Front End Alignment

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#006633" TEXT="#F7F7FF" bgproperties="fixed" background="079005a0ddvuru.png"> <div> <A HREF="http://www.vernco.com/index.htm" TARGET="_top" TITLE="http://www.vernco.com/index.htm"><U><B>home</B></U></A><B>     |     </B><FONT SIZE="5" COLOR="#FFCC66" FACE="Arial" ><B>Vern</B><B>co.com</B></FONT></div> <div> back to<B>  </B><A HREF="index.htm" TARGET="_top" TITLE="Front Axle Rebuild"><U><B>Front Axle Rebuild</B></U></A></div> <bR> <div> <A HREF="http://www.vernco.com/id173.htm" TARGET="_top" TITLE="http://www.vernco.com/id173.htm"><U><B>Site Map</B></U></A></div> <div> </div> </td> </tr><tr> <td valign="top" width=150 BGCOLOR="#669966" TEXT="#080000"> <div> <A HREF="id372.htm" TARGET="_top" TITLE="Front Differential and Housing"><U>Front Differential and Housing</U></A></div> <div> <A HREF="id404.htm" TARGET="_top" TITLE="Spindle 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HREF="id461_wheel_bearing_adjustment.htm" TARGET="_top" TITLE="Hubs and Drums"><U>wheel</U></A> or <A HREF="id373.htm" TARGET="_top" TITLE="Kingpin Bearings"><U>kingpin</U></A> bearings.  Even though camber is not adjustable on this axle, it can be verified with a simple anglefinder as shown below.  The anglefinder is resting on the flat surface of the Warn hub.  Do this check with the vehicle on a level surface:</div> <bR> <div> <A HREF="id502.htm" TARGET="_top" TITLE="Checking camber"><U><IMG SRC="80e7d610.jpg" border=0 width="125" height="97" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <bR> <div> Caster likewise is built into the knuckles, but can be adjusted with tapered shims between the leaf springs and the perches on the axle.  Adjustment of the caster is best left to professionals with the proper measuring equipment and know-how.  If the camber checks okay, and the kingpin bearings are in good shape and properly adjusted, the caster is probably okay.  Since the axle perches rest on the leaf springs, extended shackles or non-stock springs with a different curve will change the caster.  If there is any doubt, have it checked by a professional.</div> <bR> <div> The only item normally requiring attention is the toe-in adjustment, which is well within the capabilities of the average mechanic.  Measurement of the toe-in requires a bit of patience and perhaps a helper.  Once the measurements are determined, the actual adjustment is quick and easy.  Please note that adjusting the toe-in will not fix a vehicle's tendency to pull to one side.</div> <bR> <div> Adjustment of the toe-in is accomplished by fine tuning the length of each tie rod.  The two tie rods meet in the middle, permitting each wheel to be adjusted separately.  (Please note many other vehicles, including Willys wagons and truck, have a one piece tie rod instead, which is a bit easier to adjust but is not covered here.)  Each tie rod consists of a pair of tie rod ends that are threaded into the tie rod sleeve.  With right hand threads at one end, and left hand threads at the other, the overall length of the tie rod assembly changes as the sleeve is rotated.  This is the same as adjusting a turnbuckle.  The sleeve has a slot at each end, allowing a circular clamp to compress the sleeve and tighten each tie rod end in place.</div> <bR> <div> Before starting any adjustments, consider how to turn the tie rod sleeve.  Why, I'll just use my trusty monkey wrench.  With an application of brute force and ignorance, it will move.  I'll get a cheater bar on there if needed, just watch me.  Okay, I'm being sarcastic:</div> <bR> <div> <A HREF="id496.htm" TARGET="_top" TITLE="No, No, No"><U><IMG SRC="7ff7d5c0.jpg" border=0 width="125" height="92" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <bR> <div> Any gouging on the tie rod assemblies could result in cracking later, leading to a loss of control.  The clamping force imposed by a pipe wrench, etc, is enough to collapse the relatively thin tie rod sleeve.  On top of that, improper tools slip and make adjustments less precise.  The proper tool is a tie rod sleeve wrench.  These are not expensive and work wonderfully.  The specially shaped ends wedge in the slot at either end of the tie rod sleeve.  You can apply an amazing amount of turning force.  Order a <A HREF="http://www.lislecorp.com/tool_detail.cfm?detail=1016" TARGET="_blank" TITLE="http://www.lislecorp.com/tool_detail.cfm"><U>Lisle #60500</U></A> if you can't find one locally:</div> <bR> <div> <A HREF="id497.htm" TARGET="_top" TITLE="Tie Rod Sleeve Wrench"><U><IMG SRC="8017d620.jpg" border=0 width="125" height="98" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <bR> <div> Here is a picture of the wrench gripping the slot in the tie rod sleeve.  Note the clamp, which has been loosened and slid inwards to make room for the wrench.  This view is from the front, looking at the driver's side.  When the top of the tie rod sleeve is rotated aft, the tie rod assembly gets shorter:</div> <bR> <div> <A HREF="id498.htm" TARGET="_top" TITLE="Tie Rod End CloseUp"><U><IMG SRC="803af500.jpg" border=0 width="175" height="80" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <bR> <div> Ah, grasshopper, good question, how do you know how much to adjust each tie rod assembly?  Well, let's figure out how to measure the toe-in and proceed from there.  A little bit of Toe-In 101 may be in order here.  A circumferential line, real or imagined, is scribed around the perimeter of each tire.  It would be approximately in the middle of the tread, but the side-to-side placement is not critical as long as it is consistent.  An easy way to visualize this reference line is to imagine spinning the tire while up on a jack, and holding a marker to the tread area.  Let's ignore how the tire tread will jerk your marker around, and since we are in a nice pretend world, you have marked a perfect line, too.  Supermodels are hanging around in my living room, and a nice man from the bank called to say my mortgage has been paid off.  Whoa, I'm really digressing here.  I might just stay here for a while, though.</div> <bR> <div> Back to the real world, but I still have a perfect line scribed around each front tire.  Take your trusty tape measure, and measure the distance between the two lines across the front of the vehicle.  Now compare that with a measurement taken on the back side of the tires.  If there was zero toe-in, the measurements would be identical.  If the front measurement were 1/16" less than the rear, that is 1/16" of toe-in.  </div> <bR> <div> Well, now you know the theory of toe-in, and one way to measure it.  But wait, there's more.  If you decide to stop reading, and I couldn't blame you, you could rush out to your garage and accurately set your toe-in.  However, you will be missing one important detail.  When the wheels are set for straight ahead, with each wheel slightly toed in per specifications, the Ross steering gear box must also be set to the center of it's travel.</div> <bR> <div> The Ross steering gear box is not the most modern type of steering gear.  At the center of travel, the backlash in the gears is designed very tight to eliminate wandering.  Off center the backlash is much looser for easier turning effort.  This looseness is overridden by the caster effect of the front tires trying to return to the straight ahead position.  This caster action eliminates any sloppiness in the steering during a turn.  However, it is possible, and don't ask how I know this, to align the steering gear off center so that extra backlash is present with the wheels straight ahead.  The result is sloppy, wandering steering.</div> <bR> <div> Fortunately, the Ross steering gear box has marks to make sure the parts are properly aligned during assembly.  This image shows the horizontal sector shaft and the steering gear arm, which connects to the drag link.  (The drag link runs forward to the bellcrank under the radiator, where the two tie rods meet.)  The alignment marks are highlighted in red.  These are a bit hard to see on the vehicle, facing the engine block, so you may need to use an inspection mirror:</div> <bR> <div> <A HREF="id508.htm" TARGET="_top" TITLE="Sector Shaft Closeup"><U><IMG SRC="82c964e0.jpg" border=0 width="150" height="78" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <div>  <A NAME="gearbox_center"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> If these marks are aligned, and the forward arm of the bellcrank is pointing straight ahead, the Ross steering gear box should be at the center of travel.  This is where we want the steering gear to be when the toe-in for each wheel is set.  To start, <A HREF="http://www.vernco.com/tips/id510.htm" TARGET="_top" TITLE="http://www.vernco.com/tips/id510.htm"><U>unhook the drag link</U></A> and count the number of turns the steering wheel can make.  From full lock, turn the wheel back one-half the number of possible turns.  Make a mark at the top of the steering wheel to indicate this centered position.  When the gearbox is centered, the forward arm of the bellcrank should point straight forward.  If not, there may be a problem limiting travel inside the gear box, the marks are not aligned like shown above or the drag link is bent or improperly assembled.</div> <bR> <div> Dang, we are starting to feel like Mensa candidates, aren't we?  Toe-in, toe-out, hidden secret marks, the whole gamut of membership in this secret society of folks who can understand front end alignment...  Well, prepare to be humbled, as it is time to actually set the toe-in.  Any slop in the tie rods, steering bellcrank, etc. is magnified and can drive you batty.  If these components are in good condition, push the vehicle forward across a smooth, level surface with the steering wheel centered.  This will help minimize any errors from normal play in the steering system.  I also guarantee that dyslexia will set in, and you will adjust the tie rods in the wrong direction several times during the process.  If you mark the tie rods before each adjustment, it is easy to undo any errors.</div> <bR> <div> Here is what the manual specifies in the absence of a fancy alignment rack.  We will initially set zero toe-in, which means the wheels are parallel.  Then each tie rod is shortened one-half turn, which will pull the front of each wheel inwards the specified amount.  The actual toe-in never needs to be measured if the wheels can accurately be set parallel for an initial step.  What could be simpler?</div> <bR> <div> Per the manual, a straightedge is used to align each front wheel with the back.  Note how the board is touching the sidewalls in two places at the front tire.  With a perfect board, and perfectly even sidewalls, zero toe-in could be set quickly and directly in line with the vehicle centerline:</div> <bR> <div> <A HREF="id499.htm" TARGET="_top" TITLE="Straightedge"><U><IMG SRC="82e96510.jpg" border=0 width="150" height="81" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <bR> <div> Notice I threw out that "Perfect" disclaimer.  Even with a piece of fine old-growth lumber harvested from prime Spotted Owl habitat, it was difficult to get a consistent reading.  The board looked perfectly straight to the naked eye, but when flipped over while taking measurements, I had almost an 1/8" difference.  That means the board was curved by a nearly imperceptible 1/16".  Another factor is that the sidewalls are not always even on radial tires.  If you were to spin the tire, you'd see the sidewall might easily have an 1/8" of runout, perhaps even more.  There is nothing wrong with the tire, that is how radials are made.  But the combination of the board and sidewalls can lead to excessive errors.</div> <bR> <div> When you were a kid, and things weren't going well, what did you do?  That's right, retreat to your room and play with Legos.  Only now that we are all grown up, we hide in the garage.  Nothing says we can't still play with Legos.  You see, I had a brainstorm.  Well, you might disagree, but it seemed like a brainstorm to me.  The manual says a string can be used as a straightedge, but what about the uneven sidewalls?  Legos to the rescue!  In this picture, Lego blocks are used as spacers to hold the string away from the sidewall.  With my full-floater conversion, I looped the aft end of the string around the hub, but you could run the string long and tie it to the frame behind the tire.  Tie the string tight first, then slip the Legos in place:</div> <bR> <div> <A HREF="id509.htm" TARGET="_top" TITLE="String overview"><U><IMG SRC="834af480.jpg" border=0 width="175" height="72" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <bR> <div> Here is a close-up of the front wheel.  Note how the Lego is only used at the front of the tire.  From that point, the string runs to the front of the rear tire and is parallel to the vehicle centerline.  I'm using the most consistent section, the bead area of the wheel, as my reference surface, instead of the uneven sidewall.  I've taken a measurement at the front of the bead area, and then will compare it with a reading 180 degrees away.  When I have adjusted the tie rod so the toe-in is parallel, these readings will be the same.  Remember to use the same viewing angle so you don't induce an error in your readings.  <B>CAUTION</B> - For accuracy, the rim must be straight.  To check, jack up the wheel and give it a spin while watching for any runout:</div> <bR> <div> <A HREF="id500.htm" TARGET="_top" TITLE="String and Ruler"><U><IMG SRC="836af400.jpg" border=0 width="175" height="64" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></A></div> <bR> <div> Now you might say, "Hey, I don't have any Legos."  Actually you do, you just don't know it.  If there are any children within a 20 mile radius of your house, there are Legos in your carpet.  You'll never see them during the day, as they are masters of camouflage.  Stealthily they reproduce and come out at night.  Finding them is easy.  Walk across the carpet barefoot in the middle on the night on your way to the bathroom.  You will find some.  All seriousness aside, I chose Legos as the spacer blocks because they are light and are easily held in place due to the bumps on top.  You could use any sort of spacers as long as they are the same size.  The lighter the better, so they don't slip out if you have to readjust the string tension.</div> <bR> <div> You are almost done setting the toe-in.  Remember, the string is used only to set the wheels parallel with the vehicle centerline.  This only works when the track is the same front and rear.  Also, don't try to take the actual toe-in measurements against the rim.  That measurement is specified at the full diameter of the tire and will be less at the bead area of the rim.  Once you have both wheels parallel with the vehicle centerline, with the steering wheel centered, shorten each tie rod one-half turn per the manual.  This will pull each wheel in the specified amount.  Remember that rotating the top of the tie rod aft shortens the overall length.  Secure all four tie rods clamps, and try a short test drive.  Don't immediately hit the freeway onramp, but instead try short jaunts at increasing speeds.  If you feel any shimmy or undesirable motion, slow down quickly and double-check your work. </div> <bR> <div> Remember the mark made on the steering wheel to indicate when the <A HREF="#gearbox_center" TITLE="Front End Alignment"><U>gearbox is centered</U></A>?  No matter how carefully the initial zero toe-in position may have been set, it is not unusual for the gearbox to end up slightly off-center when driving straight ahead.  This could be due to factors such as minor frame twist, uneven springs, slight variations in tire diameter, etc.  You can easily change the centering of the gearbox for straight-ahead travel without affecting the overall toe-in.  If the steering wheel mark (and thus the gearbox) is offset to the left, lengthen the left tie rod and shorten the right side to match.  As long as you turn each tie rod the same amount in opposite directions, the overall toe-in will not change.  Mark the tie rods so you can keep track of how much you've rotated them.  I found that a quarter turn of opposing adjustment on each side moved the steering wheel rim about 2 inches.</div> <bR> <div> The proper weight must be on the wheels, so don't set the toe-in while on jack stands or with the engine removed, for example.  Due to the angle of the tie rods, if the springs were compressed an extra half of an inch, the total toe-in will decrease over an eighth of an inch.</div> <bR> <div>  If you take your time, and are prepared to constantly double-check your work, you should have excellent results.  There are other methods to check and set toe-in, but this seemed like the simplest means that also aligned the steering wheel with the vehicle center line.</div> <bR> <bR> </td> </tr></table></body>