I did a search on the HAMB on why wishbones are split and couldn't find anything. I was over at a friends house today and was talking about splitting wishbones. I asked him the reason why they were split. Now this guy is 59 years old and still has the 34 Ford he bought when he was 15. He said he thought the reason was because of clearance issues due to running different motors and transmissions. He said they weren't engineered to be split and that he has seen front wheel lift because of splitting. Now, he has a 394 Olds with a Ford toploader in his 34 and the only thing he changed was to put a dropped axel in it. He never had any clearance issues. So is that the reason why they were split is because of clearance issues or is there another reason.
Just because one example, or even many, exists doesn't mean the problem doesn't exist. Clearance for components other than stock is one reason, and the most common reason, why the front radius rod ***embly(wishbone) would be split. Also to allow the car to be dropped without a dropped axle being used.
Clearance for the trans is probably the main reason, oil pan next. Better to leave them unsplit if possibile, they work better the way Henry made them.
If you think about it, running a dropped axle effectively raises the location of where the hairpins mount relative to the ch***is. This would cause them to hit the bottom of the ch***is rail at some point. Splitting them to the ch***is rails obviously gets around this problem, but it also completely negates their original design intent of being able to 'rotate' around a central pivot point. Using tie-rod ends helps to some extent as there is some movement at the ch***is fixing point, but not as much as stock obviously. In my state (Western Australia) you are allowed to split the wishbones a maximum of 12 inches. I guess the theory is it allows for extra room to run larter (later-model) gearboxes, but still keeps the majority of the functionality of the original design. No... I'm not an expert, but that's how I see it. Hope that makes sense...
The dropped axle doesn't raise the mounting point of the wishbone... Splitting a wishbone is done to make clearence for different engine/transmission combo or on Model As where the bones are mounted to the transmission. Michael
Ah... there you go. Someone who knows what they're talking about! Messing with the spring would affect it though, wouldn't it?
splitting the front wishbone turns an I beam axle into an anti sway bar and it lets the motor and transmission be mounted lower a lower center of gravity and more controled suspension both improve handling
Often it was the starter motor that interfered the most. The engine oil pan wasn't in the way. What once was done for clearance issues has now become a styling cue.
The reason I split the bone on my truck,,,I installed a model A crossmember and a mono spring with reverse eyes,,,,,there was no way to use them with out spliting them. These two things add up to the bones setting much closer to the frame,,not that they are not where they would be if not split,,,but the frame itself is lower in the front. HRP
Paul's mention of the anti-sway feature is correct, then the concern becomes the same loading showing up as torque, applied to the axle. Ford I-beam, usually OK, Ford or Aftermarket Tube, a possible problem results.
Splitting the wishbone, outside of looks, generally adds stress where no stress was before. As far as a dropped axle and wishbone, when adding a dropped axle and resulting in dropping frame at ab angle, the pivot mounting point must be lowered so that the wishbone remains in the same plane to the ground as before or you have changed the camber of the axle.
It changes the caster, not much effect on the camber, lowering the rear of the bones would give more caster. Dan
Bonesplitting almost always required when not using genny drivetrains. Keeping the wishbone intact with the use of say an SBC has been done but not without some picky fabrication and h***le that most just won't want to fool with. Merely subbing in a dropped axle will not require the split but lots of other things will need addressing such as steering arms, tie rods, brakes, spindles etc. Changing out a genny spring for a rev-eye de-arched version, or using a raised crossmember, will almost certainly cause the bones to bang against the frame so a split becomes inevitable. The axle will be somewhat more susceptible to twisting forces but this usually can be minimised with good solid tie-rod ends and beefy frame mounts. With a well designed and fabbed setup the axle will still be able to angulate through a fair range of motion without stressing things overmuch. The orthodox view is that a relatively flexible beam axle should be used with split bones instead of a much stiffer tube axle but I don't doubt that many have done it successfully.
A models were easiest to modify when split, though early rodders also made strap crossmembers to pick up stock wishbone or went to longer V8 wishbones to reach trans crossmember...by itself, dropped axle makes no change in wishbone location, but other mods do. Splitting makes not just the axle but the entire car into the anti-roll (not anti sway) mechanism...in geometrical theory here, split bones allow zero roll and make roll infinitely stiff (lifted wheel time), but of course in practice they allow roll by the twisting and bending of whatever bits in the system are weakest against the roll forces. This is a poor way to get anti roll because it isn't controllable, consistent, or repeatable, and often one part (often the wishbones or their brackets) is much weaker than everything else and becomes a doomed bending component. In any case, whatever is bending or twisting probably isn't designed for that stress. You are much better off allowing free motion of suspension locaters and adding any needed anti roll with bars that do just that and can be tuned to what you need.
You can get a little "free" twist in the system when using good tie-rod ends that don't stress the other components too much but even there a steep driveway or other similar obstacle can easily bend the setup past its limit with consequent severe stress on the frame/mounts et. al. Lot of guys get away with it. Richard W. on the board here has 40K plus miles on his unlowered split-bone Tudor with no trouble so far but he's pretty careful about avoiding hitting steep driveways at an angle and getting a wheel up on a curb or some such. It's not an insurmountable problem if you're a careful thoughtful driver but if you're a ham-handed doofus be prepared to fix busted parts on occasion.
Hot rodding is all about taking parts that weren't meant to go together and making them work. Big motors in little cars = spilt wish bones. Sometimes you can work around it and sometimes you can't. When you put a Model A front cross member into a '32 ch***is it lowers the front of the car about 2 inches, then you toss a spring with reversed eyes into the equation and your un-split bones will hit the frame rails, so you've got to split them. And if you're doing a suicide front end, well you'll have no choice but to split the front bones. On a side note, a dropped axle raises the location of the spindles. It does not affect the location of the spring perches in anyway.
Alos... Never use split wish bones with a tube axle... You may wind up wth some broken welds on your axle.
AV8 made a good post about combining some stock wishbone stuff so that a split wouldn't be required. Do a search under his name. Ch***is Research makes a nice setup that keeps the bones close together at the rear and uses 3/4" Ford truck tie rod ends. My pals 46 Ford running an SBF has unsplit bones. It was that way when he got it, but during a recent C-4 rebuild he built a new saddle for the ball socket and lowered the ball perhaps 1/2" -1". Doesn't appear to be a problem with the ball a little lower, but we'll be able to tell when he gets it back on the road.
Model A crossmembers lower the car by one inch a reversed eye spring gets you an additional inch. This roadster we built has a model a crossmember, stock k-member and unsplit wishbones. If we had put the engine in the stock location (vertically) we would have had to split them, however we raised the engine to avoid this. The car still handles better than any 32 I have ever driven that had an axle under it. no sway or roll bars. The only clearance issue we have had was in building the headers. And we went to a stock eyed spring to gain some clearance.
well whats the difference between splitting your wish bones and using aftermarket radius rods. They basicly do the same thing don't they? Jim
Radius rods usually have quite a bit more rotational give in them so they can be used with tube axles and urethane adjusters without as much fear of breakage. Still not smart to overstress them too much. Radius rods with clevis ends are a common setup on T-buckets and light roadsters but rather less so on heavier cars.
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