Camber, Toe & Castor - the difference
Most people hear these words but rarely have the opportunity to understand what they mean and do.
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
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.
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.
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
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
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
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
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
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, 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