Split wishbone suspension

[Brett.C]

Back to the original question about split radius rods.

Here's a diagram that I found on the net of the Rover rear end .

Notice the slipper joint on the De dion axle.
It appears I owe PeterR an apology because in fact it is not splined as I said earlier.
The half shafts maintain lateral control so there is no need for a watts link or panhard rod.
Take away the diff and except to the upper links it looks very much like a Ford front end with split wishbones doesn't it.
Only problem is, that now it no longer has lateral restaints and so the axle joint is free to slip apart.
So what I was thinking was. What if you were to use a similar setup and attach the transverse spring to the axle without shackles at both ends? Wouldn't this then give you the necessary lateral control needed?
Of course the spring eyes would need compliant bushes to prevent any spring binding.

I would make up my own tube axle that was straight along the bottom. I would then cut it in half and fit a bronze bush in one end. This bush would need to be at least 200mm long. I would machine up a stepped spigot that would be slipped into the other axle and welded in place. The other end of the spigot would be greased and slid into the bronze bush. The joint could then be covered with a concertina rubber boot.
This would be a very simple and effective solid axle frontend and would be relatively cheap to build and best of all it would look great.

David, I'll see if I have any pics of Stewart's frontend that I can scan for you.

[Brett.C]

The only pics I could find of Stewarts car were in ASR 105 but there wasn't a good shot of the FE.
I also remember seeing it in one of the ASRF mags so maybe someone has a copy that they can post a pic from.

Here's a pic from a recent ASR article by Ted Robinette that shows the FE from a Humber Super Snipe.

It's very similar to the Poojoe. Notice that it is rear steer. The ugly arrangement on top with the lever sticking out is the shock absorber. The upper control arm is underneath and looks like a neat forged A arm. The shock units would have to go in favour of telescopics but the upper arms could be retained and bolted directly to a bracket on the side of the chassis rails. It looks like the spring assembly would bolt into a Ford style crossmember and even if it was the wrong length a new lower leaf could be made to suit. If you look closely there is a rectangular piece that seems to extend down diagonally from the upper control arm mount to the top of the spring. I haven't quite figured out what this is yet. Bump stop maybe? Anyway it's ugly and therefore would have to go.
I get the feeling that unlike the Poojoe the frame may not have to be stepped to get the thing low enough. If you were to image that the spring was at the same height as a beam axle then there appears to a reasonable amount of drop on the spindles.
Worth concidering if you could find one.

Of course the spring eyes would need compliant bushes to prevent any spring binding.

On second thoughts....I remember seeing perch mounts that swiveled to prevent spring bind. Wouldn't be too hard to make a set.

[david]

Brett,
Thanks for all the info you have given, you seem to have a lot of ideas on suspension setups. If the peugot suspension is a similar setup to that humber front I can see it looking and working pretty nicely.

I am starting to consider building a car that I can drive every day of the week, so I have to get it right. I think I might try and find a peugot to take a look at and start thinking it through properly.

As for the rover style front, it looks pretty interesting, but I reckon you could get the car far lower using the peugot style front end and I want a fairly low car. I think I will have to start reading up on suspension theory to get a better idea of what i need to do, because I dont have a lot of knowledge on it.
Thanks again.
Dave.

[david]

Brett,
Thanks for all the info you have given, you seem to have a lot of ideas on suspension setups. If the peugot suspension is a similar setup to that humber front I can see it looking and working pretty nicely.

I am starting to consider building a car that I can drive every day of the week, so I have to get it right. I think I might try and find a peugot to take a look at and start thinking it through properly.

As for the rover style front, it looks pretty interesting, but I reckon you could get the car far lower using the peugot style front end and I want a fairly low car. I think I will have to start reading up on suspension theory to get a better idea of what i need to do, because I dont have a lot of knowledge on it.
Thanks again.
Dave.

[GBS]

That is the same type of front end as the Peugeot Brett but I doubt if any part of it would be suitable for a small roadster. I worked on far too many Super Snipes and Hawks in my younger days and from what I can remember they were monsters. It would be like trying to take the front end out of a Cadillac and installing it in a Corolla. The Peugeot is a lot smaller, lighter and neater looking.

That rectangular piece that extends down is most likely a restraining strap that stops the suspension hanging down too far if the wheel ever leaves the ground. These straps were common on English cars back then. Telescopic shocks do the same job today.

I am still thinking about that Rover rear end. Its a bit too much to absorb at this time of the night.

Brian

[Brett.C]

There's one thing I didn't consider and that was the steering
With the Rover's set up the track width changes as the half shafts move up and down due to suspension travel. That's ok coz it's a rear end and the direction of the tires is fixed. However with the font end this would cause serious bump steer because the length of the drag link doesn't change. You would need to find a way of fixing the shaft so that it could only rotate and not slide in and out. There are several ways that I can think of doing this but none of them are probably suitable for the wear and tear of road use or they would be just too big n ugly.

That is the same type of front end as the Peugeot Brett but I doubt if any part of it would be suitable for a small roadster. I worked on far too many Super Snipes and Hawks in my younger days and from what I can remember they were monsters. It would be like trying to take the front end out of a Cadillac and installing it in a Corolla. The Peugeot is a lot smaller, lighter and neater looking.

I've never seen one up and personal but the upper arms look no bigger n uglier than an early jag and you could always remake them in tube.
As I said the main spring would probably have to be shortened to suit and you would also need to remove more than a few of the leaves.
And the steering box would have to go in favour of a R&P unit.
This then leaves us with only the uprights to deal with and they can't be all that big and ugly can they?
They look like they would be relatively easy to convert to discs.
Still I'd have to see one in the flesh.

[GBS]

You could possibly modify it to suit a rod but why go to all of that trouble? If you wanted to use that design of suspension then why not use the Peugeot in small light rods and save the Humber for the larger and heavier fat fended variety?

Changing the Peugeot to rear steering should not be all that difficult but unfortunately issue 105 does not explain what Stewart did. I hope to get up to the Rickshawís run next weekend and seeing Stewart lives in the area, there is a fair chance he might be there. I have seen the car before at the Rickshawís show but this time I will have a much closer look.

Brian

[Brootal]

I'm heading up there too GBS. I know Stewart fairly well, so I could introduce you to him. I doubt he will have his roadster up there though (unless someone else takes it up there), as he has his Chevy panel now. Last couple of events I've seen him at he's taken the Chevy.

[GBS]

Looking forward to seeing you there Brootal.

Brian

[29EHV8]

Brootal told me to hit this thread and let you guys know what I think of split 'bones.I run them on my car,its a 29 Av8.Check out a pic of it in the chat/forum under my intro post.I drive it everyday and drive it hard.I build rods at my shop here in Canada,The Way Back Garage.I've never bought 1-800-i want a hot rod parts.I build every thing.I only build traditional cars.I've used lots of split 'bones and have never had any trouble at all.The rear of my car has 36 split radius rods as well.Never been a problem there either.I ran the car the last 4 or 5 months with slicks on it and no problems tearin anything up.It hooks damn hard too!You guys talk about binding,have you ever thought about how much travel the rear of a traditional rod has.My car prolly has bout 2.5 inches max.It rides great.You shouldn't run split'bones with a tube axle ever!If you run hairpins with a beam axle its good cuz the hairpins flex alot.David build your car cheap and easy.Don't worry about split'bones they've been used for years and will be for more decades to come..........Shiny

[Brett.C]

In ASR's coverage of the 34th NSRA Nats I noticed that of 17 fenderless cars shown no less than 12 have hairpins, 1 has split wishies, 1 has four bars and the rest I couldn't tell.
Therefore as night follows day this is sure to become a big issue here in the near future.

[GBS]

As I said in my first entry, split rods have been used since day one but that does not change the fact that they do twist the axle and I have seen, and read warnings about, broken chassis mounting brackets, I can not see the point in spending a lot of time and money in building a modified car and fitting a suspension that relies on binding to work. Manufacturers donít do that so why should rodders? There are better ways. I think if you canít make a suspension that moves freely, then look for a different design.

My car also has 1936 Ford rear radius rods but they are joined at the front and pivot on a single point. One well known Sydney rodder told me recently he did not like í36 rods because he used them on one of his earlier rods and they kept breaking the little lugs on the rods where the axle bolts on. I asked if they were joined at the front and he said no they were about 250 mm apart. That is why they broke. My rods are about 200 mm apart at the front but, rather than bend them to meet each other, I joined them with a small piece of tube and used a rubber mount from a Range Rover rear suspension in the centre of the tube. I noticed when I lift a rear wheel 50 mm, the front end of the rod lifts 7 mm. This would immediately cause binding if I had the rods attached to the chassis at that point.

There is another rodder in my club who has a beam axle Model A with a panhard bar and four bars. I have driven it and it can change direction while going through a long sweeping corner. He tell me this is normal and a characteristic of that type of suspension. Years ago we had plenty of stock 1930s and 1940s Fords at work. I drove many of them and can not remember one behaving like that nor can I remember a customer complaining about it. Maybe it has something to do with his four bars swinging the axle through an arc and slightly altering the wheel base on one side only as the suspension moves. Split rods would do the same thing.

In issue 104 February 1998 of American Rodder magazine, long time traditional rodders Vern Tardel and Kent Fuller are setting up a traditional rear end using í36 rods. They joined them at the front and pivoted them off the same type of rubber ball that the front rods use.

In the editorial they said. ìSome designs, like ladder bars and four bar schemes - outstanding for high horsepower, hard launching drag racing - are ill suited for street applications where their resistance to turning produces stiff, choppy ride characteristics. Still, thousands of street rods have been built using one or the other of these straight line designs, causing thousands of street rodders to wonder about about and even experiment with coil over spring rates and shock valving - which of cause have little or nothing to do with the problemî.

We are told you have to split rods in order to fit many later engines. I noticed Larry OíToole has unspilt rods in the front and rear of the Chev powered í32 roadster he has been building for about the last twenty years or so. He only had to raise the engine a couple of inches and it fitted.

On my own car, I started by placing the front axle and wheels together with unsplit rods on the garage floor. The rods were set up in the correct position to get the caster angle right. I lowered the Cleveland and C4 into position over it so the transmission sump could be removed easily. The next step was to make up a couple of crude wooden chassis rails with a front kick up to fit in with the engine and front end. The body was placed in position behind the engine without the firewall recessed. The position of the body determined the position of the rear axle.

The car ended up with a 108 inch wheel base which should ride better than the standard 103 1/2 inches of a Model A. The interior has the maximum possible amount of leg room. The front axle is a dropped í47 with the spring on top of the axle. The front and rear end is a factory design with no binding and there is a hell of a lot more than 2 1/2 inches of suspension travel. The engine will be exposed and the longer engine compartment looks, in my opinion, a lot better than the shorter Model A engine bay.

I think this is a much better system than trying to stuff a V8 into a stock Model A and having to split the wishbone and cut deep into the firewall to get it in.

I think split rods are a carry over from the days when rods were built to go fast on dry lakes and drag strips. The only street use was a short trip to the drive in or cruising the main on Saturday night. Split rods were acceptable in that environment. In all of my early US magazines I can not see any reference to the type of long distance street driving that many rodders do today both here and in the US. Split rods leave a lot to be desired in those conditions.

Brian

[old32]

There is another rodder in my club who has a beam axle Model A with a panhard bar and four bars. I have driven it and it can change direction while going through a long sweeping corner. He tell me this is normal and a characteristic of that type of suspension.
Brian

The car ìrockingî on the shackles causes this. As the weight of the car tends to move sideways in a turn the chassis weight straightens the inside shackle and drops the outside shackle allowing the chassis to move up to about an inch in relation to the axle. This transfer seems to happen suddenly. (On the curve of old Keilor hill my roadster would change lanes half way up, that's with 4 inch shackles on the 39 front end, and before installation of a panard rod) Combine transverse steering this and its like turning the wheel half a turn suddenly. The cure is a panard rod.

By the way I'm running a 39 unsplit suspension in the roadster with no problems fitting the 350 and powerglide, I can even take of the trans pan with no problems.

[Brett.C]

I think split rods are a carry over from the days when rods were built to go fast on dry lakes and drag strips.

Another reason I've heard that they were used was because they increased roll stiffness on track cars.

Does drilling holes in an I beam increase it's ability to flex and so would this be a solution. Not that there's a real solution IMO, just a better compromises

(On the curve of old Keilor hill my roadster would change lanes half way up

Same thing used to happen to me when I drove my billy cart down that hill. But that was on the old old road that use to go across the stone bridge. Thanks for reminding me of it old32

[29EHV8]

GBS,I drive my car everyday.I've never had a problem with anything on the car,well except that the rear tires wear really fast!LOL.My radius rods are about 10" apart.If you are referring to my car about the 103.5" WB,my car is on deuce rails,106"WB.I didn't hafta recess the firewall either.I'm not into 4 bars,automatic trannys or billet stuff at all.I'm into traditional cars.But this is what I like.If I had a problem with my split'bones then I would address it accordingly.I just drive it,I don't even wanna park it to put tunes in it.Its just too damn fun to park!This debate will go on for years to come I'm sure.I think I'll just leave it alone.I gotta go drive my car,no time to debate this anymore.........Shiny