My thoughts on shocks and suspension

Venom

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So the whole suspension setup is something I have been contemplating for quite some time. It's definitely one of the most offroad capability related aspects of the vehicle, and also one which probably has the least number of options (****ing none, choice of shock brands doesn't count). Any "real" 4WD has a huge number of aftermarket choices for shocks, travel length, springs, sway bars, body/suspension lifts etc etc. People choose what suits them and their vehicle. It's probably one of the first things people modify after their tyres, and realistically one of the easiest. As a Subaru owner we just don't get that. Too many vehicle, modification and use variations in too small a market. It's a serious hole in the choices for vehicle modification for Subaru offroaders. Yes yes yes, it's IFS **** articulation blah blah blah. True, she ain't gonna flex like a Cruiser but surely there are cm's and maybe a few inches to be gained in travel. Potentially important considering that you are starting with small numbers in the first place.

So observing and thinking about my vehicle I've noticed a limited bump/compression, especially in the front. Next question is what is limiting travel? Cycling through my suspension today (with springs in the shocks) gave the following numbers:

With front sway bar connected, no rear sway bar (my setup for a while)
On the ground (resting height): 460mm front and rear.
Fully compressed: 420mm front 385mm rear.
Full droop/extension: 545mm front 550mm rear.

All measurements are height from centre of castellan nut to the top of the wheel arches directly above.

145mm total travel in the front and 165mm in the rear. 40mm compression in the front and 75mm in the rear. Up front at full compression there is 60mm to the top of the wheel arch. Compression up fronts seems insufficient, even for just driving around on the roads.

With the front swaybar disconnected I didn't gain any increase in travel, so we can rule that out as limiting the front travel. Good to know too.

My thinking is, normally with a full 50mm body lift kit there shouldn't really be any change in suspension geometry or travel. Except maybe the rear if you have the rear swaybar connected as the mount points on the body change by 50mm. I don't so I'll disregard that from now on.

However I do have outback shock absorbers and these are a 25mm longer strut, although same suspension travel. The factory outback has 25mm lift blocks to compensate and for arguments sake maintaining factory suspension geometry. In my vehicle this is in addition to my body lift, changing the suspensions position relative to the body by 25mm.

I'm assuming the front shock absorber has become the limiting factory in the compression of the suspension cycle. Why? By adding the 25mm longer struts without compensating in the body, the swing arms etc at their resting position are actually drooping by the 25mm. Considering that is relative to the stock suspension they should actually have 25mm MORE compression in their suspension cycle. We can rule out the swaybar too since I disconnected it.

What I'm thinking this also means is that there is at least 25mm of unused compression travel in the suspension. Cut down the bump stops? Dunno I can't remember what they look like. Probably not smart to remove them completely. Could be a really easy way to gain more compression in the front.

Another option and what I would really like to do is remove the strut top blocks, and fit 2" longer shocks. Limiting factor there is the size of the strut body and having enough room to adjust the camber/caster without hitting the strut tower. So this kinda rules out modifying factory shocks and would probably require a coil over setup. Off the shelf coil overs won't eliminate the strut top blocks. Up front the wheel arches will take 50mm more compression. Camber can be further compensated for with adjustable strut tops and lower camber bolt. So alignment shouldn't be an issue. Rears I probably wouldn't touch as they have more travel and don't have much room for more compression anyway. The problem of course is as far as I know nothing like this is available off the shelf.

What would be ideal is a coil over shock with an adjustable lower strut perch mount. That way it could be bolted into a range Subarus with different mods and adjusted to the specific vehicle. Then have an oversized bump stop that could also cut down to suit the vehicle. As long as the spring diameter is a standard coil over one there should be many spring lengths and rates to choose from which should suit.

That seems like a decent idea to me, and potentially commercially viable for someone to organise. Maybe not profitable but perhaps cost neutral with the benefit been **** hot shockies.

Anyway, interested to hear peoples thoughts/opinions. Would anyone be interested in a set of shocks like I've described above? Not pie in the sky yeah sounds great I'd love some, but seriously wanting to fork out money for a set of purpose built rebuildable shocks. These would last the life of the vehicle as they are serviceable, so higher initial investment of course over a set of factory replacement struts.
 
Maybe chat to Murray or Josh at MCA Suspension.
 
^ ^ Gidday Venom

That's an interesting analysis, and a pretty thorough write-up, mate.

While I have almost zero interest (or knowledge, FTM ... ) about the problem and solutions, I will offer one piece of advice - don't muck around with bump rubbers/stops!

IME, they perform one of the most important functions in the suspension - when all else fails, and the suspension is about to badly damage something, either body parts or suspension components, it is the bump stops/rubbers that make it a (relatively) soft landing.

One of the cars I owned for a long time (Austin Kimberley) had the BMC Hydrolastic suspension. It was a fantastic system except for two major design flaws (not counting that the rear D/S engine mount attachment flange was spot welded to the displacer housing, so required de-pressurising the suspension and removal of the displacer before welding it up - until the next time it broke! The engine mounts were also grossly inadequate to the task).

1) The Hydrolastic displacers were only 6" diameter. This was fine in their lighter bodied cars, but grossly inadequate for the heavier Kimberley with its straight six, mostly cast iron engine ... Should have been 7-7.5", at an educated guess.

2) The suspension travel was limited to about ±3/4"!! This gave the bump stops a very hard time, and they were tiny little things to start with ... UGLY :puke:.

I spent a lot of time over the 160,000 miles I did in this car replacing displacers and/or displacer connection pipes, and the itty bitty bump stops which regularly got smashed up on the front in particular.

So I wouldn't muck around with the bump stops, if I were you ... :iconwink:.

Suspension tuning and modification is best discussed with the people who are expert and very experienced with all the factors involved, as Rally has already said. I concur.
 
To be honest I am happy with my current setup for my needs. I like the idea and have some input (when I get to a computer and off my phone).

I find the KYB replacement shocks with my dobinson coils adequate. It carries my weight well and has enough articulation for the majority of my ofrroading. The biggest issue I find is that after around 60, 000km of touring and general offroad work they are fairly worn out. At the time (12 months ago) I just replaced them wiyh another set of KYB's.
 
Yeah look my current suspension setup is good, it does the job. I certainly don't have any complaints about it per se, except what is inherent in my setup with the extra 25mm and that's not the shocks fault. The lack of choice is frustrating. I guess what I'm looking at is the the next step up for offroad ability while still maintaining driveability. My plan is to keep my car as well, so long term a set of rebuildable shocks should be cost competitive (given the value of better performing suspension).

The potential is there, just not the parts.

The other thing to consider is with some adjustable struts, it could be possible to wind down the 25mm in the struts for day to day use then wind it up when needed. Although obvious problems there with suspension geometry changes, but shouldn't be an issue if its reset to normal to hit the tarmac for longer distances. That would also save driveshafts/cvs as well.

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Jacked up just enough to lift the other wheel off the ground. Probably scope for more compression in the rear too, but definitely up front.
 
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Venom, I'm meeting with my suspension guys tomorrow to look at Koni insert options.

I will see if they have any views on coilover setups.

I looked at them a few years ago but couldn't find anyone who actually knew anything about the product they sold or if they did didn't have a coilover with adequate travel.

From what I understand is any coilover that is within my price range is unlikely to be durable enough for what we ask of them. The bottom half of the aftermarket industry is aimed at the "stance" crew and only really suitable for "hardparking".
 
From what I understand is any coilover that is within my price range is unlikely to be durable enough for what we ask of them. The bottom half of the aftermarket industry is aimed at the "stance" crew and only really suitable for "hardparking".

Is that hard off-street parking? :raz: :lol: :rotfl:
 
Venom, I'm meeting with my suspension guys tomorrow to look at Koni insert options.

I will see if they have any views on coilover setups.

I looked at them a few years ago but couldn't find anyone who actually knew anything about the product they sold or if they did didn't have a coilover with adequate travel.

From what I understand is any coilover that is within my price range is unlikely to be durable enough for what we ask of them. The bottom half of the aftermarket industry is aimed at the "stance" crew and only really suitable for "hardparking".

The Koni inserts look cool, and if you don't cut the 40mm off it then it would probably be about a forester strut length overall??? I'd be interested to know if they give any additional compression or droop.

Really a coil over could be built to suit anything from drifting to rally. It's just travel, damping/rebound, spring rating and length etc etc. Like you say the entry level stuff is all about lower. Top end stuff is really pricey. Either way they would need to be setup to suit the car, as they should be anyway!

I'll try to have a chat to someone at MCA suspension tomorrow.
 
I am a little surprised that you didn't get better results by disconnecting your swaybars. It made a huge difference to my Forrie. It might be the HD springs in your car, as mine has Gen2 liberty front coils in it. The raised King Springs I had were too hard and too high and the strut would top out driving on the street.

garrettG got some longer struts made up by Hotbits for his car. I have been meaning to ask them if they can do similar for us in Aus.

https://offroadsubarus.com/showthread.php?t=2599&page=10
 
Yes I find disconnecting the swaybars I gain a good 3-4 inch each wheel in droop and around 2" compreswion in the rear. A little less up front.
However running 4.5" strut in the rear and 3" in the front it isn't really droop, as the suspension is always drooped with the extreme lift (Soon to be rectified with a full body lift). Ive found qhen installing lift kits in all sorts of Subies that SG Foresters onwards have very little rear suspension travel. Same with gen 3 onwards Outbacks due to the multi link suspension.
 
I actually only have standard height king springs, not sure a softer spring will net me any more travel as I don't have an coil bind at all. The suspension style of the Gen2 lib which was pre rear multilink might explain the differences with the sway bar gains.
 
Hmmmm, I have some Proflex coil overs with 22 cm stroke front and 25 cm rear, no more sway bars and some soft rated springs, 31 N/mm 420mm length front and 27 N/mm 500mm length rear. The rear has 2 springs per shock because of length issues and are rated 2x harder, because each spring compresses for its own ( ex : 2x 60 N/mm 250 mm length is the same as 1x 30 N/mm 500 mm length)

Soft springs is not an issue on road because the hydraulic can be stiffened but if you put a lot of load in the trunk, the rear will drop…but you can adjust the spring perches height. I always have the minimum weigh in my Foz, thus the 27 N/mm rear springs, but you can put stiffer springs if your Sub is always heavily loaded without loosing stroke…

Now I'd like to find some wide angle inner CV joints (27° vs 22° oem) for a 1' more front wheel travel…still searching...

If you look my vids -Auvergne, France- in the trip reports, you can see the suspensions work versus oem Foz's and other big fourbies.

But in the next future, I will change my Proflex coil overs because they are designed for rallying and are a bit harsh for everyday use...
 
Petter Solberg, when he drove for Subaru, said the suspension in his WRC car was softer than in the road going STI. So, for 2008 Subaru softened the STI suspension (which everybody hated) because the rally car had very sophisticated suspension and the road car did not, so it didn't work like it did on the rally car. Plus, rally cars spend most of their time on gravel stages. Anyway, if you have suspension with sufficient bump travel then it may be a matter of re-valving the Proflex and experimenting with spring rates- they both need to be done together. Or it may mean swapping over the suspension when doing off road work- which is what I do.
 
I dont have the money so I couldnt do it, but i love the idea of longer travel struts, whether coilovers or custom.

Subarus have 2 bad limitations when compared to 4WDs. No lockers (although locking centre diff & front/rear LSDs partly overcome this) and poor articulation. We just cant cruise through deeply rutted tracks like the fourbies :(

Up front, with the LCA disconnected from the hub, there's only about 2" max more droop in the LCA. This is with raised springs & 2" strut tops. There would be a lot to gain in compression though.

You won't need to cut down the bumpstop, as its length will be determined by the length of the piston and the strut housing. Its purpose is to stop the bottom of the piston touching the bottom of the housing, if it doesnt do this the piston can blow out the bottom of the strut on a hard bump!
 
Hmm, should I pull my 37mm blocks get longer struts for more travel but lose my awesome camber / caster correction? I can fit camber plates. The guys can weld on threaded sleeves to turn the Factory struts into coilovers. Bonus being that there will be heaps more tyre clearance.
 
Stilson, when saying heaps more tyre clearance, is that in terms of Height as in profile?
 
Petter Solberg, when he drove for Subaru, said the suspension in his WRC car was softer than in the road going STI. So, for 2008 Subaru softened the STI suspension (which everybody hated) because the rally car had very sophisticated suspension and the road car did not, so it didn't work like it did on the rally car. Plus, rally cars spend most of their time on gravel stages. Anyway, if you have suspension with sufficient bump travel then it may be a matter of re-valving the Proflex and experimenting with spring rates- they both need to be done together. Or it may mean swapping over the suspension when doing off road work- which is what I do.

Yes, the spring rates and hydraulic valving have been made together, but there is also some friction issues between the shock absorber (inverted) and the strut, this part has to be lubricated quite often…

Rally top mounts don't have rubber and actually don't absorb any little shock, you can count each gravel !
 
More clearance between the tyre and lower spring perch as the adjustable perch is smaller than the fixed perch.

Yes, but you will be limited by the wheel arches and too big tires will stress the transmission….but ok for the look :iconwink:
 
Lift blocks are leaving to make way for longer struts and more travel.

@jf1: I have 1mm of clearace at the moment, I see no disadvantage to increasing it.
 
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