itchy

I'm sorry I like math. Sometimes it's insteresting to understand why something works or is done, at least for me.

What would be nice to know, is the variation from factory. Based on geometry and measurements the actual shift is not significant. Which, means that everyone who has had to recenter their axle is more than likely fixing the factory offset and not recentering due to change in geometry from lowering.

RRRoamer

Exactly!

The part that bugs me is I would be VERY surprised if there was that much variation in parts alignment from the factory. These cars just aren't built the way they were in the old days. The robots that make most of the parts and assembly them tend to be pretty much on the money every single time! No worries about Monday morning hangover cars!

Oh, I did eyeball my rear bump stops. It LOOKS like I have about 2 1/2 to 3" of clearance between the top of the stop and the bump plate.

On a related side note, I did get the D-Spec struts and shocks installed today. They are a very nice improvement over stock. It definitely took some of the harshness out that the Eibach Pro springs put in...

I have a bit of pull to the right under hard braking now, so it does look like I will FINALLY take the car in to be realigned.

I have about 30,000 miles on the car since I first installed the Eibach springs and I never had it aligned. I looked at the front tires pretty closely and there is extra wear on the inside edge due to the excessing negative camber. It's not too bad though. With 40,000 miles on the tires total, I have about 3/16" of tread left (to the bottom of the water channel) on the outside and a little less than 1/8" left on the inside. The tires have been rotated twice since the springs were installed.

blkstang06

First we all have the same stock ride hight " with in a set tolerance variances" Just like the tolerance variances in pinion angle as prescribed by Ford, -2.75 to -3.75 First any one who as installed a adjustable PH bar and adjusted it will understand the Geometry Darn quick! Here it is in layman terms, the rear end of the car is basically floating over the axle on the springs as you lower the car, point A of the PH bar connected to the axle and point B of the PHbar connected to body, as the body gets closer to the axle you are changing the distance of elevation of the body verse the plain of the axle Thus changing the amount length needed by PH bar to connect these two parallel plains in a centered position!

itchy

Blkstang06,

The geometry and the behavior of that geometry are not in question. The question is why most people claim that the axle is 1/8-3/8 of an inch, when based on the linkage geometry the most you are going to see is ~1/16" offset from lowering. Tolerancing could play into this, but the difference between centered and a 1/4" offset is not trivial. The height difference between point A and point B was measured between 1.75" and 3.5"(based on measured angle) by 3 people in this thread. Assuming that those measurements are correct we are only talking about a 1/16" difference in offset after lowering.

What is the stock ride height? How much variation does Ford allow?

We could be missing the most obvious source of error, measurement with a plum bob and tape measure. It could be the spring height tolerance. It could be tolerance stacking, worst case spring height, worstcase point a location, worst case point b location, worst case panhard bar length. We won't ever know, except that some people have had to recenter their axle, so the shift is real and does happen when lowering.

I personally enjoy this type of thread, more that the "which wheels and tires look the best" Don't get me wrong it's important, but not as interesting.

SoundGuyDave

Itchy,

I agree with you completely. There is undoubtedly measurement error, so I am hoping we can come up with enough of a sample size to help minimize the error. I'm betting that it winds up being a standard-deviation plot, if you follow. And yes, this is FAR more interesting than the wheel/tire type post to me as well.

Do you have ANY sort of pull under steady-speed or light braking? If it's only under hard braking, then I would suggest looking at bump-steer as a culprit. If it also happens under light braking (flat road, hands off the wheel, the car stays straight until you ease into the brakes, then it starts to veer off to one side), then it sounds like you have one caliper that isn't grabbing as well as the other side, probably from dirty slides or caliper pins. Does the wheel try to move on you, or does the car just kind of slide over? If the wheel tries to move, then it's most likely your left-front caliper that is suspect. It the car sort of slides, then it's the left-rear...

EDIT: Body shop just called. There was something about the paint on the front bumper cover that didn't come out the way they wanted, so now it looks like I won't get my car back until Monday.... AAAAARRRRRGGGGHHH!!!!! Race season is coming up fast, and I have a LOT of work still to do!

RRRoamer

SundGuyDave,

Thanks for the insight. I'm FAIRLY sure it is alignment related as I didn't have any pulling at all until I changed the struts and shocks. No change in ride height (same Eibach Pro springs that have been on the car for over two years), I didn't touch the brake system in any way. Just remove the wheel, remove the strut, move the springs and other hardware to new strut, reinstall strut, reinstall wheel, move to next wheel. The rear shocks were even easier. I probably could have done that without even removing the rear wheel if I wanted to..

The car tracks dead straight under acceleration, as it did before I changed the struts. No issues cruising down the highway or under light braking. It is only under heavy braking that it starts to pull to the right and the steering feels very touchy as that occurs. And it does pull on the wheel a bit.

That does sound like brakes, doesn't it! The front calipers did move freely side to side (I always check the caliper is free when I have the wheels off) and the pads and rotors were replaced about 10k miles when I switched to Hawk Performance Ceramic pads. At that time, the caliper pins where cleaned and regreased with caliper grease, so they should be in good mechanical order. Needless to say, the pads look pretty much new in thickness and the rotor is in very good shape with only a bit of visible wear.

I think I might take my angle gauge out and check my camber. I suspect that I'm going to find a difference between the left and right side. If I do find it, I'll take it in for an alignment. If not, I think I need to pull those front wheels off and take a look at the brakes. Maybe I got some crap on a rotor or something and didn't get it wiped off completely before I put it back together.

Thanks again for the insight.

SoundGuyDave

I dunno.... I'm suspecting brakes a little less based on your description. Of particular note is the comment that the steering feels touchy under heavy braking. Are you running your D-Specs on a fairly soft setting by chance? My thinking here is that with the new springs and softer damper valving, you may be nose-diving just enough to go from toe-in or neutral toe to a toe-out condition, which will make the car feel very "darty." It's awesome if you're running on a very tight track (or autocross), because your turn-in is incredible, but not so "bueno" with road usage, since the car will tend to want to track the slightest imperfection in the street, and will want to fall off the crown of the road.

By all means, check your alignment angles, it's good practice to do so in any event, but I would measure the bump-steer as well. Here's a simple, home-brew way to do it... Park the car on as level and plane a surface as you can find, and make sure that you have a couple pages of newspaper under each of the front wheels. Using a string, or tape-measure, measure from the outside of the center tread groove across to the same spot on the other tire, and repeat for both the leading edge of the tire, and the trailing edge. Write down the two measurements, and subtract the rear from the front. A negative number will give you a toe-in condition, and a positive number will give you a toe-out condition. Now, pop the hood, lay a couple of moving blankets across the radiator cover (to spread load), and then pile sandbags, barbells, an extra engine block, whatever weight you have on the front of the car until the front end drops about an inch. Re-measure the toe, and then compare the two readings. The change of toe is bump-steer, which is caused by differing arcs for the lower control arm and the tie rod. Ideally, you want NO change in toe, but that's impossible to achieve without a bump-steer kit, either shimming the rack, or using one of the commercially available kits (Steeda and BMR for sure, and I think Griggs, MM and MultiMatic have them as well). I think factory calls for 1/8" toe-in, I have mine set to 1/16" toe-in, and it's quite stable, and a little crisper into the corner. I did use a bump steer kit (Steeda) and got the change dialled out.

Good luck, and let us know what it turns out to be!

RRRoamer

I think you are right on the money. I actually suspected that I had the dampening too soft yesterday. Due to hunger, I installed the struts, then took the car out to grab a bite to eat, and then came back and finished up the rear. When I first went out, I had the struts set at 4 turns out from full hard.

Needless to say, I didn't have any issues at all on the lunch drive, and I did hit the brakes fairly hard as well. For some reason, I almost ALWAYS find an excuse to use the throttle and the brakes fairly hard at least once on every trip!

After I came back and installed the rear shocks, I set everything to 6 turns from full hard (1 1/2 turns from full soft) to see what impact a soft dampening would have on the ride quality. That test run was when it got my attention with the pulling to the right. And you are right, it was VERY darty at that moment and very sensitive to the steering, but only under heavy braking.

When I came back (before I logged in and posted my original comment above!), I adjusted the fronts struts to 4 1/2 turns from full hard. Today, I took it back out for more testing and it was ALMOST exactly as before. There was a very slight pull to the right under very hard braking, but none of the sensitivity as before.

It sounds like I need to get a bump steer kit if I want to eliminate this completely. Thanks for the help! The car definitely got my attention yesterday in something other than than it's normal very positive way!

I'll have to remember the trick with using soft damping up front to cause toe-out under hard braking. I can see where that would definitely come in handy on the track!

SoundGuyDave

Glad I could help! A word of caution, though, for the track you don't want to go soft on the dampers, unless it's VERY bumpy, just spin the tie rods out a touch, equal amounts on each side. IIRC, it takes a 19mm open wrench for the jam nut, and a 12mm (or channel-locks) for the adjustment. When you're done, just spin them back the same amount. Voila! Instant toe-in to toe-out and back again. With my D-Spec setup, I run 3.5 turns out on the street, and between 1 turn out and full hard on the race course. Drag strip is full soft, all the way around. If you run the dampers soft on a road course, and hammer the brakes heading into a turn, you'll REALLY upset the balance of the car when it nose-dives on you. Also, I wouldn't run toe-out except for extremely tight courses, or for Auto-Cross, where you're turning almost constantly. As you found out, the amplified steering input is a little disconcerting, and it gets worse as your speeds climb into triple-digit territory. Keep the toe-out trick up your sleeve for tracks where 200 yards is the long straightaway, and keep the dampers as tight as you can stand. If the car almost hops over the worst bumps, it's about perfect. Oh, and check the brakes anyway. Better safe than sorry...