Camber, Toe & Castor - the difference
Most people hear these words but rarely have the opportunity to understand
what they mean and do.
TOE
This is the amount that the wheels are pointed in or out EG often called
"total toe in or out". On rear independant suspension cars this
is also adjustable, Subaru, Daihatsu etc. NOT live axle cars though. Fords,
Holdens etc. Often measured in mm this little change makes huge differences
in handling. As a car moves forward the suspension often moves back reducing
toe in, so cars are often set with 1 - 3 mm toe IN. If the car has toe out
it often tends to wander on the road more.
On all our rally cars we run about 1 - 2 mm on the front and BACK.
Rear is less important as it tends to be less likely to be affected by knocks, pot holes and kerbs. BUT it is important to be correct
CAMBER
Think of the angle of most roads, look along it and it slopes to the side
to make the water drain or is banked on fast freeway corners. This is camber,
the angle your wheel sits in relation to vertical when pointed ahead and
you look straight at the car from front or rear. Measured in degrees, most
common road cars have 0 - .5 degree std. some more. Too much NEGATIVE camber
will wear out tyres on the inside. POSITIVE wears out the outside. Look
at really old cars they often have POSITIVE camber. (I do not know why).
The correct amount varies depending on CASTOR, (see follows) and how you drive your car. If you have little castor and you love driving fast through corners then you need more NEGATIVE camber, if you do heaps of freeway driving then less is better.
THE REASON? When you turn a corner the outside tyre tends to roll under the rim, causing it to wear on its outer edge. By laying it on its side you reduce this effect. Too much and it will wear on the inside, too little and wear on the outside.
NOTE this is often used to stop wide tyres rubbing on wheel arches or suspension points, this case tyres wear is not a focus! REMEMBER too much neg camber and you will lose traction in straight ahead driving as the tyre is not flat on the road.
CASTOR
This is the best of both! BUT is often not adjustable on modern cars.
Camber stays the same if the pivot (vertically) of the car suspension is zero. EG if you turn the wheel about its axis (steer not spin) it stays the same. BUT if the axis is at an angle (for and aft) then the more you steer the car, the more camber you get!
Its hard to relate, but if you imagine looking at the LHS of the cars wheel, with front to your left, if you grabbed the top of the axis and moved it back (to horizontal) with the wheel position staying still then this is castor, then imagine, if you turned the wheel to the right 90 degrees then the wheel will lay flat, this is obviously an extreme example but best explained.
SO, the more castor the more the wheel will increase negative camber the more you turn the wheel. BUT too much castor and the car will want to wander as it has less tendency to want to point straight ahead.
REMEMBER
Check your tyre pressures, over 80% of cars have UNDER inflated tyres AND
most companies, TYRES AND CARS, suggest low, for better ride. On most Subaru's,
Hyundai's Daihatsu's etc try 35 PSI it will steer better, ride a bit harder,
but go HEAPS better!
On most cars these days we can supply camber kits to increase and allow adjustable camber, most Subarus have some adjustable limits. Castor well thats hard, but possible!
Remember that you pay for what you get, a cheap wheel alignment means just that!
rumble seat: 10/3/2000 - 1/1/1900 7:15:13 PM
bearing kingpins
Accessories
Steering wheel shake is now gone! As you remember I`d stated the front ends
on both `39 and `34 were checked by two different front end shops and were
in alignment. In a pig`s eye! After all the comments from the knowledgeable
people on this forum I became convinced the problem was the caster.... regardless
of what a couple of front end shops said. Was able to borrow a front end
machine from a good friend after hours and checked mine. He watched from
a safe distance since I`d asked him to help only verbally. Actually he did
get dirty, but then my car is always dirty! Spec`s call for 9 degrees positive.
Mine was 1-1/2 degrees positive! Bent the wish bones to get 9 degrees. No
shake. Next night I checked the `39. It had 2-1/2 degrees positive. Set
it to 9 degrees also. No shake. So you guys were right.... it was caster
all along. What torques me off is two front end shops assured me both cars
were aligned to spec`s..... at $75 each! Crooks! Only thing I can think
of for running so little caster is to make them turn easier, but they sure
shook good! Anyway, I`m satisfied now and continue to recomend bearing kingpins.
Oh yeah, I wrote Stainless Steel Brakes an E-mail, per their request, concerning
my findings.... rumble seat
JimTN: 10/4/2000 - 1/1/1900 5:39:21 AM
RE: bearing kingpins
Accessories
How did you rig up to bend the wishbones? Presuming they were not split.
Ford made a tool that was used with a long cheater pipe that was sort of
a big wrench that would hook over the outboard end of an axel to bend the
axle itself. That method would be difficult without some means to check
results. Bending the wishbones might me done in moderation with a good true
axle to `fix` a front end. I have done it on twin I beam trucks with good
results and no apparent bad effects.
rumble seat: 10/4/2000 - 1/1/1900 6:20:34 PM
RE: bearing kingpins
Accessories
Part I: To answer each question may be easier if I explain why and how I
bent the wishbone of the axle. Main reason I bent the wishbone was I didn`t
have a Ford caster bending tool as mr bill`s picture showed. I`ve not seen
one of these since I worked in a front end shop in the fifties. Also I run
a tube type dropped axle and bending them can cause them to crack and/or
break if they`re bent very much. So I elected to set the caster the way
we used to do for stock car racing .... by bending the wishbones. You have
to be able to check the amount of caster as you bend, so a front end machine
is the way to go. But I`ve bent them on a level garage floor using a caster-camber
gauge and a section of railroad track in place of the rails on a front end
rack. Bending the wishbone upwards will twist the axle and decrease the
caster. It follows bending downward increases caster. All bending is done
in the center of the wishbones. To increase the caster, we have to bend
the center of the two wishbones downward. Do one side at a time. Using porta-power
chains (regular logging type chains usually will not take the strain), chain
the center of one side of the wishbone down. Put a 6 to 12 ton bottle jack
near the rear of the wishbone. And another near the front of the wishbone.
Begin jacking both jacks upward slowly. Remember these are under a lot of
pressure so be super careful. This will bend the center of the wishbone
downward and increase the caster by twisting the axle slightly. Bend the
wishbone down about an inch and release the pressure. Check the caster.
If you go too far, remove the two bottle jacks and chain the wishbone down
where the 2 bottle jacks were. Put a single bottle jack in the middle of
the wishbone and jack it up a ways. This will decrease caster. See part
II for more info...
rumble seat: 10/4/2000 - 1/1/1900 6:46:23 PM
RE: bearing kingpins
Accessories
Part II. If you don`t have access to a frame machine, a 5 foot section of
railroad track (or something similar) can be used with some difficulty along
with two 2X4`s. The railroad track is elevated at both ends on two sections
of 2X4`s. This is done so the chain can pass under the track (or heavy steel
plate you`re using). If your car is as low as mine, I have to elevate the
car by putting wood 4X6 under each wheel so the bottle jack will fit between
the track and wishbone. Then install the chains and jacks like discussed
in Part I and bend away. Crude I know, but it works and I`ve set many using
this method after a bad wreck at the track. You have to have a caster camber
gauge. I don`t know of anyway to do it accurately without one, but others
on this forum many know of a way using levels and protractors or such. To
JWL... yes it did increase the turning effort. To Roger... spec`s are available
in old manuals or from front end shops. But if you`re in doubt, I`d set
the caster at 9 degrees positive since that is what we used to set them
all at way back when. To Harlan.... the amount to bend varies from car to
car and is dependent on a lot of things (amount of rake or car, tire diameter
differential between front and rear, air pressure, weight of usual load
(if you weigh a lot you should put that much weight in the front seat),
tweaked or worn frame and/or suspension parts, how level your frame machine
is, etc.). Additionally, radial tires seem to be a lot less sensitive to
caster than bias belted tires. Air pressure is CRITICAL! Check all tires
and adjust before you start checking anything. Hope this helps some....
rumble seat: 10/5/2000 - 1/1/1900 8:27:39 AM
RE: bearing kingpins
Accessories
Well as usual I blew it! Hit the wrong key for caster spec. Should have
been 6 instead of 9. Sorry. Will note front end spec`s from shop manual
today (and I`ll verify before I post them!).
rumble seat: 10/5/2000 - 1/1/1900 8:47:45 AM
Caster/camber
Accessories
Caster, camber, and toe-in specifications. The following are spec`s from
Motor`s Manual. The sequence is: year, degrees of caster, degrees of camber,
and inches of toe-in/out. 1934, +8-1/2, +2, 1/16 toe-in. 1935-`36, +6-3/4,
+5/8, 3/32 toe-in. 1937-`48, +6-3/4, +5/8, 1/16 toe-in. 1949, -1/4, +1/2,
see note at end of these spec`s for toe-in/out. 1950-`51, -1/4, +1/2, 3/16
toe-in. 1952, -1/2, +1/2, 3/32 toe-in. The 1949 has two different spec`s
depending on the type of idler arm mounting bracket used. Idler arms with
the bottom mounting hole threaded for a cap screw are the earlier ones and
the toe-OUT is 1/8 inch (yeah that`s toe-out!). The late ones have the bottom
mounting hole drilled through for a bolt/nut (not threaded) and toe-IN is
1/16 inch. The book calls for toe-out on the only early 1949`s. All `49-`52
have negative caster so they`re essentially dragging the wheel where the
others are pushing it.
Graphics courtesy of Hal Nesbitt