shock measurments

[Rallyho]

Has anyone recorded installed, compressed and extended shock measurements front and rear for the 99 and/or 900?

Much thanks if you can share.

[Luke]

oh me, i have, i have

I'll post when I get home

[Rallyho]

Excellent.

Thanks man.

[Luke]

Here are the lengths for a 99 with 900 style rear. All lengths are from Bilstein shocks are to the center of the eye or in the case of the rear from the center of the eye to the base of the pin (where the bushing sits):

Fronts:
extended: 14 3/4"
collasped: 10 1/4"


Rears:
extended: 18 1/4"
collasped: 12"

Note that these are the full range of the shocks unmounted, not necessarily the range as used on the car. I had those numbers somewhere too but I can't find them.

Heres a couple of my thoughts on saab suspension and shock length:

1. The front bump travel can't be made much longer or else you are bottoming the belly of the car before the suspension hits the bump stops on crowned roads

2. The front droop can be extended by removing the limit stops on the chassis(99) where the upper a-arms come through. Be wary of axles lengths though because it gets tight and I've seen a couple different lengths out there. You may also have to pound down the area under where the driveaxle come through to prevent rubbing.

3. Rear droop is limited by the shock in std setup. It can be extended but with tarmac tires or wide gravel tires you will have rubbing on the inner fender wells at full droop. Maybe an issue, maybe not.

4. We could really use progressive springs on the rear I think. The SPG springs I use are really stiff and cause the car to oversteer a lot on small bumps but still bottom hard on big jumps. Shock valving and longer more progressive bump stops (like on the front) could also be experimented with here.

5. When I put on the front coilovers with the same shock valving and spring rates as std style rally suspension I was using before, the car seemed smoother over everything but also seemed to bottom less on big jumps. Dosen't make a lot of sense. I can only attribute this to a spring with a more consistant rate and a more modern shock. My motion ratio is also slightly different with the new setup because the spring is mounted further outboard (I could do this since its a smaller diameter spring)

[Geoff]

hey Luke, I've got stock 900 rear springs on my car (SAAB S&R rally springs in the front). I used to run higher pressures in the rear to balance the car out (get the tail out a little). After I put the fiberglass hood on I had to go to lower pressures in the rear to keep the rear of the car behind the front

I remember the Arrietta's were having trouble with the rear of their 900 coming out on them. They widened the rear track (longer wheel studs and spacers) and I think they muckled around with swaybars, Mike might remember the details. I don't know if it helped. They were running the replicas of the S&R springs (front and rear) that ScanWest sold.

With a lightened car and custom front suspension you may want to experiment with your rear springs again. With the stock 900 rears and rally valved Bilsteins on the lightened 99 the rear is quite stiff.

But yeah, progressive is probably the way to go. Every 900 or 99 I've seen a photo of after landing a jump has the rear end tucked WAAAY up into the body. Somewhere I have a spreadsheet that I put together with a whole bunch of calculated and measured 99 and 900 spring rates...

[Rallyho]

The Arrietts's were getting it all wrong in my opionon. They had too much oversteer in the rear, not sure why they thought that...S&R springs and rally valved shocks. So, they widended the track and ADDED a rear swaybay...results were predictable.

I'm trying to figure out how to leave the spring locations stock, but get some top/bottom eyelet shocks into the car, perhaps with a little more travel and larger diameter piston/shaft.

I think the 900 fr and the 99 fr shock should have about the same measurements, but will check.

Thanks for the numbers Luke.

[Crazyswede]

my experience with road cars is that with either the rally springs or spg springs and spacers, the car handles well with bilsteins in front and something softer in the rear.

[Luke]

Yeah, sway bar on the rear, what were they thinking? Fun for a rally-x maybe but not what you want for a high speed left 3 with a tree on the outside

[SaabsBreakDown]

Yeah, sway bar on the rear, what were they thinking? Fun for a rally-x maybe but not what you want for a high speed left 3 with a tree on the outside

Nate Tennis was running a rear sway bar on his 99 rally car. He looked to be doing really good with it, and the car was definetly not tail happy because I could never get a good picture of him drifting. He only had a stock b-motor, so sort of a different ball game.

[Luke]

I know you've seen the guy in action.... but every photo I've ever seen of Nate he was hanging it out big time. I tried one event with a rear sway bar, wee!

[SaabsBreakDown]

I know you've seen the guy in action.... but every photo I've ever seen of Nate he was hanging it out big time.

I suspect he has fitted a rear ebrake or is practicing left foot braking, both of which he has denied to me, but I have personally seen his rear wheels mysteriously lock up going into sharp corners.. either way, he is never in my focused frame from the 4 or 5 cars to run through the corner before him. My new camera has autofocus so hopefully I can get some good ones of him in action if he shows up at DooWop. If not, I'll take even more of Garth in his 96!

[Hans]

Yeah, sway bar on the rear, what were they thinking? Fun for a rally-x maybe but not what you want for a high speed left 3 with a tree on the outside

I just completed the Thunderbird TSD rally in B.C. CA, as a navigator (first time). My friend's 900T has SPG springs, spacers, HDs in front, Touring in the rear. We put a rear bar on it recently and, after getting used to it (yes, it's looser), he likes it better. Perhaps not the same speeds as stage rally, but, then again, when the navigator screws up, the speeds go extra-legal.

For autox, pulling the front bar on a 900 works better: mo' better corner exit traction and less push. But perhaps not the safest for inexperienced drivers on the street -- it can come around on you if you're not careful.

[Luke]

Since my car is apart awaiting a few pieces for the clutch and the turbo install I decided to tinker around with the rear suspension. It’s the only thing I haven’t really gone over other than fitting rally-valved bilstiens and SPG springs. I took the springs out and worked the suspension through its motions. I was surprised to measure a solid 8” of travel at the wheel. The wheels really tuck up into the body work more than I realized at full travel. The top of the aluminum wheel is barely visible when the axle is compressed onto the bump stops and when viewed perpendicular to side of the car. I also realized that I must not be bottoming the suspension as hard as I had imagined because the way my exhaust is hung when the axle is fully compressed on the bump stops the pipe is also touching the rear axle. It had obvious dents from this but nothing extraordinarily large so it must not be a regular occurrence. By disconnecting the rear shock I was able to gain about ¾” more in droop travel, not much but something. After that the length of the rear upper links prevented any more droop. These could possibly be extended slightly but this may come at the detriment of the geometry further up in the travel. While I was at it I also measured a 900 axle vs a 99 one and found that the 900 axle has shorter upper arms cast into the axle assembly. They are almost 1” shorter than on a 99. Then I measured 99 rear upper links and found then to be 1” shorter (to compensate for the cast arm being longer). So the 99 and 900 have slightly different rear suspension geometry. When I drew it out on paper it seemed to indicate that the 99 had more “rear steer” built into the axle than the 900 because as the axle went up it moved to the rear at a faster rate. How any of this affects how our car flies through the woods; I have no idea, but I just figured I’d share my observations.

My next experiment on the rear suspension will be to fit stock 900T spring as Geoff suggested. I think that SPG springs might be too stiff especially for a notchback with a fiberglass trunk and lexan windows. I also plan on fitting solid rear upper links with spherical bearings in the hopes that they will allow more fluid suspension travel and less binding. Then I’m going to try to fit an off the shelf racing shock with valving some where around 200/100, maybe a little bit lighter. I am skeptical of the valving on my rear bilstiens I had revalved because they didn’t provide any dyno sheets. The video of a large jump at black river shows a pronounced bounce of the rear suspension on landing which to me indicated an underdampend spring.

[Rallyho]

That's interesting Luke. I've been thinking about doing solid upper links and bearings for the same reason. It might also allow you to correct left to right side wheelbase differences.

I'm no suspension engineer, but it may be that the rear damping is ultimately more important than spring rate or travel so as to help the car settle after big yumps and control pitching or "steering" the front end about in the rough stuff.

The stock bump stop locations on the 900 are ugly-rusty so I'm thinking that I'll just slip some bump stops down over the shafts on the shocks and do away with the oem stuff. That would also allow bracing between the cast arm and the axle tube. This is where my axles have always bent.

Just a thought.

[Crazyswede]

in the ATV and bike world it is important to get your bound and rebound damping dialed in appropriately. Having this setup wrong can be the difference between the car nose diving off a jump and staying level. I seem to remember our mini baja car having a slower rebound....but I may be backwards....but that car remained dead level off of a variety of jumps....where other teams mule kicked and nose dived to no end.

Also, I seem to remember the rule of thumb being that the less traction you have the softer springs you want. So for snow and ice you want a softer suspension that allows for more body roll. For hard packed dirt and gravel go stiffer.

I did look into those digressive springs a bit too. I think I understand the idea but I cant explain it right now.