Radius rods, wishbones.. got me thinking...

[TRoadster]

The other thread on scratch built wishbone got me thinking about old ford radius rods, p&j type ladder bars and hairpin radius rods. The old ford style radius rods mounted underneath the rear axle inline with the radius rod. Under some conditions, the rod mounts may crack and or break free from the radius rod. Do having the two mounts inline increase the stress unlike hairpins or p&j's that are mounted one over the other? I know the older ford rods weren't designed for the stresses of higher HP engines and that the torque tube took most of the abuse. Another question on this line. The distance between the top and bottom bars on hairpins are often 5" or so. Is it possible to move them closer together without sarificing strength? I've also seen pictures of ladder bar style rods with the two tubes offset, the bottom closer to the rear tires and the top closer to the third member but still connected as ladder bars are with tubing or gussets. Would this cause a problem? Just wondering...

 

[Youngster]

mounting the rods to the bottom or to the front of the housing dosen't make much difference. the '35 and 6 fords had a oval shaped mount for the bones. the '37 to '48 bones mounted to the two bottom holes for the brake backing plate. the reason ford did that was for clearance issues and less welding on the housing and faster build time. this type of set up will work on some cars but if you are concidering a hi hp and torque engine, there are better set ups.

5" is pretty much the norm for hair pins and ladder bars, however i have seen that go anywhere from 4" on hairpins and up to 8"on ladder bars.

i would suspect the staggered mounting you discrbed was someones atemp to be different. being different isn't always a good thing.

Ron

 

[RPM]

On the custom radius rods that we build 5 3/4 is pretty much standard. We have gone everywhere from 4-8" depending on what someone needs. Length has gone from as short as 14" to about 60". Normal length seems to be about 27-32" long.

 

[Ted Brown]

Just me here, I find that the wider the spread at the rear end, the less torque to the rod material itself, the closer they are together, the greater chance to bend that material, remember the nut cracker idea and leverage to what? The shorter the rods, the leverage goes to the rear end, the longer the leverage goes to the rods. Hair pins and ladder bars act exactly in the same way, so make them strong like RPM does, to end bending worries. This is how I look at it. Good luck with your project.

 

[Youngster]

very good point Ted...

Ron

 

[Brucer]

the current hairpins i have now , the holes are at 5 3/4 apart... if i use the hairpins i will weld a plate in the middle about 4 to 6 inches from the ends and put a couple big lignting holes in the plates... i have seen hairpins get wrapped up before, not too fun for sure..

 

[Youngster]

i have replaced bent hairpins but found afterwards they where made fron very thin wall tubing. never been a fan of gussets welded in hairpins, especially on the front end. old addage here, "been doing without them for years!" might be old but it's true.

if your talking about ladder bars, your telling me you are running goobs of hp and torque. truss them suckers good then. if your running hairpins on the back to the outside frame rails and feel you need a gusset, then be a little creative with it. add a brake pad as a step to enter and exit the car. or if you have a track theme, add crash bars to them and the brake pad.

just my thoughts wrong or right.

Ron

 

[Ted Brown]

i have replaced bent hairpins but found afterwards they where made fron very thin wall tubing. never been a fan of gussets welded in hairpins, especially on the front end. old addage here, "been doing without them for years!" might be old but it's true.

if your talking about ladder bars, your telling me you are running goobs of hp and torque. truss them suckers good then. if your running hairpins on the back to the outside frame rails and feel you need a gusset, then be a little creative with it. add a brake pad as a step to enter and exit the car. or if you have a track theme, add crash bars to them and the brake pad.

just my thoughts wrong or right.

Ron

A brake pad to enter the car, now you know better, that is waaay too close to the body to do any good, and that may be the camel that breaks the hair pins back :lol: In the very first days of my T Roadster, I ran 3/4" X.125 wall DOM tubing for all the front end stuff except the axle which was 1 3/4"X.250 wall 1040 DOM , since the front end was and is not that heavy, things worked out Ok for a few years, till I rearended a pickup that stopped for a light I was trying to make.. wrong... Well after that all my front end accessories chanced to 7/8"OD X .156 wall DOM tubing... now I have stepped up yet another size in front to 1"OD X .188 wall DOM... Rear on a small stock engine, you could probably get away with the same (rubber bushed) if you are using solid ends like heim joints, I just might want to go to the next step up again with the rear Rods, to either 1 1/8" or even 1 1/4" OD, lots of strength in larger OD sizes, and round looks better than square, even though square is twice as strong, size for size. Great for bridges, but not soo purdy for T Buckets.. hehe How do they say it? Do as I say, not as I do.. hehe

 

[Youngster]

i gotta ask this question here. the CCr plans, total, Mas, and many others have used 7/8" dom for their hairpins. our own RPM and spirit use 1". why do you feel 1 1/8 or 1 1/4 inch is necesary. with the number of cars on the road with the smaller 7/8" pieces, it seems like you're trying to re-invent the wheel.

Ron

 

[Ted Brown]

re invent???? just a real good way to ad strength to the radius rods, as the tires are much better than they were years back and the engines are a lot more powerful now days, just easier to bend things now days, so easier to go a bit larger with the OD to gain much needed strength, and the stouter look does not hurt a thing, looks more like a pro car and still keep the open radius rods...

 

[Youngster]

ok, fair enough. my taste runs more toward the traditional look of the '50's, '60's and early '70's. guess that wouldn't include the pro cars. never really liked the strip influence on the street. JMHO

Ron

 

[Ted Brown]

These type of cars are totally re-invent cars from the start, nothing stock about any part of one.. Poor ole Henry would sit up in His grave if He saw a T bucket of today... Over the years, of driving MANY MILES is how we all learn about just what we can get away with, myself, I would rather error on the safe side when out of state cruzin, as it is a bitch to fix things right, out of town.. Follow my point? I've been there and broken that, miles tell the truth, the whole truth and nothing but the truth.. hehe