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Camber adjustment 348

Discussion in 'Technical Q&A' started by RAYMAN, Apr 14, 2004.

  1. RAYMAN

    RAYMAN Formula Junior
    BANNED

    Mar 10, 2004
    315
    Oklahoma
    Full Name:
    Raymond Santilli
    I have a noticeable negative camber on the rear of my 348. Is this strictly left up to someone with one of those laser machines, or is there a half measure I can do that will at least improve over the way it is now.

    Talked to one reputable shop, he said the car may be too low, and wheels too big for his machine to work. Is this a tire shop job? or more difficult.

    Any comments appreciated.
     
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  3. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    For the mechanically inclined, with room, tools and relatively flat floor, not too tough to get good results.

    • 6 ft. level
    • Masonite, 3/16 thick, cut into 12 x 14 inch squares
    • 3/4 inch square aluminum tube, cut so it is just long enough to touch just the rim of your wheel, spanning across from top to bottom.
    • digital level like Smart level that will read vertically, and give a value off vertical in degrees.
    • monofiliment
    • plumb bob
    • short machinist's rule
    • spare alignment shims (dealer, 1, 1.5, 2, 2.5, 3 mm thicknesses)
    • wrenches/ sockets to fit the nuts on the back of the wishbone mount forks, where the shims are pinched between the forks and the frame.
    • pry bar, 12" or so
    • paint marker
    • wrenches to fit tie rod and lock nuts

    Park the car ....

    Sorry, I'll finish this later this week....


    Rob
     
  4. davey_jones

    davey_jones Formula Junior

    Sep 28, 2002
    781
    wherever it's sunny
    Full Name:
    Dave
    I have the exact same issue and I know I'll get a TON more miles out
    of those rear tyres when it's corrected. Was hoping to have it
    worked on in a couple weeks or so. So we'll see I guess..

    Being that we both have Speciales, I think the shim size needed will be
    the same for both cars. If I get mine done b4 you I'll let you know.

    dave
     
  5. RAYMAN

    RAYMAN Formula Junior
    BANNED

    Mar 10, 2004
    315
    Oklahoma
    Full Name:
    Raymond Santilli
    Excellent
     
  6. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,030
    socal
    This is a really easy job but the person who does it has to understand the full adjustability of the 348/55 design with double a-arms and coilovers. If you really want to wake up the handling in your car take it to any alignment shop who has race scales. If they have scales they understand the need for precise 4 wheel alignment with proper toe and camber and caster. Camber is not the only issue. example if you have too much rear toe you wear your tires and understeer dispite what the camber looks like. You need to weight the car to get the chassis balanced over the wheels. Then you need to settle the rear by getting the proper camber and toe! for your driving desires (and it sounds like you want to be on the small camber end of the specs for best tire wear and mellow street driving.) Then they need to set the front caster to be even on both sides and then the front camber and toe. You MUST setup the even weight of these cars first. If you do not understand why just ride your bicycle down the road in a straight line. Now ride your bike and hold your bowling ball out as far out to one side as you can. How straight are you going now? Get the picture?
     
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  8. RAYMAN

    RAYMAN Formula Junior
    BANNED

    Mar 10, 2004
    315
    Oklahoma
    Full Name:
    Raymond Santilli
    Yes I understand this is a pretty deep subject, thanks for the info, I'll keep looking for a competent shop
     
  9. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    …Sorry for the interruption…

    [size=+1]Prepare the Area[/size]

    First, we must level the area, laterally with respect to the car:

    Park your car where you’ll do the alignment, and mark the position of each tire on the ground using your choice of paint marker, duct tape or whatever. I mark a “T” on the ground, with the top of the “T” parallel to the wheel if looking down on the car from above (plan view), and a very short leg of the “T” to mark the center of the axle. You can also just draw a box on the ground surrounding each tire. We’re locating where the shims will go on the floor to yield a level surface, side-to-side, so each axle is level laterally.

    Now move the car so we can use the six foot level and Masonite shims to level the area where the car will sit.

    Place the level on the ground at each axle position, which means fist the level is placed on the ground touching the marks for LF and RF tires, placing the 3/16 inch shims at the tire location to shim up the side of the level that’s too low. Take notes, so you can quickly recreate this set-up platform in the future.

    Now do the LR and RR axle shims. Of course, you’ll only have shims at most at only one wheel location per axle.

    Don’t bother leveling longitudinally, it’s of virtually no consequence, unless your garage floor is sloped like the side of a mountain.

    [size=+1]Measure Camber[/size]

    Now roll the car onto the leveled surface.

    Check and adjust tire pressures.

    With the steering wheel placed straight ahead, and weight in the car to recreate how you typically drive (driver only, or both driver and passenger) and ½ tank of fuel or so (not too critical, if the car’s emply, go fuel it to half tank. If it’s anywhere between ¼ and ¾, you’re fine, just add the fuel level to your alignment notes.)

    Cut the aluminum tube to just touch rim outer diameter of the wheel, using this tool as a straight-edge for the electronic level. Now you may measure camber of each wheel.

    [size=+1]Set-up to Measure Toe-In[/size]

    Adjusting camber will affect the toe for the wheel being adjusted, so we must measure toe-in too.

    There are many purpose-built toe gauges, but by far the least expensive, most durable, and just as accurate is monofiliment and machinist’s rule. Racer’s We want to place reference lines parallel to the car’s longitudinal centerline. Using jack stands or other support, and weights tied to the monofiliment, place the two lines the same distance from the car’s longitudinal centerline, at the same height as the center of the wheel hub center (right at the Prancing Horse center cap).

    The most accurate method of locating the monofiliment lines and true vehicle centerline is to drop a plumb bob down from the center of the suspension lower control arm mount at the chassis. Mark this position on the floor. Measure and mark the center for the front and then rear of the car. A chalk line will work perfectly here to snap the car’s longitudinal centerline. Use the centerline to reference the monofiliment line placement.

    Yes, this is a bit of work, but the results are as good as virtually any professional alignment rack.

    My suggestion is that once you set your parallel lines, measure and record the distance from each wheel’s stub axle (remove the Prancing Horse center caps for this). Now the entire stringing process may be reproduced in a few minutes instead of an hour. Yes, with a camber adjustment, the stub axle will move, but for the purpose of alignment in your garage, we’ll ignore this affect.


    MORE TO COME…
     
  10. RAYMAN

    RAYMAN Formula Junior
    BANNED

    Mar 10, 2004
    315
    Oklahoma
    Full Name:
    Raymond Santilli
    Wow Rexrcr, those are some detailed instructions, I'm impressed! I'll have to read it a few times for it to sink in, and I'm sure everyone appreciates the effort your putting into this, look forward to the conclusion.
     
  11. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,012
    I am adding three pictures from "Prepare To Win" by Carroll Smith (may he rest in peace) since I've never seen Rob post pictures, and this is one subject that needs then to simplify the conversation.

    The first picture is how one levels a car and how one measures camber.

    Attempting to align a car with a list is fairly useless; get the ride heights set and balanced side to side.
     
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  13. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,012
    The second picture shows how a parallelagram is setup around the car to enable the toe measurements.
     
  14. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,012
    And third is how the toe measurements are taken
     
  15. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,012
    Oops the toe and parallelagram picts are reversed.

    And now back to your regularly scheduled program.
     
  16. RAYMAN

    RAYMAN Formula Junior
    BANNED

    Mar 10, 2004
    315
    Oklahoma
    Full Name:
    Raymond Santilli
    Beautiful!
     
  17. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    Thanks for posting the diagrams, Mitch, perfect.

    So, to wind this up...

    [size=+1]Measuring Toe[/size]
    As Mitch’s diagrams show, looking down at the wheel from above (plan view), use the machinist’s rule to measure the distance from the monofiliment to both the front and rear of the wheel’s rim (referenced from the orientation of the car), and subtract the smaller value from the larger. It is toe-in if the front value is larger than the rear, toe-out if visa-versa. Make certain your steering wheel is straight when measuring the front suspension alignment.

    [size=+1]Time to Adjust[/size]
    Adjusting camber is not too tough. The adjustment takes place using shims located between the lower control arm mounting forks and the lower frame rail. As stated, the factory shims come in different thicknesses: 1.0, 1.5, 2.0. 2.5, and 3.0 mm. Please note that toe-in is also changed for the rear suspension using these same shims.

    For camber-only adjustment, it’s a bit trial and error to know which shim thickness to use until you have experience. To increase negative camber, add the same thickness shim under each of the two lower mounting forks at that wheel. Do this by loosening the big nut (22mm wrench size) on the inside of the frame rail. Use a short pry bar to push the fork away from the frame. Careful, the other shims may fall, depending on their slots orientation. I always use a metric caliper to confirm shim thickness. Remember, if you use two different thickness shims on the same wheel, you just changed the toe-in value.

    When adjusting front wheel camber, always use the same thickness shim on each fork. Any camber adjustment to the front will change toe-in, which must be adjusted using the steering tie rod end links.

    After adding or eliminating shims, tighten the nuts (about 70 ft-lb) and lower the car. Roll car on and off the set-up pad by hand a few times to let the tires loose any lateral grip on the ground which occurs by just dropping the car down.

    Correct front toe using the tie rod ends. Mark the tie rod link with a paint marker for reference before rotating. Small changes in front toe may only require ¼ turn of this link. Turning one side’s link out and the other in the exact same amount will re-center the steering wheel without changing toe-in. Since this is rack and pinion steering, there is only one jamb nut, and the tie rods on each side are right hand threads.

    Rear suspension toe-in is adjusted by either adding or eliminating one shim on only one fork at each wheel. It is your choice whether to add or eliminate a shim. Be certain on the rear suspension that each wheel has the same individual toe value as this affects the “thrust alignment”, which is the rear wheels following exactly behind the front wheels. As opposed to the car looking like it is skewed to one side while driving down the road.

    Questions?
     

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