Jeep Wrangler Forum banner
1 - 12 of 12 Posts

·
Premium Member
Joined
·
10,835 Posts
Discussion Starter · #1 · (Edited)
A new thread based on questions @Rob50lx asked:


TerryC6 said:
I just finished replacing my 2.5 inch springs for 3.5 inch springs plus increasing my wheel spacer size a half inch. My front springs are on the stout side netting me almost 4 inch of lift. I only took it on a short test drive last night but if anything it handled better than it did with the shorter lift, smaller spacers. I was not expecting that. I will take it out for a longer drive today.
TerryC6 said:
Backspacing now is 2.75. My goal for just one puck though is going to have to wait until I get 70 inch wide axles.
deepbluerubi said:
More competency has to be due to the wider stance with the spacers no? Problem is for me the wheels/tires sticking out so far. Not just appearance, but I think the JL is just too large overall. I have my 20"s just even with the fender for the street. Off road, run what you want.
So yes Terry increased stance/track width along with height but didn't he also increase his potential spring rate before hitting his bumpstops?

By increasing height while staying with MC springs didn't he just add an additional xxx pounds per inch of spring rate before bottoming out?

numbers are made up; but lets make an example: Lets say the springs are linear and have 150lbs per inch spring rate. going from 2.5" -3.5" lift Terry has increase spring travel from 4" to 5" (again these numbers are made up) before hitting bumpstop.

Wouldn't the 3.5" spring now need 750lbs of force to hit the bumpstops while the 2.5" spring would only need 600lbs of force to hit the bumpstop?
Would the higher spring rate be more significant than the track width increase despite the height increase?
I don't know the actual MC spring numbers so I don't know what to think?

I am/was similar to Terry with my 2-door in that I currently run 37s with 2.75"BS and have MC 2.5" springs but I added 1" spacers to get my current 3.5" lift. I now have new MC 3.5" springs but I'm still deciding whether to stay at 3.5" or add my spacer go all the way to 4.5" lift. I know another avid Metalcloak user that went from 4.5" springs on his 4-door down to 3.5" springs with 1" spacer because he didn't like the spring rate with the full 4.5" springs. Unfortunately MC doesn't share spring rates so we have to make some assumptions that they stay fairly consistent with their spring rate for various heights.

As a side question to @TerryC6; When you finally go to 70" wide axles what backspacing do you intend to run? Isn't 70" wide axle with 4.75"BS the same overall width as stock axles with 2.75"BS?
 

·
Registered
Joined
·
801 Posts
Are you referring to yourself in the third person?
Terry's post is actually a copy of my full post that started going off topic in another thread.

Just wondering if his handling improvement came from the .5" increase in wheel spacers netting a total of 2.75" BS or whether it came from the increased spring rate before hitting bumpstops by going with a taller spring?
 

·
Premium Member
Joined
·
10,835 Posts
Discussion Starter · #4 ·
When it come to MC springs we don't know there rates. But we do know what there goal is and we do know there free lengths. MC's goals for all there lifts is to provide the advertised lift height based on a full load rig, armor, skid bumpers, the works. Except for the 2.5 inch door lift and the 5.5 inch 4 door lift the springs are shared. So a 3.5 inch 2 door lift is the 2.5 inch 4 door lift and so on.

So for a 2 door the 2.5 inch spring is 21 inches, the 3.5 inch spring is 21.5 inches, the 4.5 inch springs 22 inches and 5.5 inch springs 23 inches. So half of the lift height is based on longer springs and the rest made up by spring rate until we get to 5.5 inches which is all the longest spring. How much more the rate increase is unknown but it can't be much. The reason I went up to 3.5 inch is because I got to heavy for 2.5 inches. But @Rob50lx is correct force to get to full stuff, I don't think I will have a problem with that.

Concerning axle width my goal as been to get down to less than 2 inches of backspacing with my 6 pack shocks running 37 inch tires and doing this without modification to the shock or mounting location. The stock JK axle width is 65.375 inches. I am currently running 1.75 inch wheel spacers so the axle width is 68.875. And with my 4.5 inch backed spaced wheels I am still getting into the shock. I wish I had a wheel with 3.5 inches of back spacing as that would tell me if a 70 inch axle will fix the issue of getting into the shock.

Of course the 70 inch axle will also to address scrub radius. When we start removing back spacing from our wheels or adding spacers we are increasing scrub radius in a positive direction. I let anyone who wants to look up what a positive scrub radius does to drivability because they explain it a lot better than me. At 4.5 inches of back spacing it is not a big deal, wider than that and you start to feel the effects.

This is kind of hard to explain but with my 1.25 inch spacer driving in a straight line it felt at times a tire would get under itself and shoot you off in whatever direction it was pointing. This was not a caster issue as I have 5 degrees of it. Going to 1.75 inch spacers it feels more planted. this kind of makes since because the more positive scrub radius you have the more the vehicle is going to want to run straight. Of course your tearing you tires up doing it. Corners seems a bit more touchy but that might just be in my head because it was very windy today. But once I put the spacers on cornering did get lot more touchy than before I had them. You have to be careful not to turn in to early or you have to correct they turn in very hard for the corner.

As to whether the different spring rates of the widen stance made a difference I think it was both. As I said the wind was blown pretty good today and I was not getting blown around like I am use to. I think the slightly stiffer springs control body roll and weight transfer better. The wider stance wanted to roll in a straight line which also helped. But I would much rather just get a wider axle so I can go back to 1 finger driver and not having to pay so much attention. This setup is by no means dangerous but you do have to stay on top of it.

Sorry for the book.
 

·
Premium Member
Joined
·
17,058 Posts
The challenge in determining the spring rates and load is that we don't know for sure the wraps and distance between wraps. If they engineered them to be similar spring rates, the wraps would be different. If they just added wraps to increase length, we would have a different spring rate.

The comment on handle better... What was better? Flatter cornering, more sporty? Better tracking? I would attribute track width to some of that... But the track width came at the detriment of scrub radius. Fortunately, we aren't running lightning lap and probably don't notice scrub radius too much.
 

·
Registered
Joined
·
8,368 Posts
Terry's post is actually a copy of my full post that started going off topic in another thread.

Just wondering if his handling improvement came from the .5" increase in wheel spacers netting a total of 2.75" BS or whether it came from the increased spring rate before hitting bumpstops by going with a taller spring?
Increased height will almost ALWAYS lead to less control. The centre of gravity is raised which allows gravity to act more acutely on turns. The wider stance to a certain extent adds stability to that increased height. Now in an ideal world where steal doesn't flex then backspacing (or amount of) wouldn't make a difference, but in the real world steal does flex and bend with weight so the further out the wheels are from the wheel bearing, the more u-bend kind of flex there is and, the less flat the wheels are on the ground as a result (essentially more negative camber). Moving the wheel hub out from center of the axle hub also adds flex to the wheel itself which leaves the tire less level to the road (more negative camber). Too much negative camber of course leads to a whole bunch of other control issues.

Soooo... at the end of the day, from my eye anyway, it's not necessarily one thing or the other (lift vs wheel space), but rather attaining a proper balance between the two giving the max control and handling. Height will cause unwanted increase in the centre of gravity, but the wider stance combats that. On the other hand, too much weight beyond the wheel bearings will cause more negative camber as the steal flexes.
 

·
Premium Member
Joined
·
10,835 Posts
Discussion Starter · #7 ·
The challenge in determining the spring rates and load is that we don't know for sure the wraps and distance between wraps. If they engineered them to be similar spring rates, the wraps would be different. If they just added wraps to increase length, we would have a different spring rate.
I'll let you know later on the wraps and spacing.

The comment on handle better... What was better? Flatter cornering, more sporty? Better tracking? I would attribute track width to some of that... But the track width came at the detriment of scrub radius. Fortunately, we aren't running lightning lap and probably don't notice scrub radius too much.
Straight line tracking. But maybe unlike others I do notice the scrub radius issues. As I said hard to explain but with the 1.25 inch spacers on there you driving along nice and straight and all of the sudden your heading right or left with no input or road variations. With 1.75 on there that is gone at least so far, 50 miles on it.

As far as turning goes the turn-in point has change. And once you start your turn you have to be careful not to over turn when that outside tire becomes fully planted. This is worse with the larger spacers but like anything I will figure it out. And yes I am glad I don't have to track this vehicle.
 
  • Like
Reactions: Pressurized

·
Registered
Joined
·
801 Posts
I don't know if this helps, but here are photos of my 7 year old MC 2.5" spring with 1" TF spacer and factory upper isolator compared to the newest MC 3.5" spring with required upper MC isolator because of the new style wrap. The isolator is included and required and the springs are upside-down in the photos.

Automotive tire Wood Tread Coil spring Font


Automotive tire Coil Synthetic rubber Tread Coil spring
 

·
Registered
Joined
·
3,462 Posts
You can get a good approximation on spring rates loading up the back of the Jeep for example from a level position, then adding weights while until the rear sags 1". You can use gym weights or things that are heavy enough and you know their weight, you can seat people in the rear seats etc knowing their weight. Add enough weight until you can measure 1" sag. You can also keep adding more weight past 1" to 2" sag for example and see if the weight needed to push another 1" past the 1st one remains constant or changes. Progressive springs typically have a ligther rate in the beginning that gets firmer as the springs are loaded with weight, the spring rate might even change if the spring is compressed more than xx inches where a heavier rate might be present in what some call triple rate springs. In my truck i have Clayton 2.5" triple rate coil springs for the 2020+ Jeep JT rear. My truck is a 4th gen RAM 1500 crew cab that weights 6800-6900lbs without me in it. I've have measured i need 600lbs in the bed to drag her butt down 1". Divide the 600lbs by two (2 springs one per corner) and i get 300lbs per spring needed to make them sag 1". I know the rear JT Clayton spring rates cause Clayton publishes that info. 1st rate is 159 lbs/in, 2nd rate is 280 lbs/in, 3rd rate is 360lbs lbs/in. Only thing is i don't know where the 3rd rate starts but i've loaded the back of my truck with 1600lbs and i sag 2.5", so the 3rd rate may start after 2" or so.
You can measure front spring rates same way. have somebody standing in the front bumper and measure before and after and you can get a idea what the spring can hold. You just need to add weight until you get 1" sag, then divide the lbs by two to know the individual spring rate.
I know my RK 1.5" rear springs can hold 400lbs before they sag 1", so that's a 200 lbs/in per spring. I'll measure the front one of these days.
 

·
Registered
Joined
·
1,157 Posts
I don't know if this helps, but here are photos of my 7 year old MC 2.5" spring with 1" TF spacer and factory upper isolator compared to the newest MC 3.5" spring with required upper MC isolator because of the new style wrap. The isolator is included and required and the springs are upside-down in the photos.

View attachment 4535283

View attachment 4535284

Do you notice any ride differences from the old to the new? I have a set of 3.5 MC coils from 2018 that im going to replace with something in the 4.5” height. Wondering how their new coils are.
 

·
Registered
Joined
·
801 Posts
Do you notice any ride differences from the old to the new? I have a set of 3.5 MC coils from 2018 that im going to replace with something in the 4.5” height. Wondering how their new coils are.
I did notice a slight difference in the feel when going to newer style springs but too many changes have been made for me to determine if the difference was beneficial or not. I have no complaint about feel of the newer springs but I did observe somethings that were different.

I upgraded front springs way before I upgraded rear springs. I tested out the new 3.5" springs with the Teraflex spacer to give me approximately 4.5" in front. This made my 2-door practically level with my old rear 2.5" springs + 1" spacer. I eventually removed the front 1" spacer to get me just the MC 3.5" lift up front. This gave a slight rake which I like as the Jeep wasn't loaded for trips. Usually I'm very close to level when full loaded. I also added another 1" MC bumpstop spacer to the front but swapped over to my SumoSpring jounce bumper. These closed-cell bumpers were originally used by MC before they designed the Durospring bumpstops. I prefer the SumoSprings because they are designed as overload spring and bumpstop. They add additional spring rate when compressing. They are harder to set up correctly for length but I think are are a little better than the Duraspring bumpstop when set up properly. There is a road nearby that has very bad dips rated for 10mph. I can now comfortably handle them at 30mph without feeling like the suspension bottomed out. I believe some of that was related to new MC 3.5" springs and the 1" additional bumpstop spacer that allows the SumoSpring to come into affect earlier and smooth the final 1" of suspension compression. I think I have the SumoSprings set up where they should interfere with my intentions of maximum articulation.

I am still resolving the rear springs issue as the new MC 3.5" reduced my rear height compared to old MC 2.5" springs and 1" spacer. My old setup was .5" higher with less side to side height variance. I ran the new 3.5" springs without spacer for a short while and although they felt good, I was almost perfectly level with no doors, soft top, and missing T-case skid plate. I didn't like this because I was going to be squatting at full trip load weight and probably worse if I ever install a hard top again. I'm currently running the new MC 3.5" springs and 1" Teraflex spacer to get a healthy rake at my current "light load" configuration. I'm waiting on an older set of 3.5" MC springs to see if I can find a happy medium. Someone else had commented on a FB page that they had to go with new MC 4.5" springs in the rear to get the rake and load capacity to match the new 3.5" front springs.

I don't know if 4-doors will have the same problems? I did gain some free length but I can still easily remove my springs without disconnecting and suspension component. I need to work on creating a helper/tender spring so I don't "drop" my springs. The springs won't fall out because of the front coil tower and the rear Teraflex spacers also have a rear upper cone to keep the springs from falling out.
 

·
Premium Member
Joined
·
10,835 Posts
Discussion Starter · #12 ·
@Rob50lx when I made the swap to 3.5 inch springs my front springs where probably mislabeled as they gave me less lift than my old 2.5 inch springs. Because I have a pretty heavy Jeep the guys at MetalCloak tested a bunch of springs for me and sent there stoutest 3.5 springs they had. Netted me just over 4 inches once I installed them. The problem then became my rear springs are on the weaker side for 3.5 inch springs so instead of having a rake I am seating level. That does not work for me because like you once I load it up the nose is pointed sky high. I have a set of rear 4.5 inch springs still in the box but I want to finish the rest of mods and then give it another look. These RockSlide Engineering sliders are pretty heavy.
 
1 - 12 of 12 Posts
Top