who's running ladder bars mounted to the frame rails.

Are you referring to rear split wishbones mainly? I see a ton of cars with front split wishbones mounted to frame rails.


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This works with I-beam front axles, because the I-beam axle can twist, so that is where the forces are relieved. However, you'll also see tube front axles mounted with wishbones to the frame rails, and they have the same issues as being described here. Hairpin radius arms will help with this because the hairpins will flex, but it's still not a great idea IMO, though there are probably thousands of T's running around with tube front axles and split bones or hairpins. A 4-link system addresses this fully, but they look like crap IMO, just this side of a MII suspension. Well, that's a bit harsh....

I'll add, I've been running rear hairpins mounted to the frame rails for years with thousands of miles on them, and close inspection doesn't reveal any cracking in any of the mounts or the axle housing. I do have some improved heim joints to install though, and grade 8 bolts, just to improve what's there. The biggest problem I see with this is the binding or lack of articulation, it's a rough ride. On a positive note, it handles corners like its on rails with zero body roll.

 

Would good quality, high articulation heim joints on all 6 mounting points of a rear ladder bar setup work a lot better on a straight diff? Gary

 

Avoid 'all heim joints' on street driven cars. One at the triangulation point at front of rear ladders is O.K., as movement there is minimal. Shock from road use is murder on Heims, often seen on the ends of TIE rods and DRAG LINKS.

 

No. During any amount of body roll, the front of one bar wants to go straight up and the other wants to go straight down. The heims at the rear axle tubes will act solid, just like if it was bolted.

 

It seems to me most of cars don't have a lot of suspension travel. I think the biggest strain on the suspension is when I turn into my driveway and roll over the bump at a severe angle. I pull in slow to reduce the stress.

 

Jeez. Sounds strange that the ones at the rear won't swivel, but I'll take your advice for gospel. Still working on my Jr. Engineer merit badge. Thanx, Gary

 

So your saying I cant run stock A front bones on the rear welded directly to my axle tubes? damn

 

I like the Pete & Jake's style ladder bars. They are similar to the Ford design but work with open drive line.


Phil

 

This was a big thread in '08. When I built Fireball 5 back in '68, I insisted on keeping rear coils, and it paid off.
I built the diff. with old Ford p.u.bells with a new Frankland q.c. in between. Bought new mech. steel tubing that fit the bells and welded a 3/4 ton Ford spindle on rt. and Pontiac stub housing/brake and axle on left. This gave me full floating and double bearings with the old alum. wide 5 pattern. Now I will get to the matter of body roll/ladder flex.
I had to have open dr.shaft and didn't want to build and maintain a 4 link jungle gym, so I used 2 old Buick outer torque tubes, they are tapered and apparently just the right gauge tubing. [swag method] The big ends were fastened to the rt. and left side of the axle tubes just inside the backing plates. The front ends had tie rod ends from a Ford F 800 truck.. The Buick has an X member in just the right place.. Here the design takes a split. For most applications the front ends should be mounted together under the dr. shaft with a single Heavy swivel joint. [from bigger truck maybe] The next part was done only because it was a short track dirt car and I as tired of shuffeling rear wheels between races to get the right stagger/diameter.. So, I mounted front ends of [ladders] or radius tubes about 8 in. apart on a flat steel bar which was bolted to pivot in center.
This bar was hooked with a couple joints of old tie rod pieces thru the floor to an adjustable lever from a field drag harrow. With the lever by my seat I could stagger the rear from center to rt. or left a small amount by notches in the lever. This made a Tremendous effect in handling between early/late races and a track going rubber slick during a feature. The final line and what brings back the subject of this thread is even tho my radius tubes were only 8 in. apart, body roll and a lot of wheel travel caused enough twist to ocasionaly crack the welds between the axle tube and the old Ford p.u bells. I saw what was causing it and it surprised me but it didn't seem to hurt anything else so I just ran another bead. Maybe 3 times in 10 years. It could have been cured with a small heavy spring at each rad/axle connection The coil springs won a lot of races on tracks with holes that would hide a 600 pound sow.
So, the moral of the story is keep your legs together.
Fireball Five

 

I am considering buying very similar setup for my car, but I'm concerned about clearance with a large rear z. Is there any type of a adjustment as far as the bracket on the axle? Would I be able to move them inward towards the pumpkin if the frame rails were going to hit the ladder bars? Or would moving them inward create some new problem to worry about?


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As long as the frame rails remain somewhat standard width the kick up over the axle shouldn't make a difference.

Phil

 

Regarding moving the bars near to the pumpkin, that would change this design's ability to keep the axle square, even with a buggy type spring.

Phil

 

I have to agree.
I had some beefy ladder bars on my '56 Chevy P/U.
It had a healthy 327 in it with a 4 -spd.
It hooked up ell but made some god awful noises on turns occasionally and eventually cracked the frame.
The geometry has to be right.

 

When I built my T roadster it had hairpins front and rear. Front axle was a tube axle. The car popped and cracked when it went through any sort of dip at an angle (think pulling into a slightly uphill driveway at an angle). I think about all of the flex and twist was in the frame. Like Blues4U said above, it can work out (better) with a I-beam axle than a tube axle because the I-beam can twist compared to a tube axle that really resists twisting (think 2" diameter sway bar!). About a year ago I went through my T to finally paint everything and I rebuilt the rear suspension, converting it to triangulated 4-bar. Not only will the car go through dips or pull into driveways better, the ride overall was improved.

I'm building a '31 Ford Coupe now and built and mounted rear bars close together in the front like the Pete & Jake's shown in post #69 above. The '31 does have an I-beam front axle and I have my fingers crossed that I'll be happy with the cars manners when it comes to dips and bumps. I'll have to say though that just jacking up one wheel in my shop on the rolling chassis I can tell it doesn't like twists like the T does with the rear triangulated 4-bar.

Lynn

 

Still running my old 327?

 

My issue is the frame is a little narrower that a stock model A. Really I guess I just need to find out how far apart the brackets would be on a Pete and Jakes style set up and do some measuring. I would be moving them too far in, just a little. Similar to the picture of the rear in the post above.


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Hairpins work on tube axles, but not split wishbones. The same applies to the rear end. It can't twist like a tube axle on the front. BUT hairpins can flex enough to make it work, hopefully. Ladder bars are too rigid, and can't twist or flex, like 36 Ford rear bones, on an open driveshaft set up. So you have to triangulate them, and use bushings that can give, or use something else.

 

I see that the t-bucket frame kits that speedway offers has the set up with the rear bars mounted to the frame rails, how does this work?

 

Just selling s**t