Sponsored
- First Name
- redneck
- Joined
- Jan 3, 2020
- Threads
- 25
- Messages
- 5,417
- Reaction score
- 17,156
- Location
- Central PA
- Vehicle(s)
- 88 5.0 LX, 08 F-150 Stepside, 22 Expl Timberline
- Your Bronco Model
- Base
Excellent 1st thread Andy!!
FYI, I owned a 1986 Iroc-Z back in the day. Wish I still had it.
Ah the mid to late 80’sAre we old or what I to had 86 loved the handling drifted nicely.
Not much of an IROC guy here, I bleed blue. I used to eat them for lunch with my LX Fox body. Along with Formula Firebirds, a few Corvettes, even an SS 454 Chevy pickup. Set of gears and exhaust had me running 13.60s. Oh those were the days
Anyway, nice thread @87-Z28 , good read.
- Thread starter
- #33
I had to share a ride with my brother all thru high school and college. As soon as I graduated college, 1st week of work I ran out and bought the z28. Wanted an iroc but couldn’t find a manual. The 5 speed manual was way to much fun. Indeed, Those were the days. 
- First Name
- T
- Joined
- Mar 11, 2021
- Threads
- 18
- Messages
- 567
- Reaction score
- 698
- Location
- Berkeley, CA
- Vehicle(s)
- 2023 Badlands, 2013 Toyota Highlander, 2000 Miata
- Your Bronco Model
- Badlands
Yeah is what I was thinking as a short term solution to compensate for the increased weight of a bumper and winch. Keep the OEM Bilstein struts and change the springs. Is this already discussed at length in another thread? Is it advisable? Is there a way to calculate the spring rate needed based on added weight?
- Thread starter
- #35
Here is a thread. I think maybe dobinsons springs may fit the SAS bills. I would call them and ask. They probably have a few different options.
https://www.bronco6g.com/forum/threads/finally-found-hd-rear-springs-that-work.75520/
Sponsored
- First Name
- Jason
- Joined
- Apr 28, 2022
- Threads
- 16
- Messages
- 512
- Reaction score
- 973
- Location
- Flagstaff
- Website
- canyoncoolers.com
- Vehicle(s)
- 73 Bronco, Dodge 2500, Sprinter Van
- Your Bronco Model
- Wildtrak
I believe Eibach makes some springs for the Bilstiens.
- First Name
- T
- Joined
- Mar 11, 2021
- Threads
- 18
- Messages
- 567
- Reaction score
- 698
- Location
- Berkeley, CA
- Vehicle(s)
- 2023 Badlands, 2013 Toyota Highlander, 2000 Miata
- Your Bronco Model
- Badlands
Ah, thanks! Looks like these are the ones.
https://eibach.com/2883/E30-35-056-01-22-FORD-Bronco-pro-lift-kit
- Thread starter
- #39
Some sway bar math. This analysis considers resistance of sway bar only and provides some insight into sway bar behavior as related to its diameter.
A simple approximation for the anti-sway bar flexibility/rigidity (solid bar), is the diameter to the fourth power. A very strong relationship. The solid front bar on my OBX is 1 3/8” from the factory. So decreasing bar diameter to 1 1/4” results in 46% increased flexibility. Notice just 1/8” decrease in diameter has a significant affect. A 1” bar has 350% increased flexibility, that is getting real.
This begs to question if a 1” bar will have any real anti-sway resistance. Does it serve any purpose? If you strap on a 16 gage wire as a sway bar obviously there will be no anti-sway benefit, but also no hindrance to flex or articulation either. Ultimately not worth the effort. So clearly there is a minimum sway bar diameter to achieve any real benefit. What is that number?
A more detailed and thorough analysis of the sway bar resistance wrt the forces generated in the sway bar links is shown. Sway bar link forces are required to generate anti-sway resistance, but they also limit articulation or relative wheel travel between front two wheels. Up on one side and down on the other.
The analysis includes sway bar resistance from main bar torsion, torsion of ends, and bending of ends. Essentially five springs in series between the two sway bar links. The analysis shows that torsion of main 34” long section dominates. See first figure. Plotted is the relative sway bar link motion with respect to sway bar link forces. Sway bar links have some leverage wrt wheel motion due to their attachment location on LCA, approximately a 1.75 motion ratio.
So for different bar sizes (diameters) the sway bar forces wrt wheel motion can be plotted, see remaining figures. Shown are the OEM diameter of 1 3/8” compared to 1” bar. As estimated earlier, 1” bar is more flexible by a factor of near 3.5. So for the same resistance or force in the links, relative wheel motion is 3.5 times greater.
Considering a 4” relative wheel displacement at >60 mph to be a fairly serious sway event. Then the stock oem bar can produce 1500 lbs of resistance whereas 1” bar only produces about 400 lbs of resistance. Is that enough to calm down sway? Not sure, but with a roof top tent and heavily loaded, maybe not.
Also shown on the plots are the “walker” damper links which provide about 1.5” of travel at each wheel, so call it 3” total. For Walker links you will be near yellow curve for slow speed articulation (no damping force). And near blue curve or stock curve for high speed anti-sway.
It seems a 1” bar may be very beneficial towards flexibility, but again not sure if it will provide any real anti-sway benefits. Would be interesting to try out. I am not convinced. Maybe better to just use mechanical release (PITA) or drive without sway bar. Walker damping links seem to be a promising alternative, but will ultimately still limit max articulation.
Also shown are comparisons of 1 1/8” bar with stock and 7/8” bar. Most interesting and promising bar in my opinion is a 1” bar. A 7/8” bar doesn’t have much anti-sway value, and 1 1/8” bar is not flexible enough.
A simple approximation for the anti-sway bar flexibility/rigidity (solid bar), is the diameter to the fourth power. A very strong relationship. The solid front bar on my OBX is 1 3/8” from the factory. So decreasing bar diameter to 1 1/4” results in 46% increased flexibility. Notice just 1/8” decrease in diameter has a significant affect. A 1” bar has 350% increased flexibility, that is getting real.
This begs to question if a 1” bar will have any real anti-sway resistance. Does it serve any purpose? If you strap on a 16 gage wire as a sway bar obviously there will be no anti-sway benefit, but also no hindrance to flex or articulation either. Ultimately not worth the effort. So clearly there is a minimum sway bar diameter to achieve any real benefit. What is that number?
A more detailed and thorough analysis of the sway bar resistance wrt the forces generated in the sway bar links is shown. Sway bar link forces are required to generate anti-sway resistance, but they also limit articulation or relative wheel travel between front two wheels. Up on one side and down on the other.
The analysis includes sway bar resistance from main bar torsion, torsion of ends, and bending of ends. Essentially five springs in series between the two sway bar links. The analysis shows that torsion of main 34” long section dominates. See first figure. Plotted is the relative sway bar link motion with respect to sway bar link forces. Sway bar links have some leverage wrt wheel motion due to their attachment location on LCA, approximately a 1.75 motion ratio.
So for different bar sizes (diameters) the sway bar forces wrt wheel motion can be plotted, see remaining figures. Shown are the OEM diameter of 1 3/8” compared to 1” bar. As estimated earlier, 1” bar is more flexible by a factor of near 3.5. So for the same resistance or force in the links, relative wheel motion is 3.5 times greater.
Considering a 4” relative wheel displacement at >60 mph to be a fairly serious sway event. Then the stock oem bar can produce 1500 lbs of resistance whereas 1” bar only produces about 400 lbs of resistance. Is that enough to calm down sway? Not sure, but with a roof top tent and heavily loaded, maybe not.
Also shown on the plots are the “walker” damper links which provide about 1.5” of travel at each wheel, so call it 3” total. For Walker links you will be near yellow curve for slow speed articulation (no damping force). And near blue curve or stock curve for high speed anti-sway.
It seems a 1” bar may be very beneficial towards flexibility, but again not sure if it will provide any real anti-sway benefits. Would be interesting to try out. I am not convinced. Maybe better to just use mechanical release (PITA) or drive without sway bar. Walker damping links seem to be a promising alternative, but will ultimately still limit max articulation.
Also shown are comparisons of 1 1/8” bar with stock and 7/8” bar. Most interesting and promising bar in my opinion is a 1” bar. A 7/8” bar doesn’t have much anti-sway value, and 1 1/8” bar is not flexible enough.
- Thread starter
- #40
Adding some context to the sway bar link forces so the curves can have more meaning.
I attached some actual measured shock data from accutune offroad. Might not be exactly tuned for 6g bronco but does give an idea of shock forces. See figure. A violent high speed sway event will likely occur for shock velocities of >25 in/sec, and probably >50. From the shock curves a good digressive valving will produce >1000 lbs to resist such velocities, >500 lbs for linear shocks.
assuming shocks alone can’t resist sway effectively, then sway bar forces need to add additional resistance. It is likely that >500 additional lbs force is needed to calm down a violent sway event, just based on shock curves shown here. Possibly up to 1000 lbs, or double what digressive shocks alone can provide.
stock sway bar can easily add >1000 lbs of anti sway forces. A 1” bar will struggle to add >500 lbs of force. See previous post.
I attached some actual measured shock data from accutune offroad. Might not be exactly tuned for 6g bronco but does give an idea of shock forces. See figure. A violent high speed sway event will likely occur for shock velocities of >25 in/sec, and probably >50. From the shock curves a good digressive valving will produce >1000 lbs to resist such velocities, >500 lbs for linear shocks.
assuming shocks alone can’t resist sway effectively, then sway bar forces need to add additional resistance. It is likely that >500 additional lbs force is needed to calm down a violent sway event, just based on shock curves shown here. Possibly up to 1000 lbs, or double what digressive shocks alone can provide.
stock sway bar can easily add >1000 lbs of anti sway forces. A 1” bar will struggle to add >500 lbs of force. See previous post.
Sponsored
- Joined
- Jul 14, 2020
- Threads
- 125
- Messages
- 6,173
- Reaction score
- 7,129
- Location
- California
- Vehicle(s)
- Jeep Wrangler JKUR
- Your Bronco Model
- Wildtrak
So looks like these are for Non Sas? Maybe I'll have to look into dobson.
- Thread starter
- #42
Some track bar math.
This is the axle motion resulting from track bar that makes sense to me. Track bar length (Lo) is 44” and track bar height (Ho) is about 3” on my rig at ride height. Ho will vary based on lifted configuration. I am close to SAS lift.
track bar sweeps an arc and moves axle left to right as axle moves up and down. Figure attached shows later motion of axle (negative is towards drivers side). Notice as axle moves up it also moves towards passenger side, until track bar is perfectly horizontal (3” of vertical motion for me). Then axle will begin to move back to drivers side. It sweeps an arc.
a 2” lift for me will move axle down 2” wrt frame and cause about 0.2” of axle movement towards drivers side. Very minimal lateral axle movement.
This is the axle motion resulting from track bar that makes sense to me. Track bar length (Lo) is 44” and track bar height (Ho) is about 3” on my rig at ride height. Ho will vary based on lifted configuration. I am close to SAS lift.
track bar sweeps an arc and moves axle left to right as axle moves up and down. Figure attached shows later motion of axle (negative is towards drivers side). Notice as axle moves up it also moves towards passenger side, until track bar is perfectly horizontal (3” of vertical motion for me). Then axle will begin to move back to drivers side. It sweeps an arc.
a 2” lift for me will move axle down 2” wrt frame and cause about 0.2” of axle movement towards drivers side. Very minimal lateral axle movement.
- Thread starter
- #43
Best to have rear track bar as horizontal as possible so asymmetric vertical loads are reduced. This will minimize tendency of rear axle to roll. Track bar will resist lateral loading of rear axle and induce some corresponding vertical loads, since bar is not perfectly horizontal. Ratio of vertical loads to lateral is proportional to track bar angle and linear wrt lifted ride height.
figure shows rear axle vertical to lateral loading ratio as related to ride height for my OBX which is sitting near SAS lift. So 0 lift in figure represents near SAS ride height, which produces <10% vertical load component. Notice a 4” lift starts generating significant vertical loading. Increasing track bar length helps to re-center axle but does not decrease vertical loading. Since track bar angle has not changed. Track bar relocation to near horizontal is required to reduce vertical loading.
figure shows rear axle vertical to lateral loading ratio as related to ride height for my OBX which is sitting near SAS lift. So 0 lift in figure represents near SAS ride height, which produces <10% vertical load component. Notice a 4” lift starts generating significant vertical loading. Increasing track bar length helps to re-center axle but does not decrease vertical loading. Since track bar angle has not changed. Track bar relocation to near horizontal is required to reduce vertical loading.
- Joined
- Jun 3, 2019
- Threads
- 24
- Messages
- 998
- Reaction score
- 3,287
- Location
- Plymouth Michigan
- Vehicle(s)
- 2021 Bronco Badlands non-sas 4 door manual
- Your Bronco Model
- Badlands
Follow up question (great work by the way). Do we know if these measurements are absolute max travel? Or simply where you get into the jounce/rebound bumpers internally? Some of these options are excessively long in compression unless they have a bit of compression left that was not easily measured without a teardown.
I clear 37's (barely) in jounce under natural flex with about half an inch of spacer lift (2 of the 3 RC plates), and this is on Non Sas bilsteins which have a bit more compression than Sas bilsteins. Now if I jumped it, I'm sure id squeeze my jounce bumpers enough to get those tires to more than kiss my fender. But it wouldn't take much to keep them out. Seeing Fox at almost 1.75" longer than stock compressed length (closer to 2" for my non sas) is a huge reduction in jounce travel, probably 3-4", and an overall reduction in wheel travel. Unless some of these options are hiding travel in their bushings that is not showing up on paper, it seems like the best option for max flex is ICON. Am I missing something? I would have expected Fox and King to be chart toppers but they both seem to be the worst option for max wheel travel (not talking about damping performance).
Numbers on paper can be appealing yet deceiving at the same time.
Fox & King measurements are from us and that does not include shaft bumpers. Sure, you will likely never smash the bumpers all the way to metal on metal, but thats how they are typically measured.
The longer compressed length, ultimately allows for a larger tire size. Consider it like a longer bump stop, but its not eating into your shock travel. On those shorter compressed lengths, I would be curious to know what is needed to properly fit 37s.
If tire size and cv bind is not important, then yes looks like Icon numbers are the winner.
You're running a 1/2" spacer lift, is that a spring spacer or a top hat spacer?
Sponsored
