Suspension travel upgrades on an 80

[T Y L E R]

I'm interested in gathering your thoughts on modifying an 80's setup so you've got more suspension travel when you're done. It would be interesting to see everything laid out here from the simplest solutions, all the way to things like long play shocks, relocated mounts, and cutting sheet metal.....or 3 link etc etc.


What have you guys done so far to accomplish this task? Or perhaps .. what are you 'planning' on modifying to achieve this end?






TY

 

[Nay]

You don't need to modify the rear suspension design at all. It is a five link and will perform well for you - the panhard will tend to bind a bit at the extreme ends of travel on one side, but that is nothing you will notice. For more extreme travel, adding johnny joints (spherical ball joints enclosed in a housing) to one end of the control arms is a good idea. MAF sells this type of arm.

You will need to fab up a disconnect for the swaybars. Johnny joints or a heim style panhard would also prevent any bushing movement in the panhards (better control!) while allowing unrestricted motion, at least from a bushing perspective...the 5 links will ultimately bind no matter what bushings you use.

For the front end, a three link is the way to go. You could create a four link for extra beef, but you'd need to use larger rubber bushings on one end to allow for proper bushing deflection, and that would add slop to your front end that I think you would detest. This may sound contrary to good sense, but try to shorten the arms to around 20-22" for a mid arm length. Long arms are an enormous compromise to clearance. At 4" of lift with raised axle mounts, you can go with a shorter arm and retain excellent angles. If this type of project is meant for real use, you need to think about every millimeter of clearance you can gain at every point. This is why drop bracket kits are absolute sh*t. Don't ever drop your frame mounts - raise your axle mounts instead to achieve the exact same effect but with dramatically improved clearance instead of dramatically worsened clearance.

On the three link, you just need DOM and then use johnny joints for all of the link ends. Because there is no bind on a three link, you don't need to design for bushing deflection and can use solid joints (think excellent stability and control here). The single upper link mount can sit on top of the diff. You want about 8" of distance between the lower and upper mounts for proper axle twist control. Keep the lower mounts just below the housing, but tucked up as much as possible.

ActionJackson is posting this exact project on the hardcore corner.

https://forum.ih8mud.com/showthread.php?t=71280

You need to brace that upper link a lot more than he has done so far as it is a single point of failure, but this is your basic design. Extremely simple, excellent flex, low cost, very durable. I'd go for a shorter arm, though, as those angles are excellent and he has something like 7" of lift.

For shocks, you first need to space the travel down from your current setup. Start with these shock mount adapters from MAF:

http://www.man-a-fre.com/pa/4plusshockadapter.htm

Now you have the whole world of eye-to-eye mount shocks available to you, and the travel is spaced down from the body (you lowered the upper mount), which means your meats have better clearance and you aren't losing shock travel to longer bumpstops. I'd guess that a 12" travel shock is perfect for your 4" lift, and I'd go 14" travel for a 6" lift. I have used this type of adapter before, and they work excellently (I hate pin style shock mounts...they tend to wear the bushings excessively). On a 12" travel shock, you are engineering for about 5" up and 7" down, 4" up at a minimum. Those lower adapters also compress the shock...you can use adapters like this to tinker with the static shock compression to fine tune your suspension (or fab a new axle mount that gets it perfect). This is the single issue with out of the box 80 setups - the shocks are set up for way too much up travel and that's why people run small tires for the lift size (35's on 6" of lift is absolutely tiny for what you can accomplish by moving suspension travel away from the body).

You also need swaybar disconnects for the front. That's it and you have some seriously hardcore travel, and those johnny joints are nice for ride stability without being harsh (they basically have a poly bushing inside the housing).

You could take this same approach with a smaller lift like OME 2.5 to space down the shock travel for larger tires while still increasing flex. That would allow 35's on OME, which is what I plan to do in the future. I would want 36's or 37's on the 4" lift with at least 10"-11" of useable travel on all four ends, but then you have to start really worrying about breaking stuff, and I don't personally want to mess with that. A 3 link on OME with spaced down travel allowing long travel on 35's would be absolutely trick.

Make sense?

P.S. - if you want to come all the way back down to Slee's, and they are willing to do the custom work, I'll meet you up there to help design a prototype. Might be some options to tuck the frame mounts up beside the frame rails for ultimate clearance. Not sure if you could ever sell something like this from a liabilty standpoint, though.

Nay

 

[wb1948]

Tyler, whats with the avatar? It has been bothering me for a while.

 

[Nay]

Tyler, whats with the avatar? It has been bothering me for a while.

He's a body builder type. That avatar is kinda like all the models in women's magazines

 

[LXCRSR]

I agree with wb1948, kinda creepy avitar.

 

[Mars]

possibly taking the cake for the fastest thread to go downhill....3 posts in and we can't get off the avatar...ha

 

[davegonz]

That's funny..I've had several different reactions from people that have wandered over to my cube whenever there's a post with Tylers avatar...ranging from people thinking that it's a gay porn site to people thinking it's a body builder site...funny.

 

[Nay]

possibly taking the cake for the fastest thread to go downhill....3 posts in and we can't get off the avatar...ha

Hey, I posted a serious response...this thing may just belong in the hardcore corner and not here....

 

[OGBeno]

I think Ty should try to use the search feature here and in the hardcore section.

This kinda stuff's been gone through over and over again....like everything else I guess.

Action Jackson is one hell of a documentary wrencher. You'd get some good ideas from him Ty.
-o-

 

[firetruck41]

...we can't get off the avatar...

Speak for yourself, I never got on the avatar in the first place.

 

[Nay]

I think Ty should try to use the search feature here and in the hardcore section.

This kinda stuff's been gone through over and over again....like everything else I guess.

Action Jackson is one hell of a documentary wrencher. You'd get some good ideas from him Ty.
-o-

I'd like to see a good conversation on this. It is fairly straightforward how to accomplish the question at hand. But the larger question isn't what to do, but whether you should. Given its large size, and the major limitations that come for hardcore use because of that size, the 80 is by nature a dual purpose rig.

So should the 80's suspension be pursued for major travel gains, or is there an inherent benefit in letting it stay bound up, swaybars and all, even for the offroad use that it is truly suitable for?

Nay

 

[OGBeno]

I'd like to see a good conversation on this. It is fairly straightforward how to accomplish the question at hand. But the larger question isn't what to do, but whether you should. Given its large size, and the major limitations that come for hardcore use because of that size, the 80 is by nature a dual purpose rig.

So should the 80's suspension be pursued for major travel gains, or is there an inherent benefit in letting it stay bound up, swaybars and all, even for the offroad use that it is truly suitable for?

Nay

Just check out Slee's Yellow 80 rock crawler monster rig...

Or, again, Jackson's well-documented build-up of his monster rig...he gives reasons for his design choices, directions on how to do certain things and why, etc.

Not trying to quell a good conversation, but seriously, does Ty need all of that suspension travel for wheeling at Starbie's??

 

[T Y L E R]

Not trying to quell a good conversation, but seriously, does Ty need all of that suspension travel for wheeling at Starbie's??

It's not really about that.

Nay said a few things that honestly haven't sat well with me. In the sense they left me wanting to investigate this further. I'm not looking to go hog wild on my 80. Thats not my intent at all .. what I want to do is just exploit what I have so that I extract every ounce of potential the core of my setup has.

I agree AJ's site is kickass, and I will pour over his notes when I have time to dedicate to really absorbing it all. For now I wanted to learn enough to allow me to fomulate thoughts on what I need to do to take my present setup as far as I can. IOW's leave it be with the exception of tweaking shock mounts and such .. pretty non-invasive stuff.

To look at my 80, no one would see a difference, but if I were to go back to Slees and ramp it with the mud flaps removed, I would like to see much improvement. If changing shock mounts could achieve this, then why not go for it? If I had had more time on my Trip to Golden Co, we would have talked more about this and probably made a few more mods to accomplish this. Everything is a compromise .. I just don't want to sell myself short with this great foundation. If there are simple mods available to recover any droop loss from dropped bumps then I owe it to the 80 to check into them.

You can be damn sure I want to enjoy an 80 that can pose with the best of 'em at my local Starphuks, BUT with this latest evolution, I am hungry to expose the simple shortcomings that can be easily remedied so that once on the trail, or ramp, or a Forester in my parking space, I can climb up them with the knowledge that nothing as simple as mudflaps, plastic bumper caps, or shock mounts are holding me back!

I simply want to take this solid foundation to it fullest potential .. a true Hybrid suspension. Quite acceptable on-road manners, but also ready to flex, and droop at the drop of a dime.



TY

 

[Nay]

Hey, don't listen to me . You have a perfect setup for what you are using it for. I just don't think that this board is fully aware of how little travel is being gained from these much longer springs on lifted applications when the shocks are the same, and how limiting that is from a tire size perspective.

I've seen this before: in the late 90's the Jeep Cherokee market was about the same as the 80's are now. People were just moving beyond OME and 6" lifts were emerging. At that time, conventional wisdom was that you could only fit 32" tires on a 6" lift (tiny wheel wells), much like only fitting 35's on a 6" lifted 80. So 8" lifts became common to run 35's. Then people got smart and figured out that you have to be willing to design your own suspension with various parts and fabrication, and that the best peformance does not come from the most lift (and that this approach is incredibly less expensive than trying to make "bolt-on" really work).

Now you see 37's on 6" of lift on a Cherokee, because the mentality has shifted to designs that absolutely minimize the lift for a certain tire size (and people became willing to hack the sh*t out of the fenders...something you don't need to do on a 80). Tall lifts for the sake of tall lifts was eventually seen as foolish. Putting 315's on a 6" lift is not form following function, it is function following form, 'cause those same tires can be run on a much smaller lift. From that perspective, I've said that I think Slee's 4" kit makes the 6" kit obsolete, simply because the shocks are identical and you can run the same size tires on either.

So what you've done is a major step in the right direction. You kept the lift as small as possible for the tires you want, without having to hack up the rig. Given that you don't offroad, engineering a long travel suspension isn't in your interest, per se. Somewhat restricted flex (and this is a relative statement for sure) is not always bad...seeing it as bad is a hardcore rock crawler's perspective.

I am interested in seeing people think beyond OME without automatically thinking "more lift". What is easy to overlook is that OME designs within what they consider to be stock restrictions (J springs being an exception). It makes absolutely no sense that the stock replacement OME kit uses the same shocks as OME heavy. Why does OME do this? Because in their design parameters, 33's are the largest tire you can run on stock equipment (gears, etc). OME is designed to let you go up one tire category with nothing but springs and shocks, so even though you can run 33's stock, that's all OME designs for on a 2.5" lift. A 2.5" lift should fit 35's (with perhaps a bit of extra tinkering), but you have to be designing with that intention, and OME is not going to design in a way that forces you to do gears.

Tinkering with shock travel and suspension design should only accompany a serious goal on the other end: again, form following function. If you really want to turn an 80 into a very hardcore rock crawling machine, then you really do need to engineer a suspension to allow a lot more down travel than you will get with 11" travel shocks mounted in the stock position and front radius arms with tiny little bushings. And you need that travel spaced away from the body to allow the real meats.

And once you do all of that, you'll probably start looking back at when your rig was a lot simpler and just looked good and performed nicely in all situations, wondering why you spent so much time and energy doing something you didn't really need. Just ask NW Sickboy, who is having builder regrets as we speak, and he did it all right in a big way (redesigned front end, trimmed frame for bumper clearance, etc)

I'd LOVE more lift and all of that, but I'm committed to staying as low and simple as possible this time around, and doing my own work for the bigger tires. It's hard to resist, though, hard to resist...

Nay

 

[Walking Eagle]

If this type of project is meant for real use, you need to think about every millimeter of clearance you can gain at every point. This is why drop bracket kits are absolute sh*t. Don't ever drop your frame mounts - raise your axle mounts instead to achieve the exact same effect but with dramatically improved clearance instead of dramatically worsened clearance.

Wrong. The path the tire moves with a radius arm is going to be determined by the arc from the center of the tire to the mounting point of the arms. This isn't changed with caster plates, caster bushings, or raising your axle mounts. When you move the frame mounts, then you move the motion of the axle/tire relative to the frame. So it's not "the exact same effect".

Depending on how you raise the axle mounts, you can also create a bunch more leverage on the suspension. In the front, if you flip the arms, the center of the axle is still the same distance from the arm (more or less), it's just on top rather than on bottom. But in the back, if you start raising the mounts on the axle, it's going to get more leverage for bending the links.

I'll agree that if every millimeter of clearance is that important to you, then drop brackets aren't the right choice for you. But everything else in what I quoted is wrong.

 

[agomez]

I think Ty should try to use the search feature here and in the hardcore section.

This kinda stuff's been gone through over and over again....like everything else I guess.

Action Jackson is one hell of a documentary wrencher. You'd get some good ideas from him Ty.
-o-

Search hound police?

 

[Nay]

Wrong. The path the tire moves with a radius arm is going to be determined by the arc from the center of the tire to the mounting point of the arms. This isn't changed with caster plates, caster bushings, or raising your axle mounts. When you move the frame mounts, then you move the motion of the axle/tire relative to the frame. So it's not "the exact same effect".

Depending on how you raise the axle mounts, you can also create a bunch more leverage on the suspension. In the front, if you flip the arms, the center of the axle is still the same distance from the arm (more or less), it's just on top rather than on bottom. But in the back, if you start raising the mounts on the axle, it's going to get more leverage for bending the links.

I'll agree that if every millimeter of clearance is that important to you, then drop brackets aren't the right choice for you. But everything else in what I quoted is wrong.

Ok, it is not exact, but the effect is essentially the same if you achieve an equal static height arm angle (and I have done both on another vehicle). I'm not talking about flipping the arms - I wouldn't touch anything like that. Just don't leave them hanging way underneath the axle...there is clearance to be gained over the stock arm, which has to run under the tube.

I will change the leverage on a particular tube long before I will increase the length of the leverage arm on a frame mount. You can overbuild your arms and the mounts they attach to. It is more difficult to strengthen frame material around a drop bracket. Both sides have problems, but if you need the lift, and you need the flex, then reducing clearance is p*****g in the wind

Nay

 

[Walking Eagle]

Ok, it is not exact, but the effect is essentially the same if you achieve an equal static height arm angle (and I have done both on another vehicle).

No, the effect is not essentially the same. Raising the brackets on the axle will give put the suspension travel into a diffent part of the arc than dropping the brackets on the frame. You get more front to back motion.

 

[Walking Eagle]

Been thinking about this a bit, and I don’t think what TY is trying to accomplish is unreasonable - he just wants to make sure there isn’t any untapped potential that can be easily tapped.

Let’s go back to the basics –

What determines ride height?

The springs and the weight of the vehicle (accessories) is pretty much it. There are some other factors, but they’re small enough to ignore for the most part.

What can stop the upward travel of the axle/tire?
1. Bump stops
2. Fully compressed shock
3. Tire making contact

Which do you actually want to stop the upward travel?

The bump stops. Fully compressed shocks, unless they have internal bump stops will damage the shocks, and possibly the shock mounts as they aren’t designed for these loads. Tire making contact is the big thing we’re trying to avoid with lifts in the first place.

What can stop the downward travel of the axle/tire?
1. Fully extended shocks
2. Limiting straps
3. Binding of suspension
4. Binding of swaybars
5. Too Short brake lines

We’ll assume the proper length brake lines are on, and that the swaybars are disconnected. When I was more into Baja Bugs I know over extending shocks was an issue. I don’t know if that was more of an issue because of the speed at which the suspension was cycling? Anyway, it can be argued I guess, but for this post I’ll just assume that the suspension is not going to bind before the shock fully extends and that at slow speed it’s probably ok to let the shock fully extend? This is the one I’m most unsure of.

So, looking at this, how do you go about building your suspension? Usually it starts with tire size it seems. Let’s assume you’ve already decided on what you’re doing about caster correction and installed that – cause if you use longer arms to correct, or plates, or bushings, or droop brackets will determine where your arc ends up. For this example, we’ll say you’re starting with 36” tires. You put the tires on and with no springs on, you let it go down till it hits something. You either trim that something or you decide that is going to be full compression. Now you set up your bump stops to ½” or so above that level – the extra ½” is to let the bump stop compress. Eye to eye on the shock mounts is measured at this point, and that’s the maximum compressed length shock you can run. You can run shocks with shorter compressed length shocks, but all the travel from the compressed eye to eye distance to the compressed shock length is wasted. Ex. If eye to eye is 19” and compressed length on the shocks is 17.5” you’re not using 1.5” of that shocks potential. I think that’s where TY is with his rear set-up running 3” bump stop drop blocks rather than 2”. There is more travel in the shocks that he’s not using – it’s sub-optimized – he’s leaving performance on the table. Actually Slee’s site it says

"OME850J/OME863J coils and N73L/N74L shocks should be installed together, although they do not comprise a kit. Fitment of N73L/N74L shocks requires mandatory installation of .75" (20mm) Front and 1.25" (30mm) rear bump stop spacers to the front and rear suspension to prevent shock absorbers from bottoming out under full compression. These bump stop spacers are not available from OME and will need to be sourced from the installer."

So, lifts that use L shocks and 2” blocks, leave an extra 1.25” of compression on the front shock, and .75” in the rear.

Now the extension – if you keep the stock shock mounts you are going to be limited to whatever shock you can find with the right compressed length. And you can search, there are those that have more extension for the same amount of compressed length – remote reservoir shocks usually have a better compressed to extended ratio, but it still is a limiting factor. The other solution is to pick the shocks you want with the maximum travel that you think you will want (might as well go for the 15” travel shocks, they’re the same price as 12”), compress them and build your own shock mounts to that length. Then you won’t be limited on suspension droop until the suspension binds, and if you want to go beyond that, into 3 linking the front, and johny jointing this and that, hopefully you’re looking more places for suspension design than just here.

I can see why some have said Slee’s 6” kit has little advantage over the 4” kit if you look at the parts and what you do and don't gain. Slee’s 4&6” kits both use 2” bump stop drop blocks. Which means at full compression, you’ll have the same amount of clearance for tires – assuming you use the same arms on both – the kits are listed with Slee arms on the 6” and caster plates on the 4” – unlike Ty who’s running the arms on 4”. So if there is an advantage in clearance for big tires, it’s in how the arms locate the tire in the wheel well, not in the springs and the amount of lift. Then there is the droop. Both use the same shocks and the same mounting locations on the axle and the frame, the droop is the same. So full compression is the same, full droop is the same – what’s different? The ride height. Which as I said, won’t get you any more clearance for tires, but it will get you approach, break over and departure angles, and it will also get you a higher center of gravity which will make the vehicle more likely to tip. It also trades 2” of extension travel from ride height, for 2” more compression travel. If that doesn’t make sense, think of 0 as fully compressed to bump stops, and 8 as fully extended shocks. Say the 4” system rides at 3. So it has 3” compression travel from ride height, and 5” of droop from ride height. Then you put the 6” springs in, and you ride at 5. You have 5” of compression travel, and only 3” of droop from ride height. The articulation on both should actually be the same. Drivers side will be at 0 and passenger’s side at 8. It will just take more force to get the 6” springs to compress to 0 (spring rates being the same between the 4 & 6, the 6” has two more inches to compress, thus two times the lbf/in spring rate more force). It could be argued about which is better to have, more compression or more extension travel – but I’d say if you looked around at the systems people are running for short course and desert racing as well as for rock crawlers, you’ll find that most run a lot more available extension than compression.

My personal theory is leave at least as much compression travel as stock, and maximize the extension by shock choice and custom shock mounts. But it’s just a paper theory for 80 series – I’ve only done it on my 40 – which rides nice, and flexes well for the minimal lift that is on it.

Anyway, there’s the theory on how to maximize what you can get out of what you have without going nuts with custom links. Think this is a short enough post?

Heath

 

[OGBeno]

Search hound police?

Uh...not at all...just a friendly reminder to an old school member of the forums...

Notice the salute....