4WU 80 Series Front Axle 3 Link on a 40 (1 Viewer)

[DirtSniffer]

I am in the planning stages for how I will be setting up the suspension on my stretched 40 project that will be running 80 axles. I have no experience with linked suspensions, especially fabbing a properly setup 3 link from scratch. While I am a fairly quick learner and would probably figure it out alright, the idea of a pre-engineered 3 link setup, even if I have to pay extra, is attractive.

4WU makes a 3 link kit for the 80s. Comparing with my 80 in the driveway, the area on the 40 frame where the link mounts would land is about the same inside width as the 80, maybe a bit wider. However, the mounts land where the frame is not parallel like on the 80 frame and are widening on the 40 frame. This could be fairly easily remedied by making a thin wedge on the inner frame rails to make a parallel section of the correct width matching the 80 frame. Alternatively, I can utilize the 4WU axle mounts and links and make my own frame mounts that mimick the 4WU mounts geometry. Seeing pics like these make it look like it would be easy to slap the whole setup on easy. This would just leave me with the panhard to figure out.

One issue I can see is the top link will interfere with the 2F passenger side bell housing mount. I will be running a 60 4 speed, black box and split case, so I could remove this mount in favor of the 60 cross member. This may be why most 40 link setups (not many with detailed build threads) I see have the top link on the driver's side. My understanding, however, is that the top link would ideally be located near the diff as on the 4WU kit for pinion rotation reasons. I am also running the exhaust down the driver's side.

Thoughts? Better off starting from scratch? Maybe see if they would sell me just the axle brackets? I will be doing a lot more research before making a decision. I'll have a bare frame to stare at and take measurements on in a few weeks.

 

[DangerNoodle]

I am in the planning stages for how I will be setting up the suspension on my stretched 40 project that will be running 80 axles. I have no experience with linked suspensions, especially fabbing a properly setup 3 link from scratch. While I am a fairly quick learner and would probably figure it out alright, the idea of a pre-engineered 3 link setup, even if I have to pay extra, is attractive.

4WU makes a 3 link kit for the 80s. Comparing with my 80 in the driveway, the area on the 40 frame where the link mounts would land is about the same inside width as the 80, maybe a bit wider. However, the mounts land where the frame is not parallel like on the 80 frame and are widening on the 40 frame. This could be fairly easily remedied by making a thin wedge on the inner frame rails to make a parallel section of the correct width matching the 80 frame. Alternatively, I can utilize the 4WU axle mounts and links and make my own frame mounts that mimick the 4WU mounts geometry. Seeing pics like these make it look like it would be easy to slap the whole setup on easy. This would just leave me with the panhard to figure out.

View attachment 3331572

View attachment 3331573

One issue I can see is the top link will interfere with the 2F passenger side bell housing mount. I will be running a 60 4 speed, black box and split case, so I could remove this mount in favor of the 60 cross member. This may be why most 40 link setups (not many with detailed build threads) I see have the top link on the driver's side. My understanding, however, is that the top link would ideally be located near the diff as on the 4WU kit for pinion rotation reasons. I am also running the exhaust down the driver's side.

Thoughts? Better off starting from scratch? Maybe see if they would sell me just the axle brackets? I will be doing a lot more research before making a decision. I'll have a bare frame to stare at and take measurements on in a few weeks.

TMR, Ruff Stuff, and Balistic all make good brackets. I would recomend full custom over a kit, everything is often a bit different on each. There is a great link calculator I can send if you want, and there is plenty of info on the way link geometry works.

 

[Mike Shull]

Cool build! I can’t wait to see pictures. I went with fab parts from Ruffstuff and fully custom brackets. Use the calculator that is recommended. There is a lot of great info in both of our build threads, too.

 

[DirtSniffer]

TMR, Ruff Stuff, and Balistic all make good brackets. I would recomend full custom over a kit, everything is often a bit different on each. There is a great link calculator I can send if you want, and there is plenty of info on the way link geometry works.

Your build was one that pushed me to wanting to link. Been looking at those as well, the 4WU kit is just appealing because it is hitting the easy button. And brackets are more refined for the axle. Have not looked at link calculators yet, was waiting to get frame done so it will be easier to work things out. Which do you use?

 

[DangerNoodle]

Your build was one that pushed me to wanting to link. Been looking at those as well, the 4WU kit is just appealing because it is hitting the easy button. And brackets are more refined for the axle. Have not looked at link calculators yet, was waiting to get frame done so it will be easier to work things out. Which do you use?

I've made most of mine on the plas table at work lol. Makes it the easiest without much modification of a premade bracket. I like the TMR stuff a lot though, I use them for all my joints.

 

[DirtSniffer]

I've made most of mine on the plas table at work lol. Makes it the easiest without much modification of a premade bracket. I like the TMR stuff a lot though, I use them for all my joints.

I may not have a fancy plasma table, but I'm pretty handy with an angle grinder

 

[Mike Shull]

I may not have a fancy plasma table, but I'm pretty handy with an angle grinder

An angle grinder and a press brake work great. The towers and brackets on and above the rear axle were made with these tools. The brackets on the frame and center lower link mount area are from Ruffstuff. I have some fab parts from TMR and Ballistic, too.

 

[Mike Shull]

Thank you for the wealth of knowledge, @DangerNoodle! It's been awhile since I've bothered with anti-dive and squat. When you mention that your suspension unloads on a climb, are you referring your front end extending while being more susceptible to lifting the wheels off of the ground during a climb? Shouldn't the higher percentage anti-dive figure prevent this transfer? In other words, wouldn't a lower anti-dive cause the front to be more susceptible to lifting under acceleration and/or steep climbs?

What are your anti-squat values?

When I first did my SOA conversion on factory FJ40 springs in 1999, my values were not optimal, especially after installing the 383 a few years later. Wheelies were common for me. I worked with Alcan Spring for a month while they fabricated leaf springs that would keep the front stuck to the ground while preventing the rear from compressing too much on an incline. They did this while maintaining a comfortable ride and I thought that this was done by raising my anti-dive/squat values, but this was nearly twenty years ago.

I've needed to refresh on suspension geometry and I am placing a few links below for future reference. I welcome any and all feedback to the credibility of the content:

4-Link Suspension Guide | Anti -Squat, Anti-Dirve, and Roll Center Explained

Crawlpedia is an off-road encyclopedia featuring a complete guide to 4-link and 3-link suspension characteristics.

www.crawlpedia.com

Here are a couple of resources that I found when I did my suspension that might be useful.

Full disclaimer: I haven’t driven my Cruiser yet with the new suspension and it’s been at least 20 years previous to this project that I worked with links, and we were measuring anti-squat/dive manually. I used the calculator mentioned in the video and there are at least a few variations of this calculator, each giving a slightly different calculation. I picked two calculators and used them together to help guide my placement of the links, but I also used the space that I had available and compromised a bit where I needed. I should have this thing on the road in a year depending on the supply chain. I’ve had many delays due to availability, but I am pretty particular about a few components and I decided to wait (I.e. the King coilovers were on a 9-month back order, twice, and I didn’t make the first round.).

 

[DirtSniffer]

Here are a couple of resources that I found when I did my suspension that might be useful.

Full disclaimer: I haven’t driven my Cruiser yet with the new suspension and it’s been at least 20 years previous to this project that I worked with links, and we were measuring anti-squat/dive manually. I used the calculator mentioned in the video and there are at least a few variations of this calculator, each giving a slightly different calculation. I picked two calculators and used them together to help guide my placement of the links, but I also used the space that I had available and compromised a bit where I needed. I should have this thing on the road in a year depending on the supply chain. I’ve had many delays due to availability, but I am pretty particular about a few components and I decided to wait (I.e. the King coilovers were on a 9-month back order, twice, and I didn’t make the first round.).

Appreciate the info, I will be reading up on this soon.