4 link question..

[hotrodrookie]

I was orginally planning on using an IRS differential but it seemed like more then I wanted to do. Im new to suspension so any advice is well apreciated. I want to build a triangulated 4 link with 2 coilovers for my 59 apache. Im on a minimal budget and want to try and build all the parts myself. For a differential I'm gona try and find an explorer 8.8. They have 3.25" diameter axle tubes. What atracted me to this was this kit http://www.welderseries.com/catalog/...roducts_id=409

I have access to a cnc laser so I want to design my own flat parts then bend them and weld them. In his design the lower bars are about 23 inches long, and the upper bars are about 16". Would these be too short for my truck? He doesnt mention any specific angle to mount the bars at so if anyone has imput on the design aspects that would be great.

The only info I could find on these was for 4x4 setups, Im guessing theyre a little different? http://www.therangerstation.com/Maga..._link_tech.htm

[hotrodrookie]

Any one with info on triangulated 4 links?...

[smashingchuck]

From what I understand as far as four links go, The longer the bar, the better it's going to ride. That means your going to have to get under the truck, take a look at what you're working with, and figure out where you are going to mount the bars. Then whip out the tape measure. So let me ask you: is 23 inches too short??

As far as the angle of the angled links, I think you want to have them at a 30 degree minimum, but somebody please correct me if I'm wrong.

[Twisted Minis]

I've heard the 30 degree number before, but I don't agree with it. That only gives you a total of 60 degrees triangulation, which I do not feel will keep the axle centered firmly. I think 35 degrees should be the minimum, and 45 is the optimum number. Anything past 45 is pointless.

Bar length doesn't really determine ride quality. For something with air ride, longer is better, because you get less pinion change by nature, and you have a longer wheel arc, which means your axle won't be pulled forward or backwards drastically during travel.

He is running coilovers, which means he will have around ~4 inches of travel on average. With that, a short 4-link is perfect acceptable. Something in the 20-24 inch range for a lower bar would be fine.

What I would do, is determine how long the upper bars need to be to get the desired 35-45 degrees on each bar, and work from there. Your upper bars should be 60-70% of the length of your lower bars. This is not measured by the physical bar though, but the distance between pivot to pivot, measured parallel with the frame rail. Or they can be measured from the side of the vehicle. Those are the only points your suspension sees. Here is a diagram:


So I say figure out the length of your upper bars when they are at the right amount of triangulation. You may have to make them shorter in order to get enough triangulation. And then use that to determine the length of your lower bars.

And do not forget about Instant Center. I so many times see it way behind the axle. You will have excessive squat on acceleration.

[cajundragger]

A trick for instant center on a street drivin truck is set it around the front bumper or just set the upper bar 3 degrees down when the lower is at ride height. I have good success with this method.

I've heard 45 total degrees is fine between bars but Im really not sure. I can tell you I have 38 total degrees on my truck and its fine.

[hotrodrookie]

I dont think Ill have enough room to mount the rear tabs for the upper bars on the axle tubes in tight with the differential and point them outward towards the fraimrails. Is it possible to reverse mount the angle of the top bars and have them pitch it and mount in front onto a driveshaft loop? Or should I try and fabricate a bridge that goes over the differential to mount the rear upper tabs and then point them outward?

[hotrodrookie]

I took some measurements and the inside of the framerail is going to be about 29" when its boxed. I dont have the 8.8 rear yet but the 16" measurement is off the 7.5" thats in it. The top view shows what the 45 degree bars would look like mounted to the inside of the differential on a bridge and as well on the axle tubes. Its a rough sketch but this is what Im thinking..

Can the lower bars be outside of the framerail? I still want to mount the coilovers to the back of the lower mount too.

I was thinking 1.5" od heavy tube for the bars, 2"od tube for the end's, the four rear mounts are welded polybushing and the front four are poly bushing with an adjustable stud with jam nut.

let me know what you guys think.

[Twisted Minis]

It is actually better to have the triangulated bars mounted wide on the axle, and narrow on the frame side. It gives better control of axle wrap and torque steer, as well as keeping your roll center height constant with the vehicle.

Your bars can be mounted on the outside of the frame. The wider your bars are on the axle, the more control you will have.

On your diagram I see that you have the bars angled at a total of 45 degrees together. That isn't really what I meant. The range of 35-45 degrees is meant to be for each bar. That means your total degrees of triangulation should be between 70 and 90 degrees.

[hotrodrookie]

Im starting to feel that a triangulated setup isnt going to work out nicely with the minimal frame width. Im looking into parallel setups. I still want to fab up my own but Ive seen kits that mount outside the frame and utilize the front spring shackle holes.

Whats the math behind a parallel setup?

Are all 4 bars the same length?

Whats a good length?

Any paticular way the panhard has to be setup?

Ive herd thess utilize adjustibility for drag racing? changing the Instant Center? Any care to explain?

[Twisted Minis]

I prefer to set up a parallel 3 or 4 link with the same properties as a triangulated one. Only none of the bars are set at an angle. I still apply the same length and IC rules. The only difference is your lateral locater sets your roll center, and offers more adjustability.

You still have the option to run a wishbone, or a satchell link (triangulated lower bars).

[hotrodrookie]

So Iv been tinkering with it and this is what I came up with. Im not sure if the bars are setup correctly but I looked at some pro street adjustable 4 link kits and tried to resemble them. Im thinking on having the bars inside the framerail for more wheel wheel space. Should the bars be set up differently?

[1Bad62Pro/Street]

Any updates to the rear suspenion.?

[hotrodrookie]

Nothing yet, Im still trying to build it on paper and price out all the parts to build it. Im trying to find the best price on poly bushings and then a DOM tube that I can use for the bars as well as the end bushings. I was thinking about using 1.5" od tube with 1/4" wall. Is this overkill? Can I get away with 1" od? I'll be running a stock 5.3 vortec... Along with weld in threaded bungs for the bars and threaded studs to weld on to the bushing ends. I plan on using 1/4 plate to make all the brackets.

Just looking at all these parts and seeing how quick the prices add up makes it hard when trying to do it on a budget.

[1Bad62Pro/Street]

Yea,
I want a 4 link set-up on my 62.
So far I don't remember anyone on here who has a 4 link set-up on 1960-1962 frames here on the forum. I probably wind up just having ladder bar set-up with floaters.


http://www.competitionengineering.co...s/chassis2.asp

http://www.truckinweb.com/tech/suspe...dup/index.html

http://www.toodoc.com/4-link-suspension-ebook.html

New 55-57 Triangulated 4-link
http://www.heidts.com/

[AirMale]

food for thought...
http://www.cachassisworks.com/Storie...AC-009_WEB.pdf

[hotrodrookie]

Well I havent built much but I have been designing the parts and getting ready to fab it up. This is what the 4 link is gonna look like as well as the design for the watts link that im going to build as well.

Right now Im hung up on coilovers. I dont know what type to look for as far as adjustability and shock and spring rates. How much of a stroke would be necesarry? 5", 7"? If any of you guys have info on pro street coilover setups any info shot my way would be great.

Im thinking about mounting the coilovers on the outside of the frame rail like the NO LIMIT Fatbar kit as well as the link bars becauase the watts link is gona be in the way in the inside.

[AirMale]

IMO-in that diagram, the crossmember for the four-link should be below the frame rails.

[1Bad62Pro/Street]

[hotrodrookie]

Originally Posted by AirMale

IMO-in that diagram, the crossmember for the four-link should be below the frame rails.

Because of the driveshaft?

I was going to build a hoop in the middle, but I'll probly end up mounting the bars on the outside of the rails.

[hotrodrookie]

Anyone with input on coilovers?