I bought a new 4" drop axle for my car. I was wondering when setting up a split wish bone, how do I know where to set it? I know speed way sells brackets either 2 3/4" tall or 4 3/8" tall, how do I know which would give me my desired caster? Posted using the Full Custom H.A.M.B. App!
Set the front axle as it would be on a stock Ford chassis, you cant go wrong. As for buying parts such as the Speedway mounts, theres no such thing as a buy and bolt on piece for this sort of application as everyones chassis is set up differently, ie - front spring, ride height etc etc, you will have to modify and work with things till you get it right. I take it this is your first build as you seem to be asking a lot of questions? I hope your getting the answers you need from all the clever buggars on here. Best of luck with the build..
Yep this is my first hot rod build. I've done several muscle cars and trucks, but I'm new to all this. I'm just trying to learn as much as I can and everyone on here has been very helpful. Posted using the Full Custom H.A.M.B. App!
I gotta disagree here. A stock model A gas 0 castor. Most folks say you want 5 to 7 degrees. The more castor you have, the straighter the car will track down the road. Not enough castor and it will be easy to turn but scary on the highway. If i were you I would buy whatever brackets you like. Then set your castor angle on your axle. Then pie cut your bones until they meet your brackets.
When you split the bones you will need to use some sort of weld in bung and use a tire rod,,this is how you adjust the axle,I usually set the axle up at about 5 degrees,,that leaves adjustment for the additional amount if need. The shorter mounts is what I would use. HRP
I recently had a very interesting conversation with a man, Matt, that I would classify as being one of the most skillful, clever fabricators I have ever encountered.. Matt was working on a '29 Ford A roadster pickup that he was building for a customer.. The Ford was being extensively modified, running a "Miller" modified OHC A engine, Ford type dropped front axle, split wish bones, 5 spd trans and a highly modified quick change early Ford rear end. A discussion arose about the pro's/con's of splitting the front wish bone? I brought up the question as to why some people like to split the wish bones and why some people do not split them? Matt pointed out that generally speaking, splitting the wish bones on a traverse mounted spring front end will make the car handle well on straight line driving..i.e. Drag racing, where-as the car will not handle well in turns etc., do to the torque the front end experiences during turns... There are probably a lot of variables that can come into the picture, however, it just could be that many people spit the wish bones simply because, "everyone does it"..
Generally speaking, splitting the wishbone is done for engine/bellhousing/transmission clearance since , especialy on Model As, the wishbone mount is the bellhousing.
A lot of folks have to split them because of oil pan clearance. I personally like an unsplit wishbone as far as looks go. When u split a wishbone , you introduce bind in the geometry of your front end. Your axle becomes the weak spot and flexes ( which is fine on an i-beam axle. Much smarter folks could tell you how that effects your handling. But i have heard that drilled axles started as an improvemmet to lower the resistance the axle has to twist. Again I'm sure somebody smarter than I could elaborate.
The bones on my truck are split and they have been brought all the way out to the side of the frame,I used a Model A front cross member and set it with a 7 degree caster built in.
I think Matt needs more historical research ... I believe all the original circle track roadsters were split for the opposite reason... Also needs to drive a real hotrod with split bones in some switch backs... But for most all purposes the bones are split cause the k member with the ball is cut out or for clearance for starter,oil pan,oil filter ,exhaust
Set your front suspension up with the desired caster then make your own brackets. I set 7* of caster then made simple brackets out of 3/16" plate and gusseted them on the back side. I bought a pair of $3 shock buttons from Speedway and welded them in so I'd have the proper 7* of taper for the tie rod ends.
Respectfully have to question this. The bung welded to the bone allows for a threaded tie rod end to be installed. I can see how threading the tie rod in or out would align the axle, but how does it set caster? Posted using the Full Custom H.A.M.B. App!
I suppose if u were to lengthen the tie rod ends and push the axle forward it might tilt the axle back. It would seem that doing so would put a ton of stress on spring perches, bushings, etc.Most certainly not a correct method. Tie rod end adjustment on the wishbones should locate the axle and square it to the frame. Not adjust Castor
Get some books and read all you can, and then find a guru who has been down this road and back again. Some of the information already given makes me cringe; and not wanting to make enemies, other than with those who know they're peddling bogus info, please, please don't waste your time with replies to questions on any site unless you know the people who are giving it are Practicing Masters of the first water. No offense meant but the old saying that 'a little knowledge is dangerous thing' applies here. One 'must have book' is the one by Vern Tardel. There are others that give you the straight stuff without a lot of self-aggrandizing ego-tripping chest-thumping 'hold my beer and watch this' kind of spin. Seek out the unvarnished truth as written by people who have 'been there and done that', and own a library. Knowledge is power. The more you know, the faster you go. I think either Grumpy Jenkins, or Smokey Yunik said that, or should have. And, by no means give up because of a few set-backs; even the wizards have bad hair days.
it sounds to me like the bung he is refering to is the tapered one to take a tie rod end. Welding this into a piece of plate would let you connect the wishbone but you could move the plate mount up or down to set the caster before mounting it permanently. The lowering of hot rods and race cars had a great deal to do with splitting wishbones you get to a point where they just wont fit under the frame rails.
Actually this should be fairly simple. Make a temporary mount for the rear of the bones for the time being. Once you have the most of the weight (engine, body, etc) mocked up; adjust the height of the mount to get the desired caster. If at that time the mount is too high or low for your taste, you can pie cut the 'bones and get them to a position you like. I think the 'bones look best level or slightly sloped up to the rear, if they angle up to the front it gives the car kinda of a "broken" look. IMO
I personally like the spit bones level and mounted into the frame rail. I bought a set of the bugs from the Hamber that makes the type using the early female Model A to 34 tie rod end. If you setup the front cross member with the 5-7 degree caster when it's welded in it pretty much solves the problem, or you can pie-cut the bones as mentioned. I did a 40 Ford un-split with poly in the front spring and GM steering box way back also, it handled great. Open wheel hot rods do look good with spit bones and the oil pan clears everything better, IMO...
I inadvertently said 5,,but I always set the front cross member at 7 degrees,,1 degree give or take with wish bone adjustment is insignificant. This is not my first rodeo ,nor the first early ford front suspension I have set up in this manor. I have thousands of miles under my belt with no problem. HRP
I set my front cross member at 7 degrees, then I flipped the split wishbones upside down and pie cut them to get 7 degree caster. This let the wishbones run parallel to the ground. Running the wishbones upside down gave me enough clearance to run my tie rod and drag link under them and still above my scrub line.
MOUNTING THE SPLIT ENDS... We mounted our split A wishbone on our 32 frame with our own home made bracket. Used a short (7" ) length of 3" angle iron and drilled out a hole and welded in a tapered bung (Speedway) for the wish bone end. This angle iron was then welded to the bottom of the frame and set back from the edge of the frame about an inch. Tapered the trailing edge of the bracket for a nice streamlined effect. Ended up looking great. We avoided the "tractor" engineering look you get when you just weld a plate to the outside of the frame rail.
It appears that many here have pie cut the ends when necessary to achieve correct caster. I understand that process but do not know exactly where to make the cut. Is it in the forged casting, in the tube, or in the weld where they meet? Anyone got a photo? Posted using the Full Custom H.A.M.B. App!
I used split model A bones under the coupe in my avatar -- I made two or three (I forget) slices in the tube, bent them up so they would meet the mounting bung, welded them closed.
Fortynut, I agree 100% with every word here. I've spent most of my working life designing and building machines of various sorts. I've had a lifelong fascination with vehicle dynamics and suspension design. I've spent 40+ years off and on reading everything I can find on the subject, designing, building and collaborating on various race and road cars (mostly OT here...), and I still certainly don't consider myself any sort of authority. My advice is the same as fortynut's. Go to amazon, search "automotive vehicle dynamics" or "automotive vehicle handling" under "books", and start reading. Don't be put off by racecar related stuff, all the same geometry and laws of physics apply whether the car is an F1 or an AV8. Pictured below are some of my favourite books, and some necessary tools.
The corollary to that is: don't give an answer to a question unless you are a Practicing Master... To which I disagree completely. Solutions and answers given by neophytes are often correct and sometimes surprisingly good or novel. And while some are not, I look forward to seeing them all, using the good and ignoring the bad.