moving your leaf srping underneath the frame rail!

[Stoney]

i wanted to know if anyone had ever tried moving there leaf srping underneath the frame rail before? i am thinkin about using stock or almost stock leaf srping and moving them underneath the frame rail, which would create more flex and possiblity of a bigger lift!!

i am just wondering if anyone has ever seen this done or if i am going to be the first?!!?!?!?!

stoney

[TC]

Do it! I've been thinking about this lately also, tired sagging lift springs at $400+ bucks a set that don't last. I'm going to look at longer springs, possibly the 80's rear GM springs that are popular on lifted Toyota's. So far it's just been bouncing around in my head, I haven't even touched my XJ in weeks. Hopefully I'll start on this sometime next month. Keep us posted. TC

[Bender]

I've toyed with this idea for a while and came up with a few things.

Just by moving the mounting points under the frame rails you'll gain a good 3" of lift with your same springs. Also by moving the leaf spring mounting points inward on the axles you will increase the leverage applied to them by the wheels causing more sway on the road. Significantly more I'd imagine seeing as you wouldn't need as stiff of spring for the same lift. This will also net easier articulation on the trails. Also, if you chance that isn't enough flex for you a buggy leaf setup would be quite easy.... some have done this already I believe.

The main drawbacks of this are the time and re-inforcing required. At foward spring mount you'd need to reinforce the framerail to handle that extra leverage. You'd also need to re-locate your axle perches so lots of grinding, cutting, and welding is in order. The rear shock mounts will also need to be moved as they are currently located on the axle right were the spring perches will need to go. Also, if you have the stock gas tank skid it will have to go as it mounts directly to the frame rail where the shackle mounts will now be. You'd also need to find a way to securely mount and aftermarket bumpers, trailer hitches etc.

[Slip Kid]

I think it's a good idea as long as it's reinforced. It has the potential to be much stronger than stock. The stock spring hangers are a weak point, and will eventually rust and the springs shoot up through your floor. I've toyed with the idea before, but I will probably end up just reinforcing the existing mounts.

[CheapXJ]

just looking at it...

where are you gonna put your hitch/gas tank skid of ya have them?

I'm having trouble with exhaust routing back there with all that junk and I cannot just put a turn down on the exhaust due to legal issues... (stupid PA insepctions)

It would be hella sweet to do that though. perhaps a bolt on hanger mated to a reinforced plate in the rear so it would accept a YJ type shackle

[Cresso]

I've seen it done - I'm trying to find pics now. It resulted in exactly what has been stated here - more flex, more body roll. I believe the one I saw had the gas tank swapped out for a fuel cell that had been moved up into the rear storage area. I can't recall exactly, but I think the shackes were mounted straight to a custom bumper, negating the need to remove the stock mounts and fab new mounts through the frame. I don't remember if this person used longer springs or just moved the axle back to account for the farther back shackle.

[JeepFreak21]

Originally posted by Cresso
I've seen it done - I'm trying to find pics now. It resulted in exactly what has been stated here - more flex, more body roll. I believe the one I saw had the gas tank swapped out for a fuel cell that had been moved up into the rear storage area. I can't recall exactly, but I think the shackes were mounted straight to a custom bumper, negating the need to remove the stock mounts and fab new mounts through the frame. I don't remember if this person used longer springs or just moved the axle back to account for the farther back shackle.

That's what I'm considering doing...
I figured, since I have a hitch, I'll make a custom bumper and mount the spring hanger to that.... trouble with that is, if you use your current springs, it'll move the axel back a good 3 inches... then you have to worry about hitting the gas tank w/ the diff when you flex.

[TC]

I think a better way would be to retain the same spring perch location as stock, that way you don't have to change spring pads, rear shackles, or anything between the two springs. The way to do this wouldn't be that difficult, you could use the stock front hanger as one part of the attaching point with a plate or box along side the "frame rail" ahead of the original hanger. This would strengthen the whole area considerably. I'd prefer this over narrowing the mounting locations of the perches for stability reasons and simplicity. If the replacement springs are exceptionally long you could rework the shackle mounts in the rear fairly easily. TC

[Matt]

I did it - I will elaborate more tomorrow but really the only issue is the gas tank clearence - and yes I made it work with the 20gal tank and a cut down OEM skid still attached...

I made a plate that connected to the old welded nut on the frame for the OEM position and completed one side of the hanger (other side is 4" angle iron welded to the underside of the frame)
Matt

Buggy leaf and all...

http://home.off-road.com/~wanderingwillys/xjpics/ramp11.jpg

[Stoney]

hey matt is it drivable on the road! cuz this is my daily driver!!

but i am also a very good driver!!!

stoney

[CRASH]

but i am also a very good driver!!!

Just stay out of Stoney's way at any gas stations......

Is it just me, or does the thought of leaf spring hangers dangling below the frame rail sound like a recipe for major hangups in the deep rocks?

CRASH

[Ed A. Stevens]

Bill Ansell moved the leafs under the frame, but changed back after a month or two. The flex was great, but the roll stiffness was too soft for his use, and he could not get a good shock angle to provide adequate dampening. The sidehill stability was poor.

The factory mounts can be built-up as well, to gain the same lift, leaving the wide leaf spacing.

The shackle box cover and tab addition to relocate the rear mount is now on more than a few XJ's.

Relocating the front mount with the same style of cap and bracket (using 2x3 box tubing) has the advantage of reducing the potential for suspension jacking, in additon to the raw lift height gain.

The drawback of leaf mount relocation is reduced ground clearance, but the close proximity of the relocated mount to the radius of a 33 or 35-inch tire makes them hard to hit. With the larger tires the loss of clearance is less critical at the mounts, much like LCA drop brackets on the front suspension.

The other issue is driveline length and driveshaft spline plunge travel. Moving the front leaf mount centerline height further away (lower than) from the foward u-joint pivot centerline height will alter the relationship between the t-case and pinion throughout the travel range. You will need a longer draveshaft with a greater sline travel range (although most of the aftermarket SYE shafts should not have a problem).

[ashmanjeepxj]

Originally posted by Matt
I did it - I will elaborate more tomorrow but really the only issue is the gas tank clearence - and yes I made it work with the 20gal tank and a cut down OEM skid still attached...

I made a plate that connected to the old welded nut on the frame for the OEM position and completed one side of the hanger (other side is 4" angle iron welded to the underside of the frame)
Matt

Buggy leaf and all...

http://home.off-road.com/~wanderingwillys/xjpics/ramp11.jpg

I wana see some more pics matt!!

Im not a fan of moving the perches in-board.
Stability was brought up, and I agree, it would be soft, flexy but not stable.

Matt, this is my 3/4elip plan.. Ill be running my d70 rear with the perches welded to the factory cherokee leaf perch width.

I will use a factory Xj no lift leaf back for the 1/2 elip adn use two leafs out of an F350 pack I have for the top 1/4elip.

I will flip the XJ pack so the longside goes to the front. I dont want to stretch my wheel base that much so Ill make new mounts further forward then stock.

I plan to get 8.5in of lift from the shackle and the f350 leafs.
I want the upper 1/4elip to not be fully compressed at ride height.
Have a fixed frame end mount like yours to limit the down travel unlike the double shackles.

yours looks like the top single leaf 1/4elip has no up travel compression.

what do you think?

Yes I know my described set up will cuase some big anti squat due to the angle on the lower 1/2elip but I have the stuff and want to give it a try. Ill later on build a link set up to fix the anti-squat and eventually replace the "free" leafs with some coilovers..

I have a 2dr and will severly trim instead of increasing the wheel base. I have some skinny bucket seats to replace the back seat so I can extend my wheel wells forward to where the bench used to go. Gas tank I want to move up anyways.

for now just fitting 37s and keeping it full width.

What do you think of my 3/4elip plan?

[TC]

I don't think ground clearance will be much of an issue, this type of mod only makes sense for those with the larger tires, plus thats one more reason to maintain full width...tires closer in line to the mounts. TC

[CRASH]

I don't think ground clearance will be much of an issue, this type of mod only makes sense for those with the larger tires,

How does this logic work? You get tires that are 6" larger in diameter, thereby increasing ground clearance under the frame rails by 3", only to eat up that three inches with a spring mount?

I don't get it...... :huh:

CRASH

[Ed A. Stevens]

Originally posted by CRASH
How does this logic work? You get tires that are 6" larger in diameter, thereby increasing ground clearance under the frame rails by 3", only to eat up that three inches with a spring mount?

I don't get it...... :huh:

CRASH

How far forward, from the leading edge of the tire radius, is the spring mount with the larger tire? Is there more, or less, room to hang the mount now hanging under the frame rail elevation on a rock before the tire radius has you climbing the obsticle?

The mount may be the same height off the ground (three-inch mount and three-inch taller tire), but it's also three inches closer to the tire's leading edge.

[ashmanjeepxj]

Originally posted by CRASH
How does this logic work? You get tires that are 6" larger in diameter, thereby increasing ground clearance under the frame rails by 3", only to eat up that three inches with a spring mount?

I don't get it...... :huh:

CRASH

The mount is frame height not axle height.

Axle height ground clearance is like you said increased by every inch in radius.

but the leafs are mounted to the frame so there clearance depends on amount of lift and tire size..

so to add a 6in taller tire, a 37 in my case you also add 8in of lift. so the fame is 11in taller then stock so the 3in drop is not "that" bad.

that was what TC NAXJA Member was saying...

[Stoney]

hey crash not too argue too much but u would have the same amount of ground clearance if u use the same leaf springs but the frame will be taller!! also why would u do long arms or anything else to lower the grand clearance!! again jsut stating an idea!

stoney

[CRASH]

My point is that there are so many negatives to this mod, ground clearance issues being one of them, that I can't imagine why you would want to do it.

The roll axis is going to be horrible, which is going to make steep, off-camber climbs feel really scary, so you'll compensate by adding leafs, which will make the ride horrible and unbalance the spring rates front to back.

Stoney, don't you remember us always making fun of CJ guys and their "covered wagon" rigs? One of the reasons is they are always getting hung on their leaf spring mounts in the rear on those ledgy, technical climbs. Just as they get their back tires to start crawling up an obstacle, they'll hang up on that mount. It's damn near a guarantee. Despite what Ed says, about the hangers relationship to tire size, those mounts are very vulnerable.

To each his own, and it should make for an entertaining experiment. I say go for it, you guys always provide good comic relief on the trail, and I'd hate to take that away from you.....

CRASH

[JnJ]

Ya, some of the CJ guys are getting smart and sinking their mounts into the frame. We already have that..kind of.. :)

[Matt]

Originally posted by ashmanjeepxj
I wana see some more pics matt!!

Im not a fan of moving the perches in-board.
Stability was brought up, and I agree, it would be soft, flexy but not stable.

Matt, this is my 3/4elip plan.. Ill be running my d70 rear with the perches welded to the factory cherokee leaf perch width.

I will use a factory Xj no lift leaf back for the 1/2 elip adn use two leafs out of an F350 pack I have for the top 1/4elip.

I will flip the XJ pack so the longside goes to the front. I dont want to stretch my wheel base that much so Ill make new mounts further forward then stock.

I plan to get 8.5in of lift from the shackle and the f350 leafs.
I want the upper 1/4elip to not be fully compressed at ride height.
Have a fixed frame end mount like yours to limit the down travel unlike the double shackles.

yours looks like the top single leaf 1/4elip has no up travel compression.

what do you think?

Yes I know my described set up will cuase some big anti squat due to the angle on the lower 1/2elip but I have the stuff and want to give it a try. Ill later on build a link set up to fix the anti-squat and eventually replace the "free" leafs with some coilovers..

I have a 2dr and will severly trim instead of increasing the wheel base. I have some skinny bucket seats to replace the back seat so I can extend my wheel wells forward to where the bench used to go. Gas tank I want to move up anyways.

for now just fitting 37s and keeping it full width.

What do you think of my 3/4elip plan?

I see two issues - the frame is not very thick at all where I mounted the buggy leaf - this is fine because it really only sees the loading of the YJ mainleaf's (buggy leaf) spring rate - when at ride height the shackle rests on the underside of the frame plated with 1/8" - a f-350 pack will load the entire weight of the vehicles rear end onto that point in the frame...

This leads to number two that area of the frame rail is very difficult to reinforce so it could handle those loads - if you were to do this I would just go quarter elip in the back for all the work its going to take.

Do you have a reason for not wanting to go with a simple single buggy leaf?

Borton has nicely done the spring flop and really only had issues with the gas tank - however if you move the main eye foward that would be solved...

Here are some pics of both the frame mount and the buggy in action...

http://home.off-road.com/~wanderingwillys/xjpics/Buggy_leaf/buggyup1.jpg

http://home.off-road.com/~wanderingwillys/xjpics/Buggy_leaf/buggydown2.jpg

http://home.off-road.com/~wanderingwillys/xjpics/ramp4.jpg

http://home.off-road.com/~wanderingwillys/xjpics/rear2.jpg

http://home.off-road.com/~wanderingwillys/xjpics/Crossmember/anti_wrap_bar1.JPG

Last one I promise! - shows the height of the brackets and for all you long arm haters you can see the 3-link crossmember mounted along with the RE drop brackets - Matt
http://home.off-road.com/~wanderingwillys/xjpics/Crossmember/xmember1.jpg

[SyCo]

Matt, where did you get those spring perches and how much were they if you don't mind me asking?

[Goatman]

I'm with the naysayers on this one, I don't think it's a very good idea. The negatives are loss of stability and loss of ground clearance. Flex just isn't much of an an issue any more. It's very easy to get good flex with what is already commonly known, and it's been demonstrated over and over again that too much flex, and it's resulting lack of stability, actually hurts trail performance. Like Ed already said, Bill Ansell tried this and didn't like it at all, and went back to the stock location.

The other thing that hurts trail performance is less ground clearance. We're all figuring out how to keep things tucked tight up inside the frame rails, like using high clearance cross members and slid plates. We already drag the whole frame over rocks, and scrape the bottom of the stock spring hangers, so moving the spring hangers below the frame would just make it worse. anyone who says this isn't, or wouldn't, be a problem just hasn't done much rock crawling. If you run mud, then who cares, but then why would you need more flex, and why would you want less stability?

The proof is in trail performance......... :confused:

[Matt]

Originally posted by SyCo
Matt, where did you get those spring perches and how much were they if you don't mind me asking?

They are home built - cost ~3.50$ each :D

I would agree with both Goatman and Crash if it were not for one thing...

When I ran the OEM 5 link up front is was very floppy and had terrible manners (worked great on the trail but that was about it) I then went to the 3-link I use now and the whole rig became much more stable - both front and rear - I can't explain why but the difference was night and day - I think it has some to do with the changes I made to the roll axis at either end...

In that picture of the jeep on the ramp that is a 30 degree ramp and the rear tire is still firmly planted on the ground; I cant even rock the jeep...

What both of you say makes sense its just my experience that mine is different - luck perhaps...

Ed S. I agree completely - I rarely touch those hangers and when I do I am scrapping my diff and or axle tube on the same item... I hit the frame on my rig once in a blue moon so I have not fixed them since they are working for me :rolleyes: Just my 2 ct's

Matt

[Jekyll]

Originally posted by Goatman
(snip).....Like Ed already said, Bill Ansell tried this and didn't like it at all, and went back to the stock location....(snip)
I can appreciate the concerns regarding possible instability, but it's difficult to use Bill's setup as an example of what should and shouldn't work. If anyone remembers seeing photos of his leaf pack...way-past-worn-out leaves that reverse cambered while the Jeep was sitting on flat ground, shocks that were also past their due date and mounted very close together at the top.

[ashmanjeepxj]

Originally posted by Matt
I see two issues - the frame is not very thick at all where I mounted the buggy leaf - this is fine because it really only sees the loading of the YJ mainleaf's (buggy leaf) spring rate - when at ride height the shackle rests on the underside of the frame plated with 1/8" - a f-350 pack will load the entire weight of the vehicles rear end onto that point in the frame...

This leads to number two that area of the frame rail is very difficult to reinforce so it could handle those loads - if you were to do this I would just go quarter elip in the back for all the work its going to take.

Do you have a reason for not wanting to go with a simple single buggy leaf?


I wanted to go buggy leaf for now cuase I didnt want to build links for the rear yet...

Yea yea, the 1/4 elip would be better with well designed links...

I just want to get my 1tons under the jeep fast and have the stuff to do the 3/4eilp in the garage..

Other wise Ill have to save up for 8 spherical bearings or johney joints $$$, some threaded weld-n-inserts $, and some tube $$...

Maby I should just do the tirangulated 4 link I want now, and not even bother with the 3/4 elip idea...

Yea maby I should just wait.. its only been a year collecting parts so far...

The susupension joints are the High cost.. RE jonny joints $38 each or so, or get the BIG spherical bearings 1.25in $50each.

Then $12 each of the threaded inserts...

3/4 elip free, free... some scrap metal, welding time..

I dont know, talk me into something...

[Matt]

Go the whole 9 yards and do the quarter elip - you will thank yourself later with the tuning options and the wrap control...

That is the other bit I forgot - do not even try to do a buggy with out making a traction bar (add one more heim into the mix and you have just used as many as would be needed for a four link...)

The links will give you alot more ability to grow and tinker if you go to something else - say, coilovers :rolleyes: later on...

Your right just wait a little while longer (eat some ramen) and do it the correct way, HTH

Matt

[ashmanjeepxj]

Originally posted by Matt
Go the whole 9 yards and do the quarter elip - you will thank yourself later with the tuning options and the wrap control...

That is the other bit I forgot - do not even try to do a buggy with out making a traction bar (add one more heim into the mix and you have just used as many as would be needed for a four link...)

The links will give you alot more ability to grow and tinker if you go to something else - say, coilovers :rolleyes: later on...

Your right just wait a little while longer (eat some ramen) and do it the correct way, HTH

Matt

Why 1/4 and 4link and not 3/4 elip and 4link?

I will only consider a 1/4 elip with a fixed frame mount not a hinged "no controlled drop" type 1/4 elip.

Im thinking if I run the same 1/4elip for the upper part of the 3/4 eilp it would have more wheel travel then just the same top 1/4 eilp section fixed to the frame...

you said it would be difficult to make a 3/4 elip out side the frame, but if I did a fixed 1/4 eilp I would also mount it out side the frame for added stability, so it wouldent be much harder to just do the 3/4 elip.

ground clearance, that has been brought up afew times on this thread.. woudl be ALOT better on the 1/4 elip set up,

and like you said the 1/4 elip woudl be more eaisly adjustable. jsut change the shackle length at the frame end for more height... on the 3/4 eilp any more shackle will decrease ground clearance...

I should just do what all the comp buggies do.. a 1/4 elip
:rolleyes:

Id also want two more jonny joints for the alxe ends of the shacle mounts on a 1/4 elip. That will save the main leaf form twisting.

Im almost decided to do 1/4 elip, now to decide under frame or out board of the frame?

[Matt]

Outboard...

I just got some f-550 spring packs for the 1/4 ellip in my willys - I am going to use the whole pack and mount them inverted with the shackle end on the axle and the main eye on the frame - there will be two hydraulic rams (one each side) attached to spring clamp/ center pin area for ride height and off-camber control :rolleyes: I figure what ever I build has to be complex so why not run with it... ;)

Matt

[ashmanjeepxj]

Originally posted by Matt
Outboard...

I just got some f-550 spring packs for the 1/4 ellip in my willys - I am going to use the whole pack and mount them inverted with the shackle end on the axle and the main eye on the frame - there will be two hydraulic rams (one each side) attached to spring clamp/ center pin area for ride height and off-camber control :rolleyes: I figure what ever I build has to be complex so why not run with it... ;)

Matt

Thats cool.. My runaway project mind has also thought about doing hydrolic rams...

Theres always somethign cooler to try...

:eek: Im getting tired I need a vacation..:fuse:

[Matt]

Yup that rig was/is pretty darn cool but I had thought for along time about a little 4 cyl diesel and big hydro pump for a completely hydro rig - fluid motors at the wheels and an independant suspension like this guy did...

Major props for building it; no matter if it catches fire and explodes the second time out - got that much farther than the ideas floatin around in our heads :rolleyes:

Matt

I am still toying with the idea of a long hydro cylinder with some quick connects so I could use it like a highlift :D

[Stoney]

ok now i am still trying to figure out this ground clearance issue!! so i drew this quick little picture!!http://www.extrememopar.com/upload/framerail.jpg
i know it is bad!

No matter where u mount the leaf spring mounts the ground clearance will depend on the hight of the tires and the leafs springs! if u make mounts 10 inches lower and if u have 10 inch leaf srping the ground clearance will still be the same as if 10 inch leaf springs with stock mounts!

just trying to firgure out ur guy's logic here????

stoney

[Matt]

I think crash was comparing across standard frame to ground distances - but the way mine is set up is like your drawing - the brackets provide some of the lift... Likely why I do not scrape my frame as often others is the fact that although my leaf spring is pretty flat the frame is a fair distance from the mounts... I think it comes down to personal preferance and experiance...

As tire size increases you get more tire towards the edges of the spring and shackle hangers and even though the mounts hang below the frame the tires begin lifting that portion of the frame sooner so it does not contact the offending object...

My 3ct's: if you run 38's and 7"+ lift you should not be all over your frame - unless you drive like an idiot :rolleyes:

Matt

PS Stoney - my appologies for the severe highjacking we just finished up!

[Goatman]

Well, I don't think anyone doubts that I do serious rockcrawling regularly. I say that to put a little experience into my comments. When you are scraping over a rock or ledge, it matters little what amount of lift you have. The tires drop out if the frame is on a rock, so whether you have 5" of lift or 8" of lift only means how much your tires are drooped at the time.

Sure, you're drawing is correct, and so is your thought process, but only when you're sitting still, not when you're in a boulder field. You may only get hung up every now and then, depending on what type of trails you want to run, but when you do those around you will point at your lower spring hangers and get a kick out of ribbing you about it. One thing about these forums, unless you know the person who is making the comments, you never know how much real world experinece is behind the knowledge or opinions that are given. Wheeling in rocks is different than wheeling in Moab or wheeling on dirt and mud, so building phylosophies are also different. If you want to run moderate trails but look cool with tons of flex and big tires, it also doesn't matter much. Stoney, you want to wheel in the CA mountains and deserts, don't hang your springs beneath your frame. Unless, of course, you don't mind a good ribbing now and then. :D

[Stoney]

i really appricate ur input goatman and i don't doubt u AT ALL! and i diffently respect u and know u have a lot of experiance!

i was just trying to figure out the logic about what u were saying! I am still deciding on this idea and looking at all the pros and cons to it! so thank you very much for ur (suggestions?)!!

stoney!

[CWESNER]

Seems like a lot of work and a lot of stuff in the way, just put in a coil link system or install a wider axle (D60) if all you looking for is more flex.

[ashmanjeepxj]

Originally posted by Goatman
Wheeling in rocks is different than wheeling in Moab

:roflmao: :roflmao:

[CRASH]

You haven't had fun until you've wheeled with the "kids" for a weekend!

Heckling their rigs is just the beginning!

CRASH

p.s. I'm just giving youi hard time Stoney........

[CRASH]

Well, I don't think anyone doubts that I do serious rockcrawling regularly.

Everyone knows you are just as big a web wheeler as Jes, Paul Sinclair and :farmer: boy, so we should all take any advice you dispense with a big grain of salt. :D

CRASH

[Paul S]

This would be the # 1 worst mod you could do to an XJ. There are a few simlpe things that make the XJ work so well in the rocks, the recessed spring hangers rank right at the top of that list. Take a look at the amount of work the Toyota guys put into frenching their spring hangers, or consider that TJ's sacrifice rear control arm angles in order to mount them flush against (or in) the frame.
Paul

[Stoney]

Originally posted by CRASH
Everyone knows you are just as big a web wheeler as Jes, Paul Sinclair and :farmer: boy, so we should all take any advice you dispense with a big grain of salt. :D

CRASH


LOL!!!!!!!!!!!!!!!!!!

[Ed A. Stevens]

Originally posted by Paul S
This would be the # 1 worst mod you could do to an XJ. There are a few simlpe things that make the XJ work so well in the rocks, the recessed spring hangers rank right at the top of that list.
Paul


I don't know if I would call lowering leaf spring hangers the #1 worst modification of an XJ, but for my current usage I drive my lowrider and slide the frame, rocker rails and rear corners off the rocks, rather than risk a full stop by adding more dropdown snag brackets. I'd have to think it through, for the wheeling I see, before adding to the rock catcher appendages.

I have a hard enough time snagging the little step lip on the bottom of the D44 pumpkin (time to exercise the grinder). The loose rocks in JV add to the challenge by changing the lines on all the obsticles (the guy in front of you will rearrange the trail). This constant change prevents a driver from simply following the established line, because the rocks move as they are driven over, and will catch anything they can snag. 33's are little doughnuts compared to the tires most of the regulars run, and the holes they leave swallow 33's with ease.

One thing I did notice in one of the modified photos was a slide rail angle cut on one of the forward spring brackets pictured. The angle cut would prevent a hard stop in the rocks (forward, but maybe not backwards, although the leaf should help there).

The other issue mentioned is the relative lowering of the roll axis compared to the CG for the rear suspension. Relocating these leaf hanger brackets is as close to a body lift you can achieve with an XJ. The roll axis elevation will not physically change, but the CG is raised (an extra leaf may be needed, or an anti-sway bar, to restore the resulting loss of roll stiffness).

The other result of lowering the front bracket hanger is less anti-squat for the same lift. This is something that could work for, or against, the performance balance of the front and rear working together on hillclimbs.

[ashmanjeepxj]

Originally posted by Ed A. Stevens

The other result of lowering the front bracket hanger is less anti-squat for the same lift. This is something that could work for, or against, the performance balance of the front and rear working together on hillclimbs.

The rear of the leafs will also lower the same amount as the front is lowered, so there is tille to no angle change on the leafs but since the center of gravity is increase the anti squat like you said will be smaller...


Anti squat= (force vector interseciton height)/ (Center of gravity)

Now caluculating the anti squat of a linked sytem I understand, but on a leaf spring how do you draw up the force vector intersection?

you need two vectors comming off the leafs and should have an intersection somewhere close to the center of gravity...

[Cresso]

I was considering moving the leaf springs under the frame for a long time and never once did I consider leaving the front spring mount underneath the frame to be a viable solution. I believe notching the frame, reinforcing the bujeezus out of it and mounting the front of the leaf spring essentially inside the frame rail to be the best method. This will also give you a flatter spring (closer to horizontal mounting position, not leaf arch), assuming you have the rear mount in the stock location. Flatter=more potential for flex.

[Ed A. Stevens]

Originally posted by ashmanjeepxj


Anti squat= (force vector interseciton height)/ (Center of gravity)

Now caluculating the anti squat of a linked sytem I understand, but on a leaf spring how do you draw up the force vector intersection?




With a leaf system you treat AS% analysis like a radius arm. The axle force vector is a line from the center of the axle (through the leaf pack radius arm clamped on the axle tube), to the pinned end at the chassis (the Instant Center). The intersection of the wheel contact patch IC force vector is also through the pinned leaf end on the chassis, to the front axle centerline, where the force vector intersection height is measured.

With a body lift, or relocation of the both leaf ends on an XJ, the IC height at the pinned end of the leaf arm does not change and neither does the wheel contact patch, so the force vector intersection height does not change. Only the CG height changes.

Use the same analysis model with a longer shackle and you can prove the AS% increases with the longer shackle (a taller front pin location, usually 1/2 the shackle length, and a taller CG).

Analyze what happens when the rear end jacks into full extension, with a highly angled leaf half radius arm, and the AS% goes way up under the dynamic load, sometimes to the point it dumps all the weight back onto the front axle -- and BAM, wheel hop.

[Matt]

Originally posted by Ed A. Stevens

One thing I did notice in one of the modified photos was a slide rail angle cut on one of the forward spring brackets pictured. The angle cut would prevent a hard stop in the rocks (forward, but maybe not backwards, although the leaf should help there).

The other result of lowering the front bracket hanger is less anti-squat for the same lift. This is something that could work for, or against, the performance balance of the front and rear working together on hillclimbs.

Thank you Ed! As always what I was trying to explain you lay out very simply. The only time I have had "problems" hitting those brackets is on a few of the big downed logs we have around here - and it is a really minor problem usually when one rear tire come up causing the other side to be loaded and decreasing the ground clearence - just back up a little and give it a good blip of the throttle to get some momentum - once the tire gets up to the log you go on up - I have yet to get actually hung up on them in the last 2 years even while running 33's

I lowered the front eye of the spring just a hair as the junkyard CJ lift shackle I used for the back was not quite tall enough and I did not want to get into frenching the frame

For those wondering what type of terrain I run here are two examples: A. plenty of sloppy stuff (log with fill in front) B. also some nice rocks and big hills C. (not shown) all of the above with 24 - 96" of snow on it :rolleyes:

It works for me and thats what keeps me happy...

A.
http://home.off-road.com/~wanderingwillys/Trails/TA_Matt_2_22_03.jpg
B.
http://home.off-road.com/~wanderingwillys/Trails/isabelle12_15_02_4.jpg

Matt