gmantoo

I just installed Eibach springs on my '02 pro 5. The car looks great. I got 1-1/4" drop both front and rear. It is just shy of looking radical, so it's just what I wanted. The car also corners flatter, which was a nice supprise.

Installation is straight forward and can be accomplished with basic hand tools and a spring compressor.

I ckecked out the suspension/breaks forum and FAQ's pretty well before I did this, and planned to head straight to the alignment shop when finished. I just assumed it was necessary to get a front end alignment and did not question exactly why until my dad asked me and I was forced to consider. Here is what I came up with: As far as I can tell the front end is only adjustable for toe in/out, but this setting is not effected when the car is lowered, and therefore would not require adjustment. There appears to be no way to adjust for caster, so an alignment would not be required on account of that. Camber could be changed by moving the top of the strut, which would require enlarging the holes in the strut tower, or by bending the lower portion of the strut housing. I know the camber changed when the car was lowered, but only by the amount it normally chances as the suspension goes through it's stroke. The top of the tires are in slightly, but I can't remember if this is negetive or positive camber. So here ar the questions I have:
1) How much negative/positive camber is permissible before tire wear becomes a factor?
2) How much does this value change when a p5 is lowered 1.25"?
3) What is the desirable number for camber on these cars from a handling perspective?
4) Am I making any sense?
I look forward to everyones comments

slamprotege5

I did not get a wheel alignment...steering does not pull, and tires do not wear. I figured I just lucked up when I lowered mine. I think I would have gotten one, if I could have gotten on a rack

gmantoo

I guess that is what I am a little curious about: exactly what is "it"? The only adjustment is for toe in, which does not change when the car is lowered. What exactly did the alignment shop do to your car for the money they received? Perhaps you got a Pseudo Alignment! (sorry, couldn't resist)

Sir Nuke

its better to be safe than sorry....if your tires start to ware bad...it usually shows up to the naked eye about the time its too late and your tires are ruined....and that is a good $200 at least....I will be lowering my P-5...and you can bet I will be getting the alignment checked.

carguycw

First, your car''s camber and caster are adjusted by rotating the tops of the struts. Unless you marked the strut tops and put them back in the exact same position when you reassembled them, there is a good chance that the alignment is wrong now. Second, the slop in the bolt holes can change the alignment when the suspension is reassembled. Third, as has already been pointed out, toe DOES change when the car is lowered due to the car's suspension geometry.

Get the alignment checked. $50 now is a lot cheaper than a $250 set of tires later.

gmantoo

Chris,

Good points. I did some thinking about what you said and then took some measurements and did some trig. Here is what I found:
The "slop" in the bolt holes of the strut towers is about 1/32". The strut is about 20" long. This means that no more than about 1/10 of a degree total change would be possible for camber or caster. Also, if this were an issue there would be star washers under the nuts to make sure the top of the strut could not move.

As far as the toe changing when the ride height is changed, I'm not so sure this is correct either. I understand that the rack is fixed, as has been pointed out , but so are the anchor points for the control arms. The only way that toe could change with ride height is if the relationship between the rack and the control arms is progressive as opposed to linear. Also, this would mean that most of the time toe would be incorrect because the suspension is always moving. I have a jig that I can use to measure for toe. I will use it and a jack to take toe measurements at several ride heights and report back with hard numbers.

gmantoo

Are saying that it is possible to make small adjustments to camber with whatever available "slop" there is in the lower strut mounting holes and bolts? What are the torque numbers for these? There was no discernable play in mine with everything loose, but I was only feeling it by hand. How do you manipulate the hub into the proper position prior to torquing down the bolts? Thanks in advance for your reply.

I'm still not convinced about toe changing with ride height. It would be true only if the geometry of the control arms and the tie rods were different. What would force a design engineer into this compromise? I'm not trying to be argumentative, this is a serious question to which the correct answer will lead to better understanding of this topic. Thanks again.

carguycw

Just to expand a little on what Jesse said...

The toe will change because McPherson strut suspension has inherent geometry problems. The whole design is a compromise. The camber and toe curve of a McPherson strut is not ideal because it locates the wheel with a shaft that can only move straight up and down, when it really needs to move in a curved path.

Modern strut cars are designed to have a good camber curve and good toe geometry when the car is sitting at normal ride height. However, it's basically impossible to design a McPherson strut suspension that will maintain the same toe setting when the suspension moves, especially if it moves into the extreme ranges of its travel- like when you lower the car several inches.

This is why race teams with seriously lowered McPherson strut cars often relocate the steering racks or use spacers to move the strut pickup points around. They do it to maintain proper toe geometry. This is also why most sports cars (Miatas, FD RX-7's and Corvettes, to name a few) use unequal length control arms, not McPherson struts.

Also, the correct torque spec for the strut-to-knuckle bolts is 69-93 lb-ft.

gmantoo

Thanks for supplying the missing link Chris. Good explaination this compromising aspect of Mc Strut front ends. I was told by someone else that the front toes out when you lower and that the rear toes in, and that both can be adjusted on the p5. The front via the tie rods and the rear via ecentrics. True?

pollax

Camber should not be an issue when lowering a MacPherson strut suspension.

Doing my calculations, The max amount of change you can make to the cameber using the slop in the bolt holes is .089 degrees which is hardly much at all.

The issue is toe. When lower the Protege, the car should toe out slightly. The question is how much does the toe change with a mild 1.5 inch drop? Is it enough to make a difference?

carguycw

I have also heard that the front toes out, and this seems logical from looking at the front suspension, although I do not have personal experience to back this up. I honestly don't know about the rear; however, keep in mind that the rear suspension is not a classic Chapman strut arrangement, it's a multilink setup that's very similar to unequal length control arms. The rear probably has better toe geometry than the front.

And yes, the adjustment methods you listed are correct.

gmantoo

Well, I'm convinced. Sorry to be such a pain in the #%&

Here is what I learned at a good alignment shop (Charlie's Drop Shop, Portland, OR.) as I watched the service tech do the job.

1) The Protege is one of a few cars with a Mac Pherson strut front end designed to allow for camber and caster adjustment. There are four mounting positions for the top of the strut, each 90 degrees apart. So if you drop the strut down, rotate the top 90 deg, and button it back up you will have changed both camber and caster. This is because the top bearing is ecentric so each position locates the top of the strut differently. You can see this if you look at your strut towers. The big hole in the tower and the bearing are not concentric. Duh....I must admit that I feel like a doo-waah for not having picked this up myself. Especially after Chris practically spelled it out for me! (thanks for trying)

2) the rear is adjustable for toe via ecentrics located at the inboard end of the two most rearward suspension links. (right in front of the gas tank) You can't tell by looking, because they look like regular bolts, there is no neon sign identifying them, but if you mess with these you are adjusting the rear toe in/out.

After installing the Eibach pro springs and putting everything back exactly (I think) as before the baseline measurements were:
Left front: caster +2.24 deg, camber -.48deg, toe -5/32"
Right front: caster +1.40 deg, camber -1.12deg, toe -9/32
Left rear: camber - .80deg , toe 0
Right rear: camber -.84deg, toe +3/32

Between left and right front this is a large difference in both camber and caster. Perhaps I didn't put the front end back exactly how it was, although I paid very close attention and think I did. It also apears that the front toed out quite a bit if you assume that the stock setup should bave been slightly positive.

I suspect the camber and caster were off before I lowered, but cannot prove it. After all is said and done I would have to say I have learned quite a bit about this subject and would like to thank everyone for their input. I would not hesitate to have a new car checked for alignment, let alone one that has been lowered.