I'll be sending my '32 Heavy axle off to Okie Joe to be straightened and setup for my spindles, and this got me wondering. I'll get an axle back with the proper stock caster, what that is measured to or from is unknown to me, and it can change at any time in the build, or with a change in tire size front or rear, crossmember placement can also change it. So the question is when does the castor get checked on a '32 frame with split '32 bones? Bob
I set the rear end first, have my tires and wheels bought and on, mount the front axle to the cross member ,then mount your split bones so the axle is 6 degrees back.
Set your front axle castor and rear differential angle with the car at ride height. Same with the engine. It is nice to have the exact tires and wheels you are going to run on the car when you do it, but not mandatory. You can also weld in front cross members (which set the front axle castor) with just a pair of rails and cross members, but you should still set the front and rear of the frame at ride height when you do it. By the way, the axle itself will set the camber which is the top of the tire in or out measurement. The caster is what you establish when you weld in your front cross member to the proper angle as the king pin inclination will follow the crossmember angle. There is a such thing as an adjustable leaf spring perch to make your king pin angle different than your crossmember angle, but the best way is to get it right to begin with. Rule of thumb is 5-7 degrees tilted back towards the firewall. There are some kick ass threads on this if you hit the search button, but this is the general idea. Good luck, -Abone.
I've come up with a bunch of dimensions that work over te years but generally speaking, the castor needs to be dialed in while he chassis is being fabbed. Lock the chassis on ride height, assemble the axle and 'bones and set your castor accordingly. Check again when you have the drivetrain in and weight on the springs. I like 7-8 deg. on the street just because it will run a little better at highway speeds. As Hot Rod Nut mentioned above, 6 works nice for easy steering around town and parking and the like. All depends on what you want the car to ultimately excel at. Everything in a build is at least in part a compromise.
Thanks! I could never afford to buy all four new tires before the chassis gets faded, they would be dry rotted and useless by the time the project was running . Bob
Don't mean to steal the thread.....I've always set adjustment at ride height which means to me that you want the engine weight, which I understand for split bones. This is what I did on the 34, but on the 33 I have a 4-bar set-up and I've always thought ride height / weight didn't matter......opinions?
Flamedabone hit it on the nose when he said that your "camber" was preset when okie Joe dropped the axle. That is part and parcel with dropping the axle correctly. I can't add anything to what the others said on setting the caster and all seem to be on the same page. i'd agree that on a long term build it is a bit wasteful to buy a new set of tires and have them sit in the shop on the rims for years on end until you get the car running but you should be able to come up with a set of used tires that are the correct size for pocket change or less and be able to set it and roll it around on them until the time comes for those new tires.
If you can't afford the wheels and tires you want, go to a junkyard and buy stuff there for frame set-up.I keep stuff like that just for set up- right now I've got a pair of my old truck tires on the back of a coupe frame I'm doing- 30" diameter, and a set of 24" dia. on front all on 15" rims. I like to switch tires, rims, hub caps, baby moons,trim rings,painted rims with chrome lugs, etc- really changes the look of the car and drives all my buddies nuts .I used to run slicks to shows once in awhile, but got caught in the rain on the highway, did a 180* and decided that wasn't such a great idea( but after it was over, and no damage done, decided it was kinda fun!)
Camber is set by the axle dropper and should be to factory settings. Caster is not a function of the axle, as the axle is straight - all the bosses are in line when viewed from the end. The caster is set by the bones. Traditionally they have been cut and rewelded to give the correct caster. If unsplit just bolt them up, if split, the height of the rear of the bones relative to the frame is what matters. Mart.
When I set mine, I didn't have the tires to use to establish ride height or a set of junk tires either. So I went on the Coker website and got the height of the tire I wanted to use and obviously, half of that measure is where the spindle should be at. You can then set the axle with the spindles on jack stands at the height where the spindles should be in relation to the tire size you want to run. Posted using the Full Custom H.A.M.B. App!
Cheap solution is cut a plywood circle of your tire diameter, drill a center whole and lug holes and bolt it on.
For the sake of making it easy to understand we will use balljoints as an example. Caster is the upper spindle location in relationship to the lower spindle mount, so with ball joints one is usually. forward or backward of the other. As in positive caster the upper ball joint would be behind the lower balljoint, as from front to back of car. Caster is measured by turning the front tire say to the left, usually 20 degrees and a reading taken with camber/caster gauge, lets say its 0, now we turn the tire right again to 20 degrees and we take another reading, lets say it 4 degrees so now we take both readings and do the math 0 plus 4 = 4 so we have 4 degrees of caster. What you are actually doing is reading either kingpin or balljoint inclination.. You can change it by either adjusting the radious rods or like i have done it many times (and the way it was done in the old days of straight axles) is actually bend the the king pin bosses on the axle. We still have the old tooling to do this. Camber can be bent also. We do a great many straight axle rods and never ever had any problem bending them. I usially set them up with 4 to 5 degrees caster with the passenger side have 3/8 degree more csster to counter road crown. Set camber at 1/8 pos passenger side, 3/8 pos driver side with a 1/16 inch toe in. Drive great, handle great, wears tires excellent.
Right or wrong, I really think the final placement of the split wishbone tie rod end to chassis makes or brakes the look of the car. Since most time is spent looking at cars vs. driving I know were mine will connect. Bob
When you get it on the road, take it to real front end shop and not just a gas station with a modern computer alignment machine operated by a young kid that just follows the direction of the machine. The machine can't think all it knows is what is programed into it. Put the radius rods where they look good to you and have the final castor adjusted to get the desired spec. I beam axles aren't the same. Ball joint specs are different. Get your specs from a Motors Manual for the year and model of your car. A good front end shop can input your specs and adjust your axle to meet those specs. So many fly by night shops just "set the toe and let it go" That is not an alignment.
The set the toe and let it go idea is because as you stated most dont know what to do without acomputer to tell them and the few that do kno dont have the equipment to set up a straight axle. We still use plumb bob hand gauge, if you dont understand what caster, camber actually is and know exactly what your doing the hand gauge is worthless to you, we have hired and fired many "alignment" men because without a computer they couldnt do anything. Wouldnt have a computer aligner for anything. Caster split can be bent into the axle beam with the car totally done. Still do it today on semi trucks. There isnt much difference between balljoints vs. Kingpins as far as camber is concerned, a tire touches the ground in the same way no matter whats holding it. Caster is a little different only that most older cars run around 2 degrees caster, straight axles run more. More caster makes the car more stable but there are trade offs, higher caster makes them harder to turn at very low speed without power steering, it also cuts the corners of the tires. Turn the steering wheel on an older ford pick up and look how the tire kicks over onto the edges of the tire when turning. They run between 4 to 5 degrees caster.
The old spec books that I have seen all recommend min 4.5*- max 9* for the old king pin front ends so that the tires will return to straight when you release the wheel. Ball joints don't need as much castor to return as the king pins do to overcome the friction. I usually go for around 7 degrees on a king pin front ends. These are just recommendations any degree with in the range should be just fine. I was always taught to match the camber side to side and not to have 6* on one side and 9* on the other even though they are both within specs. Pic one and make the other match. That is how I was taught.
Yeah we put 3/8 degree more caster in the right wheel, passenger, this counteracts road crown. Most roads have a natural crown to shed water so we just compensate for it. Usually without it they have a tendency to drift right... Alot depends on the roads in your area..
Lostone, what would you set caster on a '32 with stock wheelbase at if it was running bias ply tires? How about radials? Now how about the toe-in for each? Do you set them different if they are running an old Ford box or a Vega? Obviously the Vega is going to return easier on it's own and the F-1 (or other old box) will take more "work" to get home.
The actual title of the was "at what time in the build do I set the caster". The simple answer for that is when you are building or welding in the front cross member. You can take a front spring mount welded into a frame at 0 degrees and mount the spring, yank the wishbones down, bind it all up and attach them. but at that point your front spring is bound up enough that it is compromised. A much better way to go about it is to weld the front cross member in at the desired caster angle you want, then attach the spring and make your wishbone mounts. That way nothing is bound. Now, one last little bit of though about caster. It changes as the rake of the car changes. Most of us don't build flat cars, so when the rear end elevates 1 degree, the caster angle becomes 1 degree less. So lets say you built it with 7 degrees dialed into the front cross member while it was on your table. You get it all together and with a 2 degree rake on the car, your caster is now at 5 degrees. As most have said, 4-8 degrees is the accepted caster for most early Ford type applications. I prefer my cars to be on the heavy side of that because of the long straight, high speed roads that I deal with out here in the west. So, when building a chassis, I'll dial in about 7 degrees into the cross member at the time I weld it in, and end up with 5-6 degrees in the finished car. Clear as mud?
Lots of guys building A's and '32's set the front crossmember flat to the top of the frame rails so the radiator mounting pads sit correctly. I think the manufacturers of the new crossmembers should put more tilt into the middle of the crossmembers. But, that said, isn't it the job of a spring to bend, so if it has a degree of bend just sitting there, it shouldn't hurt it too much?
Actually, even the stock "A" cross member has some amount of caster angle dial into it right from the get go. IO haven't put a protractor on one to double check. but I would guess that it's right around 4 degrees. The after market stuff runs more like 5-7 degrees built in. But no, putting the spring in a bind really is to be avoided. A degree or two isn't the end of the world, as a matter of fact it incurs that in normal suspension travel. But 5-7 degrees of bind from a starting point? Nope. They are ugly as sin, but the articulated early Ford type spring perches that everybody made in the eighties and nineties are quite a revelation on a cross spring front suspension simply for that reason. They allow it all to work...
Alchemy, i take many factors in setting an alignment. I first ask how do you spend most of the time driving it ? Hiway or town, how does it feel to you ? Wanders, stable etc. Then i look at the car. Lets say 32 you spend most time on hiway, you say it wanders alittle with radials, if your caster is 4 degrees i will bump it up to around 5 1/2. Dont car bout the gear as most the time your drivin straight down the road and not much turning. Lets say 32 intown driving, i try to keep caster down just to aide in steering and prevent corner wear on tires, radial tires have softer side walls so they tend to roll the edge of the tires over when turning. If your tires show corner wear then i will check 2 things, caster and air psi. If your runnin radials with a 44 psi rating but runnin 32 pound. I will raise tire psi to 38 psi to help stiffen the side walls. Bias tires have a stiffer side wall so its more forgiving on caster and tire pressure. If you notice corner wear on tires with higher caster 3 or more, 4 or more straight axle raise tire pressure will usually do alot to aliviate the wear, never past max on tire. Caster is drivability only, only really affects tire wear on cornering.
Oh btw you asked bout toe, i set toe according to camber and really not much else. Camber and toe work together. New cars do this, they run neg camber then more toe in. Camber whether neg or pos needs to be known first in order to set proper toe. Toeing in wears the outside of a tire, toeing out wears the inside. So i need to know camber first. If i have 1 neg camber, which will wear the inside of the tire, i will set toe to a good 1/8 inch in, this will wear the outside of the tire, so with neg cam wearing the inside, toe in wearing the outside i end up with a flat wearing tire, now i can raise camber to 0 and toe in a light 1/16 and again flat tire wear but also pick up longer tire life, raise camber to 1 pos, toe OUT strong 1/16 to light 1/8 again flat tire wear but cut tire life say 8 to 10,000 miles on 60,000 mile tires.. camber and toe ALWAYS work together... something many alignment shops have forgotten..
I'll throw something in here for the thinking type. If you set the axle king pin caster angle to 7 degrees, perceived wisdom says you must also set the spring and crossmember to 7 degrees also. That is a logical conclusion. But in reality, the axle moves in an arc centred on the wishbone pivot. (or radius rods). The spring should be set at an angle to follow this arc. Lets say your wishbone is horizontal, running parallel to the ground. The spring is above the axle so you have to imagine a line from the wishbone pivot to the spring. The angle of the spring and crossmember should be tangential to this line (or arc). If everything is more or less stock, it all works out ok. But lets say you have a high stepping gasser style A, where the radius rods run downhill to the axle. The axle is then canted back to get 7 degrees of caster. In this case the spring should not be set back at 7 degrees, but should be following the arc of the radius rods, probably at a near vertical angle rather than angled back. All theoretical, I guess, but it is something that occurred to me but I have never heard it mentioned before. Mart.
Lostone, thank you for all your good info. I wish your shop was closer to me so I wouldn't have to do it all myself.
The Jalopy Journal
