Building my triangulated 4 link

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Craig Burriss

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Hey y’all,
I’ve decided to go ahead and start ordering some parts to build my triangulated four link for my Duster.
This is where I’ll post updates on the project.
I was originally going to go with the RMS inboard kit, but after doing some research, I figured with some time and effort, I could spend about half as much or less if I build it myself with this universal kit that seems to be made and sold by about a dozen different people for a dozen different vehicles, all of the kits are the exact same and size. They’re on eBay, Jegs, and a few places I’ve never heard of.
So now my plan is to get this kit,
61A146BC-F5EE-407C-9D29-FC195E10FDC8.jpeg
with the RMS front inboard mounting bracket...
This
B1B84274-CF25-4210-BA60-0125717E71FF.jpeg

For the coil overs, I’ll probably go with some QA1s, and am planning on reinforcing the upper shock mounts with either some C-channel or square tubing welded to the frame rails.
I haven’t ordered anything yet, but am planning on ordering the above in the next day or so.
Anyone have any input?
 
The factory shock mounts are no where near where the coil-overs should be on a triangulated 4-link. You can see on the RMS the coil-over mount is well ahead of the axle.

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Or this one by member rapom65
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The generic kit may be somewhat helpful, but you might be better off just buying ends and tubing. Welding will be required no matter what, so, rather than buy a kit with parts that will need to be modified it may be better just to build your own. Especially since the kit you're buying is just a couple of tubes that are probably the wrong length with rod ends, and it appears only one side is adjustable so you'd have to remove one end to adjust them. And a few brackets. But again, to me it looks like you'll get a few things you can use, a few things you'll need to modify, and a few things you'll have no use for at all.

@rapom65 built a triangulated 4-link for his Duster. His install is here Rapom's Rocket - just another Duster build thread

He used a parts kit I don't think is available anymore, but here's the list...
  • 4 x 1-1/8" Rod Ends LH thread w/ jam nuts
  • 4 x 1-1/8" Rod Ends RH thread w/ jam nuts
  • 4 pairs x 3" Wide Poly Bushings
1.5"x .25" Wall Upper & Lower Link Bars:
  • 2 x Lower Bars - 21" (Center to Center of Bushing Holes)
  • 2 x Upper Bars - 9.5" (Center to Center of Bushing Holes)
All Hardware Use Grade 8:
  • 8 x 9/16" x 4 1/2" Bolts
  • 16 x 9/16 Flat Washers
  • 8 x 9/16 Lock Nuts
  • 8 x 9/16 Regular Nuts for ease of mock up
  • 4 x Lower Link Tabs cut for 3" axle tube
  • 4 x Upper Link Tabs need to be cut for 3.5" axle tube to turn on the angle
  • 4 x Upper Link Tabs @ shock cross bar (will have to be trimmed to fit on angle)
  • 4 x Upper Shock Tabs with 1/2" hole (this depends on upper bolt of rear coil over shock)

  • 36" x 1.75" x 3/16" wall minimum for shock/link cross bar
  • 16" x 36" x 1/8th" plate steel for Link Boxes & plates for shock cross bar to frame (Ron used 3/16" sheared 4xsides, 2xtops, 2xfronts, 2xbar plates)

  • 2x RideTech 90000159 Tri Link Bracket (trim off shock tabs on back side) RideTech 90000159 RideTech Replacement Tri-Link Mounting Brackets | Summit Racing
  • 1x RideTech 90001928 Billet Shock Mounts (2 in the package) RideTech 90001928 RideTech Billet Shockwave Lower Shock Mounts | Summit Racing

  • 8 x zerk fittings, drill and tap rod ends (NAPA)

Not saying that's the only way to do it, and maybe rapom65 will chime in on anything he'd do different. RMS also has the install instructions for their triangulated 4 link on their website, you can get an idea of what it would take to build something similar to what they have. I just don't see that generic kit being all the helpful, it just locks you into some cheap hardware.
 
We run a single triangulated 4 link on our tube frame road race car , the lower links are triangulated only, they converge at the center of the diff housing at the bottom
and form a close to 90* , the top links are straight and parallel to the ground, this is called a "lotus link " style and has been used on MANY SCCA national championship GTL cars,It puts the roll center very low ( at the convergence point) it was built by Robbinson racing in GA. I have been thinking on trying it on a V8 car for a while using some 7075 link material, As far as coil-over location the stock location should work after reinforcement if you have good shock body clearance. The wider the mounting points from center of chassis the better. Dont over spring, you can calculate shock ratio based on location, See Accutune Off Road for some cool shock tech, off road mostly but the calculators they use to have are slick, real good suspension needs to be compliant and use its travel. Just some thoughts.
 
We run a single triangulated 4 link on our tube frame road race car , the lower links are triangulated only, they converge at the center of the diff housing at the bottom
and form a close to 90* , the top links are straight and parallel to the ground, this is called a "lotus link " style and has been used on MANY SCCA national championship GTL cars,It puts the roll center very low ( at the convergence point) it was built by Robbinson racing in GA. I have been thinking on trying it on a V8 car for a while using some 7075 link material, As far as coil-over location the stock location should work after reinforcement if you have good shock body clearance. The wider the mounting points from center of chassis the better. Dont over spring, you can calculate shock ratio based on location, See Accutune Off Road for some cool shock tech, off road mostly but the calculators they use to have are slick, real good suspension needs to be compliant and use its travel. Just some thoughts.

On an A-body if you run the coil overs behind the axle like the stock shocks you’ll have issues with both fuel tank clearance and tail pipe routing. The stock shocks barely fit back there, coil overs are quite a bit larger in diameter.

There’s also some advantages to running them in front for the geometry.
 
We run a single triangulated 4 link on our tube frame road race car , the lower links are triangulated only, they converge at the center of the diff housing at the bottom
and form a close to 90* , the top links are straight and parallel to the ground, this is called a "lotus link " style and has been used on MANY SCCA national championship GTL cars,It puts the roll center very low ( at the convergence point) it was built by Robbinson racing in GA. I have been thinking on trying it on a V8 car for a while using some 7075 link material, As far as coil-over location the stock location should work after reinforcement if you have good shock body clearance. The wider the mounting points from center of chassis the better. Dont over spring, you can calculate shock ratio based on location, See Accutune Off Road for some cool shock tech, off road mostly but the calculators they use to have are slick, real good suspension needs to be compliant and use its travel. Just some thoughts.
Got any pictures? I am interested as I’m trying to decide currently between the lotus link and a parallel 4 link with a watts on a car I am building.
 
I built a triangulated 4 link for my 73 Cuda, I used an Art Morison kit which is pretty much like the kit you showed. I triangulated the top bars because I felt this was a better way to go. The biggest issue is that there isn't a lot of room and you have to build a reinforced connection point for the bars. I have seen some guy actually run the bars into the inside of the car which kind of eliminates the back seat or at least requires some serious modification of the rear seat. That said, if you are willing to alter that sheet metal behind the seat it opens up a lot of possibilities.

One thing I will say is that at least in my case there was not big range of movement of the rearend up and down. I talked to Morison about it and they said that was relatively normal due to the design and the short bars.

I used the stock crossmember to mount the shocks but I removed it and redesigned it a bit as well as reinforced the crap out of. I used Strange single adjustable coil overs (because Morison sells them).
 
Image-1.jpg

Nissan H-190 Diff , 60" track width , cant see the uppers but there is about 10" of seperation between the top and bottom links.
 
On an A-body if you run the coil overs behind the axle like the stock shocks you’ll have issues with both fuel tank clearance and tail pipe routing. The stock shocks barely fit back there, coil overs are quite a bit larger in diameter.

There’s also some advantages to running them in front for the geometry.


^^^^^^^^^^^^^FACT^^^^^^^^^^^^^
 
View attachment 1715664753
Nissan H-190 Diff , 60" track width , cant see the uppers but there is about 10" of seperation between the top and bottom links.
Very cool thank you. I don’t like heims mounted in single shear, but a double shear mount could be made easily enough. Anything you’d change if you did it over again? How strong is that Nissan diff? How much power are you putting through it?
 
On an A-body if you run the coil overs behind the axle like the stock shocks you’ll have issues with both fuel tank clearance and tail pipe routing. The stock shocks barely fit back there, coil overs are quite a bit larger in diameter.

There’s also some advantages to running them in front for the geometry.
Now that I’m looking at it, that makes sense.
 
One thing I will say is that at least in my case there was not big range of movement of the rearend up and down. I talked to Morison about it and they said that was relatively normal due to the design and the short bars.

A relatively short range of travel is one of the main drawbacks to a triangulated 4 link. It’s also why the design, angle and length of the links is really important, it’s not hard to build a triangulated 4 link that has binding after only a very short suspension travel.

Like everything suspension related it’s a trade off. On an A-body, getting everything to fit without moving stock the fuel tank or altering the rear floor and back seat involves compromises that do effect how adjustable the triangulated 4 link is and how much travel it can offer.

For road racing, a 3 link is generally preferable, it’s more adjustable and doesn’t typically limit the travel as much. But again, fitting a 3 link design into an A-body is problematic unless you start moving stuff around. Which is why the A-body kits are all triangulated 4 links, because you can get it to fit with a stock fuel tank, tailpipes, etc.

Qa1 has that 6 link rear suspension that bolts in, it’s even more limiting for travel. But it bolts in. All about compromise and what’s important to you.
 
Very cool thank you. I don’t like heims mounted in single shear, but a double shear mount could be made easily enough. Anything you’d change if you did it over again? How strong is that Nissan diff? How much power are you putting through it?

H-190 will handle a fair amount of sports car power. these are light cars (1700lb) and we were pushing 185 hp and spinning 9200 RPM with a Nissan(Datsun) A-14
the pic above is from a friends car , same chassis , i used a speedway quick change rear with a variloc diff. Wouldnt change anything , its a national championship winning design.
IMGP5427.JPG




I play around with Off road suspension a bit too
3 link front 4 link coil conversion Jeep XJ now on Unimog Portal axles

IMG_4260.JPG
IMG_4259.JPG
IMG_3627.jpg
 
H-190 will handle a fair amount of sports car power. these are light cars (1700lb) and we were pushing 185 hp and spinning 9200 RPM with a Nissan(Datsun) A-14
the pic above is from a friends car , same chassis , i used a speedway quick change rear with a variloc diff. Wouldnt change anything , its a national championship winning design.
View attachment 1715664903



I play around with Off road suspension a bit too
3 link front 4 link coil conversion Jeep XJ now on Unimog Portal axles

View attachment 1715664907 View attachment 1715664908 View attachment 1715664909
Very cool thanks for the reply. I dabble In off road a little as well.
8E9BEDB2-A0B5-4AD8-8FAF-626847CFE7EE.jpeg
A94DACDF-FA6A-480B-8F40-DF6D53F9816A.png
BC7BA4D9-29D9-46EA-8D9D-BE21FF897AF7.png

Just a Dabble.:thumbsup:
 
Just ordered the RMS inboard relocation boxes because I know that no matter what I do, I’m going to use those. I’ve decided against ordering the cheap shiz from eBay because it looks sketchy.
Now I’m trying to decide if I want to use heim joint rod ends or just poly bushings. Summit has some 5/8” heim joints, and tube adapters that are very affordable.
I’m thinking of ordering all of the joints and misc. mounting tabs from Summit, and then ordering some 1.5” dom tubing .25” wall, from RuffStuffSpecialties. I can get it shipped from them for less than anywhere local, plus they’re an American company so I don’t feel as bad as I would ordering from eBay.
My classes start back today so that might slow down the process.
 
Just ordered the RMS inboard relocation boxes because I know that no matter what I do, I’m going to use those. I’ve decided against ordering the cheap shiz from eBay because it looks sketchy.
Now I’m trying to decide if I want to use heim joint rod ends or just poly bushings. Summit has some 5/8” heim joints, and tube adapters that are very affordable.
I’m thinking of ordering all of the joints and misc. mounting tabs from Summit, and then ordering some 1.5” dom tubing .25” wall, from RuffStuffSpecialties. I can get it shipped from them for less than anywhere local, plus they’re an American company so I don’t feel as bad as I would ordering from eBay.
My classes start back today so that might slow down the process.

I think not using those cheap kits is a good idea.

For a street car I would be inclined to use poly bushings. Ruffstuff sells bushed DOM sleeves that could be incorporated into the links. Bushed DOM Sleeve

RuffStuff is local to me, probably only a 30 minute drive or so from where I'm at
 
Well I bit the bullet and ordered I think everything but the coil overs, and nuts/bolts.
I was originally going to order the cheapest crap possible and make it work, but then I remembered that I drive the sh** out of my car and don’t want my axle flying out and killing me and/or a family on the same road as me.
I'll try to put together a parts list of everything ordered so far.
 
Well I bit the bullet and ordered I think everything but the coil overs, and nuts/bolts.
I was originally going to order the cheapest crap possible and make it work, but then I remembered that I drive the sh** out of my car and don’t want my axle flying out and killing me and/or a family on the same road as me.
I'll try to put together a parts list of everything ordered so far.
Good call
 
Here's what I've ordered so far.
I decided to go with Poly bushings on both ends of the link bars.
@72bluNblu, I liked the link you posted above for the weldable bushings, but they were out of stock for every size, so I ordered some tubing and bushing inserts to make my own. as seen on line 5 and 21
I didn't realize that a few of these items were sold in pairs, so I'll have some extras.
I also found out that I have full access to my college campus machine shop!
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All of the materials have arrived.
Whenever my car is almost out of gas, I’m going to start tearing it down to start the project.
 
Well my car is basically out of gas now. It looks like the weather for the next couple of weeks is going to be great too, so I SHOULD be able to get a lot done. The car has been doing so good lately as a daily driver that I really don’t want to tear into right now. But I want to get this done. Guess I’m going to start taking measurements and disassembling now.
 
Well my car is basically out of gas now. It looks like the weather for the next couple of weeks is going to be great too, so I SHOULD be able to get a lot done. The car has been doing so good lately as a daily driver that I really don’t want to tear into right now. But I want to get this done. Guess I’m going to start taking measurements and disassembling now.

I know how you feel! Every time I do an upgrade project on my Duster I run into the same thing. That’s why my T56 sat on my bench for a couple of years. It’s my daily and when it’s working I want to be be driving it! Smaller projects aren’t bad but doing a big tear down with fabrication is a different ball game.

At least with the 4 link you should be able to go back to the leaf springs pretty easily if you hit a snag. With the T56 and the crossmember and tunnel mods you get to a “point of no return” pretty fast. Since you’re doing an inboard relocation at the same time it basically means none of the stock mounting points for the leaf springs are effected until you take the spring perches off the axle. If you don’t need to do that right away you can just bolt the springs back on.
 
I know how you feel! Every time I do an upgrade project on my Duster I run into the same thing. That’s why my T56 sat on my bench for a couple of years. It’s my daily and when it’s working I want to be be driving it! Smaller projects aren’t bad but doing a big tear down with fabrication is a different ball game.

At least with the 4 link you should be able to go back to the leaf springs pretty easily if you hit a snag. With the T56 and the crossmember and tunnel mods you get to a “point of no return” pretty fast. Since you’re doing an inboard relocation at the same time it basically means none of the stock mounting points for the leaf springs are effected until you take the spring perches off the axle. If you don’t need to do that right away you can just bolt the springs back on.
It took me about 4 months to get my car driving with my t56. But the car wasn’t really “driving” before that lol
 
It took me about 4 months to get my car driving with my t56. But the car wasn’t really “driving” before that lol

Yeah mine was off the road for about 3 months when I did the T56 in it. I had it done it 2, but using the wrong hydraulic throwout bearing the first time cost me another month.

The 4 link should be a lot easier compared to the T56 conversion!
 
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