Linking a LUBR

[Yeller]

That will work an might fit under the floor. There are a ton of options out there

 

[JSmall]

That will work an might fit under the floor. There are a ton of options out there

I ended up purchasing the Artec 9 inch truss today. It was on sale and I've read good things about it.

 

[mavereq]

I'm still not sure about using left and right threads vs all RH threads. I've read a few different builds and it's about 50/50. The vendors that sell universal 4 link kits use RH and LH threads in their kits.

For my lowers I welded joints on the axle end and rh threads on the frame ends. I run rh/kg on the uppers so I have some adjustability without removing links. I've been sliding the lowers on rocks with no issue so far.

 

[mavereq]

Have you thought about a parallel 4 link with panhard (5 link)?

 

[Yeller]

I've done them but they bind. Very tunable for the street but I personally don't care for how they work.

 

[JSmall]

Have you thought about a parallel 4 link with panhard (5 link)?

I looked into it, but bought brackets for a triangulated 4-link. I hope I have enough triangulation when I'm done.

 

[mavereq]

I'm sure yeller has a little more insight, but those brackets are going to make your uppers and lowers the same length. The rule of thumb is to have your uppers a bit shorter. I think it was about 75%.

 

[mavereq]

Our frames are narrow so it's hard to get enough triangulation on the uppers. I added more triangulation on the lowers to make up for it.

 

[JSmall]

I'm sure yeller has a little more insight, but those brackets are going to make your uppers and lowers the same length. The rule of thumb is to have your uppers a bit shorter. I think it was about 75%.

I might have to rethink my brackets then. I would think the uppers would actually be a little longer with the brackets which won't be good. The upper mounts on the axle will be rotated to the rear to get the pinion angle correct which would make the overall length longer....I think.

This is why I'm asking the questions. Thanks for the input.

 

[mavereq]

Some people like long uppers for a better pinion angle at droop. The way it was explained to me is that you're more stable with shorter uppers and less verticle separation between the frame mounts than the axle mounts. Basically, you should end up with some anti squat, but there is less antisquat as your suspension droops. If your ass lifts or hops while climbing, the diminishing antisquat should settle your ass end instead of continuing to hop.

 

[Yeller]

No worries about the upper control arm length, it will be just fine. Just be sure to put the lower brackets on the housing as close to end of the housing as is practical, it will be more stable and give more than enough triaglulation. Also put the lowers at or above center line of the axle tube, just make sure you have 8" vertically between the lowers and uppers at the housing. Your plan and parts list is great, have faith.

As for anti squat. The bracket you are using is adjustable for that. I like being slightly more aggresive than a lot of guys, my rule of thumb is the frame side should have 50% of the vertical seperation of the axle, so if your at 8" at the axle then 4" at the frame, its a good comprimise. Shocks play a huge factor in the bounce, I tend to use a stiffer shock, it helps with drivability on the street and stops the hop unless you miss the tune on the links. I try to keep the lower links with less than 15* of slope at ride height, it eliminates the anti squat issues associated with longer upper links, it also allows the for slightly more agressive anti squat with the positives without the negatives.

I'll touch on the "75%" rule. It applies to short wheel travel or tall lifts with steep lower links, with a low stance and fairly flat lower arms, it becomes a none issue. Most of my builds use the same length upper as lower, but its no worries if they are a few inches longer it will still work great, its more about the tajectory of where the links go through space horizontally than length.

Here's a pic of a rig with equal length control arms, designed by one of the most anal, has to be right engineers I know, that has experience with what works, and it does, have faith. The link geometry on this rig is very close to what you are looking at doing.

 

[mavereq]

Good info yeller

 

[mavereq]

I'm around 75% on uppers. Going any longer gives up triangulation on the uppers. So far my setup has been working well.

 

[JSmall]

No worries about the upper control arm length, it will be just fine. Just be sure to put the lower brackets on the housing as close to end of the housing as is practical, it will be more stable and give more than enough triaglulation. Also put the lowers at or above center line of the axle tube, just make sure you have 8" vertically between the lowers and uppers at the housing. Your plan and parts list is great, have faith.

As for anti squat. The bracket you are using is adjustable for that. I like being slightly more aggresive than a lot of guys, my rule of thumb is the frame side should have 50% of the vertical seperation of the axle, so if your at 8" at the axle then 4" at the frame, its a good comprimise. Shocks play a huge factor in the bounce, I tend to use a stiffer shock, it helps with drivability on the street and stops the hop unless you miss the tune on the links. I try to keep the lower links with less than 15* of slope at ride height, it eliminates the anti squat issues associated with longer upper links, it also allows the for slightly more agressive anti squat with the positives without the negatives.

I'll touch on the "75%" rule. It applies to short wheel travel or tall lifts with steep lower links, with a low stance and fairly flat lower arms, it becomes a none issue. Most of my builds use the same length upper as lower, but its no worries if they are a few inches longer it will still work great, its more about the tajectory of where the links go through space horizontally than length.

Here's a pic of a rig with equal length control arms, designed by one of the most anal, has to be right engineers I know, that has experience with what works, and it does, have faith. The link geometry on this rig is very close to what you are looking at doing.

I'm around 75% on uppers. Going any longer gives up triangulation on the uppers. So far my setup has been working well.

Such great information and expertise in this thread. I'm glad I started it because I've learned so much. I'm not looking for a crazy flex machine, just something with good road manners and decent off-road.

 

[kb6677]

Score another couple of equal length on 4 link. The ugly truggy pic is still serving as a trail beater today. The "pretty" chassis pic was a buggy from a few years ago which was a very fun ride. Both have equal length links on the rear. In addition to better pinion angle, you can also influence your geometry by the amount of triangulation at the tcase end. The buggy has more than the truggy but both perform very well.

 

[mavereq]

Score another couple of equal length on 4 link. The ugly truggy pic is still serving as a trail beater today. The "pretty" chassis pic was a buggy from a few years ago which was a very fun ride. Both have equal length links on the rear. In addition to better pinion angle, you can also influence your geometry by the amount of triangulation at the tcase end. The buggy has more than the truggy but both perform very well.

How do you change triangulation at the tcase end?

 

[Yeller]

KB I always enjoy and admire your projects you turned out some nice machines over the years.

Let me touch on another subject about stability. Do not pick where to place your springs without the tires mounted that you plan to run. You will want the springs and shocks mounted as far out board toward the tire as posible it helps so much with stability, more than I can explain with out writing an engineering book....

Oh and I appreiciate that we're all listening, sharing and learning quite often the good points get lost over debates. I don't know it all but like to share what I know because I can't build them all and I want you to have the best performing truck possible so if we meet we can wheel instead of wrench and winch

 

[kb6677]

How do you change triangulation at the tcase end?

Look at the pic on the left and you will see the lowers and uppers at the end near the tcase are almost side by side. Look at the pretty chassis and you will see the uppers actually go "across" the lowers at the tcase end-more triangulation(triangulated 4 link). We had the whole anti squat cog discussion when he built my rig back in the day, explaining why there was "more triangulation" on the tcase end of the rear 4link. When we built my truggy in the garage I spoke with him at length. I think he just wanted to get me off the phone and said, "since you are using the stock frame rails, side by side will be fine for a trail rig". To copy his design we would have been into some hoopty stand off mounts from the frame or running another tube across specifically to mount the lowers. Space, tcase mount and ds would have become a problem. The stock style rails and cab forward presented some problems on both ends just like an eb-imagine that

 

[mavereq]

I was referring to our frame width when I asked that. I considered building the frame mounts recessed into the frame rails to get them a bit wider.

My next build is going to be a full tube chassis. I want to set the suspension up without all the limitations.

 

[Yeller]

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My next build is going to be a full tube chassis. I want to set the suspension up without all the limitations.

Hence the reason there is no factory frame under my bronco. I didn't want to be limited by what what was there but but my own design.

Part of the advantage to double triagulated is it has less rear steer when it articulates. The parallel style like we've been discussing has a little more but if the links are relatively flat at ride height that motion is reduced and with the springs and shocks as far outboard as possible it does a good job of controlling any funky handling it may cause.