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Thread: Front End Alignment Question

  1. #1
    BadAsp427's Avatar
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    Front End Alignment Question

    I spent several hours going through very methodically a complete alignment on my roadster yesterday. I have a LongAcre camber/caster gauge, used string, tow plates, etc and am very confident that I'm very close to right on the specs called for.

    Here is my question, I went out for a couple drives today and I'm not getting any "self-centering" action in the steering. I have no pull or abnormal feelings in the drive. But when I turn the wheel, and release the hold on the wheel, it just stays right there, does not come back to center. Does not even feel like it is trying to come back to center.

    I have the front set up like this.

    I have a manual rack with Elec Power Steering with IRS.

    4 1/4" ride hight
    +7* Caster
    -0.5* Camber
    Toe 1/16"
    This is exactly as the manual calls for.

    Thanks for any help you can share. Like I said, other than the self centering thing, it seems to be driving nicely. Now if I could just get a title and tags for it I would not have to keep an eye in the mirror so much...

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    Senior Member Fixit's Avatar
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    We're running parallel courses, as I just cleaned up after finishing my alignment!

    Looking at pg. 495 of the manual, I would read it that you need to adjust to 3* caster, not the 7* a power rack needs.
    (You're using a manual rack, with an electric "assist" added - not the true hydraulic power rack).

    Thoughts??
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    He has power steering so 7* caster should be right. Are you sure you have positive caster?

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    Senior Member Fixit's Avatar
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    Where I was going with this is it is mechanically a manual rack (electric assist added to the input shaft)... not a "mechanically/hydraulic" power rack.
    John D. - Minneapolis 'Burbs

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    Yes, I understand. More positive caster (like 7*) helps with stability and returning to center, but makes the steering wheel harder to turn. With power steering of any kind, he should be able to dial in 7* of positive caster for greater stability and return to center, and the extra steering effort introduced by the 7* positive caster should be provided by the power steering. If your caster is set correctly, I would check for any binding components in the front suspension.

  6. #6

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    Quote Originally Posted by Driver_WT View Post
    He has power steering so 7* caster should be right. Are you sure you have positive caster?
    This is the correct answer. Doesn't matter what type of PS it is - hydraulic or electric - you can still use more caster. The reason is that with more caster, it requires more effort to move it off center.

    If you're not getting any return to center, you most likely have positive caster. Cut a piece of 1/2" angle iron just long enough to rest on the upper and lower ball joint studs, between the castle nuts. It should be obvious that the lower ball joint is further forward than the upper ball joint. That's positive caster.

    If your lower ball joint is to the rear of the upper ball joint, you have negtive caster.
    Last edited by Bob Cowan; 01-19-2019 at 09:40 AM.
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  7. #7
    Senior Member Big Blocker's Avatar
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    I think that's reversed . . . if the lower ball joint is forward of the upper ball joint, that's positive caster.

    Think of a shopping cart wheel axle and the wheel mounting point. The axle is behind where the mounting point attaches to the frame - this causes the wheel to "follow" the mounting point. That is positive caster.

    Doc
    Last edited by Big Blocker; 01-19-2019 at 01:24 AM.
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    Senior Member Paul2STL's Avatar
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    Big Blocker is right if the lower ball joint is forward then it is positve caster. It doesn't sound like you have positive caster. I did the same thing and thought I had positive caster but once I did the ball joint measure I was at 1 degree positive and my wheels wouldn't center. Put as much caster as I could and got it to 7.5 degree. Wheels center after that. I suggest recheck your measurements.
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    BadAsp427's Avatar
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    Thanks everyone for the discussion. I have the 7* positive caster. That I'm positive of. Everything is smooth and free, no binding. Here is a quick video of what I'm experiencing...

    NOTE, the video is just snippets of my drive today and you should watch my hands. You can see I'm not having any problems steering, very light handed and in fact will let go of the wheel a few times with zero pull either direction. Except on the small side streets, most of my speeds are between 40-55 mph


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    Senior Member CraigS's Avatar
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    Although I did install a Fast Freddies PS on a friends car I have not spent a lot of time it. I believe there is a way to adjust the assist level on your PS. If so, I wonder what reducing the assist might do. One other thing that might come into play is the friction adjustment on the rack. This is on a PS rack but manual should be similar
    PS rack adjuster by craig stuard, on Flickr
    On the PS rack the jam nut is maybe 2 inches so I use a huge pair of channel lock pliers or a long chisel and hammer to loosen it. The part that is the actual adjuster is a 3/4(?) bolt head recessed inside of the jam nut. My adjustment technique is to drive similar to the beginning of your video. At 20 mph the wheel won't quite self center. At 35-40 and more it should self center. I take the tools with me on my road test so I can pull into a parking lot and adjust it. Under the adjuster you have a compression spring, and under that, you have a rubbing block that contacts the rack. Adjust about 1/8 turn at a time.
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    Senior Member rich grsc's Avatar
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    Easy to know these cars. On the upper A-arm the rear adjuster is turn in, the front adjuster is turned out. So, longer in front, shorter in the rear.

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    Senior Member edwardb's Avatar
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    The power steering system Carl installed on this build isn't the Fast Freddies or regular hydraulic. It's an EPAS system on the steering shaft. You can find a lot of opinions for this approach. Shown in his build thread here: https://thefactoryfiveforum.com/show...l=1#post343878. Not sure whether that has any bearing on self-centering while driving. The video looks reasonably sorted to me. Maybe should self-center more, but I'm not positive given the setup and the lower speeds where that's attempted. As it should be.
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    Not a waxer Jeff Kleiner's Avatar
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    I've made no secret of the fact that I'm not a fan of the EPAS systems I have driven. Shut it off or pull the fuse to disable it then go for a drive. If you truly have 7-8 degrees of positive caster it'll be hard to turn at low speed in manual mode but should definitely want to stay on and return to center.

    Jeff

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    BadAsp427's Avatar
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    Thanks all.... I'm going to be going out and doing some more testing with it today. The power steering is fully adjustable and with a simple turn of the knob I can turn it off or the other way have steering that I can blow on the wheel and make it turn. I'll also try the "remove the fuse" option as Jeff suggested. I'm also going to recheck all of my settings now that I've driven it a little to double check them. I'm also going to be changing my tire pressures so that could change some of my settings as well. Since the car is driving really nice I'm not overly concerned about the self centering, but I believe I will find the problem in rechecking all my settings... Fingers crossed... Thanks again everyone... other comments are of course still welcome!

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  15. #15
    Not a waxer Jeff Kleiner's Avatar
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    Also make certain that you have toe in, not out. I like to see more than 1/16 and recommend 3/32".

    Jeff

  16. #16
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    Quote Originally Posted by BadAsp427 View Post

    The power steering is fully adjustable and with a simple turn of the knob I can turn it off or the other way have steering that I can blow on the wheel and make it turn.
    As an (very happy) EPAS convert I have two thoughts:

    One is that the video looks like the EPAS power is turned all the way up - it just appears to be full power assist. This observation doesn't really matter, whatever you like in that regard (but see below).


    Second is a question - where is your EPAS unit mounted?

    I can kind of imagine that if the EPAS is mounted down close to the rack - there could be enough resistance in the steering shaft back to the steering wheel (u-joints etc) to be affecting this.

    The EPAS unit has a torque sensor on the input side - if there is any resistance whatsoever between the input and the steering wheel it's going to read that as driver input on the steering wheel and apply power assist.


    This potential problem had not occurred to me until I saw your video.

    I installed mine between the firewall and the instrument panel, but mostly just to hide it and get it out of the weather - There may be a significant side benefit of having the torque sensor right at the steering wheel.

    Back to observation one - I think this potential effect would be most noticeable with the power assist turned all the way up.


    https://thefactoryfiveforum.com/show...ll-A-Part-EPAS

  17. #17
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    I've done a bit of research on EPAS units, as I'm considering putting one on my '67 Mustang. Lack of self-centering is a common complaint about EPAS units, both in OEM installations and aftermarket kits. Adding in as much caster as you can will definitely help, as will turning down the assist level, but from what I understand they're not going to feel like a regular power rack and pinion steering system.

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    Quote Originally Posted by JohnK View Post

    from what I understand they're not going to feel like a regular power rack and pinion steering system.
    Mine feels exactly like my manual rack did, except without the heavy lifting.


    I have also added a 1.5:1 steering quickener between the EPAS and the rack - I have occasionally tried a 2:1 quickener, but the EPAS barely carries that load.

    I had thought about moving the EPAS down in the footbox and putting the steering quickener between the EPAS and the steering wheel, but I think I see now why that would be a bad idea...

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    Did you resolve the issue of it not returning to center?

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    One thing a lot of people overlook when doing a home alignment is having the car level. I've done hundreds of alignments and if the rack is not level the alignment will never come out right.

    If one side of the car is higher or lower than the other, both camber measurements will be off and if the front to rear level is off, then caster measurements will be inaccurate. Most garage floors are pitched towards the door for drainage, this will mess up your caster angles. A few inches of off level is huge.

    Level should NOT be measured on the frame. where the tires hit the floor is where you want it level. A good laser level is perfect and use pieces of plywood under each wheel, so all 4 corners are level to eachother.

  22. #21
    BadAsp427's Avatar
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    Quote Originally Posted by mosh1999 View Post
    Did you resolve the issue of it not returning to center?
    Not 100%. As in the above note, I know my floor is not 100% level and I suspect this is part of my problem. I can say that it is feeling very good and I should have my title/registration in a week or so and will be taking it to Autometrics in Charleston to have them set it up right. They are too busy getting ready for Sebring to be able to get me in right now. But I'm excited to see just how close I am...

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