Thread: How to build an early hotrod frame

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Here are 2 pics. One shows stripped Courier prior to cutting just in front of spring. 2nd shows 9" ford differential in place. Camera is out of order, will add more later.

Here is one of entire car.

Interesting---whats with the skull on the rear differential---I've never seen that before.

Go to carskulls.com or search ebay motors for "skull t bucket".

Nice photoshop.

Let me guess....the blurred fron tires gave it away.

Originally Posted by Aster

Nice photoshop.

It's good to see you making your presence known, Rick! I've been intending to contact you, but you know how that goes ...

I'll take a picture of that intake we talked about and e-mail it to you.

Jim

I haven’t added anything to this post in a long time, but every once in a while as I cruise thru all the hotrod postings, I see an absolutely perfect example of a point I have been trying to make. The man who is building the car in these 2 pictures (a Vicky), has nailed something absolutely perfect!!! There is always a lot of controversey about where to attach the front of split wishbones to the frame after they have been split. Yes, in the old days rodders split them and moved them out to the frame rails---and they worked---sort of. But---attaching them to the framerails is geometrically incorrect, and it throws a bind into the rear suspension. The correct way to do this is to separate the wishbones (or hairpin radius rods) only as much as you need to in order to clear the driveshaft. This means attaching them to a crossmember which fits between the frame rails. This is the absolutely best method for coils, coil-overs, or transverse leaf springs. You will also need to add a Panhard rod (anchored to the drivers side framerail ) or a Watts link, to center the chassis on the rear axle assembly. This method of attaching the front of the radius rods or hairpins close together at the front, allows the rear suspension to function as old Henry intended it to when these cars were designed.

Nice job Brian. I like how you are making sure this thing retain the old retro spring fit and appl the geometry of the bars. I would love to see the spring perches. My curiosity alone wishes to see it. I like what you're doing with it.

Nitrowarrier---All ya gotta do is ask. Another builder from Texas has been in touch with me, asking me questions about his build, and spring perches. I am going to attemp to add his email, his pictures, and my answer---brian

Here are the pictures I took of the rear of my truck, last week Sorry about the delay.
Anyway, have not done a thing to any of this since Wednesday night.
Let me know what you think?

And here is my response:

Hi Ken---That looks fine---a couple of comments---I can't see clearly, but if it isn't there already, there needs to be a triangular gusset tying your spring hanger plates back to the rear axle tube, or they are going to bend (or tear out a peice of axle tube where they are welded to it). the shackles are hanging fine.That panhard rod is shorter than I like to see---generally, the plate that picks up the end of the panhard rod should come off the 2 bolts to the immediate left of the bolts which you have used, to make the panhard bar longer---(longer is better)---Brian

and here is the picture (model) I sent to him

Keep pics coming as you continue on. I like where it's headed.

I just received the following email from Kris---
Thanks a lot for taking the time to share your knowledge on that build! amazing. do you have any cads/specs on how to set up a pickup frame? im building a 39 ford pickup. im starting on the frame and have no idea what to measure or where to start. can any of your writeups apply to what im building?

thanks again
-kris
Hi Kris---Yes, everything I have posted is relevant to your build. Start at the beginning and read it thru completely. You are the man who has to make the decisions about how you want to build your truck. do you want to run full fendered, or fenderless---are you going to have the truck setting on top of the frame rails, or are you going to channel it. Are you going to run a full length box, or shorten the existing box, or run without any box at all. Are you going to run the stock 39 front suspension, or go to the aftermarket for a dropped axle. Are you going to run a suicide perch, or utilize the original front crossmember. what engine and tranny are you going to use. what rearend.--What rear suspension. transverse leaf, or coils, or coil overs. What radius rods---or will you split the original wishbones. Or maybe a 4-bar---parallel or triangulated, with a track bar. Are you going to "kick-up" the rear frame with Z, or maybe even put a double Z in your frame to get the front end "down in the weeds. Maybe you will want to "bag it" on all 4 corners and not run any springs. These are all decisions you have to make. If you don't know what some of these terms mean, or if you can't find it in this post somewhere, then use the "search" function and look it up. My post specifies "early hotrod frame", which basically covers the cars from the late 1920's to the middle 1930's, but the knowledge is applicable to almost any hotrod that is being built with a I-beam or tubular style front axle, a frame, and an engine and a body.

Very good commentary and example for rear ladder bar installation with the Vicky example. In that case these are good, ol', but still viable, Pete & Jakes parts. http://www.peteandjakes.com/parts/3334/33_ladder.htm That's not to say crafty folk can't learn from this and build their own, but credit is due where credit is due. Since he used P&J ladder bars, and it looks like their lower shock brackets, he likely used their spring hangers too. They have two styles, one with a single mounting; http://www.peteandjakes.com/parts/33...ngmounting.htm , and one with two mounting positions for height adjustment; http://www.peteandjakes.com/parts/32...ngmounting.htm

One thought on the fellow from Texas, though it's a little tough to make out from the pic, it looks like he could get some "bottoming" of the spring on the hanger bracket if there's enough shackle movement given that it's over the spring rather than outboard of the spring end as is typically done.

Originally Posted by brianrupnow

I have been asked to expound a bit on underslung suspensions. They are really an oddity in the hotrod world, and though some people have run them with success, I do not recomend them. In this type of front suspension, the parallel leaf springs (not transverse) are mounted above the frame rail and the front axle is also mounted above the frame rail. This type of front suspension gives the car an extremely low center of gravity, and an extremely low roll center. It gained favour with some of the champion road racing cars that were built in the late twenties and early to mid thirties, because it enhanced their ability to corner very rapidly during winding road races, without rolling the car over. Underslung suspensions have a certain "eye appeal" because of the fact that they are so "different" in appearance, but have never gained real popularity. They are inherently unsafe, because in the event of a broken main leaf on either front spring, the entire chassis will immediately lay down on the road, and it becomes impossible to steer the car to a safe stop. One of my earliest hotrods, that I built in 1965 had this type of front suspension in it, when I bought it as somebody elses semi finished project. Sadly, like many young hotrodders, at 21 years old my ambitions far outstripped my "know how" and finances, and the car was never completed.---it was stripped, parted out, and disappeared forever.

Brian, bless you for sharing your time and knowledge with the rest of us. I really appreciate it. I have a question about this cute little T with the longitudinal leaf springs. Shouldn't the springs be flipped? If you visualize the front tires going over a bump with the frame remaining in its static position, it looks to me like the springs are being worked contrary to how they were designed originally.

Why does the Panhard rod need to be anchored to the driver side frame rail? Why not the passenger side?
Because---On a cross steer car, where the drag link goes from the steering box (which is attached to the drivers side framerail) over to the spindle arm on the passenger side of the car, as the front suspension moves up and down thru its travel, the drag-link itself acts like a Panhard bar. You want the Panhard bar on the rear of the car to have the "fixed point" on the same rail as the steering box and the moving end (which does swing thru an arc during suspension travel) to be attached to the suspension on the same side of the car as the drag link is attached to.---If not, steering can be "twitchy" when you run over a bump at speed..