Thread: Rearend links- 4 link, 3 link, parellel, angled???

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I am building the frame for my 38 Fiat Topolino.
I have looked at pictures, read tech stuff, looked for pictures I saw once but cant find now etc, etc.

I am frustrated and at the point of hanging the rear end and I havnt made up my mind as to which way to go. So before I make that final decision as to what I am going to do, I though I would give you guys a shot at blowing the cob webs out of my head and giving me a direction that makes sense to me.

Here are the issues-
The car is short and the drive shaft will only be about 14" long from center of u-joint to u-joint.
The seats are shoved back quite a ways and legnth of links (or should I say shortness of legnths) is critical just to fit in the car.
Long angled ladder bars is out of the question, no room.
Long parellel ladder bars is not my first choice so I have eliminated that for the moment.
Given the room I have to work with a 4 link would be the best.
I have seen some 3 link setups, if thats what you call them, and that is interesting to me, here is why.
The upper links (in a 4 link) to be 15-16" long ends up into the back of the seats. (no problem with bottom links, enough room down there) and angled is out of the question (yes I can use a panhard bar)
The 3 link systems I have seen puts the upper link slightly into the seats but its in between the seats and that would work.

How important is the legnth of the upper links or link?
Can I make it work with something like 13-14"?

I guess the discussion can start here. I know its a dynamic and complex question but I just had to ask to see what you guys have to say.

Any pictures would be helpfull.
Thanks

I was going to say mine are 13''-14'' long but after measuring them that's the tube length. the complete bars with rod ends are more like 20''

When we were building the rear suspension for my Dodge truck, we needed a very short locating system, and came up with a custom made set from Suicide Doors. It is a triangulated 3 bar setup, and uses a wishbone shaped upper bar to locate it fore and aft and sideways too. Mine is set up with an S10 rear, and uses their adapter plate to mount the rear of the upper bar, but if you use another rear, like a 9 inch Ford, you can weld mounts right to the housing.

Here are a few shots of mine.

Don

I was hoping you would see this Don, thats the setup I wanted to take another look at.
Does that 3 link work well?

Oh yeah, when I push the truck around the shop it goes nice and straight. I haven't had it on the road yet, but Dan is familiar with this setup from the bagged S10 world, and says it works great. I can't see any reason it wouldn't work ok, and it takes up very little length. Suicide Doors makes some very nice stuff, and they will custom make them to your dimensions.

Don

Oh Yeah, I forgot its not on the road yet. I dont know why, you seem to pop them out like they're easy.

Please tell me this, when one rear wheel comes up (twisting the rear relative to the frame) is it the bushings that squish to allow it to do that?

Thanks
Jim

Yep, it has more travel than one would think. I have jacked up one side of the axle when working on it, and it goes up quite a bit with no binding. They use these on lowriders and those guys put them through some crazy angles, leaning to one side, etc. On the typical hot rod, the wheels really don't move up and down all that far anyways. Maybe a couple inches at the most.

It really is a pretty simple solution to the length problem.

Don

i use a joint from the jeep world called johnny joints and they work very well.
http://www.redrock4x4.com/shop/categ...1_426_427.html

Here is another one in the Fordor Dan was building originally.

Don

Well you are correct on the sd link setup. And yes we do put these things through some crazy angles. But I have to say that your upper bar total length is in relation to the bottom bar length plus the total of suspension travel. Plus your mouting points are a direct relation to your instant center and bar lengths. Now to get a good handleing car (truck) You need to keep in mind the wheel base length. Because too short will result in great turning capabilities but less straight line stability. And vise versa. One rule of thumb when figuring out what kind of length you will need for your project would be almost 1/3 the length of the wheelbase should be your bar length.

I have one question for you. Do you have the option of running your suspension on the outside of the frame? I design alot of suspension for our industry I can help you out with what we do. I would be more than happy to do that. You can see what we do if you look at some of the pictures on the site under misc pics.
http://www.seriouslyinsaneautoconcep...sc%20pages.htm

Did you say crazy angles?


Air Shocks and Johnny joints.

Yes crazy angles
so call me CRAZY but what are johnny joints? I have never heard of anything like that.

Here are Johnny Joints

[QUOTE=maddddog]I am building the frame for my 38 Fiat Topolino.
I have looked at pictures, read tech stuff, looked for pictures I saw once but cant find now etc, etc.

What kind of power are you going to be throwing at this Topolino? And what is the endgoal as to where you want it to work best, like street, strip, or both?

we call those super pivots.