Front Wishbone Help

[JeepFreak21]

Well, now that the Jeep's down again and I may be getting a daily driver, I've spent the last week searching through everything that might give me some insight (front wishbone, rear wishbone, double triangulated 4 links, front suspension in general, and Beezil, Beezil, Beezil), but I still feel like I have a lot of unanswered questions. Most of the pictures were useless red X's on almost all of the threads I found. This isn't the only board I've searched on, but I have yet to find a complete front wishbone thread, so I was hoping we could get into some depth while trying to stay focused on wishbones.

Some of the questions I have are:
-With a heim at the axle end of the wishbone, can/do the threads on the heim provide the vertical movement or does it need an uber complicated bearing like Beezil made?
-Which way should the heim/bushing be mounted?
-Would a RE SuperFlex Joint (or the like) work at the axle end of the wishbone?
-What's the ideal length for the links?
-Would it be possible to mount the wishbone (upper link(s)) to the lower links or would that be defeating the whole purpose?

I'm sure more questions will come up, but that's all I had off the top of my head.
Thanks,
Billy

[xj92]

I don't have firsthand experience, but I'll answer you according to my understanding.
*If you mount the wishbone to the lowers you lose the tri-link feature, it becomes a radius-arm setup and the upper arms don't offer side-to-side stability, so you'd have to keep the track bar. No need to do a wishbone if you want to do this.
*The threads in the heim don't provide any movement usually since they're locked in place with a locknut, they're just there for length adjustability.
*There have been people with the heim facing horizontal and some with it vertical. My opinion is that horizontal would be better to give better side-to-side stability.

[JeepFreak21]

*If you mount the wishbone to the lowers you lose the tri-link feature, it becomes a radius-arm setup and the upper arms don't offer side-to-side stability, so you'd have to keep the track bar. No need to do a wishbone if you want to do this.

oh, duh :dunce:

*The threads in the heim don't provide any movement usually since they're locked in place with a locknut, they're just there for length adjustability.

Anybody know what OneTon or VintageSpeed did for their vertical movement?

Thanks,
Billy

[Phil]

I think something like an RE joint would work really well there. It doesn't allow horizontal movement, so you maintain the rigid triangulation that you need to be able to eliminate the track bar. However, it still allows free rotation for flex.

A heim may work just as well and I believe that OneTon uses a big heim for his upper. I may be wrong. I would think you want the heim to be vertical, so you can mount it in double shear, sandwich it between the two plates. I don't think a joint in good condition should allow lateral movement.

I have no experience with either of these, really, and no fab experience, but that's the way I see it anyhow.

[JeepFreak21]

A heim may work just as well and I believe that OneTon uses a big heim for his upper. I may be wrong. I would think you want the heim to be vertical, so you can mount it in double shear, sandwich it between the two plates.

Yeah, OneTon does use a (very large) heim for his, I was just wondering what gave it the movement equivilent to what Beezil's uber bearing provides. I remember quite a difference of opinion on the way the heim mounts in XJoachim rear 3 link thread. It would be possible to double sheer either way, but which way is the heim rated for more load?
Billy

[Beezil]

You DO NOT need a complicated joint.

and you shouldn't run one either, there's no point in it really unless you want to for the challenge and fun.

I actually ENJOY doing things like that, its about the only reason I can give to do it.

go to a BIG heim.

simple, proven, and almost indestructable....

otherwise, consider using ALL HEIMS for the rest of the links....

I have 20 heims used on my jeep, and besides the timken bearing wishbone joint, don't have any other kind of joint....whats good about this is, if i break a joint, i only have to carry a couple-few spares....."common parts" are a good thing.......

[JeepFreak21]

You DO NOT need a complicated joint.

and you shouldn't run one either, there's no point in it really unless you want to for the challenge and fun.

I actually ENJOY doing things like that, its about the only reason I can give to do it.

go to a BIG heim.

simple, proven, and almost indestructable....

otherwise, consider using ALL HEIMS for the rest of the links....

I have 20 heims used on my jeep, and besides the timken bearing wishbone joint, don't have any other kind of joint....whats good about this is, if i break a joint, i only have to carry a couple-few spares....."common parts" are a good thing.......


I was hoping to reuse some of the long arm parts (Superflex joints and lower arms at least) that I have put 50 miles on since I got them. I do like the idea of the common parts, but is that your main reasoning?
Thanks,
Billy

[CRASH]

I was hoping to reuse some of the long arm parts (Superflex joints and lower arms at least) that I have put 50 miles on since I got them. I do like the idea of the common parts, but is that your main reasoning?
Thanks,
Billy

You may have set the record for the shortest time on a new suspension before ripping it out and starting over. :laugh3:

CRASH

[JeepFreak21]

You may have set the record for the shortest time on a new suspension before ripping it out and starting over. :laugh3:

CRASH

We need a :laughcry: smiley.
Billy

[Beezil]

I was hoping to reuse some of the long arm parts (Superflex joints and lower arms at least) that I have put 50 miles on since I got them. I do like the idea of the common parts, but is that your main reasoning?
Thanks,
Billy
yeah its my main reasoning, if you have other joints on hand, you might as well use them!

I'm a big fan of j-joints too.....I had four on hand when i did my set-up, I just couldn't use them in certain areas, since I have them stuffed in MINIMUM clearance areas.....

oh, almost forgot.......shaddup Nay, I still have the t-shirt.

I really don't like you!

"crash out loud"

(LOL)

[BrettM]

heims absolutely SHOULD be mounted with the bolt verticle for the end of a wishbone. they are much stronger that way.

now that's not to say that is couldn't work with the bolt mounted horizontal, especially if you use a 1" or bigger heim, but if you're building from scratch you might as well do it the right way the first time.

also, you haven't made mention of what you're going to do for steering? with a wishbone and no trackbar your axle will travel straight vertically, which means you need either hi-steer (or crossover) with a very flat draglink, or full hydro steering.

[JeepFreak21]

heims absolutely SHOULD be mounted with the bolt verticle for the end of a wishbone. they are much stronger that way.

now that's not to say that is couldn't work with the bolt mounted horizontal, especially if you use a 1" or bigger heim, but if you're building from scratch you might as well do it the right way the first time.

also, you haven't made mention of what you're going to do for steering? with a wishbone and no trackbar your axle will travel straight vertically, which means you need either hi-steer (or crossover) with a very flat draglink, or full hydro steering.


I'm running hi steer and my drag link is pretty darn flat (And I may run a drop pitman arm). I don't plan on doing full hydro for quite a while. I'm convinced that this well create acceptable behavior on-road after reading the "CJ's didn't have trackbars" argument over and over again.
Billy

[MaXJohnson]

You might find that while you can build a wishbone strong enough to control lateral loads, it will still have enough "give" to contribute to mushing steering feel.

I suspect this is one of the reasons Beezil and OneTon run hydro steer.

[vintagespeed]

Some of the questions I have are:
-With a heim at the axle end of the wishbone, can/do the threads on the heim provide the vertical movement or does it need an uber complicated bearing like Beezil made?
-Which way should the heim/bushing be mounted?
-Would a RE SuperFlex Joint (or the like) work at the axle end of the wishbone?
-What's the ideal length for the links?
-Would it be possible to mount the wishbone (upper link(s)) to the lower links or would that be defeating the whole purpose?

I went through something similar Freak, I didn't like my 3link + TB and it was basically undriveable at freeway speeds due to DW. If I tweaked the caster/toe & rotated the tires just right it was ok, but I wanted the suspension to be right. I spent a week or so on POR reading & reading until I understood all of the geometry that I THOUGHT I had a grip on, I was wrong in a few ways.

With the unibody & lots of lift you've got problems getting the link angle within an acceptable range. I had to lower my LCAs 2.5" below the frame rail to get my AD (anti dive) axis back & below my CG, this is important if you want the front braking/accelleration lift to be correct, like anything there are compromises.

The other factor about my suspension that I didn't like was body roll, with the TB you have 2 roll axises, one at the frame mount & one at the axle mount. This makes your rig roll harder to one side than the other & just generally sucks on coilovers & 12" lift. With the new wishbone mounted 7" above the axletube I have raised my roll axis to a point where it's just below my CG, body roll is much much improved and it's now balanced side to side.

Link separation is something you need to consider. If you're running larger tires you'll want more link separation to give the links the leverage they need to withstand hi-torque situations, this was another factor in dropping my LCAs below the frame & raising the center link mount. I have about 8.5" of link separation at the axle and 6.5" of link separation at the frame, I'm running 38.5s.

My links are 26.5" long (ctr - ctr), no magic number really. I moved the front axle forward about 1", which didn't change any clearances really because I also flattened my link angles and increased the arm length which keeps the axle from moving very far forward during articulation. Even with the wheelbase stretched this amount, my tires dont get any closer to the front bumper than they did before.

I kept the LCAs I was using previously & just tapped one end for a 4" long 1" dia bolt. I welded the JJs I cut off onto the end of the bolt to stretch the arm length & make it adjustable. (Similar ends to the Currie pre-fab ends)

I butchered the UCA I was using before & used one of it's JJs for my wishbone center link. The JJ has 23deg of movement and is plenty for dropping the axle to the limits of the 14" coilovers. I do have a center limit strap that I'll be mounting soon that will keep the axle from dropping anymore than 3" below ride height (at the center anyway). I used a center mounted JJ because I wanted to keep my wishbone simple & tight to the oilpan. I didn't want to move my axle forward a great deal or mount the wishbone ahead of the axle because this would affect arm length & geometry and my LCAs were already built. I currently have less than 2deg of caster change throughout the range of travel, this is good because I wanted to drive it on the freeway occassionallly.

One thing to consider when debating full hydro is the strain you remove from the upper wishbone. My cylinder is mounted directly to the axle so when I turn there is virtually no stress on the UCA at all, it's all pushed through the T/R into the axle. All the wishbone has to do is keep the body over the axle, that's it, no steering stress anymore. This is a big plus with big rubber. Just sucks that I had already welded in an ORGS SBS2 into my framerails......oh well, made a nice steering valve mount! :)

Sorry for the long reply but I thought you might want to hear my decisions & why. I'd use the joints you already have, Richard Burrow (FullSizeXJ) is runnnig a rear triangulated 3 link with a SuperFlex joint & he gets full travel out of his 16" SAWs, that's how I knew my 14s wouldn't be a big deal.

Here's pics of my 3link front completed:

http://www.ofoto.com/I.jsp?c=7ha7rx...n&x=0&y=-y9utwh

Here's the build pics of the 3link:

http://www.ofoto.com/I.jsp?c=7ha7rxr.8zze49dz&x=0&y=iejoin

Hope that helps, I'm very happy with my setup, it works great, flexes good & is driveable again. I just drove 200 miles to JV & back for my wedding and aside from the tire wobble from the 38.5" x 14.5" TSL SXs & beadlocks, all was well. No more DW.

-jb

[Redcbr007]

are your C/O dual rate? If so, what spring rates are you using? 500/300?


-Red

[JeepFreak21]

...
Sorry for the long reply but I thought you might want to hear my decisions & why....
Hope that helps, I'm very happy with my setup, it works great, flexes good & is driveable again. I just drove 200 miles to JV & back for my wedding and aside from the tire wobble from the 38.5" x 14.5" TSL SXs & beadlocks, all was well. No more DW.

-jb

Thanks a lot for such a complete response man! That's really insightfully. The reason I don't want to do full hydro at the moment is because it kinda scares me for street driving. I don't want to have to trailer this thing to the 'Con and elsewhere! After making that drive to JV, how do you feel about that? Is it not as bad as the rumors?
Thanks,
Billy

EDIT: Looks perty damn good Vintage! Do you have any pics of the chassis side wishbone mount? It looks like it's inboard of the pseudo frame rails right at the point where it goes up for the front wheel wells?

[vintagespeed]

are your C/O dual rate? If so, what spring rates are you using? 500/300?


-Red

Yes, there's 2 coils which actually equal 1 progressive rate but most refer to this setup as dual rate.

500/300 would be pre-runner coil rates, I wanted soft & driveable for flex. If your coils are too stiff they wont flex, the back will do all the work. You have to think "balance".

-jb

[vintagespeed]

... Is it not as bad as the rumors?

No, it's defintely NOT as bad as the rumors. It's a little faster than I'd like but you can have that adjusted or order a steering valve with more appropriate turn speed.

I have 2 kids & I didn't feel weird about driving it long highway miles with them onboard.

Would I daily drive it this way? Not if I had a long commute, but it really doesn't feel any different than stock steering. The only issue I have is that after driving for a while the steering wheel will slowly move around & wont be where it was when you left, the cylinder doesn't change it's volume but I think that the steering valve allows some fluid to leak from side to side thus changing where the steering wheel is in relation to the cylinder. Like I said it's minor & doesn't cause any ill effects.

The manual steering is a bit better than stock. It's the best steering I've ever had.

-jb

[Beezil]

I suspect this is one of the reasons Beezil and OneTon run hydro steer.nope......was NEVER a reason....I know I'll never be able to get you to believe this, but my front suspension has way less give than a front leaf sprung vehicle...

ask anyone who has ever seen my rig "righted" if when the weight of the entire vehicle was side-loading the links, if they ever noticed the slightest give....

I've tested JUST the wishbone when it is disconnected from the axle....

using a pony 3/4" pipe clamp, I can't deflect the arm at all.

http://www.quartersawn.net/images/wishbone60.JPG
I went to hydro steer for one reason only.....to be able to steer big tires in the rocks.

http://www.quartersawn.net/images/wishbone61.JPG

http://www.quartersawn.net/images/wishbone62.JPG

[JeepFreak21]

No, it's defintely NOT as bad as the rumors. It's a little faster than I'd like but you can have that adjusted or order a steering valve with more appropriate turn speed.

I have 2 kids & I didn't feel weird about driving it long highway miles with them onboard.

Would I daily drive it this way? Not if I had a long commute, but it really doesn't feel any different than stock steering. The only issue I have is that after driving for a while the steering wheel will slowly move around & wont be where it was when you left, the cylinder doesn't change it's volume but I think that the steering valve allows some fluid to leak from side to side thus changing where the steering wheel is in relation to the cylinder. Like I said it's minor & doesn't cause any ill effects.

The manual steering is a bit better than stock. It's the best steering I've ever had.

-jb


That's really good to hear. Just for the record, what setup did you use for your hydro?
Billy

[JeepFreak21]

heims absolutely SHOULD be mounted with the bolt verticle for the end of a wishbone. they are much stronger that way.

now that's not to say that is couldn't work with the bolt mounted horizontal, especially if you use a 1" or bigger heim, but if you're building from scratch you might as well do it the right way the first time.


So, what if it's not a heim at the end of the wishbone? Beezil's first bushing was mounted with the bolt horizontal and I believe whatever it is he's using now is also mounted with the bolt horizontal.


I don't mean to keep using Beez as an example of the perfect setup, but his setup is the one I have pictures of for comparison... if I wanted to just copy his (or someone else's) junk, I wouldn't have opened this topic up for discussion.

Billy

[vintagespeed]

That's really good to hear. Just for the record, what setup did you use for your hydro?
Billy

I ordered the steering valve & reservoir/filter from Sean (Station) @ www.performanceoff-road.com. It's a Danfoss valve. $475.

The lines are build yourself Goodyear lines and the cylinder is a Chief 2x8x1.125 model I got from Surplus Center. $60.

-jb

[vintagespeed]

I don't mean to keep using Beez as an example of the perfect setup, but his setup is the one I have pictures of for comparison... if I wanted to just copy his (or someone else's) junk, I wouldn't have opened this topic up for discussion.

Billy

I liked Beez's setup except for the heims & the complex center link. Yes it'll give 360 deg. of rotation but it's long & it looks like the axle was moved forward a bit to compensate. I was originally going to mount a JJ with the bolt horizontally mounted and I didn't because I thought that sideloading may be an issue with the JJ. As it turns out, the sideloading isn't as big of an issue as I made it out to be.

-jb

[Beezil]

it looks like the axle was moved forward a bit to compensate.
102" of wheel base my man.

[JeepFreak21]

OK guys, anybody have any input on the ideal length for the upper wishbone?
Billy

[Willis]

So, what if it's not a heim at the end of the wishbone? Beezil's first bushing was mounted with the bolt horizontal and I believe whatever it is he's using now is also mounted with the bolt horizontal.
Billy

Pretty much any other joint you can mount with the bolt horizontally. For the Heim, you'd want the bolt mounted vertically because of the side loads. The balls of Heims are pressed into the bodys and with a horizontally mounted bolt, you are putting a lot of side load on the same plane the balls are pressed in. If you lay the Heims down (vertical bolt), the side loads are in the same plane as the front/rear loads, pushing the ball against the sides of the body. You can still do double sheer with a vertical bolt, you just make a pocket for the joint to slide into.

Steve

[sintax]

JB:

Any pics of your shock hoops?

I am really digging how you set everything up. I can't wait to take a look at it in person. I may have to steal some of your design ideas.

-Scott

[JeepFreak21]

OK guys, anybody have any input on the ideal length for the upper wishbone?
Billy


Nobody? Anybody have any good book recommendations? This aspect is somewhat vital.
Thanks,
Billy

[Willis]

Most books that cover the subject are race car chassis books, so you have to get a basic understanding from it, then convert it to a 4wd application. They also usually deal with independant front. How many race cars you know of with solid front axles? I wish there was a 4x4 specific chassis/suspension book.

If you do want to do some reading, Chassis Engineering by Herb Adams, Fundamental of Vehicle Dynamics by Thomas D. Gillespie, and Race Car Dynamics by Milliken and Milliken.

I have mine all drawn out for what I have planned with a parabolic upper. What I end up with is a 27" lower, and a 21.75" upper. I want some pinion change built in, and I get a total of 12* of change from full compression to full droop. I end up with about 70% anti-dive at 7" of lift. The more lift, the higher that number will go.

Have you read this?
http://www.naxja.org/forum/showthread.php?t=15764&

There's a lot of good tech others have supplied, they got me on the right track and really cleared some things up for me.

Steve

[vintagespeed]

Nobody? Anybody have any good book recommendations? This aspect is somewhat vital.
Thanks,
Billy

It's all going to depend on your mounting location for the frame ends. You really can't throw out a 'standard' dimension. You COULD (theoretically) mount the wishbone & LCAs at the center of the frame, making them somewhere around 4ft long.

The longer your links, the better your angles but the weaker the link is.

-jb

[vintagespeed]

Most books that cover the subject are race car chassis books, so you have to get a basic understanding from it, then convert it to a 4wd application. They also usually deal with independant front. How many race cars you know of with solid front axles? I wish there was a 4x4 specific chassis/suspension book.

If you do want to do some reading, Chassis Engineering by Herb Adams, Fundamental of Vehicle Dynamics by Thomas D. Gillespie, and Race Car Dynamics by Milliken and Milliken.

I have mine all drawn out for what I have planned with a parabolic upper. What I end up with is a 27" lower, and a 21.75" upper. I want some pinion change built in, and I get a total of 12* of change from full compression to full droop. I end up with about 70% anti-dive at 7" of lift. The more lift, the higher that number will go.

Have you read this?
http://www.naxja.org/forum/showthread.php?t=15764&

There's a lot of good tech others have supplied, they got me on the right track and really cleared some things up for me.

Steve

Yeah, I wish I'd read some good suspension books. I gleamed what I could from POR & my first setup was "trial & error".

Are you sure you want 12deg of pinion/caster change? Why? The pinion will be pointing away from the tcase at full droop making your driveline angles worse. Or am I missing it?

-jb

[Willis]

Are you sure you want 12deg of pinion/caster change? Why? The pinion will be pointing away from the tcase at full droop making your driveline angles worse. Or am I missing it?

-jb

At droop, the pinion rotates upward 6*, at compression, the pinion rotates down 6*. I will have my axle set up with about 12* of pinion angle. I want it to rotate down some at compression. One drawing I had, had the pinion angle not changing at all. So I played with link lengths and mounting points a bit.

Steve

[JeepFreak21]

Most books that cover the subject are race car chassis books, so you have to get a basic understanding from it, then convert it to a 4wd application. They also usually deal with independant front. How many race cars you know of with solid front axles? I wish there was a 4x4 specific chassis/suspension book.

If you do want to do some reading, Chassis Engineering by Herb Adams, Fundamental of Vehicle Dynamics by Thomas D. Gillespie, and Race Car Dynamics by Milliken and Milliken.

I have mine all drawn out for what I have planned with a parabolic upper. What I end up with is a 27" lower, and a 21.75" upper. I want some pinion change built in, and I get a total of 12* of change from full compression to full droop. I end up with about 70% anti-dive at 7" of lift. The more lift, the higher that number will go.

Have you read this?
http://www.naxja.org/forum/showthread.php?t=15764&

There's a lot of good tech others have supplied, they got me on the right track and really cleared some things up for me.

Steve

Yeah, I've read over that thread about 4 times now. Thanks for the numbers, at least that gives me a starting point.
Billy

[JeepFreak21]

It's all going to depend on your mounting location for the frame ends. You really can't throw out a 'standard' dimension. You COULD (theoretically) mount the wishbone & LCAs at the center of the frame, making them somewhere around 4ft long.

The longer your links, the better your angles but the weaker the link is.

-jb


I was asking because I know when researching 4 link rears, it's more important to get the length and angles and then make them fit (ie. cut the floorboards to get the mounts high enough), so I assumed that would be the approach for this also.
Thanks for the help,
Billy

[vintagespeed]

I was asking because I know when researching 4 link rears, it's more important to get the length and angles and then make them fit (ie. cut the floorboards to get the mounts high enough), so I assumed that would be the approach for this also.
Thanks for the help,
Billy

You could also lower the LCA mounts, it's about proper link separation not necessarily about cutting up the floor. :)

-jb

[vintagespeed]

At droop, the pinion rotates upward 6*, at compression, the pinion rotates down 6*. I will have my axle set up with about 12* of pinion angle. I want it to rotate down some at compression. One drawing I had, had the pinion angle not changing at all. So I played with link lengths and mounting points a bit.

Steve

I'd like to see the drawings if you have them in digital format. Just curious about your link mounting distances.

In most of my research for this & the last project I played with link lengths alot too. The original plan was to mount the wishbone & the LCAs at the same level inside the frame but there just isn't enough room & I didn't want to experiment any more with this build.

Another factor to consider in link setup is the axle mount locations. You never want your links to have a point in travel where all the axises line up.
It's kind of difficult to explain but when all the pivot points line up with axle center your link does nothing to control torque.

"O" is the axletube when viewed from the side, sorry for my crappy drawing.

O
.+===========+ - when the axle torques this arm will resist it.

O+===========+ - when the axle torques, this arm will do nothing.

If you follow the drawing, you'll see that in the second example the control arm will have no leverage over the axle torque and will depend on the other link (upper most likely) to control ALL of the torque load. This could overwhelm your design if you dont plan it in from the beginning.

In the first example the control arm can resist the torque generated at the axle center because it is mounted below & behind axle center. This means that the axle would have to move far upward in it's arc, outside of it's practical limits, for all the pivots to line up. It will always maintain torque control over the axle.

Hope that helps a little bit in your design.

-jb

[JeepFreak21]

I'd like to see the drawings if you have them in digital format. Just curious about your link mounting distances.

In most of my research for this & the last project I played with link lengths alot too. The original plan was to mount the wishbone & the LCAs at the same level inside the frame but there just isn't enough room & I didn't want to experiment any more with this build.

Another factor to consider in link setup is the axle mount locations. You never want your links to have a point in travel where all the axises line up.
It's kind of difficult to explain but when all the pivot points line up with axle center your link does nothing to control torque.

"O" is the axletube when viewed from the side, sorry for my crappy drawing.

O
.+===========+ - when the axle torques this arm will resist it.

O+===========+ - when the axle torques, this arm will do nothing.

If you follow the drawing, you'll see that in the second example the control arm will have no leverage over the axle torque and will depend on the other link (upper most likely) to control ALL of the torque load. This could overwhelm your design if you dont plan it in from the beginning.

In the first example the control arm can resist the torque generated at the axle center because it is mounted below & behind axle center. This means that the axle would have to move far upward in it's arc, outside of it's practical limits, for all the pivots to line up. It will always maintain torque control over the axle.

Hope that helps a little bit in your design.

-jb


Yeah, I'd love to see some drawing also. And thanks for the insight Vintage!
Billy

[JeepFreak21]

Yeah, I wish I'd read some good suspension books. I gleamed what I could from POR & my first setup was "trial & error".

Are you sure you want 12deg of pinion/caster change? Why? The pinion will be pointing away from the tcase at full droop making your driveline angles worse. Or am I missing it?

-jb


Hey, I was looking through the most recient JP Mag and noticed that they put out a book called "How to Modify you Jeep Suspension and Chassis for Off Road". Anybody read this? I'm thinking it may be helpful.
Billy

[JeepFreak21]

I keep looking at this picture of Matt's wishbone setup, and I can't figure out how his pinion doesn't end up pointing at the ground during droop. Anybody wanna help me understand this?
http://www.xjdb.com/albums/xjs/new_lowers3040.jpg
Thanks,
Billy

[vintagespeed]

I keep looking at this picture of Matt's wishbone setup, and I can't figure out how his pinion doesn't end up pointing at the ground during droop. Anybody wanna help me understand this?
Thanks,
Billy

Not to bag on this setup too much, but I doubt that proper geometry was a part of the equation.

Isn't that the 3link that folded during breaking?

-jb

[Beezil]

Hey, I was looking through the most recient JP Mag and noticed that they put out a book called "How to Modify you Jeep Suspension and Chassis for Off Road". Anybody read this? I'm thinking it may be helpful.
Billy

I have it.

total waste of money.

if you want, I'll post pictures of me setting that book on fire to help illustrate how useless i think this book is.

anything JP publishes sux.....

cancel your subscription today.....

[JeepFreak21]

I have it.

total waste of money.

if you want, I'll post pictures of me setting that book on fire to help illustrate how useless i think this book is.

anything JP publishes sux.....

cancel your subscription today.....

:laugh2: Well, you just saved me $15. Thanks!
Billy

[JeepFreak21]

OK, did some more research which of course equals more questions...
I drew out some very basic designs so that I could get the concept of the archs made during articulation and the only way I could get the pinion to stay pointed at the t-case during articulation was to make the upper and lower arms the same lenth and have them mount right next to each other on the frame side. I noticed this is close to what Beezil has, but not what VintageSpeed and others have done. I would think that mounting the arms (that are the same length) at the same height on the frame, would create quite a bit of antidrive. Am I incorrect or does Beez just not care cuz his rig never sees the street? Anybody have any basic drawings to help me understand?
Thanks,
Billy

[Beezil]

my rig is not a street rig, however, its road manners are very kind.....it does not dive too much during heavy braking.

[JeepFreak21]

my rig is not a street rig, however, its road manners are very kind.....it does not dive too much during heavy braking.


Then what is effected by having 6" vertical seperation at the frame compared to none? It's gotta have some effects, right?
Billy

[Beezil]

Then what is effected by having 6" vertical seperation at the frame compared to none? It's gotta have some effects, right?
Billy

I have about 7 1/2" of vertical sepration at the axle, and about 4-ish at the frame end.....

designing the front became more of a challenge of fitment more than anything else.....I worked harder on just getting links to work with the constraints of the cherokee front end more than trying to mess around dialing in anti-dive and roll axis and that sort of thing......I worried about all that stuff when I went to design the rear......less junk in the way.

just keep researching, clicking on links, and reading......plenty of good por discussion, but you'll have to identify who the spobi-spewing idiots are....go into it slowly and carefully, and once you start, just go with your instincts and gut feelings.....

[JeepFreak21]

designing the front became more of a challenge of fitment more than anything else.....I worked harder on just getting links to work with the constraints of the cherokee front end more than trying to mess around dialing in anti-dive and roll axis and that sort of thing......I worried about all that stuff when I went to design the rear......less junk in the way.


That's exactly how I planned to go into it, but I've been stranded away from the jeep and stuck in the house for about a week now, so I'm stuck reading discussions instead of laying under the jeep to see what might work.
Thanks!
Billy

[Beezil]

try playing with string....

tie-off some lines between various points.

this will help you SEE the relationships better......beats paper.

[vintagespeed]

As Beez said, mock up a model it's a good start.

As for the anti-dive. If you're not running alot of lift (like 10") it probably wont be too much of a factor, the higher you are the more sketchy it will be.

Having your frame end links at the same height will make the suspension (AD wise) much like a radius arm setup. The links will be pulling/pushing at the same vertical plane.

If you want it to work & drive closer to stock then make your link positions closer to stock separation. The factory built in alot of link separation for a reason and the closer you are to that the more drivable it will be.

My link separation at the axle is a little more than Beez's but I only did that cause I'm running 38.5s and it was recommended to get closer to 8" with 38s.

-jb

[JeepFreak21]

I'm wondering if we can get Goatman's opinion (I know it's hard to pry out of him :laugh: ) along with everyone else on incorporating a wishbone upper to mid arm length lowers... maybe even mounted where Goat mounted his. I think I'll page him :D
Billy

[Goatman]

I'm wondering if we can get Goatman's opinion (I know it's hard to pry out of him :laugh: ) along with everyone else on incorporating a wishbone upper to mid arm length lowers... maybe even mounted where Goat mounted his. I think I'll page him :D
Billy

Oh my gawd, you want to drag my sorry ass into this discussion? I'm not much on all the book learnin' stuff, and I hardly ever wheel my rig......... :)

Now you made me read this whole thread and I've been staying away from it. :) To answer your question in PM, my lowers are 19.5" long. My upper is 16.5" long, and I have 7" of seperation between the lowers and uppers on both the axle and frame. I know it's not a part of this discussion, but FWIW, my track bar frame mount is 7.5" above the axle tube centerline, and the frame mount is 6" below the frame. The track bar is mounted just slightly higher than the upper arm on the axle. If I understand this stuff correctly, this gives me a better roll axis in the front.......and the blocks and flat springs give me a better roll axis in the back.........ahhh, didn't mean to get off the subject. :spin3: :)

I don't see that particular link design makes any difference to link length. In other words, you get generally the same characteristics from a longer or shorter arm regardless of the specific link design. I do believe you want your upper and lower links to be close to the same length. I hate to see that pic you posted of the triangulated 3 link with the wishbone upper, that design is so far from ideal that it's a shame for anyone to see it. The length of my arms is the result of where I wanted the mounts to be, considering the space I had to work with on the upper, and ground clearance on the lowers. I would like my upper arm to be an inch or two longer (or an inch lower which can't be done), but we live and learn. Getting the pinion to point where we want it to throughout the suspension cycle is something to plan for.

Back to the track bar for just a moment. If some thought is given to the track bar positioning, there just isn't anything negative about running one. It sure makes link design easier. I know Jim had problems, but he has bigger tires and more lift, and he's willing to drive on the street with hydro steering. A wishbone upper verses a track bar is purely owner preference......I don't see any performance advantage.

[Willis]

Yeah, I'd love to see some drawing also. And thanks for the insight Vintage!
Billy

Sorry, I don't have any digital drawings, nor do I have a scanner. My lowers mount between the stock LCA mounts and the x-member. I have it drawn so the LCA bolt is acutally mounted right at the bottom of the framerail. The upper is mounted behind and under the stock UCA mount by probably an inch(maybe more?). The upper I have tried to keep pretty parallel with the ground(about 5*), and it's axle mount is probably about an inch in front of the vertical axle center line. I have about 7" of separation at the axle and 3" at the body, but this may change when I build it. I have my drawing drawn with the front axle pushed forward about 1".

If you end up with shorter links, don't worry about it, Goatman has had great sucess with his mid arm setup, and to tell you the truth, mine will probably change many times before I actually build it (cause who knows how accurate my drawing is).

Steve

[JeepFreak21]

Sorry, I don't have any digital drawings, nor do I have a scanner. My lowers mount between the stock LCA mounts and the x-member. I have it drawn so the LCA bolt is acutally mounted right at the bottom of the framerail. The upper is mounted behind and under the stock UCA mount by probably an inch(maybe more?). The upper I have tried to keep pretty parallel with the ground(about 5*), and it's axle mount is probably about an inch in front of the vertical axle center line. I have about 7" of separation at the axle and 3" at the body, but this may change when I build it. I have my drawing drawn with the front axle pushed forward about 1".

If you end up with shorter links, don't worry about it, Goatman has had great sucess with his mid arm setup, and to tell you the truth, mine will probably change many times before I actually build it (cause who knows how accurate my drawing is).

Steve


Do you have any idea what length that makes your arms? And what degree the lowers sit at? I'm assuming the lowers will be inboard of the unibody rails, but do you know about how much?
Thanks,
Billy

[Willis]

Do you have any idea what length that makes your arms? And what degree the lowers sit at? I'm assuming the lowers will be inboard of the unibody rails, but do you know about how much?
Thanks,
Billy

It puts my lowers at about 17*. I plan on having about 7" of lift. The lowers will be mounted just in board of the frame. I have seen a couple cool ideas where the LCAs were mounted in a pocket "in" the framerail. May be more trouble than it's worth though. I have the LCAs drawn at 27" and UCAs at about 22". I may make my lowers shorter, but that will make them steeper.

After really playing with Anti-dive number, angles, percentages, etc, it seems like it's really not as important in the front as the rear.

Steve

[Ed A. Stevens]

With the unibody & lots of lift you've got problems getting the link angle within an acceptable range. I had to lower my LCAs 2.5" below the frame rail to get my AD (anti dive) axis back & below my CG, this is important if you want the front braking/accelleration lift to be correct, like anything there are compromises.

The other factor about my suspension that I didn't like was body roll, with the TB you have 2 roll axises, one at the frame mount & one at the axle mount. This makes your rig roll harder to one side than the other & just generally sucks on coilovers & 12" lift. With the new wishbone mounted 7" above the axletube I have raised my roll axis to a point where it's just below my CG, body roll is much much improved and it's now balanced side to side.

-jb


I have been too busy lately to read many threads, this one included, but jb has identified two issues that are often missed: the location of the IC in relation to the CG (it must be on the opposite side of the CG from the controlled axle), and assuring a predictable height for the roll axis (the goal of a level track bar, and a three link advantage with long travel).

I don't know how much PORing it took for you to find guidance on these two small issues, but I gave up trying to get across the reasoning for considering how these impact handling (the ususal POR bs filter was not effective on these issues). Good work.