My thoughts on shocks and suspension.

Venom · Post by **Venom** » Thu Jun 26, 2014 12:33 pm

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. We're left discussing HD or standard springs, 1" or 2" strut blocks or body lift. It's kinda chicken feed stuff. Yes yes yes, it's IFS shit 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 shit 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.

Venom · Post by **Venom** » Thu Jun 26, 2014 12:52 pm

Found these which seem pretty cool, ride height and travel adjustable! Seems like a really good price too.

http://mcasuspension.com/blue-series/

Venom · Post by **Venom** » Thu Jun 26, 2014 4:10 pm

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.

vincentvega · Post by **vincentvega** » Thu Jun 26, 2014 6:14 pm

I was going to suggest you talk to Murray Coote (MCA suspension) but I see you found them on your own.

He does the suspension on Brumbyrunner's race car. You should talk to him about some long travel struts that do without your strut top blocks.

brumbyrunner · Post by **brumbyrunner** » Thu Jun 26, 2014 6:45 pm

Be prepared for two and a half grand for one front strut.

Venom · Post by **Venom** » Thu Jun 26, 2014 11:34 pm

Well I'm not going to drop 10g's on a set of shocks. I'm sure they'd be ****ing awesome though. If i was investing that much may as well go with the 114.3 stub axles for stronger bearings, custom swing arms with maybe some extra track width and flares.

brumbyrunner · Post by **brumbyrunner** » Fri Jun 27, 2014 12:39 am

You're on the right track though Venom.

Wheel travel in an IFS car is limited by the CV joints. There is very little extra droop (rebound travel) to be gained over the factory settings but f you want to run the CV angles right to their maximum, you can gain a small amount of travel here.
As you assume, quite large gains in wheel travel can be found in compression (or bump travel). If you completely remove your front strut and cycle the hub by hand through it's range of travel you'll find your measurements will almost double. The problem in ustilising all that travel, is that at full bump, the front of the car hits the ground. The way to fix that, is by larger diameter tyres, but then you run into packaging issues with the tyres not fitting in the wheel arches. It also raises problems with legalities and, especially with a Subaru, drivetrain strength.

You found your Liberty front strut has about 145mm travel. The MY & L series are closer to 125mm. The Brumby I race has 255.

YouTube · Post by **El_Freddo** » Fri Jun 27, 2014 5:54 pm

^ Some great info in there Stuart!

brumbyrunner wrote:You found your Liberty front strut has about 145mm travel. The MY & L series are closer to 125mm. The Brumby I race has 255.

^ That last bit is awesome!

While we're restricted in the articulation of our subarus my idea is to make up for that articulation with use of traction aids. This is why I believe that a manual locker up the back and some form of LSD up front would be the easiest solution IF a rear locker was to become available.

There will be situations were more wheel travel up and down (down especially I reckon) would be a good advantage but from what I've seen so far, with the pretty serious 4wd'n we've been having a go at, I reckon a front LSD is the best step forward followed by a rear LSD as well - both are easily available at the moment.

I know you've got both diffs with LSDs and you're itching to get a bit more out of your setup, but I also reckon you're avoiding your study

And why not if you've got a garage like that!

Cheers

Bennie

AndrewT · Post by **AndrewT** » Fri Jun 27, 2014 7:22 pm

Yeah we can make up for it somewhat with traction aids....don't forget the centre diff too ElFreddo

Also remember the other key factor - driver skill and technique! I rekon Suby drivers end up being more skillful that other "real" 4x4 drivers when offroading. Due to the (let's face it) much lesser ability of our cars in many offroad situations, we end up honing our skills such as throttle control, speed control, choosing the best line to take etc.

As mentioned, hard to get a lot more articulation out of our cars with different shocks/suspension when it may just result in ruining CV joints anyway. I do agree that even the little 1% and 2% advantages here and there do add up though.

Venom · Post by **Venom** » Mon Jun 30, 2014 9:54 am

Whats to stop me putting rear shocks up front minus lift block, should be about the right length? apart from the top camber bolt but that shouldn't be too hatd to work around.

YouTube · Post by **El_Freddo** » Mon Jun 30, 2014 2:51 pm

Venom wrote:Whats to stop me putting rear shocks up front minus lift block, should be about the right length? apart from the top camber bolt but that shouldn't be too hatd to work around.

Dunno mate, it would be interesting to find out. My thoughts are that the hub bolt pattern at the base of the strut will be different to stop people from doing this.

I've often wondered about trying to do the same to the rear of the L. I still reckon an airbag system I haven't designed yet would work best for what I want.

Cheers

Bennie