Suspension Basics (Primer) -- Call for Input (1 Viewer)

[jaymar]

So, question. Everyone talks about shocks and springs and radius arms and drop brackets (and drop boxes) and caster plates and washer mods and so on and so forth, and that's all good info. But where's the love for everything else? It seems a little like those guys who blast their upper bodies at the gym, and look awesome--but it's all carried on these little toothpick legs. You duck the haymaker, sweep a leg and they're done. Obviously an imperfect analogy; 80 stock parts are hardly toothpicks. But still; you change or beef one thing, and others are affected--sometimes catastrophically.

Yes, there's a ton of very detailed information on specs in the compiled suspension spec thread, here:

Compiled 80 series suspension component spec thread... shocks, coils & more.

80 series coil & shock specs A few years back 80 series suspension was fairly easy to figure out & purchase since there was only a few of options to chose from. Recently there has been a few suppliers stepping up to play in the USA 80 series market offering more options. Now with a plethora of...

forum.ih8mud.com

But that seems largely for the advanced practitioner, so to speak. A title search of this forum shows zero hits on "suspension primer" or "suspension basics." It seems to me that something like that would be useful to those who--like me--have never touched a suspension component. (You remember those days, right?)

So how about some really ground-level information to give those new to this a basic understanding of what happens when you lift the vehicle, the various options for addressing alterations to the stock geometry--and just what the heck is meant by Stage 1, 2, 3, 4, etc.

For example, I'm running on a stock-height OME suspension installed by the PO in 2011, and four blown-out OME shocks (also courtesy the PO). 33" tires and no desire to ever go above 35." I'm about to put in a new suspension with a modest lift, "estimated" at 2 inches. This to handle extra weight more than anything else. Front coils for 110-240 lbs over stock, rear 220-660 over stock. According to the lift kit maker, that means...

• Front Coil Springs
• Rear Coil Springs
• Front Shocks
• Rear Shocks
• Rubber 2° Caster Bushing Kit
• Steering Damper
• Upper Trailing Arms ***
• Lower Trailing Arms ***
• Front Panhard Bar ***
• Rear Panhard Bar ***
• Adjustable Drag Link ***

But the same company also offers a 2" lift kit that does NOT include the items marked with *** above.

So what's the deal here? Do these *** things actually need to be modified, or not? The very fact that there's a kit without them implies they may be optional. (Or perhaps people just plan to pick those parts up somewhere else?) For that matter, do you really need the steering damper?

If they are optional, at what lift height to they become mandatory? How high do you have to be before you need extended brake lines, or a lowered LSPV bracket? Or who-knows-what-else? Does lift affect camber as well as caster? And what's all this about disconnecting sway bars (also called anti-sway bars; how's that for clarity)? What's the problem with 3-links? When do you need double cardan driveshafts? Do you need longer driveshafts? Shorter? Which suspension mods can be dangerous, and under what conditions?

You can see how this might confuse a newcomer. Leave them in suspense, even.

So, for the uninitiated--what do all these things do, and what conditions are they meant to correct or improve? Sure, newbies could go threadhopping for a week (or a year) to find out--but why not put that info here, or link it from here, to make it easy? Also, maybe an at-a-glance checklist to kick things off. What should be looking at doing for a 2" lift? 3" 4" 5" 6" or giraffe-height lift? My limited understanding is that the higher you go, the more unstable and out of whack things get, with cost and complexity hurtling skyward like Apollo. (Or maybe Jeff's c*ck rocket; you get the idea.)

 

[Squeegee]

I think I can handle all the stuff needed for a 2” lift.

So the requirements for lifting your car is very simple. You’ll need springs and shocks. That’s the bare bones necessities. To some degree caster correction is optional, technically you “can” drive the car without it but I ALWAYS recommend using it.

I believe that with a 2”, brake lines should be extended because they probably need to be changed out anyway. Our 80s aren’t spring chickens anymore. I get mine off of rock auto and theirs a thread that has the parts number here on mud.

Since we’re on the topic of brakes, you should raise the lspv, it’s not required but it’s good practice. I just topped out the factory adjustment on mine. Anything more than a 2” lift you should probably get a bracket to extend it further.

With this lift height, in my opinion, things like rear upper and lower control arms are completely unnecessary.

In my opinion, things like adjustable panhards should not be added at any lift because you should be fixing your panhard angle/ centering your axle through other methods. But your panhard angle/ and your axle being centered is not something you have to worry about with a 2” lift.

You mentioned caster angles in your question. Your caster angle can be summed up by how your upper trunion bearing is positioned over your lower trunion bearing. Under stock conditions your upper trunion bearing sits a little behind the lower one, imagine looking at a clock and the upper is at 1 o clock and the lower is a 7 o clock. Caster changes when you lift your car and the upper trunion bearing starts to move toward the front of your car, and the higher you lift it the more it starts to roll the axle, imagine the upper being at 11 o clock and the lower being at 5 o clock.

Caster correction, through caster plates, bushings, radius arms, or the eimkieth RAM, all return the caster so that the upper trunion bearing is behind the lower.

Oh and camber is not affected by lifting your car. You can adjust camber with a solid axle but it’s only with aftermarket parts and you shouldn’t worry about this.

Sway bars. I dropped the front about 2” and drove around, but inevitably just took it off. And I never did anything with the rear, it doesn’t seem to be an issue me with a 2” lift.

3 links. Well 3 links are great when they are designed correctly. Designing them correctly involves a lot of homework, a 3 link calculator, and fabrication skills. If you don’t utilize all 3 of these things, you’re pretty much just guessing at how the suspension will act on and offroad and making a car that performs worse. That’s why people think that 3 links have “problems”, it’s just poor design.

Driveshafts. You don’t really have to worry about them until 3-6” of lift. But all 80s are different, when I had a 4” lift I didn’t have any vibrations, but some people do. Generally, with a 2” lift you can leave your driveshafts alone.

God I hope all of this made sense, it is very late

 

[jaymar]

I think I can handle all the stuff needed for a 2” lift.

So the requirements for lifting your car is very simple. You’ll need springs and shocks. That’s the bare bones necessities. To some degree caster correction is optional, technically you “can” drive the car without it but I ALWAYS recommend using it.

I believe that with a 2”, brake lines should be extended because they probably need to be changed out anyway. Our 80s aren’t spring chickens anymore. I get mine off of rock auto and theirs a thread that has the parts number here on mud.

Since we’re on the topic of brakes, you should raise the lspv, it’s not required but it’s good practice. I just topped out the factory adjustment on mine. Anything more than a 2” lift you should probably get a bracket to extend it further.

With this lift height, in my opinion, things like rear upper and lower control arms are completely unnecessary.

In my opinion, things like adjustable panhards should not be added at any lift because you should be fixing your panhard angle/ centering your axle through other methods. But your panhard angle/ and your axle being centered is not something you have to worry about with a 2” lift.

You mentioned caster angles in your question. Your caster angle can be summed up by how your upper trunion bearing is positioned over your lower trunion bearing. Under stock conditions your upper trunion bearing sits a little behind the lower one, imagine looking at a clock and the upper is at 1 o clock and the lower is a 7 o clock. Caster changes when you lift your car and the upper trunion bearing starts to move toward the front of your car, and the higher you lift it the more it starts to roll the axle, imagine the upper being at 11 o clock and the lower being at 5 o clock.

Caster correction, through caster plates, bushings, radius arms, or the eimkieth RAM, all return the caster so that the upper trunion bearing is behind the lower.

Oh and camber is not affected by lifting your car. You can adjust camber with a solid axle but it’s only with aftermarket parts and you shouldn’t worry about this.

Sway bars. I dropped the front about 2” and drove around, but inevitably just took it off. And I never did anything with the rear, it doesn’t seem to be an issue me with a 2” lift.

3 links. Well 3 links are great when they are designed correctly. Designing them correctly involves a lot of homework, a 3 link calculator, and fabrication skills. If you don’t utilize all 3 of these things, you’re pretty much just guessing at how the suspension will act on and offroad and making a car that performs worse. That’s why people think that 3 links have “problems”, it’s just poor design.

Driveshafts. You don’t really have to worry about them until 3-6” of lift. But all 80s are different, when I had a 4” lift I didn’t have any vibrations, but some people do. Generally, with a 2” lift you can leave your driveshafts alone.

God I hope all of this made sense, it is very late

Thanks for all the info! My brake lines are maybe 4 yrs old; changed those out when I changed the brake assemblies. Never thought about changing the setting on the LSPV with a lift; should I? I was thinking it might need to be physically relocated. Did a little snooping and found the following thread just on this...

LSPV with 2.5" OME - https://forum.ih8mud.com/threads/lspv-with-2-5-ome.66931/

I also find myself wondering if the vehicle is actually going to wind up back around stock height, once loaded up and settled--in which case, the adjustments made to accommodate the increased height might have to be undone...

 

[Malleus]

You asked for the basics, here you go (it's in the Resources section):
T453, Suspension, Steering and Handling

not 80 series, or even Land Cruiser, specific, but it does describe the basics. This is(was) the course Toyota uses (used) to train the service technicians.

 

[Squeegee]

Thanks for all the info! My brake lines are maybe 4 yrs old; changed those out when I changed the brake assemblies. Never thought about changing the setting on the LSPV with a lift; should I? I was thinking it might need to be physically relocated. Did a little snooping and found the following thread just on this...

LSPV with 2.5" OME - https://forum.ih8mud.com/threads/lspv-with-2-5-ome.66931/

I also find myself wondering if the vehicle is actually going to wind up back around stock height, once loaded up and settled--in which case, the adjustments made to accommodate the increased height might have to be undone...

It’s really up to you! By no means is it 100% necessary. I just moved mine up about the same amount that I lifted the 80

 

[gummycarbs]

and just what the heck is meant by Stage 1, 2, 3, 4, etc.

That's pure marketing B.S. Doesn't mean anything.

So what's the deal here? Do these *** things actually need to be modified, or not?

It depends entirely on how *your rig* behaves and what *your standards* are.

Put a "heavy" 2.5" lift on the rear of a light rig and you're going to end up with 3"+. This amplifies the effects of a lift on the rear. Your rear driveshaft u-joint is now operating at the wrong angle. It may make noise or vibration, and it definitely will wear faster.

You might need adjustable upper and/or lower rear control arms. I don't, because I cut and welded mine to get the correct length.

How high do you have to be before you need extended brake lines, or a lowered LSPV bracket?

I don't know about the brake line cutoff, but your LSPV height should be adjusted to compensate for *any* lift you install, if you want optimal braking performance.

Does lift affect camber as well as caster?

No, unless you installed offset trunnion bearings. The Australians apparently do this for some improvement in cornering that may or may not only affect RHD rigs.

You can see how this might confuse a newcomer.

That's why a newcomer should just buy from someone like Slee with expertise in assessing a customer's needs and goals.

I don't like routing people through sales channels, but if you don't already have a solid grasp on all of the subjects you brought up, you can either dive in and spend a lot of time learning (and probably making mistakes), or you can pay for expertise.

 

[jaymar]

That's pure marketing B.S. Doesn't mean anything.



It depends entirely on how *your rig* behaves and what *your standards* are.

Put a "heavy" 2.5" lift on the rear of a light rig and you're going to end up with 3"+. This amplifies the effects of a lift on the rear. Your rear driveshaft u-joint is now operating at the wrong angle. It may make noise or vibration, and it definitely will wear faster.

You might need adjustable upper and/or lower rear control arms. I don't, because I cut and welded mine to get the correct length.



I don't know about the brake line cutoff, but your LSPV height should be adjusted to compensate for *any* lift you install, if you want optimal braking performance.



No, unless you installed offset trunnion bearings. The Australians apparently do this for some improvement in cornering that may or may not only affect RHD rigs.



That's why a newcomer should just buy from someone like Slee with expertise in assessing a customer's needs and goals.

I don't like routing people through sales channels, but if you don't already have a solid grasp on all of the subjects you brought up, you can either dive in and spend a lot of time learning (and probably making mistakes), or you can pay for expertise.

Thanks! Rear will have cargo box, double swingout and spare, along with half the weight of sliders; I was thinking that would prevent excessive lift in rear…

 

[leonard_nemoy]

For a 2" lift start with springs, shocks, and caster correction.

Than go drive it and flex it out good. Check the brake lines while flexed, if they aren't stressed or tearing than don't worry about them, many people run a 2" lift on these rigs with factory brake lines.

If the brakes don't work as well after the lift than consider adjusting or deleting the lsvp. Again many people run a 2" and don't touch the lsvp.

Start basic and add more to fix any issues you find.

 

[jaymar]

How likely is it I'll need extended bump stops with a 2-2.5" lift?

 

[Squeegee]

How likely is it I'll need extended bump stops with a 2-2.5" lift?

It depends on the shocks. I run dobinsons 4” lift shocks with a 2” lift. I had to extend the rear bumps down 1.5” and I left the fronts alone. A shock with a shorter body will require a smaller bump stop extension

 

[jaymar]

It depends on the shocks. I run dobinsons 4” lift shocks with a 2” lift. I had to extend the rear bumps down 1.5” and I left the fronts alone. A shock with a shorter body will require a smaller bump stop extension

How do I figure that out before installation? Sounds like it would depend on shock travel an spring compression, and can't really be calculated beforehand, unless someone else has already done it with the same setup?

 

[Squeegee]

For dobinsons shocks, it’s in the suspension sticky

 

[jaymar]

Any tips on what to check/clean/replace when installing coils, shocks, radius arms, steering damper (and possibly upper/lower trailing arms, both panhards and drag link)? Also--what else seems reasonable to do 'while down there?'

Basically, I don't want to look at it again for a very long time, so better to do whatever now.

 

[Squeegee]

Any tips on what to check/clean/replace when installing coils, shocks, radius arms, steering damper (and possibly upper/lower trailing arms, both panhards and drag link)? Also--what else seems reasonable to do 'while down there?'

Basically, I don't want to look at it again for a very long time, so better to do whatever now.

Probably just bushing There’s not much down there

 

[robnicko]

Thanks for all the info! My brake lines are maybe 4 yrs old; changed those out when I changed the brake assemblies. Never thought about changing the setting on the LSPV with a lift; should I? I was thinking it might need to be physically relocated. Did a little snooping and found the following thread just on this...

LSPV with 2.5" OME - https://forum.ih8mud.com/threads/lspv-with-2-5-ome.66931/

I also find myself wondering if the vehicle is actually going to wind up back around stock height, once loaded up and settled--in which case, the adjustments made to accommodate the increased height might have to be undone...

I doubt the vehicle will end up at stock height when loaded unless its either overloaded or springs have failed

I run OME 850/863 on mine and have dual drawers(always full) , fridge & Kaymar spare wheel carrier. When fully loaded with gear I really havent measured but it doesnt look any different - just feels more plush.

Brake lines - I recommend the brake line going to the diff be extended by a couple of inches. Remember that if the original is still there it has been like that for many years with a consistent bend in it and now your straightening that bend and effectively stretching the 'formed' bend every time it articulates. This along with the age of it is reason enough to change it

LSPV - defintely adjust to suit the lift

 

[jaymar]

Hey thanks for the insights. Brake lines about 4yrs old now.

 

[Broski]

How do I figure that out before installation? Sounds like it would depend on shock travel an spring compression, and can't really be calculated beforehand, unless someone else has already done it with the same setup?

I like to do my own checking, One thing that's really nice about coils is that you can leave them out and cycle the suspension to see what's happening.

Take your new shocks and fully compress them by hand and put a mark on them, then mount them up with out the new coils now you can cycle the suspension. if you get to your mark before the bump stops then bump stops are to short. Like wise let the suspension fully droop out if there tension on you brake lines then there to short.

You also need to add a extra 1/2" of compression to you bump stop calculation, in other words you shocks need at least 1/2 to 3/4" more up travel after they reach the bump stops to account for the compressing of the bump stops on hard hits.

In the end your shocks limit droop and bump stop limit up travel with in the boundaries of a 80s suspension.

If you take the time to do this you well know exactly what you suspension is doing ( most don't ) and you won't have to go back and change or fix things later.

Trying to do this with the coils in well give you a false reading.

This is just the basics but you get the idea.

I do this with any modification that has to with the suspension ( fitting large tires, adding hydro assist and so on ) just like the big Boy do