- Location
- Bakersfield, CA
I get asked now and then about my mid arm 3 link front suspension, and to answer the most recent question I thought I'd post it here so others can read it and search for it. The new suspension came about while I was installing a front HPD44 and rear Tera60. Clicking on any of the colored type will take you to a pic of the subject.
First thing is the goals I was after. I wanted good control arm angles, good ground clearance, and hard upper control arm bushings to better control front axle wrap. I drew out various suspension designs in chaulk on the garage floor and determined that long arms were not what I wanted because of the dramatic decrease in ground clearance. So, I simply moved the mounting positions slightly, and lengthened the arms slightly, and ended up with a design that, on paper, gave me good arm angles and good ground clearance.
The lower control arm axle mounts are even with the center of the axle tubes. The frame side LCA mounting position is 2.5" further back and 1" lower than stock. The old mounts were removed and new mounts fabbed, with a good amount of frame reinforcement done in the process. The bottom of the mounts are only 1/2" lower than the stock mounts, and since they are only moved rearward 2.5" and are tapered on the back, there is very little ground clearance lost over the stock mounts. The arms are 19.5" long and use johnny joints on both ends.
There is one upper control arm, on the passenger side, and the axle mount is 9" higher than the lower mount. The mount is integral with the trackbar mount, which ended up making a semi-A arm out of the track bar and UCA. The track bar mount is 7" higher than the center of the housing tubes, which keeps it aligned with the drag link. The UCA frame mount position is 1" further back and 2" lower than the stock position. The upper arm is 17" long and uses a johnny joint at the axle and a rod end at the frame. The track bar uses johnny joints at both ends.
Here are the basic specs. The LCA's are 19.5" long and are at a 12* angle at ride height, the UCA is 17" long and is at a 7* angle at ride height. The frame side upper and lower arm seperation is 6.5" and the axle side seperation is 9". The reason for the single upper arm is to eliminate any binding of the suspension, like there is on the stock style XJ 4 link or the typical radius arm (RE style) long arm. This allows the use of hard joints instead of rubber since no bushing deflection is needed to handle any binding when articulating. The use of hard joints eliminates front axle wrap, which was one of the design goals.
This setup has worked very well, and I feel that the design goals were achieved. The ride and handling are very good, as well as trail manners, both on the street and hauling across the desert, and there have been no breakdowns of any of the components after 3+ years of pretty hard use. Since this suspension has been installed, I've driven the XJ from central CA to Moab twice, and to CO twice, and to AZ three times, as well as numerous trips to the desert and mountains of CA. I began towing to the trails last year, because I bought a truck and camper to stay in, but I wouldn't hesitate to jump in the Jeep and drive it anywhere.
There are a couple of things that were changed since the original build. I felt there was too little anti-dive, with more brake dive than I wanted, so I raised the UCA axle mount 2". Originally the UCA axle mount was 7" higher than the LCA mount, now it is 9" higher, and the brake dive is gone. There was also a tendancy, under just the right situation, for the passenger front tire to climb and the drivers side tire would climb with it. This only happened to me a couple of times, and wasn't hard to control with slight throttle adjustment, but it hasn't happened again since raising the UCA axle mount the 2". Another thing is that the UCA frame side rod end was mounted using a 1/2" bolt (grade 8, like everything) and misalignment spacers. The 1/2" bolt ended up being hard to keep tight, and it has been replaced with a 5/8" bolt, which is working out fine.
Here are some more pics.
First thing is the goals I was after. I wanted good control arm angles, good ground clearance, and hard upper control arm bushings to better control front axle wrap. I drew out various suspension designs in chaulk on the garage floor and determined that long arms were not what I wanted because of the dramatic decrease in ground clearance. So, I simply moved the mounting positions slightly, and lengthened the arms slightly, and ended up with a design that, on paper, gave me good arm angles and good ground clearance.
The lower control arm axle mounts are even with the center of the axle tubes. The frame side LCA mounting position is 2.5" further back and 1" lower than stock. The old mounts were removed and new mounts fabbed, with a good amount of frame reinforcement done in the process. The bottom of the mounts are only 1/2" lower than the stock mounts, and since they are only moved rearward 2.5" and are tapered on the back, there is very little ground clearance lost over the stock mounts. The arms are 19.5" long and use johnny joints on both ends.
There is one upper control arm, on the passenger side, and the axle mount is 9" higher than the lower mount. The mount is integral with the trackbar mount, which ended up making a semi-A arm out of the track bar and UCA. The track bar mount is 7" higher than the center of the housing tubes, which keeps it aligned with the drag link. The UCA frame mount position is 1" further back and 2" lower than the stock position. The upper arm is 17" long and uses a johnny joint at the axle and a rod end at the frame. The track bar uses johnny joints at both ends.
Here are the basic specs. The LCA's are 19.5" long and are at a 12* angle at ride height, the UCA is 17" long and is at a 7* angle at ride height. The frame side upper and lower arm seperation is 6.5" and the axle side seperation is 9". The reason for the single upper arm is to eliminate any binding of the suspension, like there is on the stock style XJ 4 link or the typical radius arm (RE style) long arm. This allows the use of hard joints instead of rubber since no bushing deflection is needed to handle any binding when articulating. The use of hard joints eliminates front axle wrap, which was one of the design goals.
This setup has worked very well, and I feel that the design goals were achieved. The ride and handling are very good, as well as trail manners, both on the street and hauling across the desert, and there have been no breakdowns of any of the components after 3+ years of pretty hard use. Since this suspension has been installed, I've driven the XJ from central CA to Moab twice, and to CO twice, and to AZ three times, as well as numerous trips to the desert and mountains of CA. I began towing to the trails last year, because I bought a truck and camper to stay in, but I wouldn't hesitate to jump in the Jeep and drive it anywhere.
There are a couple of things that were changed since the original build. I felt there was too little anti-dive, with more brake dive than I wanted, so I raised the UCA axle mount 2". Originally the UCA axle mount was 7" higher than the LCA mount, now it is 9" higher, and the brake dive is gone. There was also a tendancy, under just the right situation, for the passenger front tire to climb and the drivers side tire would climb with it. This only happened to me a couple of times, and wasn't hard to control with slight throttle adjustment, but it hasn't happened again since raising the UCA axle mount the 2". Another thing is that the UCA frame side rod end was mounted using a 1/2" bolt (grade 8, like everything) and misalignment spacers. The 1/2" bolt ended up being hard to keep tight, and it has been replaced with a 5/8" bolt, which is working out fine.
Here are some more pics.
