hop is caused by the spring twisting, so stopping that will stop the hop.

 

 

I'm pretty sure the rods in that photo wouldn't be street legal... Hanging down wayyyyy too low. Will look into summit though.

[NZXD 2,328]

Yeah the stop the spring winding up.

 

A mate has them on an XW, and they work.

[broken-wheel 659]

that's so fucking agricultural..... i would not use that, what you got there it's called "slapper bars"

 

here you go, this is how it's mean to look like

 

 

 

 

 

[Nath 1,975]

Nice! That looks way less ghetto than the other picture.

 

Could be wrong but I think the rule is that you can't have any suspension components hanging lower than the outer edge of the rim.

[NZXD 2,328]

Yes those look a lot better, search caltracs, think they are a bit of coin but the best design.

 

You could also get new lowered king spring leaves, part of the reason you could be getting wind up is due to the age and quality of the original xd springs.

[broken-wheel 659]

yeah, well on the watts link rear end in the XE/F the lower control arm is just as low as in the pic above, the slapper bars are not legal afaik

[Nath 1,975]

Yes those look a lot better, search caltracs, think they are a bit of coin but the best design.

 

You could also get new lowered king spring leaves, part of the reason you could be getting wind up is due to the age and quality of the original xd springs.

Yeah no doubt. The lowering blocks probably don't do much to help either.

 

Probably will end up getting new rear springs at some point anyway, but if I can fix it for 100 bucks as opposed to 600 that'd be cool.

[broken-wheel 659]

don't the springs from AU waggon and Ute fit? or at least a few leaves so you can re-do yours? would cost fuck all

[NZXD 2,328]

The main spring won't fit from wagon or ute, the rest could do but would depend on centre hole placement.

 

I wouldn't bother about the old school traction bars.