I finally had time to work on my own junk after spending a lot of time on others. I've been meaning to do a suspension refresh and it gave me the opportunity to compare shocks, springs, and answer the argued question "do springs affect ride quality?".
I want to clarify there is absolutely nothing scientific about any of my experiments. Any of the ride characteristics are only gauged by butt dyno and nothing else.
First a little background.
When I bought my TJ in 2011, it had a pro comp lift with the ES3000 pro comp shocks. The control arm bushings were shot, steering was shot, the thing drove like a covered wagon.
It had a hard top, hard doors, big rear bumper with tire carrier, and I added a big front bumper and a heavy 36"x36" Tuffy security box in the back. I added steel wheels, front steel flat fenders, and steel rear fenders. Needless to say, the thing was as heavy as a tank.
I researched suspension systems and finally settled on a Metalcloak short arm lift with Bilstein 5100 shocks. I changed everything out at the same time so I can't say what caused the ride to be the way it was. But in all fairness, it was very smooth. Firm, but smooth. That was corroborated by my kid when I took him for a drive right after without telling him about the changes. There was nothing jittery, clunky, or bumpy. It was just very smooth.
After I started putting my Jeep on a diet, I could feel the suspension stiffen up and bumps would become jolting at times. I learned that the combination of suspension and shocks I had was good for heavy rigs. Metalcloak springs and Bilstein 5100 shocks. Even with all the weight, the MC springs kept the ride height at 3.5". I'm leaving the control arm joints out of the equation as I can tell no difference with those form old worn out MC joints back to new ones.
Fast forward to today.
I had already decided to go with and purchased Currie 4" springs with the LJ rears which have a 1/2" longer free length. My goal was to regain the extra 1" bumpstop requirement for the Metalcloak springs (MC requires 3" of BS and Currie requires 2" BS). I also decided that I am going to eventually outboard the rear so I can have tunable shocks. However, I'm not at that point yet so I decided to replace my existing 10 year old Bilstein 5100's with another set of 5100's. Earlier in the year I purchased the Rancho 5000x to test drive with to see if I liked them as well (more on that later).
I figured this was a great opportunity to see if springs affect ride quality. I also took the opportunity to compare shocks and comment on their quality of ride (butt dyno only).
So, I did things in this order: Removed the Bilstein 5100's and took the rig for a short drive with just the 10 year old MC springs. Then I came back and added the new Bilstein 5100's and took it for another drive. This drive included a rutted out horse trail with bumps etc. I returned to the shop and removed both the shocks and the old springs. I installed the new Currie springs without the shocks. I took it for a short drive and returned to the shop. I added the Bilstein shocks and took the same drive on the rutted trail as earlier and then returned to the shop.
These are my findings:
MC Springs Only
The ride with just the old MC springs was far stiffer than I thought it would be. Prior to leaving on the drive, I bounced the front and rear bumpers and could feel the play and anticipated a lot of sway on the test drive. I was surprised to learn that the springs felt very firm. They still bounced some, just no where near what I had anticipated. I would not define the ride as stable either just for clarification.
Currie Springs Only
After installing the Currie springs I did the same bumper bouncing as I did for the MC. The Currie springs felt far more active and bouncy. I got it on the road and, as expected, they had far more bounce and sway than the MC springs.
MC Springs and new Bilstein Shocks
I was hoping and anticipating to feel the same feeling that I did when the suspension was new 10 years ago. I learned that the new 5100's were better than the old ones, but not smooth like they were with all the weight. I am still happy with them but was hoping for smooth.
Currie Springs and new Bilstein Shocks
I didn't know what to expect at first, although I was anticipating the ride to be slightly softer compared than with the MC springs. As I began to drive I could definitely tell a slight difference. I know you want to me to quantify that....slight as in I could tell, but it didn't make a difference in ride quality that would make a difference.
Rancho 5000x and old MC springs
Awhile back I tried the Ranchos and did not like them. They felt really squishy and not very responsive. I also hated the fact that you have to run the rears can down. They just aren't for me.
Other Miscellaneous Info
The old MC springs gave me the advertised 3.5" of lift when they were new. After shedding all the weight, the front and rear springs still measured at 3.5" which tells me they were sagging before the weight loss. The 4" Currie springs came in at 4.25" in the front and a whopping 5.25" in the rear. Scratching my head I realized that the TJ only had the spare tire in it and an empty tank of gas. I loaded everything up as if it were trail ready and went to fill up the gas tank. After that, I drove to a certified scale with it coming in at the 4120 lbs. I returned back to the shop and remeasured everything. The fronts had no change while the backs settled in at 4 3/4". Don't forget the LJ rears have a 1/2" longer free length. I'm expecting the springs to eventually settle to about 4 1/4" from what others have told me about the springs.
Conclusion
Swapping over to the Currie springs will allow me to recapture that extra 1" of uptravel in the rear. I will be reworking some things to try and take advantage of that.
The springs only rides was a great experiment simply to feel the difference between the two sets of springs as well as let me truly feel if I could tell the difference if the springs made a difference on ride quality or if that was solely the job of the shocks. While I could slightly tell, I'll leave ride quality to the shocks.
As far as shock ride quality, the Rancho's are just too squishy and non-responsive. The Bilstein 5100's are better than the Ranchos by far and are actually very good if you have a heavy rig. Having put my TJ on a diet, I weighed it today with a full tank of gas, tools, spare tire, rear steel armor and it came in right at 4120 lbs. The 5100's felt way better when the rig was heavier, plain and simple. It's not bad now, but this experiment gave me a LOT of information on where I want to take it in the future. Outboarding the rear and tunable shocks front and rear are firmly on my radar. I know I can find that sweet spot again via tuning. My goal is to get it smooth as it was when it was heavy, but with what it weighs now.
I want to clarify there is absolutely nothing scientific about any of my experiments. Any of the ride characteristics are only gauged by butt dyno and nothing else.
First a little background.
When I bought my TJ in 2011, it had a pro comp lift with the ES3000 pro comp shocks. The control arm bushings were shot, steering was shot, the thing drove like a covered wagon.
It had a hard top, hard doors, big rear bumper with tire carrier, and I added a big front bumper and a heavy 36"x36" Tuffy security box in the back. I added steel wheels, front steel flat fenders, and steel rear fenders. Needless to say, the thing was as heavy as a tank.
I researched suspension systems and finally settled on a Metalcloak short arm lift with Bilstein 5100 shocks. I changed everything out at the same time so I can't say what caused the ride to be the way it was. But in all fairness, it was very smooth. Firm, but smooth. That was corroborated by my kid when I took him for a drive right after without telling him about the changes. There was nothing jittery, clunky, or bumpy. It was just very smooth.
After I started putting my Jeep on a diet, I could feel the suspension stiffen up and bumps would become jolting at times. I learned that the combination of suspension and shocks I had was good for heavy rigs. Metalcloak springs and Bilstein 5100 shocks. Even with all the weight, the MC springs kept the ride height at 3.5". I'm leaving the control arm joints out of the equation as I can tell no difference with those form old worn out MC joints back to new ones.
Fast forward to today.
I had already decided to go with and purchased Currie 4" springs with the LJ rears which have a 1/2" longer free length. My goal was to regain the extra 1" bumpstop requirement for the Metalcloak springs (MC requires 3" of BS and Currie requires 2" BS). I also decided that I am going to eventually outboard the rear so I can have tunable shocks. However, I'm not at that point yet so I decided to replace my existing 10 year old Bilstein 5100's with another set of 5100's. Earlier in the year I purchased the Rancho 5000x to test drive with to see if I liked them as well (more on that later).
I figured this was a great opportunity to see if springs affect ride quality. I also took the opportunity to compare shocks and comment on their quality of ride (butt dyno only).
So, I did things in this order: Removed the Bilstein 5100's and took the rig for a short drive with just the 10 year old MC springs. Then I came back and added the new Bilstein 5100's and took it for another drive. This drive included a rutted out horse trail with bumps etc. I returned to the shop and removed both the shocks and the old springs. I installed the new Currie springs without the shocks. I took it for a short drive and returned to the shop. I added the Bilstein shocks and took the same drive on the rutted trail as earlier and then returned to the shop.
These are my findings:
MC Springs Only
The ride with just the old MC springs was far stiffer than I thought it would be. Prior to leaving on the drive, I bounced the front and rear bumpers and could feel the play and anticipated a lot of sway on the test drive. I was surprised to learn that the springs felt very firm. They still bounced some, just no where near what I had anticipated. I would not define the ride as stable either just for clarification.
Currie Springs Only
After installing the Currie springs I did the same bumper bouncing as I did for the MC. The Currie springs felt far more active and bouncy. I got it on the road and, as expected, they had far more bounce and sway than the MC springs.
MC Springs and new Bilstein Shocks
I was hoping and anticipating to feel the same feeling that I did when the suspension was new 10 years ago. I learned that the new 5100's were better than the old ones, but not smooth like they were with all the weight. I am still happy with them but was hoping for smooth.
Currie Springs and new Bilstein Shocks
I didn't know what to expect at first, although I was anticipating the ride to be slightly softer compared than with the MC springs. As I began to drive I could definitely tell a slight difference. I know you want to me to quantify that....slight as in I could tell, but it didn't make a difference in ride quality that would make a difference.
Rancho 5000x and old MC springs
Awhile back I tried the Ranchos and did not like them. They felt really squishy and not very responsive. I also hated the fact that you have to run the rears can down. They just aren't for me.
Other Miscellaneous Info
The old MC springs gave me the advertised 3.5" of lift when they were new. After shedding all the weight, the front and rear springs still measured at 3.5" which tells me they were sagging before the weight loss. The 4" Currie springs came in at 4.25" in the front and a whopping 5.25" in the rear. Scratching my head I realized that the TJ only had the spare tire in it and an empty tank of gas. I loaded everything up as if it were trail ready and went to fill up the gas tank. After that, I drove to a certified scale with it coming in at the 4120 lbs. I returned back to the shop and remeasured everything. The fronts had no change while the backs settled in at 4 3/4". Don't forget the LJ rears have a 1/2" longer free length. I'm expecting the springs to eventually settle to about 4 1/4" from what others have told me about the springs.
Conclusion
Swapping over to the Currie springs will allow me to recapture that extra 1" of uptravel in the rear. I will be reworking some things to try and take advantage of that.
The springs only rides was a great experiment simply to feel the difference between the two sets of springs as well as let me truly feel if I could tell the difference if the springs made a difference on ride quality or if that was solely the job of the shocks. While I could slightly tell, I'll leave ride quality to the shocks.
As far as shock ride quality, the Rancho's are just too squishy and non-responsive. The Bilstein 5100's are better than the Ranchos by far and are actually very good if you have a heavy rig. Having put my TJ on a diet, I weighed it today with a full tank of gas, tools, spare tire, rear steel armor and it came in right at 4120 lbs. The 5100's felt way better when the rig was heavier, plain and simple. It's not bad now, but this experiment gave me a LOT of information on where I want to take it in the future. Outboarding the rear and tunable shocks front and rear are firmly on my radar. I know I can find that sweet spot again via tuning. My goal is to get it smooth as it was when it was heavy, but with what it weighs now.
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