Rally Front Suspension

[MattWatson]

Hey All,

So now that the 85 is finished, I can start to focus on the '86 and getting it prepped into a super mean rally car, meaning it will be decently cheap (say under 10k or so) and handle decently well. The plan is to start out with a bone stock motor except for T5 to keep everything simple.

So on to suspension.

There are a couple questions I had just by looking at the suspension and wondering a couple things:

Coilovers seem like a bit of a waste of space, but ultra cool. Running small diameter springs limit travel and then you are sticking everything on top of the top wishbone, so your shock end could also end up being the limiter of travel. Luke, when you did this, you extended up the spring perches in order to bolt through the coilover and gain as much vertical space as possible correct?

What about something like leaving the shock out of the equation totally, and just extending up the spring perch, but designing it similar to the stock one (eg, the spring seats up as high as possible)? You could then fab up a stronger lower shock mount, and continue to mount the shock the same way it is now, which would gain you 8 inches of extra shock body length, and you would be able gain a few inches of coil length for droop, but be able to also use say a 5" spring to allow the spring the extra travel.

Does that even make sense, or am I smoking something funky here?

Luke, on your coilover setup, are you pretty much pushing the bounds of travel with the car anyway?

In my mind, hypothetically you would have a helper spring/section for droop that would only really be in play for those situations, a section/spring for regular use, and then a spring that came mainly into play during bottoming out scenarios. The last two would then have to be sized appropreatly so that you got the rate you needed throughout normal use, then ramped up during bottoming out.

Thoughts arguements etc? Or just use SPG springs and deal with it?

[jdwertz]

Here is what I have been working on. Should only need to come up with a solution for the bottom ball joint. I will be removing the top control arm all together and cutting/welding in a flat box for the top spring perch. BTW these are 9k knuckles...

[Mezzanine]

Here is what I have been working on. Should only need to come up with a solution for the bottom ball joint. I will be removing the top control arm all together and cutting/welding in a flat box for the top spring perch. BTW these are 9k knuckles...

Pardon my ignorance, but what do you gain going to the 9k knuckles? Are they significantly lighter? Not trying to knock you, just curious what you gain for a not insignificant amount of work.

[Luke]

Luke, when you did this, you extended up the spring perches in order to bolt through the coilover and gain as much vertical space as possible correct?

Correct, by pushing the upper mount up to the level of the bottom of the hood, there's just enough space for a 6" stroke shock and a 14" spring (you typically need at least twice the shock travel in spring length to avoid coil bind.

Luke, on your coilover setup, are you pretty much pushing the bounds of travel with the car anyway?

Yep, we've pretty much maximized what is available in the basic design. Actually I use heavy nylon limit straps to keep the suspension from drooping too far, and we also cut out the upper a-arm lower rest and clearanced the lower opening for the axle shaft. Its basically at the point where other things would have to be pretty heavily redesigned to get any more travel.

[jdwertz]

Here is what I have been working on. Should only need to come up with a solution for the bottom ball joint. I will be removing the top control arm all together and cutting/welding in a flat box for the top spring perch. BTW these are 9k knuckles...

Because I can remove the spring/top control arm and use this setup to run air struts(I know it's not most people's thing here). The advantage is to havjng the strut mount on top of the knuckle

[Crazyswede]

Be forewarned...my comments below start to wander a little as I ponder the possibilities with this design.



I think the double A arm is a more robust design than the McPherson strut. The double arm design's weak point tends to be the ball joints but even they can be an issue with the strut design. I give you Kudos for trying something different with the 9k strut setup and I think it would take less modification to install it into a 900 allowing for a multitude of coil over options. The coil over setup in Luke's cars has been through 2 full revisions with a lot of development on each. The amount of work he did to install them was substantial and if you were to pay a shop to copy the setup you could easily be looking at thousands of dollars in car prep and mod time.

You can get very long travel out of both designs but the thing you want to watch with the 9k setup is that your axles and axle travel is not designed around them. You will want to make sure there is no interference or binding. However....in thinking about this idea it would be much easier to eliminate the top arm and make a custom bottom arm that could be mounted almost anywhere and at any length.


EDIT: even further pondering results: if you are going to do all the work to install a 9k strut why not just source something even better and more common from a Subaru, mitsubishi, VW etc...something you can source any spring/strut/race/rally setup for.

[Mezzanine]

I think the double A arm is a more robust design than the McPherson strut.

This.

I have a lot of experience being talked out of hairbrained ideas by my friends, so please let me return the favor. Double wishbone or A-arm designs are so much better than Mac struts. Again, I'm not trying to be a jerk, but please...think about the children! Mac struts are so common because they allow more room in the engine bay, not because they're particularly good. They can be quite good, but not without extensive R&D.

That said, if you can make it work for you, knock yourself out. I'd second Crazyswede in looking to another strut if you're going to go through all the work.

[Luke]

Here is what I have been working on. Should only need to come up with a solution for the bottom ball joint. I will be removing the top control arm all together and cutting/welding in a flat box for the top spring perch. BTW these are 9k knuckles...

Because I can remove the spring/top control arm and use this setup to run air struts(I know it's not most people's thing here). The advantage is to having the strut mount on top of the knuckle

Not totally sure I understand what the final product will look like? There will be some sort of a box that corrects the 9000 knuckle to the 900 upper a-arm and the spring will sit on that box? or the 900 a-arm will no longer exist and a strut will replace it? The upper spring towers will definitely need to be raised to fit the 9000 strut length if that's the case, but I don't see what advantage a strut provides? The rally guys with stock struts constantly are breaking front suspension; blowing out upper bearings and mounts, bending inserts etc... A stock SAAB front suspension can survive as much abuse as the $4000 DMS,proflex,reigers special struts that most other teams are forced to use.

[MattWatson]

Luke, do you have an opinion on whether you would go coilovers again, or just go for coils and longer travel shocks?

The only advantage I can really see is that you have the ability to use tender and helper springs with a coilover that you really don't have with a free spring. I took a look around and can't seem to find any dual rate springs that would seem to me (all be it unedumacated) to work effectively in this type of setup.

Ideally, I am looking at not doing coilovers, but trying to increase travel if possible. So I am still thinking longer spring than stock SPG, but with rates to facilitate more droop travel. I don't know if a spring/shock tower extension would be needed or not considering everyone seems to use a spacer with the SPG springs to achive the proper rally ride height anyway. Anyone know of any rates that may or may not work, or is custom really the only way to go here?

[jdwertz]

However....in thinking about this idea it would be much easier to eliminate the top arm and make a custom bottom arm that could be mounted almost anywhere and at any length.

This is my idea. I haven't been able to express my plans very well as I'm typing on my phone currently. I will be removing the entire top control arm and spring and making a custom lower control arm to adapt the 9000 ball joint. The spring perch will be reboxed to accept a strut/coilover.

I will not be using 9k struts. The whole purpose of this is for me to gain the lower strut mounting point on the knuckle. In my opinion this makes a coilover setup a hell of a lot easier than having to make serious modifications to the body like Luke has done and it gives the car a much lower center of gravity for handling.

I'm sure what Luke has done works great for his rally car but my build is more focused on a rat/restomod style.

[Crazyswede]

Luke, do you have an opinion on whether you would go coilovers again, or just go for coils and longer travel shocks?

The only advantage I can really see is that you have the ability to use tender and helper springs with a coilover that you really don't have with a free spring. I took a look around and can't seem to find any dual rate springs that would seem to me (all be it unedumacated) to work effectively in this type of setup.

Ideally, I am looking at not doing coilovers, but trying to increase travel if possible. So I am still thinking longer spring than stock SPG, but with rates to facilitate more droop travel. I don't know if a spring/shock tower extension would be needed or not considering everyone seems to use a spacer with the SPG springs to achive the proper rally ride height anyway. Anyone know of any rates that may or may not work, or is custom really the only way to go here?

The coil over car is impressive and very nice to ride in when you are launching off jumps and taking big hits etc. However we had just as much fun running in the historic car with the traditional suspension setup. It really is quite amazing as to how robust and how well the stock 99/900 suspension setup works. A good set of springs and rally valved bilsteins are not only relatively inexpensive and easy to fit to the car but they work so well. You will want to reinforce the shock mounts and the A arms but thats all basic stuff.

[MattWatson]

The coil over car is impressive and very nice to ride in when you are launching off jumps and taking big hits etc. However we had just as much fun running in the historic car with the traditional suspension setup. It really is quite amazing as to how robust and how well the stock 99/900 suspension setup works. A good set of springs and rally valved bilsteins are not only relatively inexpensive and easy to fit to the car but they work so well. You will want to reinforce the shock mounts and the A arms but thats all basic stuff.

Yah it always comes back to the just get something together and start rallying, or getting something that is wiz-bang cool with all the bells and whistles. You can probably tell where my hear lies

Saabs are just nice for the fact that you can "just go rallying" with a thousand or so into suspension that will last through a lot of events where the VW, subaru, etc strut folks have to rely on big expensive stuff to go fast and last more than an event or two.

[Luke]

Luke, do you have an opinion on whether you would go coilovers again, or just go for coils and longer travel shocks?

The only advantage I can really see is that you have the ability to use tender and helper springs with a coilover that you really don't have with a free spring. I took a look around and can't seem to find any dual rate springs that would seem to me (all be it unedumacated) to work effectively in this type of setup.

Ideally, I am looking at not doing coilovers, but trying to increase travel if possible. So I am still thinking longer spring than stock SPG, but with rates to facilitate more droop travel. I don't know if a spring/shock tower extension would be needed or not considering everyone seems to use a spacer with the SPG springs to achive the proper rally ride height anyway. Anyone know of any rates that may or may not work, or is custom really the only way to go here?

I would not bother with the effort for go to coilovers again. If I built another over engineered car, I'd probably using a 5" spring with a custom seat with a very small range of adjustment at the spring for tweaking height.

Something like this but even more compact:


The upper spring tower would need to be moved up an inch or two to give enough real estate for a little bit longer spring and the adjusters.

But to Seth's point, we stepped back to basics with the Historic car and still had a ton of fun and were really surprised at how well it actually did on all but the roughest washboards and big woops where the long legs of the other car really shine.