Fiat, Second Time Around

[62ChevyII]

I think the 3-link will act like a 4-link as far as instant center and need to meet at an imaginary point out in space to work right. A 3-link will still let the rear housing rotate slightly as it moves through its arc like a 4-link does. I see very little difference in the 3-link and 4-link when using it in a drag race situation other than it will be more complicated to make brackets. I'd build it with the theories explained in that suspension link I posted earlier. I'd also put lots of adjustment in it since you are kind of in unfamiliar territory.

I would come up with a theoretical instant center that you think is in the ball park for your combo and lay that out on the floor on a big piece of cardboard. Draw a line from your rear end brackets to your instant center to find the location of your middle adjustment holes in your front brackets. Then on the arc of the 3-link bars make a couple holes above and below those holes on your brackets to provide lots of adjustment. As an example, I think my ChevyII 4-link has an instant center of around 60" out and about 5 or 6" up off the floor.

Ladder bar's instant center is located at the center of the front pivot point and very limited on adjustment compared to a 3 or 4 link.

The main draw back I see with the 3 link is if a rod end fails on the upper link you are gonna crash, if you have a 4 link, you have some fail safe built in.

 

[bob w]

Got the trans crossmember in. That was easy.

 

[bob w]

In the middle of the pic is one of the adjustable shocks I got at the last swap meet of the year. They are English so I 'spose they won't work during Tea Time.

Did the layout and started making the front mounts for the lower bars. I too think the 3 link will act like a 4 bar set up. On my Crosley I aimed the 4 link at the front axle. It launches quite well, but I'll admit I leave at an idle and mash it. Haven't used the trans brake yet and it might be a different story that way. I'll aim the 3 link at the front axle, for starters. There will be more adjustability in the top bar than you see in the lower bars. Regarding rocking side to side, it probably will and as a result will get a sway bar.

The hope for this car is for it to be a triple threat: Street use, drag race and autocross.

 

[BigIrish]

You are really rockin' on this build. You stopping to sleep?

Looking good. [P

 

[bob w]

You are really rockin' on this build. You stopping to sleep?

Looking good. [P

I'm retired and have the time. When I'm not working on the Fiat, I'm working on the Plymouth Pickup.

Thanks for the kind remarks.

 

[bob w]

The Fiat is naked! Removed the body to finish the 3 link rear suspension. It's tough on the old body to crawl in and out the rear wheel well. The lower bars adjust from horizontal to about 20 degrees up and the top bar adjusts from horizontal to about 20 degrees down. The bars are a beefy 1 1/4" in diameter.
Next, it's on to building the rear frame.

 

[bob w]

Move To the Rear

Got the rear triangle tacked in place. Made the upper spring cups. The plan is to mount them on 1" threaded rod to make the ride height adjustable. Sorta like some dirt and asphalt cars.
Sure am grateful for the tubing notcher my friend Jim from Atlanta brought me.[cl
There will be a rear anti-sway bar but I'll need advice on selecting the type of material (tubing vs round bar, CroMo?) and diameter to assure it works correctly.

 

[hotrod preacher]

lookin good...

i'm thinkin' drivin that thing will be like drivin a go-kart on steroids![ddd[cl

 

[bob w]

More Pipe

Made a number of short tubing lengths to tie the lower portion of the rear hoop together. Also finished the adjustable upper spring mounts. I'll be able to set ride height and use either 12" or 10" springs.
The lower shock mounts are finshed too.

 

[bob w]

A better view of the upper spring mount. Now worrying over how to make a decent looking upper shock mount.
I was researching Schroeder anti-sway bars. NIce stuff. But I have no idea how stiff of a bar is needed for this rig, for good cornering.

 

[roddguy1]

I've been following along on this one Bob, and love what your doing. Makes me wish I could spend that kind of time with my project. Are you still thinking of cutting doors into the body?

 

[bob w]

Working on the Watts Link. The two long holy pieces will be welded to the rear axle housing. It allows for three settings for roll center. I should recieve the Heim Joints and Four Bar Ends tomorrow and will then be able to make the links.
Rodguy1, yes indeed, I intend to cut doors into the body. I have read your advice several times and still have some questions. Look for a Private Message in a few days. Barring that, if you see a Black S-10 with a Fiat body in the back pull in your driveway, you might want to lock the doors!

 

[bob w]

It might be a bit over-built.

 

[earthman]

And who doesn't love to see overbuilt? Your build threads are always a treat Bob.

 

[Cyanide Jello]

Awesome build so far man... I love the adjustable coils for the rear... I've never seen it done like that before... I would like to know why you went w/ a straight forward 3 link and not a triangular 3 link... You wouldn't have necessarily needed the Watt's link b/c the triangular piece would have prevented side to side movement...

 

[roddguy1]

http://i256.photobucket.com/albums/hh179
Rodguy1, yes indeed, I intend to cut doors into the body. I have read your advice several times and still have some questions. Look for a Private Message in a few days. Barring that, if you see a Black S-10 with a Fiat body in the back pull in your driveway, you might want to lock the doors![/QUOTE]

Oh for heaven sakes don't be following my advice..... I just make it up as I go. lol. ;) Just kidding. If there's anything you think I can help you with I'll be glad to help. :D

 

[bob w]

Hoo boy, I shoulda just put a panhard rod on the thing. Lots of work and a few revisions to get this far. Ever since I was a little kid I've wanted a Watts Link and now I have one!
To Poison Gelatin: The reason for the style of 3 link on this car is they are supposed to corner well. I've never built one and wanted to try it.

 

[bob w]

Still have to make the outer mounting brackets for the connecting links, shorten the links and weld the threaded bungs in the outer ends. Then the remaining welding and sanding will be done.

 

[TiredIronGRB]

Over-achiever...

 

[bob w]

The Watts Link is done, as are the upper rear shock mounts. Spent some time figuring out were/how to mount a fuel cell. I'll be calling Summit in the morning.
I welded 1/8" by 3" sill plates along the outer frame tubes. The body now rests on them. Needed to put the body on and set some wheels in place just to remember where this project is heading.