Projects Building a Tube Chassis for my '36 Ford Sedan

Yeah, that L-Tec is one hell of a welder.

I've had this one since the early to middle '90's and with the exception of having to change out the trigger microswitch year before last, and reline the torch lead every so often, it has welded many miles of wire without complaint.

ESAB has since bought out L-Tec and discontinued/upgraded that machine, so they can't be had new anymore.

I don't know if the new model they replaced it with is better or worse or what.

I also have Lincoln multi-process power supply with an LN-7 wire feeder atop it. I've never really liked the LN-7 torch all that much, but Dad really prefers it.

It's just as well, because I like the L-Tec better anyway.

Everyone I've ever met that's had one has said similar things about this model of L-Tec welder.

Sometimes a company just hits a good lick.

BTW, for several years I raced dirt modifieds very similar to IMCA cars, but under different sanctions (NASCAR, UMP, USMTS, etc).

 

Thats a sweet looking chassis. Excellent engineering and craftsmanship.

I had been planning to use my asphalt modified racing background to suspend my project on a more traditional custom/home built frame, but deep down I really want to do a complete tube chassis.
The chassis is not started because I can't seem to decide which way to go, and am still working on my mastercam skills.

Regardless, I'm subscribing.
Time to go have a look at your body work thread.

-Row Z

 

Love the modified in your avatar. I raced pretty much the same thing for several years.

There isn't much in that body work thread yet, except disassembly.

Body work is next.

 

First off amazing work and just the thought that went into it is amazing!!
To the guys who feel not traditional enough you can still take note and apply some tech used here to a more traditional looking frame.

That said, you see a lot of these threads on forums where the part becomes the hero and the fab just gets everyone nuts. Then it falls off as adapting into a functional working part never happens. People use tried and true parts as it assures that it is one less thing to go wrong during final assy and that first drive.

I am curious as to how you cam about using some of the set ups and geometry for the suspenions? It appears to be taken from a race chassis so how will this apply to being a road car? Will all those heim joints hold up? Have you ever applied this tech before??

Again not bashing just want to see past the cool laser cut parts. At least you aren't part of the new dimple die on every part I can find.

Then the biggie how much are these going for??

 

I made the suspension design from scratch.

Starting with the diameter and width of the tires and what their attitude needs to be at maximum roll and ride height, I designed the linkages to provide a smooth transition from static ride height to full bump and full droop, with my aim to control wheel camber in both directions as best I could.

The design is not lifted from anything. All the parts were designed for this car specifically.

The heims are teflon lined for maximum durability in grit laden environments. They are heat treated 4140 bodies with full hard 8620 balls that have been hard chromed, with teflon injected between them as a self lubricating wear surface. They will last as long as a good hard polyurethane bushing will, and will locate far better.

People have trouble with heims on the road because they buy the absolute cheapest heim they can find, with a soft steel body and a hard steel ball, and metal on metal contact. Those heims wear out really fast in a race car too, because they're junk.

Good heims last a long time.

In all, I've got three years of design work in the suspension geometry, I am confident that it will function as I intended it to.

Price wise, you're looking at ~$12k for a roller just like this one. Price will vary according to what hubs, and what spindles, and what kind of rear end you want to use. Quick change is more expensive, Wilwood hubs would have been cheaper, cast Howe spindles and 5x5 hubs would have been a little higher, etc.

I haven't figured the price of the bare frame yet, but ballpark would be $6k-$8k fully welded. DOM would be more, obviously.

Also, if the heims really bother you, the front suspension can be done with poly or UHMW bushings for about the same price. I would suggest staying with heims in the rear, but those can be changed out as well (you will just lose some compliance because of the limited range of motion of those kind of bushings).

As for "how I apply the tech", I'm afraid I don't really understand what you're asking.

The "tech" is already applied. There it is, soon to be rolling. I would not consider a rolling chassis to be a "part" that a person could fixate on. It's an assembly of many parts, all of which are integrated to form the foundation of the car.

I'm not fixating on the chassis, I'm simply building what should come first, first.

 

Thats some beautiful work. What type of welder was used?

 

I wanna see the body sitting on the new chassis

 

An L-Tec MigMaster 250. I love that welder.

You and me both.

I'm going to remove what's left of the floor, fix the two big rust spots up front, and then it'll be time to temporarily hang the shell on the chassis to set the stance/rake and make sure there haven't been any crap-ups.

Then it'll be time to fabricate a great many things (body mounts, floor, firewall patches, fix all the mangled fenders, etc).

Stay tuned.

Second coat of black goes on the suspension parts tomorrow.

Hopefully they'll be cured enough to handle by the end of the week. I'm not gonna hold my breath though, 'cause it's like 2 degs F outside, and the shop has been 45 degs F for most of that cure.

Could be March before they're hard enough to handle.

 

I have never before seen rear suspension brackets that bolt on. Is that common on circle track cars? I am also stumped by the "fifth link" on the top of the housing. What exactly is its purpose? The four links should prevent any "housing wrap-up" so I don't get what the fifth link does ... unless it is there to eliminate the possibility of the rear rotating within the bolt-on brackets.

Are you going to be adding a swaybar as well?

The "panhard" bar bracket is also bolted on, would that not be prone to sliding on the housing?

I have some experience with drag car rear suspensions and this bolt-on stuff is new to me. I also find it interesting that no one else has commented on the bolt-on aspect, so that suggests to me that it IS common in some form of racing.

Not being critical here, just curious ... what with never having come across this before.

PS I actually have an L-tec tig.

 

I have never before seen rear suspension brackets that bolt on. Is that common on circle track cars? I am also stumped by the "fifth link" on the top of the housing. What exactly is its purpose? The four links should prevent any "housing wrap-up" so I don't get what the fifth link does ... unless it is there to eliminate the possibility of the rear rotating within the bolt-on brackets.

Are you going to be adding a swaybar as well?

The "panhard" bar bracket is also bolted on, would that not be prone to sliding on the housing?

I have some experience with drag car rear suspensions and this bolt-on stuff is new to me. I also find it interesting that no one else has commented on the bolt-on aspect, so that suggests to me that it IS common in some form of racing.

Not being critical here, just curious ... what with never having come across this before.

 

Well, first off, there are only three fore/aft links, two down low, and one up on top.

The multiple holes allow you to change the bar angles to tune the car under accel/decel.

Bolt-on brackets are very common on circle track cars, because they make contact with each other and concrete pretty regular like, bent tubes happen a lot.

With bolt-on brackets, you can strip them off and put them back on the new housing or tube without having to start over from scratch.

They also allow you to move the mounts around without a lot of trouble, so you can use them to tune the car as well.

The force required to overcome the friction on the clamp-on mounts and spin or slide them is pretty massive. Far past the point where you've bent something. They will move if you hit them hard enough, but by that time, there are other things bent, so it's all got to come apart to be fixed anyway.

The upper link is there to control axle wrap. The black housing has a high rate spring inside it, to help cushion the rear tires under acceleration. It absorbs some of the torque at low road speeds by letting the axle wrap up some (to keep the tires from spinning), and then gives it back once the road speed has come up. It's a traction aid, similar to how traction bars work with leaf springs. It's called a "Pull Bar" in oval racing. It's used in both pavement and dirt cars (the setup is slightly different, but they're more or less the same).

Not sure about a rear anti-roll bar yet. I will probably end up using one, but I won't know how big until I've driven the car hard a few times and gotten a feel for how much roll I've got to deal with.

Same with the front bar. I know I'll be using one, but I won't know how big until I've run it.

 

Anybody got any opinions on the two colors of Chromate Primer that are available?

I like the green better myself, but the yellow seems like it was used more during WWII and before.

Do you think anyone would even notice a detail like that?

 

Thanks for the reply. As mentioned, I had never seen bolt on stuff like that before (other than dragster engine mounts I guess), so I appreciate you explaining it to me.

 

Quote: "Well, first off, there are only three fore/aft links, two down low, and one up on top".

I just went back and took a look at your pics again. Not sure we are talking about the same thing here ... in this pic (hopefully it posted) I can clearly see two upper (mounted to the housing tubes) and two lower (also mounted to the housing tubes) rear suspension links (2 links one side, two links other side is how I am coming up with 4 links). I am referring to your "pull bar" as a fifth link (mounted to the top of the "pumpkin"). I am NOT a mechanical genius (my words) but I am back to not understanding the need for the pull bar. The rear axle should not (again, in my opinion and experience) even be able to wrap-up with a fourlink suspension. For example Pro Stock drag cars run a fourlink similar to what you have in your car, and their axles do not wrap-up and they do not utilize a "pull bar". In my opinion (doesn't mean I am correct though), the only way the rear can wrap-up is if the links themselves bend, or the bolt-on brackets rotate on the housing. In your case, I just assumed the fifth link was neccessary because of the bolt-on brackets.

Please keep in mind ... I am NOT trying start a war here, I just don't understand it yet.

 

Under normal circumstances, with rigidly mounted links, you'd be correct, but two of the five links shown are not rigidly mounted. The two bottom links and the center upper link are the only three with rigid mounts.

Those two upper links out near the brake rotors are not attached to the housing at all.

Those links attach to sleeves that slip fit over the housing tubes and rotate freely.

They are there as brake mounts. Go back and look at some of the other pics right around where you found that one, and you will see that the brake caliper is mounted to a sleeve and that sleeve is what those upper links control.

This is a method of controlling brake torque separately from acceleration torque.

The pull bar (center upper link) is angled downhill to create anti-squat under acceleration torque. The pull bar will literally try to lift the whole car by its forward mount. Under acceleration.

However, if the brakes are mounted directly to the housing tubes, that downhill angle will turn into pro-squat, and the rear tires will unload dramatically. There will be severe wheel hop under hard braking.

So, there are two ways to fix that. Either run the pull bar dead level, which doesn't help accel, but doesn't hurt decel either, OR decouple the brake forces from the rear end housing.

I went with option two. The torque from braking is transmitted from the brakes, to the bracket, to that sleeve (which rides on, but is not solidly attached to the rear end housing), to another bracket, to those upper links, and back into the chassis.

Because those links run uphill, the forward (pushing) force they receive creates a jacking force that increases the load on the rear tires, instead of decreasing it like the above rigidly mounted brake scenario.

This lets you run more rear brake bias, and thus carry more speed into any given corner (drive in deeper, brake harder), which is a distinct advantage in a competition situation.

It's a complicated rear suspension, one which I've never seen on this board before, so it's understandable that you'd not recognize what you're looking at. Only circle track guys would recognize it at all.

If it's still not clear, I'll gladly go through it again, maybe from a different angle.

So long as people are willing to learn, I've got no problem explaining things until everyone gets it (unless they're being intentionally obtuse).

 

Are you going to leave the fame in primer ???

If not, what difference does the colour make ?

 

I really appreciate your patience with my questions/comments. I get it now. I was not aware that the upper-outer two links were not solidly mounted. Makes sense to me now. I assumed the "fifth link" was a "damper" of sorts (it may be) but it is really the "third" link. I am actually not a fan of true four-link rear suspensions myself (for street driven cars that need to turn corners) due to binding. I believe the three-link is the best way to go (as far as "bind-free" operation), those "caliper bars" threw me off though.

Thanks again for taking the time to walk me through it.

 

I like the 4 bars.

I have them on several cars, and with stiff rubber mounts on one side there is no bind.

And there is tunabillity ( even a-symetric, like Mallock did with TAM, or Trailing Arm Magic )

The one I dont like is the triangulated 4 link...


Thanks again for showing this suspension setup Coolhand, and explaining it.

I was completely unfamiliar with this kind of suspension untill you started telling us about it...

 

I was actually a little hesitant as far was questioning your suspension. I am pretty sure more than a few posters would have gotten rather "snarky" and defensive. As mentioned, I do appreciate you taking the time.

 

Yes, the chromate primer will be the final color. The chassis tubes will have already been sealed with an oil based protective primer, so it's not going to rust, I just want the greenish color of the zinc chromate as a way to tie in to the aviation theme. I will also be doing some solid riveted structure and I'd like to paint the interior sheetmetal in the same green chromate color to leave it. To somewhat evoke the look of an early military aircraft.

No worries men, I knew that something as weird looking as this all was would bring with it some questions.

It helps that I know (and have seen) that these suspensions work. In that regard, I'm not breaking any new ground here, just introducing it to a new audience, so to speak.

A rigid mounted four link with spherical end bearings will bind in body roll, which is what makes it attractive to drag racers. The rear end housing is essentially turned into a giant anti-roll bar.

It only works with the rubber bushings, because they distort enough to allow the suspension links to slightly change their CtoC length when a bind crops up.

I'm with you on the triangulated four link. They're in a bind at all times, even with rubber bushings.

People get snarky when they run out of arguments.

I knew this "whiz-bang" looking suspension would draw a lot of attention and questions, so I was prepared to defend my design by explaining what was going on and why I chose to do things the way I did.

I do get grumpy sometimes, especially when the first post is not in the form of a question, but rather an accusation.

That happened in my fabricated spindles post. A guy rolled in and suggested that they simply weren't strong enough and that a destructive test would be the only way to know for sure if they were safe. No data on his end, he made his introduction by way of suggested that I had built unsafe parts.

Not a good way to kick off a productive discussion, ya know?

You were respectful, and I got the impression that you wanted to learn, not make accusations, so I was respectful in return.

I can be a grumpy bastard if something hits me wrong though, no question.

 

Hehehe, abrasive personalities and strongly held opinions can sometimes be very detrimental to some very interesting and informative threads.

There are a handful of very technically clued in and switched on people here, not many, but it is they that keep me constantly coming back here.

That green chromate etch primer commonly used on aluminium airframes probably would look really good on a tube space frame such as yours. But it would look quite wrong on the traditional boxed hot rod frame rails.

For chassis paint on something a bit more conventional, I intend to try finding out what that satin black paint is that all the car manufacturers use.
It is tough as nails, and actually does not look too bad IMHO.

 

That was my thinking as well, yes.

 

Ryan, I commend you on your lengthy and thorough explinations of this type of rear suspension. I worked on a Nascar team and although they differ from them, it more resembles the Nascar Modified's suspension package with a little twist and turn here and there. Can't wait to hear how it handles on a road course and/or autocross course.

Keep the pics coming !!!
(now...get back to work)

 

Ryan, (I keep wanting to call you Luke)

How much travel is in that pull bar front to back? I have never seen one up close. I am curious about pinion angle change when you really romp on it. If I remeber right you said there was a spring inside of it, is it the same as a coil over spring and can be changed out relatively easy? What kind of spring rate do you run in there, I assume it vary based on track conditions? and finally has anyone run this setup (pullbar) on the street?

Lot of questions, no accusations!

 

You and me both.

I'm going to remove what's left of the floor, fix the two big rust spots up front, and then it'll be time to temporarily hang the shell on the chassis to set the stance/rake and make sure there haven't been any crap-ups.

Then it'll be time to fabricate a great many things (body mounts, floor, firewall patches, fix all the mangled fenders, etc).

Stay tuned.

I am glad you will be keeping the fenders now I want to see it even more ,looks like a really fun project, please keep us updated!

 

You can change the spring, but they're spendy. Way stiffer than most coil over type springs, and smaller OD too. The mfg makes several different rates though.

Most folks don't change the spring unless the traction picture has changed drastically, like going from dirt to pavement. Going from dry concrete to dry pavement, or dry to wet, or changes of temperature don't result in big enough differences in traction to warrant a spring change.

For subtle changes in available traction, you can change the bar angle to alter the amount of anti-squat you use. The bar angle also changes how fast the spring winds up and unwinds.

A steep angle loads the spring hard and fast, but it gives back all the load pretty quickly too, so if the traction isn't there, you'll break the tires loose before you've built up your ground speed. Less angle buffers slower, but gives the torque back slower too, so the ground speed has time to build up.

The more torque the surface can handle, the steeper the bar can be run.

I've pretty much just got the two settings, the top one for wet, and the bottom one for dry running.

The spring in this pull bar is rated at 1,600 lbs per inch. If it gets more than a quarter or three eighths of an inch of travel in this car with these tires, I'll be mightily surprised.

If it gets over half an inch of travel, I'll put a stiffer spring in it.

Pinion angle change will be in the 1-2 deg range (less than 2 degs for sure, likely about 1.25 degs). I'll start with 3 degs down from vertical on the pinion, so it won't break over center.

We used to get upwards of 2" of travel on our pull bars on the dirt, but those only used 600 lb per inch springs (and the motors had ~750 HP too).

The pinion angle change doesn't hurt anything, even breaking over center (from pinion down to pinion up) isn't that big of a deal. But with this setup that won't really be an issue. If we could run 750 HP through the U-joints with 6 degs of pinion angle change without issue, I'm not a bit worried about this setup, even if it maxes out (2 degs change).

I have seen many guys use a rubber buffered torque arms in other street/road race/autoX cars, and it works just fine. That's a variation on the same theme. Pull bars don't get used a lot with production based cars because of the head room they require. You'd have to remove the entire rear seat pan to make room for one to operate.

That's one more reason that I'm not all that heartbroken about the floor being rotten in my 36. I'd have just had to cut it all out for clearance anyway.

 

Well, I didn't get the suspension recoated until today, so assembly will have to be pushed back until the end of next week or so.

When it's cold, the paint stays rotten forever it seems like.

 

Took more time than I originally intended, but I got it down onto jackstands today and assembled the suspension:







Add wheels and tires, and we have a full fledged roller:

















I'll still respond here to new posts, but I won't be adding any new picture updates here.

The body mounts and cage building will all be added to the original build thread.

 

Nice job. I added floated brakes on a few street cars that I have built, and people thought that I lost my mind. I also use the clamp on brackets on alot of the rear end housings that I build. I am currently going to install a full floating 9" rear end under my '70 Mach I, and I just may float the brakes as well.

 

Thank you.

Even if there weren't performance gains to be had, floating the brakes solved a lot of the packaging problems you run into with a traditional 90/10 shock type three link setup.