Front suspension alignment

[tmoretta]

I have mostly completed the rear suspension alignment on my 818 (with a lot of pointers from this forum). I am a little confused on the procedure for the front. On page 81 of the assembly manual, it states to adjust the upper control arm to the "desired length". I am thinking that the control arm adjusting sleeves are of different lengths to accommodate the 3 to 4 degrees of positive caster. Should the horizontal face of the balljoint mount be maintained parallel to the inner pivot arm? I know that to adjust camber both sleeves must be turned equally, but can one be turned more than the other to add caster, or is the correct amount of caster engineered in by FFR?

[Wayne Presley]

you turn them the same amount and direction to adjust camber, adjust them different directions to adjust the caster. Adjust them a varying amounts to adjust caster and camber simultaneously.

[Frank818]

Plz let us know if you achieve the recommended camber/caster without cutting the threads or modifying the UCAs.

[tmoretta]

you turn them the same amount and direction to adjust camber, adjust them different directions to adjust the caster. Adjust them a varying amounts to adjust caster and camber simultaneously.

So in adjusting the caster, one will not induce "bump steer" or some other undesirable handling situation? The built in angle of the suspension upright is not already the correct amount of caster?

[Wayne Presley]

So in adjusting the caster, one will not induce "bump steer" or some other undesirable handling situation? The built in angle of the suspension upright is not already the correct amount of caster?

Ride height, caster will both effect bumpsteer. Whether that is better or worse would have to be measured. And with all the varying parts connected together, there is no way to design it to be perfect every time for every frame.

[Wayne Presley]

The rear short leg does most of the camber adjustment, the front does most of the caster. The one I did today had -3.0 camber and +3 caster to start with. I wanted that caster and wanted -1° camber. I turned the short leg until I had -1.5° camber and got the rest from the front leg. That gave me 2.8° caster. I had to go out on the long leg a little more and go in on the short one just a smidge to get what I wanted.

[tmoretta]

By the way, this car, although an 818S, will be a partly street, partly track day car. I am thinking of going 1.5 degree neg. front camber, 1.0 degree neg. rear. Any ideas? What are the suggested settings for the R car?

[Wayne Presley]

The 818R alignment depends on tires used, springs and downforce.

[tmoretta]

Understood. But - what are the FFR recommendations for alignment on the 818R? I only have the manual for the S model, and would like to know how the specs differ.

[Wayne Presley]

if you give me some of the variables of your car I can recommend a setting.

[Mitch Wright]

This might help:
From the FFR 818R supplement manual

Car set-up can vary a good deal based on the experience and style of the driver. These set-up tips are to help get a good idea of both a decent baseline setting to start from and to help save some time in the initial trial and testing phase by listing what has worked well for the factory cars and customer cars that have shared their feedback.
Front Suspension:
The key to any good suspension is getting the moving parts to move with as little bind or friction as possible so that the shock and spring combo can do their job and be consistent. Using polyurethane bushings can be a big help in terms of maintaing the geometry under hard loads but any time that style mount is used is should be checked for freedom of movement when tight. Likewise the upper control arms should be well greased and the end nuts set so the arms will fall to vertical under their own weight. If the arms stay horizontal then the nuts are to tight. Also like any race car suspension all the joints need to be greased and inspected regularly, with race tires this means before every event.
Front camber settings can be tire dependant but in general we dial in more and more camber until it starts to take away front grip under braking. Usually this happens around 3.0 degrees negative camber.
Front caster settings can vary depending on driver size and strength as well as tire size, steering rack ratio, and even steering wheel size. Adding caster can add front grip and stability but eventually the steering becomes heavy and the car can weight jack (the corner weights get thrown off when the wheels are turned). For the standard racks we usually will go to about 3.5 degrees for the older slower ratio and 3.0 for the later WRX (2006+ and all STI) quicker racks. If you are running power steering then you can raise the caster up to the 5-7 degree range and this will help the over-assisted feel from the front end being so light as well.
Front Toe and Bumpsteer should be run to keep good steering feel and prevent the car from darting on initial turn in. We usually run just a little bit of toe in, 1/16 in. total, in the front and set the bump steer as close as possible to zero. Since you will have a little bit of bump steer you want it to toe the wheels out under compression and our baseline setting for that (on the lower ride height) is to space the rod end 2-7/16 inch down off of the spindle. Having the car toe out in bump will stabilize the feel under turn in but to much will make the car feel darty under braking. Small increment will also make big changes here so when experimenting you can change just 1/16 in. shims and feel the difference in the car. Also the amount of caster affects the bumpsteer as well by raising or lowering the steering arm, so if your range of caster is far off the baseline then you may want to start with your own measurements for bump steer spacers.
Front Lower control arm length plays a big role in the adjustments you can make to the suspension, both in terms of alignment and also for tire fitment. There are 3 different ways to adjust the trackwidth to get to the setting you want. The front bushing carriers on
the factory arms have offset holes so spinning them 180 degrees from how they are shown in the assembly manual will bring the inner pivot inboard 3/8 in. when flipped.
The arms on the bushing carrier look different to make it easy to differentiate which is the long one. The flat side is the shorter side and the indented side is longer.
The chassis also has two set of holes in the mount for the bushing carrier. Just moving the wider arms to the outer mount would most likely be to large an adjustment but pivoting the bushing sleeve as shown above to move the arm back some of the distance gives a good setting.
Moving just the rear of the arm to the outer holes works to add more caster if you spin the bushing mounts to avoid going to far. (particularly with poly bushings)
Finally the control arms and flipping the stem on the arm that slides into the front bushing. This will put the smaller flat surface against the control arm and the larger flat on the bolt head side.
Standard OEM mounting location
Rear Suspension
Stem spun 180 degrees for more caster.
Rear Toe in is a very critical setting on all of the 818s. Running a good amount of rear toe in will stabilize the car and make it much more fun to drive hard and much more stable exiting corners. Baseline setting for rear toe should be 5/16 in. total toe in. If you want to experiment from there then we recommend going in 1/16 inch increments.
Rear Camber setting should be similar to the front and is also tire dependant. -2.5 degrees is a good starting point and taking tire temperatures and watching tire wear patterns will allow you to adjust from there. On a full racing slick with a slightly softer sidewall start at -3.0
Rear Roll Steer is adjustable by lengthening or shortening the upper trailing link. Roll steer is equally important to rear toe in as it has the same affect as the suspension rolls through its travel. The baseline setting for rear roll steer is zero which means the lower lateral links are parallel when viewed from the front. In order to adjust the rollsteer park the car at ride height on flat ground and measure from the ground up to both ends of each lateral link. Subtract the difference in height from the inside to the outside on each link to get the total amount the inner pivot is higher than the outer. To adjust to zero rear rollsteer change the length of the upper trailing arm until both lateral links change by the
exact same height. Another way to describe this is the long bolt in the bottom of the spindle that attaches both lateral links should be parallel to the flat bottom of the car.
General:
Spring rates were set from the factory based on the most aggressive combination for the R model. Since a mid-engined car will tend to understeer at low speeds and then can switch to snap steer at higher speeds the balance of the car is very important. The rates we give are optimized for using high downforce to counter the tendency for the car to get loose at higher speeds. If you are not running a rear wing then we highly recommend swapping the springs and running the 500lb coils in the front of the car. This will make the car understeer at low speeds but gives much better driveability at higher speeds on track. If you are doing mostly autocrossing and the speeds are lower then running the stock 500 rear/300 front is most likely going to be faster. Also this would be one time when keeping the front sway bar for tuning is a good idea as well.
Scaling the car is essential to making sure the car is balanced handling wise and under heavy braking. Getting the cross weights even is the most important thing as it is difficult due to the driver position being offset to get the two sides to be equal both front and rear. If you are running the sway-bar then disconnect it to scale. If you don’t have scales or any method to set cross-weights then it is worth taking the car to a race shop to get it done. Just be sure your ride height and alignment are set first. If you can’t get anywhere to scale the car then measure the spring collars to get them even across the front and even across the back. Then if you have one front wheel that consistently locks up under braking raise that corner by a half turn at a time until they are even.
Aerodynamic balance also can play a big role in how the car handles and ultimately how fast it will go. It is easy to overdo one end of the car and end up with a car that is slower and harder to drive even though it has more total downforce than before. Matching components and having built in adjustment (usually rear wing angle) is the key to finding the perfect set-up. As a starting point these are good baseline combinations we have used.

[tmoretta]

My car is an 818S: FFR supplied springs and shocks, urethane bushings in all four lower control arms, adjustable rear lateral arms, 17mm front sway bar, street splitter and rear spoiler, aggressive Dunlop street tires (215 40 17, 245 40 17. Thanks Wayne.

[tmoretta]

I have cut the threads of the longer sleeves, and I still may not be able to achieve more than 1degree neg. camber. Also, FFR has been unable to give me the alignment specs. for the R model. Since I am building a street/track 818, I was hoping to set the alignment somewhere in between the specs. of the S and R model.

[tmoretta]

Thanks Mitch. This is the info I was trying to get from FFR.

[Buzz Skyline]

I'm a tad confused about the camber recommendations in the 818R supplement. They adjust camber until straight line braking starts to degrade. That suggests that you want the most camber you can possibly get without jeopardizing braking.

It makes sense if more camber is always better. Certainly for Macpherson strut cars (like the WRX), which develop positive camber when the strut is compressed, you want to dial in a lot of negative camber. But A-arm cars like the 818 don't have the same problem - instead the 818 should develop more negative camber as the suspension is compressed. Potentially, you could end up developing too much camber and losing grip in a turn.

I ran my WRX in autocross with -3 degrees of camber or a bit more, which seemed to work well. So I would have thought the 818 would need much less to achieve the same results while cornering.

In short, I'm not convinced that more is better when it comes to camber (which is what setting up camber with braking performance seems to imply). I would tend to go with little (maybe zero) camber to begin with, and then test the effect of cranking up camber on turning, not on braking.

[Mitch Wright]

E-mail Jim and have him send you the R Supplement manual.

[Wayne Presley]

tmoretta, I'd go with +3° caster, -1.0° camber, 3/16" total toe in on the front. -.75° camber and 1/4" total rear toe in.
With the S springs, you are going to have more body roll and the street tires do not have nearly the traction of a DOT race tire or slick.

[Frank818]

tmoretta, I'd go with +3° caster, -1.0° camber, 3/16" total toe in on the front. -.75° camber and 1/4" total rear toe in.
With the S springs, you are going to have more body roll and the street tires do not have nearly the traction of a DOT race tire or slick.

Just to make it clear, that is a recommendation for an R with S springs and street tires?
If yes, isn't that sort an S, then?

[Wayne Presley]

Just to make it clear, that is a recommendation for an R with S springs and street tires?
If yes, isn't that sort an S, then?

Nope, it's an 818S

[tmoretta]

Thanks so much Wayne and Happy Thanksgiving.

[Frank818]

I would like to add some info to this thread (for which I don't have the answer), since we are talking about front suspension alignment, can we also include the best way to torque the LCAs?

I've seen different techniques and I do not understand what each does or doesn't that the other might.

I am talking specifically about the rear bushing big nut, the one facing the firewall that we mostly have to drill a hole through the FW if we want to torque it with a gun. I am also talking about the front bushing bolts, those on the inner side close to the steering rack and rad.

When you torque those 4 bolts/nuts on those 4 corners, the LCAs will be tied up and if you press/pull down/up they will slightly move cuz the rubber bushings will tear, making the LCAs move like a spring. That is normal, AFAIK.

But what technique do you use to decide the angle you will give the LCAs when you torque those bolts?

Do you torque them when LCAs are leveled to ground? So that when the car is on wheels, the LCAs will be angled downwards (cuz the shocks/springs are long enough to push the LCAs downwards when you install them)? Resulting in tearing a bit the bushings, but when the suspension compresses, the LCAs will move up, leveling to the ground so that the bushings will have no tension when you are compressing the suspension.

The other way I know is you torque at ride height with normal weight, which means when the suspension is compressed by its design and weight of the car, so that the bushings have no tension when the suspension is not "at work" and when it does obviously the bushings will then have some tension up or down.

What should be a good way to do it? Or maybe it doesn't matter and suspension specs aren't affected either way?

[Hindsight]

Frank, new control arms come with the rear bushing installed and torqued with a paint line. My assumption was that they had them properly aligned from the factory. FFR wants you to swap sides on the bushings, and in doing so, you obviously have to remove and re-install them, but before I did that, I noted the angle of the rear bushing brackets and it appeared to me that they were parallel with the control arm, meaning, the desired orientation of the control arm with zero load on the bushing is horizontal to the ground. But that's just my assumption. Maybe someone who knows 100% will chime in.

Also, I don't think the bushing should be "tearing". They are made to flex like this. Tearing would definitely be a problem.

[Frank818]

Sorry, flex, yes. Not tearing. Tearing is too aggressive. Bushings flex and is normal. Not tearing.

My rear bushings tabs were parallel with LCAs and therefore to the ground as well. I have torqued them back that same way. I have the same assumption as you, but since I don't understand the differences of one way vs the other, it left me with doubt.

[freds]

Sorry, flex, yes. Not tearing. Tearing is too aggressive. Bushings flex and is normal. Not tearing.

My rear bushings tabs were parallel with LCAs and therefore to the ground as well. I have torqued them back that same way. I have the same assumption as you, but since I don't understand the differences of one way vs the other, it left me with doubt.

Take a look at

http://thefactoryfiveforum.com/showt...-Dummies/page4

Post 154 and the following post discussion on torquing the bushings.

fred

[Frank818]

Fred, what on Earth would we do without you. Tnx for pointing it back, I knew I have asked before but couldn't remember it was in a build thread.

So we use those 4.5" blocks and drop the chassis (not the wheels) on them? So that the wheels touch the ground at ride height but that the chassis is supported by the blocks.

Then that means we probably don't keep the OEM angle, as the tabs are parallel to LCAs and most probably on the 818 the LCAs will be pointing down slightly at ride height.
In this case it's ok not to follow OEM specs?

[freds]

Exactly. The OEM specs are for a car with a different ride height.

fred

[Scargo]

In the R supplement it says "The rear mount for the control arm is spaced up using spacers or washers to be even with the frontmount. ..."
I don't see that in the above quoted information. What I am looking for is the difference, if any, in the height of the front and the rear pivot points of the front LCA in the R suspension locations. I measure the UCA to be level with the bottom of the frame and I wonder if FFR designed in any angle to the LCA pivot which might affect anti-dive geometry.

[Frank818]

Here's my first issue of the year.
About ride height, I have followed the method with the wood blocks under the chassis and 10psi tires. But the car does not even sit on the blocks. The springs are adjusted to their maximum extension without coming off of the hat, my bolts on the LCAs are loose so that the bushings don't keep the car higher. I am at 5" exactly up front and 5.75" in the rear (maybe the rear requires the engine to sit lower?). I am using 215/40/17 23.7" diameter tires.

2015-01-01 12.00.19.jpg

I can't go lower than that. What have I done wrong?

[wallace18]

Here's my first issue of the year.
About ride height, I have followed the method with the wood blocks under the chassis and 10psi tires. But the car does not even sit on the blocks. The springs are adjusted to their maximum extension without coming off of the hat, my bolts on the LCAs are loose so that the bushings don't keep the car higher. I am at 5" exactly up front and 5.75" in the rear (maybe the rear requires the engine to sit lower?). I am using 215/40/17 23.7" diameter tires.

2015-01-01 12.00.19.jpg

I can't go lower than that. What have I done wrong?

IMO you are wasting your time trying to align or ride height a car without engine or trans and most everything installed. You can do it at the running go cart stage but recheck everything when kit is completed. That is how I do all my builds. Wayne is an expert IMO on 818 alignment ask him.

[Wayne Presley]

Do you have the motor and trans in? If not don't bother to set the alignment.

[Frank818]

I must have misunderstood the procedure, then, it said "you do not need any particular weight at all". I'll wait till there in, then.

[Wayne Presley]

You could do it by removing the shocks

[Frank818]

Considering the time it takes to remove and reinstall the shocks, I'd rather wait for the engine/tranny.